Network Working Group                                            A. Chen
Internet-Draft                                                    R. Ati
Intended status: Standards Track              Avinta Communications Inc.
Expires: May 15, 2017                                  November 11, 2016


                    IPv4 with Adaptive Address Space
           draft-chen-ati-ipv4-with-adaptive-address-space-00

Abstract

   This document describes a solution to the Internet address depletion
   issue through the use of an existing Option mechanism that is part of
   the original IPv4 protocol.  This proposal, named EzIP (phonetic for
   Easy IPv4), discusses the IPv4 public address pool expansion and the
   Internet system architecture enhancement aspects.  It was originated
   by a study called ExIP (Extended IPv4) analyzing the use of the first
   available octet (eight bits) in the reserved private network pools
   (10/8, 172.16/12 and 192.168/16) to achieve a moderate address space
   expansion factor of 256 by each, while maintaining their familiar
   operation characteristics.  Along the way, a parallel yet similar
   effort, called EnIP (Enhanced IPv4), was discovered.  EnIP fully
   utilizes the same private network pools to increase the address space
   by a factor of 17.1M with end-to-end connectivity.  EzIP is a
   superset that proposes one unified format for not only encompassing
   the considerations of both, but also identifying additional
   capabilities and flexibilities.  For example, EzIP may expand an IPv4
   address at least by a factor of 256 to as high as 256M without
   affecting the existing IPv4 public address assignments, while still
   keeping intact the current private networks for the 256M case if
   desired.  The EzIP is in full conformance with the IPv4 protocol, and
   supports not only both categories of connectivity, but also their
   interoperability.  The traditional Internet traffic and the IoT
   operations may coexist simultaneously without perturbing their
   existing setups, while offering end-users the freedom to choose one
   or the other.  If the IPv4 public pool were reorganized, the
   assignable pool could be multiplied by 512M or even up to 2B times
   with end-to-end connectivity.  EzIP may be deployed as a firmware
   enhancement to the Internet edge routers or private network gateways
   wherever needed, or simply installed as an inline adjunct module
   between the two, enabling a seamless introduction.  The 256M case
   establishes a spherical layer of routers providing a complete
   interconnection between the Internet and end-users.  This
   configuration enables the entire current Internet and private
   networks characteristics to remain intact.  These proposed interim
   facilities would afford IPv6 more time to orderly reach the maturity
   and the availability levels required for delivering a long-term
   general service.



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Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on May 15, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  EzIP Overview . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  EzIP Numbering Plan . . . . . . . . . . . . . . . . . . .   5
     2.2.  EzIP System Architecture  . . . . . . . . . . . . . . . .   9
     2.3.  IP Header with Option Word  . . . . . . . . . . . . . . .  12
     2.4.  Examples of Option Mechanism  . . . . . . . . . . . . . .  12
     2.5.  Basic EzIP Header . . . . . . . . . . . . . . . . . . . .  13
     2.6.  EzIP Operation  . . . . . . . . . . . . . . . . . . . . .  15



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     2.7.  Generalizing EzIP Header  . . . . . . . . . . . . . . . .  15
   3.  EzIP Deployment Strategy  . . . . . . . . . . . . . . . . . .  17
     3.1.  Architecturally . . . . . . . . . . . . . . . . . . . . .  17
     3.2.  Functionally  . . . . . . . . . . . . . . . . . . . . . .  18
     3.3.  Permanently . . . . . . . . . . . . . . . . . . . . . . .  18
   4.  Updating Servers to Support EzIP  . . . . . . . . . . . . . .  18
     4.1.  Fast Path . . . . . . . . . . . . . . . . . . . . . . . .  18
     4.2.  Connectivity Verification . . . . . . . . . . . . . . . .  19
     4.3.  Domain Name Server (DNS)  . . . . . . . . . . . . . . . .  19
   5.  EzIP Enhancements . . . . . . . . . . . . . . . . . . . . . .  19
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  23
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  23
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  23
   9.  Conclusions . . . . . . . . . . . . . . . . . . . . . . . . .  23
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  24
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  24
     10.2.  Informative References . . . . . . . . . . . . . . . . .  24
   Appendix A.  EzIP System Architecture . . . . . . . . . . . . . .  25
     A.1.  EzIP System Part A  . . . . . . . . . . . . . . . . . . .  25
     A.2.  EzIP System Part B  . . . . . . . . . . . . . . . . . . .  26
     A.3.  EzIP System Part C  . . . . . . . . . . . . . . . . . . .  26
     A.4.  EzIP System Part D  . . . . . . . . . . . . . . . . . . .  27
   Appendix B.  EzIP Operation . . . . . . . . . . . . . . . . . . .  29
     B.1.  Connection between EzIP-unaware IoTs  . . . . . . . . . .  30
     B.2.  Connection Between EzIP-capable IoTs  . . . . . . . . . .  35
     B.3.  Connection Between EzIP-unaware and EzIP-capable IoTs . .  44
   Appendix C.  Internet Transition Considerations . . . . . . . . .  45
     C.1.  EzIP Implementation . . . . . . . . . . . . . . . . . . .  45
     C.2.  SPR Operation Logic . . . . . . . . . . . . . . . . . . .  47
     C.3.  RG Enhancement  . . . . . . . . . . . . . . . . . . . . .  47
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  48

1.  Introduction

   The huge growth in the Internet of Things(IoTs) devices has exploded
   the demand for IP addresses.  It would be useful to have a unique
   address for each Internet device, such that if desired, any device
   may call any other.  The Internet of Things (IoTs) would also be able
   to make use of more routable addresses if they were available.
   Currently, these are not possible with the existing IPv4 facility.

   By Year 2020, the population and number of IoTs are expected to reach
   7.6 billion and 50 billion respectively, according to a recent Cisco
   online paper [Internet-of-Things-Market-Forecast].

   The IPv4 dot-decimal address format, consisting of four octets each
   made of 8 binary bits, results in the maximum number of assignable
   public addresses of 4.295 billion (calculated by 256 x 256 x 256 x



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   256, to be 4,294,967,296 (decimal exact).  Using the binary /
   shorthand notation of 64K representing 256 x 256 (decimal 65,536),
   the full IPv4 address pool of 64K x 64K may be expressed as 4,096M,
   or 4.096B.  Clearly, the demand is more than 13 times over the
   inherent capability available from the supply.

   IPv6 with 128-bit hexadecimal address format offers a potential
   solution to this problem, but its global adoption appears to face
   certain challenges [IPv6], [EtherType].  Network Address and Port
   Translation (NAPT - commonly known simply as NAT) on private networks
   together with Carrier Grade NAT (CGNAT) over the Internet have been
   providing the interim solutions thus far.  However, NAT modules slow
   down routers due to the state-table look-up process.  As well, they
   only allow an Internet session be initiated by their respective own
   clients, impeding the end-to-end setup requests from remote devices
   that certain IoT operations desire.

   If the IPv4 capacity could be expanded to eliminate this address pool
   deficiency while maintaining the familiar established operation
   conventions, and perhaps even offers reasonable reserve, the urgency
   will be relaxed long enough for the IPv6 to mature on its own pace.

   To increase the Internet public address pool, there have been various
   proposals in the past.  Among them, two recent efforts in particular
   are referenced by this draft, namely ExIP [ExIP] and EnIP.  The ExIP
   study focuses on reclaiming part of a reserved private network
   address block, for example the third octet of 192.168/16, to be
   publicly routable at the edge of the Internet.  By making use of this
   octet as semi-public address, the number of assignable public
   addresses is increased by a factor of 256 to become 1049B which is
   more than 20 times of the expected IoTs.  This address expansion
   could be implemented in an inline module called Semi-Public Router
   (SPR) collocated with the Internet Edge Router (ER).  Of course, the
   size of the resultant private networks will be reduced accordingly.

   The Enhanced IP (EnIP) [EnhancedIpV4] project proposes to increase
   the available IPv4 public address space by a factor of 17.1M.  Like
   IPv6, EnIP results in full end-to-end connectivity among the enhanced
   addresses.  The EnIP implementation module, "NAT and EnIPNAT/
   translator", replacing existing private network gateway, is very
   similar to the SPR.

   EzIP merges these two schemes into one uniform solution.  Neither
   Internet Core (/ backbone) Router (CR), nor private network Routing
   Gateway (RG) needs to handle the Options added to the resultant IP
   header, since their designs recognize and preserve this Option
   mechanism, yet are not programmed to process the specific EzIP
   information.  Even the Edge Routers (ER) may stay unchanged, if the



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   SPR is deployed with the adjunct configuration during the
   introductory phase.

   The assignable IPv4 compatible public address pool may be expanded
   significantly more upon incorporating other available IPv4 resources
   by the EzIP technique, as discussed in the latter part of this
   document.

   The rest of this draft begins with outlining the EzIP numbering plan.
   A modified IP header called EzIP header is introduced for carrying
   the EzIP address data in the Option words.  The overview of the
   Internet architecture as the result of being expanded by the EzIP
   scheme, the EzIP header transitions through various routers and the
   operation considerations are discussed next, with details presented
   in Appendices A, B and C, respectively.  Utilizing the EzIP approach,
   a range of possibilities of expanding the publicly assignable IPv4
   address pool as well as enhancing the Internet operation flexibility
   are then described.

2.  EzIP Overview

2.1.  EzIP Numbering Plan

   The ExIP technique which is the foundation of the EzIP plan began
   with making use of the reserved private network address pools in very
   much the same manner as Private Automatic Branch eXchange (PABX)
   telephone switching machines utilizing locally assigned "extension
   numbers" to expand the Public Switched Telephone Network (PSTN)
   capacity by replicating a public telephone line to multitudes of
   reusable private telephone numbers, each to identify a local
   instrument.  At the first sight, this may seem odd, because the
   extension numbers of a PABX belong to a separate set from that of the
   public telephone numbers, while private network IP address is a
   specific subset reserved from the overall IPv4 pool that is otherwise
   all public.  However, recognizing that neither of the latter two is
   allowed to operate in the other's domain suggests that the proposed
   EzIP numbering system indeed may mirror the telephony case.  In fact,
   the very basic form of the EzIP numbering is to make explicit the
   familiar subnetting process of 192.168/16 that has been performed
   routinely by consumer RGs (Residential / Routing Gateways) on
   residential premises for a long time.

   To facilitate the following discussions, the 32 bits in a private
   network address notation are divided into three parts, namely
   Network, Extension and IoT No.'s as shown in Figure 1 below.






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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Network No.    -     Extension No.     :      IoT No.     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 1: EzIP Address Notation (Generic)

   The number of bits in the Extension No. part determines the
   multiplication factor to be applied by the EzIP process.  The
   trailing IoT No. bits determine the size of the resultant private
   network.  The Network No. part is the specific binary value of the
   remaining leading bits (the prefix) identifying an address block that
   will be reserved from the public IPv4 pool.

   Following the general concept of subnetting, the unit for expanding
   an address does not need to be restricted to the boundary of an
   octet.  This allows potentially finer grain resolution.

   How to utilize the 32 bits leads to tradeoffs among EzIP operation
   characteristics.  For example, maintaining the private network
   properties or establishing the end-to-end connectivity is just a
   matter of whether there are bits reserved for the IoT No.

   This notation may be used to present two general categories of EzIP
   address expression:

   a.  To retain the private network characteristics, the EzIP
       subnetting makes use of only the first available octet.  For the
       common three private network address pools, we will have the
       following:

       1.  In Figure 2, 8 bits are available for IoT No., resulting in
           private networks each capable of 256 IoTs.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            192.168            - Extension No. :    IoT No.    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 2: EzIP-1 (8 bits of 192.168/16 semi-publicly addressable

       2.  In Figure 3, 12 bits are available for IoT No., resulting in
           private networks each capable of 4K IoTs.






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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           172.16      - Extension No. :        IoT No.        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 3: EzIP-2 (8 bits of 172.16/12 semi-publicly addressable)

       3.  In Figure 4, 16 bits are available for IoT No., resulting in
           private networks each capable of 64K IoTs.


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       10      - Extension No. :            IoT No.            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 4: EzIP-3 (8 bits of 10/8 semi-publicly addressable)

   b.  To allow direct access from the Internet, EzIP makes use of all
       available bits in a reserved private network address as Extension
       No., leaving no bit for the IoT No.  The resultant private
       network will have no RG, but only one IoT that is directly
       connected to the Internet.

       1.  In Figure 5, 16 bits are assigned for Extension No.,
           resulting in 64K IoTs directly addressable from the Internet.


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            192.168            -          Extension No.        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    Figure 5: EzIP-4 (16 bits of 192.168/16 semi-publicly addressable)

       2.  In Figure 6, 20 bits are assigned for Extension No.,
           resulting in 1M IoTs directly addressable from the Internet.










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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            172.16     -             Extension No.             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure 6: EzIP-5 (20 bits of 172.16/12 semi-publicly addressable)

       3.  In Figure 7, 24 bits are assigned for Extension No.,
           resulting in 16M IoTs directly addressable from the Internet.


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       10      -                 Extension No.                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 7: EzIP-6 (24 bits of 10/8 semi-publicly addressable)

       4.  For cross reference purpose, EzIP-1 through EzIP-3 are the
           same numbering types used by the ExIP study, while EzIP-4
           through EzIP-6 are used by the EnIP project.

       5.  Figure 8, summarizes the number of possible publicly and
           privately assignable addresses for each original IPv4 public
           address under different configurations.
























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                       +===============+================+==============+
                       | 192.168/16    |   172.16/12    |     10/8     |
         ==============+===============+================+==============+
          Basic IPv4   |               |                |              |
         --------------+---------------+----------------+--------------+
          Address Bits*|      32       |       32       |     32       |
         --------------+---------------+----------------+--------------+
            Public     |       1       |        1       |      1       |
           Private     |      64K      |        1M      |     16M      |
         ==============+===============+================+==============+
             (ExIP)    |    EzIP-1     |    EzIP-2      |    EzIP-3    |
         --------------+---------------+----------------+--------------+
         Address Bits* |      40       |      40        |      40      |
         --------------+---------------+----------------+--------------+
           Semi-Public |     256       |     256        |     256      |
            Private    |     256       |       4K       |      64K     |
         ==============+===============+================+==============+
             (EnIP)    |    EzIP-4     |    EzIP-5      |    EzIP-6    |
         --------------+---------------+----------------+--------------+
         Address Bits* |      48       |      52        |      56      |
         --------------+---------------+----------------+--------------+
           Public      |      64K      |       1M       |      16M     |
          Private      |       1       |       1        |       1      |
         ==============+===============+================+==============+

      Figure 8: Possible original IPv4 under different configurations

       6.  Notes:

           1.  * -- Effective Overall Public Address Length

           2.  For each Public-Private pair, the numbers of addresses
               are multiplicative, not additive.

2.2.  EzIP System Architecture

   With six basic EzIP expansion types, it is difficult to include them
   all in one single system architecture diagram.  To facilitate the
   presentation, a partial system diagram covering only the 192.168/16
   (EzIP-1 and EzIP-4) portion as presented below will be utilized for
   the discussions that follow.  A complete set of system architectural
   diagrams is presented in Appendix A.  Refer to Figure 9 and Figure 10
   for only the 192.168/16 (EzIP-1 and EzIP-4) portion shown:








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                                       +------+
                        Web Server     | WS0z |
                                       +--+---+
                                          |69.41.190.145
                                          |
                                          |  +-----+
                                          +--+ ER0 |
                                             +--+--+
                                                |
                                         +------+-------+
                                 +-------+   Internet   +--------+
                                 |       |(Core Routers)|        |
                              +--+--+    +--------------+     +--+--+
                        +-----+ ER1 |                   +-----+ ER4 |
                        |     +-----+                   |     +-----+
                        |                               |
             EzIP-1     |69.41.190.110       EzIP-4     |69.41.190.148
                     +--+--+                         +--+--+
         +-----------+     +-------+       +---------+     +------+
         |     +-----+ SPR1|       |       |   +-----+ SPR4+--+   |
         |     |     +-----+       |       |   |     +-----+  |   |
         |   192.168.2.0 ... 192.168.255.0 |   |              |   |
         +-----+                           |...|              |...|
               |192.168.1.0                |   |    +---------+   |
            +--+--+                        |   |    |             |
        +---+ RG1 +--+            192.168.0.1  |    |  192.168.255.255
        |   +-----+  |                         |    |
        | Premises 1 |              +----------+    |
        |            |              |    Premises 4 |
        |192.168.1.3 |192.168.1.9   |192.168.4.10   |192.168.4.40
     +--+--+      +--+--+        +--+--+         +--+--+
     | T1a | .... | T1z |        | T4a | ....... | T4z |
     +-----+      +-----+        +-----+         +-----+

         Figure 9: EzIP System Architecture-A (192.168/16 Portion)
















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         +--------------------------+-----------------+----------------+
         |                          |   Basic IPv4    |  EzIP-capable  |
         +--------------------------+-----------------+----------------+
         | Internet Edge Router (ER)|  ER0, ER1, ER4  |  ------------  |
         +--------------------------+-----------------+----------------+
         | Internet of Things (IoT) |    T1a, T4a     |    T1z, T4z    |
         +--------------------------+-----------------+----------------+
         | Routing Gateway (RG)     |       RG1       |  ------------  |
         +--------------------------+-----------------+----------------+
         | Semi-Public Router (SPR) |  -------------  |   SPR1, SPR4   |
         +--------------------------+-----------------+----------------+
         | Web Server (WS)          |  -------------  |      WS0z      |
         +--------------------------+-----------------+----------------+

                  Figure 10: EzIP-1 and EzIP-4 Components

   The following discussions references the above two figures:

   a.  Referring to the left portion labeled EzIP-1 of Figure 9, instead
       of assigning each premises a public IPv4 address as in the
       current practice, an SPR like SPR1, is inserted between an
       Internet Edge Router (ER1) and its connections to private network
       Routing Gateways like RG1, for utilizing the third octet as
       192.168.nnn/24 (nnn = 0 through 255) to identify respective
       entities.  The RG1 serves either a LAN or a HAN.  On each LAN /
       HAN, the fourth octet "mmm" of of 192.168.nnn.mmm/32 continues to
       be used by the RG1 to identify the IoTs it serves.  This is how
       common RGs are being configured today anyway (Factory default
       values of nnn are usually 0, 1, 2, 10, etc.)

   b.  The right portion of Figure 9 is labeled EzIP-4.  Here SPR4
       assigns the full range of the available 192.168/16 IP addresses
       (the third and fourth octets) individually to T4a through T4z.
       Consequently, these IoTs are directly accessible from any remote
       device on the Internet.

   c.  Since the existing physical connections to subscriber premises do
       appear at the ER, it is natural to have SPRs be collocated with
       their ER.  It follows that the simple routing function provided
       by the new SPR modules may be absorbed into the ER through a
       straightforward operational firmware enhancement.  Consequently,
       the public - private demarcation line will remain at the RG where
       currently all utility services enter a subscribers premises.

   d.  To identify each of these devices, we may use a three part
       address format "Semi-Public: TCP Port No.".  The following is how
       each of the IoTs in Figure 9 may be identified.




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                   RG1: 69.41.190.110-192.168.1.0
                   T1a: 69.41.190.110-192.168.1.0:3
                   T1z: 69.41.190.110-192.168.1.0:9
                   T4a: 69.41.190.148-192.168.4.10
                   T4z: 69.41.190.148-192.168.4.40

   e.  Note that to simplify the presentation, it is assumed at this
       juncture that the conventional TCP (Transmission Control
       Protocol) [RFC793] Port Number, normally assigned to T1a and T1z
       by RG1's NAT module upon initiating a session, equals to the
       fourth octet of that IoTs private IP address that is assigned by
       the RG1's DHCP (Dynamic Host Configuration Protocol) [RFC2131]
       module as and ":3" and ":9", respectively.  Such numbers are
       unique within each respective private network.  They are adequate
       for the discussion purpose here.  However, considering security,
       as well as allowing each IoT to have multiple simultaneous
       sessions, etc., this direct correlation shall be avoided in
       actual practices by following the NAT operation conventions as
       depicted by the examples in Appendix B.

2.3.  IP Header with Option Word

   To transport the EzIP Extension No., we will make use of the Option
   word in the IP header as defined in Figure 9 of [RFC791].  This
   mechanism has been used for various cases in the past.  Since they
   were mostly for utility or experimental purposes, however, their
   formats may be remote from the incident discussion.

2.4.  Examples of Option Mechanism

   The following two cases specifically deal with the address pool
   issues.  They are referenced here to facilitate the appreciation of
   the Option mechanism.

   a.  Case 1: EIP (Extended Internet Protocol) [RFC1385] (Assigned but
       now deprecated Option Number = 17) by Z.  Wang.  This approach
       attempted to add a new network layer on top of the existing
       Internet for increasing the addressable space.  Although
       equipment near the end-user would stay unchanged, equipments
       around the Internet Core Routers (CR) apparently had to go
       through rather involved upgrade procedures.

   b.  Case 2: EnIP (Enhanced IPv4), [EnhancedIpV4] (temporarily
       utilizing Option Number = 26 by W.  Chimiak).  This work makes
       use of the reserved private network addresses to extend the
       public pool by trading the private network operation for end-to-
       end connectivity.  The EnIP and ExIP approaches closely resemble
       each other.



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2.5.  Basic EzIP Header

   The basic EzIP header format uses the Option ID field to convey the
   value of the "Network No." as well as the length of the "Extension
   No.".  This header has the capacity to handle up to two octets of the
   "Extension No." on either end of a connection.  Refer to Figure 11.



        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|      Total Length (28)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |                       Source Host Number                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |                  Destination Host Number                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |   (------)    |      (4)      |     No.-1     |     No.-2     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     7 | (Destination) | Option Length |  Destination  |  Destination  |
       |   (------)    |      (4)      |     No.-1     |     No.-2     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 11: Basic EzIP Header (Two Octet)

   For transporting an IP header for T4z at the Source end and RG1 at
   the Destination end, Figure 12 depicts an EzIP header example:
















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|      Total Length (28)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |               Source Host Number (69.41.190.148)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (69.41.190.110)            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP-4     |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (4)      |    No. (4)    |    No. (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP-1     |     EzIP      |   Extended    |    End of     |
     7 | (Destination) | Option Length |  Destination  |  Option List  |
       |    (0x9B)     |      (3)      |    No. (1)    |   (00000000)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 12: EzIP Header Example 1

   Note that the Option IDs 0x9A (Option Number = 26) and 0x9B (Option
   Number = 27), both representing Network No. 192.168/16 while
   conveying the Extension No.'s being two and one octet, respectively,
   in the above figure, are arbitrarily chosen from the currently
   available Option Numbers list [IPparameters].  Since RG1 extension
   No. has only one octet, the "End of Option list" Option is used to
   fill up word 7.  If the transmission direction is reversed, types of
   EzIP extension used by the Source and the Destination will be
   interchanged as well.  The unused octet will now be at the end of
   word 6.  The "No Operation" Option should be used as the filler shown
   in Figure 13.
















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|      Total Length (28)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |           Source Host Number 69.41.190.110)                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |        Destination Host Number (69.41.190.148)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |       No      |
     6 |   (Source)    | Option Length |    Source     |   Operation   |
       |    (0X9B)     |      (3)      |    No. (1)    |   (00000001)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     7 | (Destination) | Option Length |  Destination  |  Destination  |
       |    (0x9A)     |      (4)      |     No. (4)   |    No. (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 13: EzIP Header Example 2

2.6.  EzIP Operation

   It would be very tedious and distracting to go through half a dozen
   of EzIP types, covering all combinations of IP header configurations
   and their transitions through the network.  To better convey the
   general scheme, Appendix B presents examples of EzIP header
   transitions through routers among IoTs having EzIP-1 and EzIP-4 types
   of addresses, with and without EzIP capability.  To introduce the
   EzIP approach into an environment where EzIP-unaware IoTs like T1a
   and T4a will be numerous for a long time to come, a SPR must be able
   to follow certain decision rules to determine which type of service
   to provide for achieving a smooth transition.  Appendix C outlines
   such logic and related considerations

2.7.  Generalizing EzIP Header

   a.  The basic EzIP header shown in Figure 11 with up to two octet
       Extension No. format is not capable of EzIP-5 and EzIP-6 types
       with 20 and 24 bit, respectively.  One extra octet is needed on
       each end of a connection.  An additional word in the header,
       however, will have only two octets unused.  To take advantage of
       this spare resource, we might as well consider a header format
       shown in Figure 14 that can transport the full 4 octet (32 bit)
       extension addresses of both ends.  This is similar as the EnIP



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       [EnhancedIpV4] header, except more flexible by allowing EzIP type
       being independent of that at the other end.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (8)|Type of Service|      Total Length (32)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |                      Source Host Number                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |                    Destination Host Number                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |     EzIP      |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (6)      |     No.-1     |     No.-2     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |    EzIP ID    |     EzIP      |
     7 |    Source     |    Source     | (Destination) | Option Length |
       |     No.-3     |     No.-4     |     (0X9A)    |      (6)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Extended    |   Extended    |   Extended    |   Extended    |
     8 |  Destination  |  Destination  |  Destination  |  Destination  |
       |     No.-1     |     No.-2     |     No.-3     |     No.-4     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 14: Full EzIP Header (Four octet)

   b.  In brief, Figure 12 or Figure 13 with seven words (40% overhead)
       having two octet capacity is suitable to transport EzIP-1 through
       EzIP-4 types consisting of one or two octet Extension No.  EzIP-5
       and EzIP-6 require the next IP header size which is eight words
       (60% overhead) as shown in Figure 14.

   c.  Being a superset, utilizing "No Operation" or "End of Option
       List" type of fillers, Figure 14 is capable of handling
       information for EzIP-1 through EzIP-4 just as well.  The question
       then becomes; whether the extra 20% overhead when handling EzIP-1
       through EzIP-4 headers is tolerable?  If so, the single Figure 14
       format may be used for all EzIP cases.

   d.  With the "Network No." prefixes of the well-know private network
       addresses all explicitly carried by the IP header of every packet
       as shown in Figure 14, the Option Number only needs to identify
       the length of the "Extended No.".  Consequently, one Option



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       Number is sufficient to represent EzIP-1 through EzIP-3 that only
       the first available octet is used for the Extension No.
       Similarly, one single Option Number representing EzIP-4 through
       EzIP-6 conveys the condition that all available bits are to be
       used for Extension No.

   e.  One potential drawback of the full four octet EzIP header is that
       it may cause Internet routers to intercept a packet for
       containing a disallowed (private network) IP address, although
       positioned at a location of the header normally not designated
       for address information.

   f.  By harmonizing EzIP-4 to EzIP-6 (EnIP) with EzIP-1 to EzIP-3
       (ExIP) into one common (EzIP) format, enjoying which operating
       characteristics will simply be the result of a user subscribing
       to an EzIP address type appropriate for how he wishes to use his
       IoT.

3.  EzIP Deployment Strategy

   Although the eventual goal of the SPR is to support both web server
   access by IoTs from behind private networks and direct end-to-end
   connectivity between IoTs, the former application should be addressed
   first to immediately relieve the basic address shortage issue.  Once
   the IoTs on both ends of an intended connection are served by SPRs,
   it will be natural to realize the latter

3.1.  Architecturally

   Since the design philosophy of the SPR is an inline module between
   the Internet ER (Edge Router) and the private network RG (Routing
   Gateway), SPR introduction process may be flexible.

   a.  SPRs may be collocated with ERs to begin providing the CGNAT
       equivalent function.  This may be done immediately without
       affecting the existing Internet (edge and core) routers.  EzIP-
       capable IoTs will then take advantage of the faster bi-
       directional routing services through the SPRs by initiating a
       communication session with an EzIP header.

   b.  Alternatively, a SPR may be deployed as an adjunct module before
       an existing RG to realize the same EzIP functions on private
       premises, even if the serving Internet Service Provider (ISP) has
       not enhanced ERs with the EzIP capability.  This empowers
       individual subscribers to enjoy the new EzIP capability on their
       own.





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3.2.  Functionally

   a.  First, an ISP should install SPRs in front of business web
       servers so that new routing branches may be added to support the
       additional web servers for expanding business activities.
       Alternatively, this may be achieved by deploying new web servers
       with the SPR function builtin.

   b.  On the subscriber side, SPRs should be deployed to relieve the
       public address shortage issue, and to facilitate the access to
       new web servers.

3.3.  Permanently

   a.  In the long run, it would be best if SPRs are integrated into ERs
       by upgrading the latters firmware to minimize the hardware.
       Appendix C details the considerations in implementing these
       outlines.

4.  Updating Servers to Support EzIP

   Although the IP header Option mechanism utilized by EzIP was defined
   a long time ago as part of the original IPv4 protocol, it has not
   been used much in daily traffic.  Certain current Internet facilities
   were thus optimized without considering the Option mechanism.  They
   need be adjusted to provide the same performance to EzIP packets.
   There are also utility type of servers need be updated to support the
   longer EzIP address.  For example:

4.1.  Fast Path

   Internet Core Routers (CRs) are currently optimized to only provide
   the "fast path" (through hardware line card) routing service to
   packets without Option word in the IP header.  This puts EzIP packets
   at a disadvantage, because EzIP packets would be put through the
   "slow path" (processed by CPU's software before giving to the correct
   hardware line card to forward), resulting in a slower throughput.
   Since the immediate goal of the EzIP is to ease the address pool
   exhaustion issue, subscribers not demanding for high performance
   traffic may be assigned with the facility provided through EzIP.
   This gives time for Internet routers to update so that EzIP packets
   with authorized Option numbers will eventually be recognized for
   receiving the "fast path" service.








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4.2.  Connectivity Verification

   One frequently used utility for verifying baseline connectivity,
   commonly referred to as the "PING" function in PC terminology, needs
   be able to transport the full EzIP address that is longer than the
   standard 32 bit IPv4 address.  There is an example of an upgraded TCP
   echo server in [RFC862].

4.3.  Domain Name Server (DNS)

   Similarly, the DNS needs to expand its data format to transport the
   longer IP address created by EzIP.  This already can be done under
   IPv6.  Utilizing the experimental IPv6 prefix defined by [RFC2928],
   EzIP addresses may be transported as standardized AAAA records.
   These topics are discussed in more detail under the IETF
   [EnhancedIpV4].

5.  EzIP Enhancements

   To minimize disturbing any assigned addresses, deployed equipment and
   current operation procedures, etc., the EzIP derivations so far are
   conducted under the constraint of utilizing only the existing three
   reserved private network address blocks.  Beyond such, there are
   other possibilities.  In the long run, EzIP may significantly expand
   the current IPv4 public address pool through the employment of such
   additional resources outlined below:

   a.  In reviewing the IP Option Number assignments [IPparameters], it
       is discovered that more than a dozen of them are currently
       available.  That is, besides five numbers, 26, 27, 28, 29 and 31
       that have never been assigned, there are eleven numbers assigned
       earlier but have been deprecated due to the end of associated
       experiments.  If we take six such numbers, one to represent each
       of the six EzIP extension types, the EzIP-1 to EzIP-3 cases will
       multiply the IPv4 public address pool by a factor of 256,
       individually, or a combined factor of 768, resulting in
       3,145.728B, or 3.146KB publicly assignable addresses.  Similarly,
       we can use one Option Number for each of the EzIP-4, EzIP-5 and
       EzIP-6 cases to multiply IPv4 pool by 64K, 1M and 16M (a total of
       17.1M) fold, respectively, to the combined total of 69.894MB
       addresses.  These capacities are over 63 and 1.4M times of the
       expected Year 2020 IoTs, respectively.

   b.  EzIP-8: If all Option numbers were made available, each
       representing one EzIP Network No. prefix, up to 32 private
       network address blocks, like the 10/8 could be utilized by EzIP.
       To determine the upper limit of this scenario, let's assume that
       we could employ 31 additional 10/8 type address blocks, say by



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       re-designating 11/8 through 41/8 as private network blocks.
       These enable us to expand each existing IPv4 public address by 32
       x 16M or 512M fold.  Since this block of 512M addresses have to
       be removed from the basic public pool, the resulting total
       addresses will be (4.096B - 512M) x 512M, or 1,835MB.  This is
       over 35M times of the predicted number of IoTs (50B) by Year
       2020.  It certainly has the capacity to deal with the short- to
       mid- term public IP address needs.

   c.  The above may be condensed for a more efficient operation.  For
       example, a single 224/3 block contains the same amount of 512M
       addresses may be chosen upon re-allocation of currently assigned
       IPv4 public addresses so that just one Option Number may
       represent it.  Now that we have freed up 31 Option numbers, we
       could allocate up to 31 more /3 address blocks for EzIP operation
       that provides even more extension address resource.  However,
       this last step will exceed the total capacity of the IPv4 pool.
       On the other hand, this line of reasoning leads to the next
       observation.

   d.  EzIP-9: One interesting consequence of the EzIP header in
       Figure 14 capable of transporting the full 32 bit private network
       address is that the Extension No. may be as long as practical.
       That is, we can go to the extreme of reserving only one bit for
       the Network No., and leaving nothing for the IoT No.  With these
       criteria, the current IPv4 pool may be divided into two halves,
       reserving one half of it (about 2B addresses) as a private
       network with prefix equal to "1" as the Network No., and all
       trailing 31 bits designated as Extension No.  Each of the
       remaining 2B addresses (with prefix equals to "0") of the basic
       IPv4 pool may then be expanded 2B times through the EzIP process,
       resulting in a total of 4BB addresses that are IPv4 compatible
       and capable of full end-to-end connectivity.  This is roughly 80M
       times of the Year 2020 IoTs.

   e.  EZIP7: The following compares various IPv4 public address pool
       expansion configurations.  On the other hand, this full 32 bit
       EzIP addresses transport facility may be applied to the elusive
       IPv4 240/4 block (240/8 to 255/8) consisting of 256M addresses
       that has become "RESERVED for Future use" [AddressSpace] as the
       result of the historical address assignment evolution.  Since
       this block is not suitable for being used as public address, it
       might as well be re-classified as an additional (the fourth)
       reusable private network pool.  Then, the SPR may use this block
       as the extension address pool in the EzIP process.  Following
       this approach, each current IPv4 public address may be multiplied
       by 256M times based on only one Option Number.  Following this
       approach, each current IPv4 public address may be multiplied by



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       256M times based on only one Option Number.  Since the 240/4
       block could not be used for public addressing, the size of the
       publicly assignable IPv4 pool has actually been only 3.84B (the
       difference of 4.096B and 256M).  So, the net public addressable
       pool created from this approach is 983MB (3.84B x 256M), which is
       over 19.6M times of the expected Year 2020 IoTs.  This scheme is
       very close to EzIP-8.  Although half of the capacity, this
       manifestation has the advantage of circumventing reassignment of
       public IPv4 addresses.  The following compares various IPv4
       public address pool expansion configurations.  Refer to
       Figure 15.


    +---+---------+------+--------+---------+----------+-----+---------+
    | Extension   |Option|Effect. |Expansion|Assignable| SUP/|Connect- |
    |   Scheme    | Used | AddBits| Factor  | Pub Add  | DMD |  ivity  |
    +=============+======+========+=========+==========+=====+=========+
    |         IPv4 Public Address Block Assignments Unchanged          |
    +---+---------+------+--------+---------+----------+-----+---------+
    | E | EzIP-1  |   1  |   40   |   256   |  978.69B | 19.6| PrivNet |
    | x +---------+------+--------+---------+----------+-----+---------+
    | I | EzIP-2  |   1  |   40   |   256   |  978.69B | 19.6| PrivNet |
    | P +---------+------+--------+---------+----------+-----+---------+
    |   | EzIP-3  |   1  |   40   |   256   |  978.69B | 19.6| PrivNet |
    +---+---------+------+--------+---------+----------+-----+---------+
    | E | EzIP-4  |   1  |   48   |    64K  | 244.67KB |  5K |EndToEnd |
    | n +---------+------+--------+---------+----------+-----+---------+
    | I | EzIP-5  |   1  |   52   |     1M  |   3.82MB | 77K |EndToEnd |
    | P +---------+------+--------+---------+----------+-----+---------+
    |   | EzIP-6  |   1  |   56   |    16M  |  61.17MB |  1M |EndToEnd |
    +---+---------+------+--------+---------+----------+-----+---------+
    |EzIP-7(240/4)|  1   |  64    |   256M  | 978.69MB | 20M |EndToEnd |
    +=============+======+========+=========+==========+=====+=========+
    |          IPv4 Public Address Block Assignments Adjusted          |
    +-------------+------+--------+---------+----------+-----+---------+
    |   EzIP-8    |      |        |         |          |     |         |
    |  (224/3)    |     1|   56   |   512M  |   1.84BB | 37M |EndToEnd |
    +-------------+------+--------+---------+----------+-----+---------+
    |   EzIP-9    |      |        |         |          |     |         |
    |  (Half of   |   1  |   63   |     2B  |      4BB | 80M |EndToEnd |
    |  IPv4 Pool) |      |        |         |          |     |         |
    +=============+======+========+=========+==========+=====+=========+

               Figure 15: IPv4 Address Multiplication Factor

   f.  Notes: With reference to above Figure 15





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       1.  EzIP-1 through EzIP-7: Assignable Public Addresses calculated
           with the net basic IPv4 public address pool of 3.823B after
           removed of the 240/4, 10/8, 172.16/12 and 192.168/16 blocks
           from the basic 4.096B.

       2.  EzIP-8 and EzIP-9: Assignable Public Addresses calculation
           started from scratch based on the full IPv4 pool of 4.096B
           minus only the specific portion used for extension purpose.

       3.  "SUP/DMD": Ratio of EzIP SUPplied publicly assignable
           addresses to IoT DeManD by Year 2020.

       4.  Each group of EzIP-1 to EzIP-3 and EzIP-4 to EzIP-6 may use
           only one Option number if "four octet" EzIP headers are used.

   g.  It is important to note that schemes summarized in Figure 15 are
       not mutually exclusive but mostly complementary.  Except the last
       two cases (EzIP-8 and EzIP-9) that are intend to demonstrate the
       potential public address sizes by starting from the full 4.096B
       IPv4 pool ignoring the current assignments and reservations,
       EzIP-1 through EzIP-7 may be applied to the same public IPv4
       address since they are distinguished from one another by the
       Option Numbers representing the network prefix and the number of
       Extension No. bits.  These enable an ISP to offer a rich mixture
       of addresses for the subscribers to choose from.

   h.  An address extended by EzIP-4 through EzIP-7 directly connecting
       an IoT to the Internet could nevertheless be replaced by a
       private network established through an RG as described at the end
       of Appendix B.  The EzIP-7 can best take advantage of this
       approach, because the 240/4-address block is totally segregated
       from the three conventional private network pools, thus avoiding
       confusing the Internet routers.  Essentially, the subscribers,
       appearing as private networks and directly connected IoTs, will
       interface with a complete spherical layer of secondary ERs (made
       of the SPRs) that wraps the entire existing Internet within by
       utilizing a never assigned address pool.

   i.  In summary, the EzIP technique may expand the current IPv4 public
       address pool with a wide range of multiplication factors.  It may
       be 256 folds while maintaining the current private network
       properties except with reduced size, and from 64K to 256M folds
       while offering direct end-to-end connectivity.  In addition,
       multiplication factor of 512M may be achieved with some re-
       assignments of the IPv4 blocks.  Lastly, the address capacity
       could even become 1B times of the current 4B pool with fully
       direct end-to-end connectivity.  However, these last two EzIP
       manifestations rely on significant realignments of the current



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       address blocks.  In between, we could have an IPv4 based Internet
       that can simultaneously support private networks along with
       directly accessible IoTs for interconnectivity and
       interoperability.

   j.  Overall, EzIP-7 may be the optimum choice.  It utilizes a block
       of IPv4 addresses that could not be assigned as public
       identifiers anyway.  It needs only one Option Number.
       Furthermore, existing private network setups may remain intact.
       Essentially, EzIP-7 introduces a new layer of routers (made of
       the SPRs) that expands the Internet address capacity by 256M fold
       uniformly, with minimum disturbance to the current Internet
       operations.

6.  Security Considerations

   This document does not introduce any security issues as the EzIP
   solution is based on an inline module called SPR that intends to be
   as transparent as possible to the Internet traffic and hence no
   overall system security degradation is expected.

7.  IANA Considerations

   None.

8.  Acknowledgements

   The authors would express their deep appreciation to Dr. W.  Chimiak
   for the enlightening discussions about his team's efforts and
   experiences through the EnIP development.

9.  Conclusions

   This draft RFC describes an enhancement to IPv4 operation utilizing
   IP header Option mechanism.  Because the design criterion is to
   enhance IPv4 by extending instead of altering it, the impact on
   already in-place routers and security mechanisms is minimized.  To
   resolve the IPv4 public address pool exhaustion issue, a technique
   called EzIP (phonetic for Easy IPv4) making use of the reserved
   private network address blocks is proposed.

   The basic EzIP intention is to maintain the existing private network
   configuration.  If an Extension No. for EzIP is chosen from the very
   end of the 32 bit reserved private network address, leading to no
   address bit available to assign on the resultant network, the IoT
   being served is directly accessible from any remote device in the
   Internet.  An IoT may communicate through the Internet with either




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   type of the connectivity, depending on which type of extension
   address its owner wishes to subscribe and to utilize with.

   The basic EzIP header uses two added words (or 40% overhead) to the
   IP header for transporting two octets of an Extension No.  To carry
   the full four octet EzIP extension address, a third added word is
   needed resulting in a 60% overhead.  The latter, being a superset of
   the former, may be used for all EzIP cases if the extra 20% overhead
   is tolerable for cases when the larger capacity is not necessary.

   At the extreme end of the spectrum, the EzIP scheme could be
   configured to support an IPv4 compatible pool of up to 4BB addresses
   with full direct end-to-end connectivity.

   Last but not the least, the "RESERVED for Future use" 240/4 block may
   be re-classified as the fourth reusable private network pool, so that
   the SPR may use it as the EzIP extension address.  This pool can
   multiply each current IPv4 public address by 256M times based on only
   one Option Number, while all existing subscriber premises setups
   (private networks and directly connected IoTs) may remain unchanged.
   This manifestation of EzIP technique may be the optimal solution to
   our needs.

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

10.2.  Informative References

   [AddressSpace]
              "IANA IPv4 Address Space Registry",
              <http://www.iana.org/assignments/ipv4-address-space/
              ipv4-address-space.xhtml>.

   [EnhancedIpV4]
              Laboratory for Telecommunication Sciences08, "IPv4 with 64
              bit Address Space", 06 2016, <https://tools.ietf.org/html/
              draft-chimiak-enhanced-ipv4-03>.

   [EtherType]
              AMSix, "Ether Type Distribution", <https://ams-
              ix.net/technical/statistics/sflow-stats/ether-type>.




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   [ExIP]     Avinta Communications, Inc., "IPv4 with 40 bit Address
              Space, draft-ietf-wgname-docname-00",
              <http://www.avinta.com/phoenix-1/home/
              IETF-Draft-ExIP.pdf>.

   [Internet-of-Things-Market-Forecast]
              Nishiths Blog Files Wordpress, "IoT Forecast: Cisco IBSG,
              April 2011",
              <https://nishithsblog.files.wordpress.com/2014/04/
              internet-of-things-market-forecast.jpg>.

   [IPparameters]
              "Internet Protocol Version 4 (IPv4) Parameters",
              <http://www.iana.org/assignments/ip-parameters/
              ip-parameters.xhtml>.

   [IPv6]     Stats Labs Apnic, "IPv6 Capable Rate by Country",
              <http://stats.labs.apnic.net/ipv6>.

   [RFC1385]  "EIP: The Extended Internet Protocol, A Framework for
              Maintaining Backward Compatibility",
              <https://tools.ietf.org/html/rf1385>.

   [RFC2131]  "Dynamic Host Configuration Protocol",
              <https://www.ietf.org/rfc/rfc2131.txt>.

   [RFC2928]  "Initial IPv6 Sub-TLA ID Assignments",
              <https://tools.ietf.org/html/rfc2928>.

   [RFC791]   "INTERNET PROTOCOL, DARPA INTERNET PROGRAM, PROTOCOL
              SPECIFICATION", <https://tools.ietf.org/html/rfc791>.

   [RFC793]   "TRANSMISSION CONTROL PROTOCOL",
              <https://tools.ietf.org/html/rfc793>.

   [RFC862]   "Echo Protocol", <https://tools.ietf.org/html/rfc862>.

Appendix A.  EzIP System Architecture

A.1.  EzIP System Part A

   The EzIP-1 and EzIP-4 portions of the EzIP system has already been
   shown as Picture 9 in the main body of this Draft document.








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A.2.  EzIP System Part B

   The EzIP-2 portion maintains private network operation
   characteristics, while EzIP-5 portion delivers end-to-end
   connectivity as shown in Figure 16.


                                       +------+
                        Web Server     | WS0z |
                                       +--+---+
                                          |69.41.190.145
                                          |
                                          |  +-----+
                                          +--+ ER0 |
                                             +--+--+
                                                |
                                         +------+-------+
                                 +-------+   Internet   +--------+
                                 |       |(Core Routers)|        |
                              +--+--+    +--------------+     +--+--+
                        +-----+ ER2 |                   +-----+ ER5 |
                        |     +-----+                   |     +-----+
             EzIP-2     |69.41.190.120       EzIP-5     |69.41.190.158
                     +--+--+                         +--+--+
         +-----------+     +-------+       +---------+     +------+
         |     +-----+ SPR2|       |       |   +-----+ SPR5+--+   |
         |     |     +-----+       |       |   |     +-----+  |   |
         |     | ................. |       |...|              |...|
   172.16.1.0  |172.16.2.0  172.31.240.0   |   |    +---------+   |
            +--+--+                        |   |    |             |
        +---+ RG2 +--+            172.16.1.0   |    |  172.31.255.255
        |   +-----+  |                         |    |
        | Premises 2 |              +----------+    |
        |            |              |    Premises 5 |
        |172.16.2.3  |172.16.2.9    |172.16.5.10    |172.16.5.40
     +--+--+      +--+--+        +--+--+         +--+--+
     | T2a | .... | T2z |        | T5a | ....... | T5z |
     +-----+      +-----+        +-----+         +-----+

         Figure 16: EzIP System Architecture-B (172.16/12 Portion)

A.3.  EzIP System Part C

   The EzIP-3 portion maintains private network operation
   characteristics, while EzIP-6 portion delivers end-to-end
   connectivity.  See Figure 17.





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                                       +------+
                        Web Server     | WS0z |
                                       +--+---+
                                          |69.41.190.145
                                          |
                                          |  +-----+
                                          +--+ ER0 |
                                             +--+--+
                                                |
                                         +------+-------+
                                 +-------+   Internet   +--------+
                                 |       |(Core Routers)|        |
                              +--+--+    +--------------+     +--+--+
                        +-----+ ER3 |                   +-----+ ER6 |
                        |     +-----+                   |     +-----+
                        |                               |
             EzIP-3     |69.41.190.130       EzIP-6     |69.41.190.160
                     +--+--+                         +--+--+
         +-----------+     +-------+       +---------+     +------+
         |     +-----+ SPR3|       |       |   +-----+ SPR6+--+   |
         |     |     +-----+       |       |   |     +-----+  |   |
         | ... | ................. |       |   |              |   |
         |     |                   |       |...|              |...|
   10.1.0.0    |10.3.0.0      10.255.0.0   |   |    +---------+   |
            +--+--+                        |   |    |             |
        +---+ RG3 +--+              10.1.0.0   |    |    10.255.255.255
        |   +-----+  |                         |    |
        | Premises 3 |              +----------+    |
        |            |              |    Premises 6 |
        |10.3.0.3    |10.3.255.9    |10.6.0.10      |10.6.0.40
     +--+--+      +--+--+        +--+--+         +--+--+
     | T3a | .... | T3z |        | T6a | ....... | T6z |
     +-----+      +-----+        +-----+         +-----+

            Figure 17: EzIP System Architecture-C (10/8 Portion

A.4.  EzIP System Part D

   Utilizing 240/4, the EzIP provides a "spherical shell" of routable
   addresses wrapped around the entire current Internet (CRs and ERs),
   separating it from the subscribers' IoTs that are either directly
   addressable from the Internet such as T7z, T8z, or behind existing
   private networks like RG7, RG8.See Figure 18.








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                                       +------+
                        Web Server     | WS0z |
                                       +--+---+
                                          |69.41.190.145
                                          |
                                          |  +-----+
                                          +--+ ER0 |
                                             +--+--+
                                                |
                                         +------+-------+
                              ER1  ------+              +-----  ER4
             Interconnect                |              |
                 with         ER2  ------+   Internet   +-----  ER5
              Preceding                  |              |
               Figures        ER3  ------+(Core Routers)+-----  ER6
                                         |              |
                                 +-------+              +--------+
                                 |       |              |        |
                              +--+--+    +--------------+     +--+--+
                        +-----+ ER7 |                   +-----+ ER8 |
                        |     +-----+                   |     +-----+
                        |                               |
                        |69.41.190.170                  |69.41.190.180
                     +--+--+                         +--+--+
         +-----------+     +-------+       +---------+     +------+
         |     +-----+ SPR7+--+    |EzIP-7 |   +-----+ SPR8+--+   |
         | ... |     +-----+  |... |       |   |     +-----+  |   |
         |     |     +--------+    |       |...|              |...|
   240.0.0.1   |     |     255.255.255.255 |   |    +---------+   |
               |     |                     |   |    |             |
        +------+     |               240.0.0.1 |    |   255.255.255.255
        | Premises 7 |              +----------+    |
        |            |              |    Premises 8 |
        |247.0.0.3   |247.0.0.9     |248.0.0.10     |248.0.0.40
     +--+--+      +--+--+        +--+--+         +--+--+
     | RG7 | .... | T7z |        | T8z | ....... | RG8 |
     +-----+      +-----+        +-----+         +-----+

           Figure 18: EzIP System Architecture-D (240/4 Portion)












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       +--------------------------+-----------------+----------------+
       |                          |   Basic IPv4    |  EzIP-capable  |
       +--------------------------+-----------------+----------------+
       |                          |  ER0, ER1, ER2, |  ------------  |
       | Internet Edge Router (ER)|  ER3, ER4, ER5, |                |
       |                          |  ER6, ER7, ER8  |                |
       +--------------------------+-----------------+----------------+
       |                          |  T1a, T2a, T3a, | T1z, T2z, T3z, |
       | Internet of Things (IoT) |  T4a, T5a, T6a, | T4z, T5z, T6z, |
       |                          |                 | T7z, T8z       |
       +--------------------------+-----------------+----------------+
       |                          |  RG1, RG2, RG3  |                |
       | Routing Gateway (RG)     |  RG7, RG8       |  ------------  |
       +--------------------------+-----------------+----------------+
       |                          |  -------------  |   SPR1, SPR2,  |
       | Semi-Public Router (SPR) |                 |   SPR3, SPR4,  |
       |                          |                 |   SPR5, SPR6,  |
       |                          |                 |   SPR7, SPR8   |
       +--------------------------+-----------------+----------------+
       | Web Server (WS)          |  -------------  |      WS0z      |
       +--------------------------+-----------------+----------------+

                     Figure 19: EzIP System Components

Appendix B.  EzIP Operation

   To demonstrate how EzIP could support and enhance the Internet
   operations, the following are three connection examples that involve
   SPRs as shown in Figure 9.  These present a general perspective of
   how IP header transitions through the routers may look like.

   1.  The first example is between EzIP-unaware IoTs, T1a and T4a.
       This operation is very much like the conventional TCP/IP packet
       transmission except with SPRs acting as an extra pair of routers
       supported by CGNAT.  In addition, SPR4 may be viewed as a full-
       fledged RG minus DHCP and NAT support, because it assigns its
       IoTs with static addresses from the entire range of reserved
       192.168/16, instead of the common much smaller pool of
       192.168.nnn/24.

   2.  The second one is between EzIP-capable IoTs, T1z and T4z.  Here,
       the SPRs process the extended public IP addresses in router mode,
       avoiding the delays due to the NAT type of operations.

   3.  The last one is between EzIP-unaware and EzIP-capable IoTs.  By
       initiating and responding with a conventional IP header, T1z and
       T4z behave like an EzIP-unaware IoT.  Thus, all packet exchanges
       use the conventional IP headers, just like case 1. above.



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B.1.  Connection between EzIP-unaware IoTs

B.1.1.  T1a Initiates a Session Request towards T4a

   In Figure 20.  T1a initiates a session request to SPR4 that serves
   T4a by sending an IP packet to RG1.  There is no TCP port number in
   this IP header yet.



        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (5)|Type of Service|       Total Length (20)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.3)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 20: EzIP System Components

B.1.2.  RG1 Forwards the Packet to SPR1

   In Figure 21 RG1, allowing to be masqueraded by T1a, relays the
   packet toward SPR1 by assigning the TCP Source port number, 3N, to
   T1a.  Note that the suffix "N" denotes the actual TCP port number
   assigned by the RG1's NAT.  This could assume multiple values, each
   represents a separate communications session that T1a is engaged in.
   A corresponding entry is created in the state table for handling the
   responding packet from the Destination site Since T4a's TCP port
   number is not known yet, it is filled with all 1's.















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.0)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (3N)        | Destination Port (All 1's)    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 21: TCP/IP Header: From RG1 to SPR1

B.1.3.  SPR1 Sends the Packet to SPR4 through the Internet

   In Figure 22, SPR1 allowing masqueraded by RG1 (with the Source Host
   Number changed to be its own and the TCP port number changed to 1C,
   where "C" stands for CGNAT) sends the packet out through the Internet
   towards SPR4.  The packet traverses through the Internet (ER1, CR and
   ER4) utilizing only the basic IP header portion of address
   information (words 4 and 5).


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (1C)        | Destination Port (All 1's)    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 22: TCP/IP Header: From SPR1 to SPR4






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B.1.4.  TCP/IP Header: From SPR1 to SPR4

   Since the packet has a conventional IP header without Destination TCP
   port number, SPR4 would ordinarily drop it due to the CGNAT function.
   However, for this example, let's assume that there exists a state-
   table that was set up by a DMZ process for redirecting this packet to
   T4a with a CGNAT TCP port number 410C (the composite of the third and
   the fourth octets, "4.10" of T4a's Extension No.).  In Figure 23,
   SPR4 sends the packet to T4a by constructing the destination address
   accordingly.


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (1C)        |   Destination Port (All 1's)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 23: TCP/IP Header: From SPR4 to T4a

B.1.5.  TCP/IP Header: T4a Replies to SPR4

   In Figure 24, it interchanges the Source and Destination
   identifications to create an IP header for the reply packet.

















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.4.10)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |      Source Port (410C)       |   Destination Port (1C)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 24: TTCP/IP Header: From T4a to SPR4

B.1.6.  SPR4 Sends the Packet to SPR1 through the Internet

   In Figure 25 SPR4 sends the packet toward SPR1 with the following
   header through the Internet (ER4, CR and ER1) who will simply relay
   the packet according to the information in word 5 (Destination Host
   Number).


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |      Source Port (410C)       |  Destination Port (1C)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 25: TCP/IP Header: From SPR4 to SPR1








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B.1.7.  SPR1 Sends the Packet to RG1

   In Figure 26, RG1 address is reconstructed by using the information
   in the CGNAT state-table stored in SPR1.


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (192.168.1.0)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (410C)      |  Destination Port (3N)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 26: TCP/IP Header: From SPR1 to RG1

B.1.8.  RG1 Forwards the Packet to T1a

   In Figure 27, T1a address is reconstructed from that of RG1 and the
   state-table in the NAT based on Destination Port (3N).


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (192.168.1.3)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |      Source Port (410C)       |  Destination Port (3N)        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 27: TCP/IP Header: From RG1 to T1a




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B.1.9.  T1a Sends a Follow-up Packet to RG1

   To carry on the communication, T1a in Figure 28 sends the follow-up
   packet to RG1 with a full TCP/IP header.

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (6)|Type of Service|       Total Length (24)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |                Source Host Number (192.168.1.3)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (69.41.190.148)            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     6 |       Source Port (3N)        |   Destination Port (410C)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 28: TCP/IP Header: Follow-up Packets From T1a to RG1

B.2.  Connection Between EzIP-capable IoTs

   The following is an example of EzIP operation between T1z and T4z
   shown in Figure 9.  Each knows its own full "Public - EzIP : Private
   network addresses", "69.41.190.110-192.168.1.0:9 " and
   "69.41.190.148-192.168.4.40" respectively, as well as the other's.
   Note that Tz full address does not have the IoT No. portion.  It is
   directly addressable from the Internet.

B.2.1.  T1z Initiates a Session Request towards T4z

   T1z initiates a session request to T4z by sending an EzIP packet to
   RG1.  There is no TCP port number word, because T4z does not have
   such and that for T1z has not been assigned by the RG1's NAT.














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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (28)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.9)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |       No      |
     6 |   (Source)    | Option Length |    Source     |   Operation   |
       |    (0X9B)     |      (3)      |     No. (1)   |   (00000001)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     7 | (Destination) | Option Length |  Destination  |  Destination  |
       |    (0X9A)     |      (4)      |     No. (4)   |     No. (40)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 29: EzIP Header: From T1z to RG1

   Note that 0X9A and 0X9B are temporarily selected from the available
   "IP Option Numbers" [RFC1385].  They were employed by prior efforts
   to facilitate the presentation of, EnIP and ExIP, respectively.
   These convey the concepts of transporting the value of the "Network
   No." as well as the number of octets needed in the "Extension No.".
   That is, both Option Numbers represent 192.168/16 as the EzIP Network
   No. prefix, while individually conveys two or one octets used in the
   Extension No., respectively.

B.2.2.  RG1 Forwards the Packet to SPR1

   In Figure 30 RG1, allowing to be masqueraded by T1z, relays the
   packet toward SPR1 by assigning the TCP Source port number, 9N, to
   T1z.  Since T4z is directly connected to the Internet, there is no
   private network information to fill the Destination portion of the
   TCP word.











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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.0)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.148)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |       No      |
     6 |   (Source)    | Option Length |    Source     |   Operation   |
       |    (0X9B)     |      (3)      |     No. (1)   |   (00000001)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     7 | (Destination) | Option Length |  Destination  |  Destination  |
       |    (0X9A)     |      (4)      |     No. (4)   |     No. (40)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |       Source Port (9N)        | Destination Port (All 1's)    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 30: TCP/EzIP Header: From RG1 to SPR1

B.2.3.  SPR1 Sends the Packet to SPR4 through the Internet

   In Figure 31 , SPR4 sends the packet to RG2 by reconstructing its
   address from the Option number and the Extended Destination No.





















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (192.168.4.40)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |       No      |
     6 |   (Source)    | Option Length |    Source     |   Operation   |
       |    (0X9B)     |      (3)      |     No. (1)   |   (00000001)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     7 | (Destination) | Option Length |  Destination  |  Destination  |
       |    (0X9A)     |      (4)      |     No. (4)   |     No. (40)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |       Source Port (9N)        | Destination Port (All 1's)    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 31: CP/EzIP Header: From SPR1 to SPR4

B.2.4.  TCP/EzIP Header: From SPR1 to SPR4

   In Figure 32, SPR4 sends the packet to RG2 by reconstructing its
   address from the Option number and the Extended Destination No.





















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |             Source Host Number (69.41.190.110)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (192.168.4.40)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |       No      |
     6 |   (Source)    | Option Length |    Source     |   Operation   |
       |    (0X9B)     |      (3)      |     No. (1)   |   (00000001)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     7 | (Destination) | Option Length |  Destination  |  Destination  |
       |    (0X9A)     |      (4)      |     No. (4)   |     No. (40)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |       Source Port (9N)        | Destination Port (All 1's)    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 32: TCP/EzIP Header: From SPR4 to T4z

B.2.5.  TCP/EzIP Header: From SPR4 to T4z

   In Figure 33, T4z replies to SPR4 with the full T1z identification
   (69.41.190.110-192.68.1.0:192.168.1.9N conveyed by Option ID 0X9B
   together with the compact address string 69.41.190.110-1:9N) to
   create an EzIP header for the reply packet.



















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.4.40)                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (4)      |     No. (4)   |     No. (40)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |     End of    |
     7 | (Destination) | Option Length |  Destination  |     Option    |
       |    (0X9B)     |      (3)      |    No. (1)    |   (00000000)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |      Source Port (All 1's)    |   Destination Port (9N        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 33: TCP/EzIP Header: From T4z to SPR4

B.2.6.  TCP/EzIP Header: From T4z to SPR4

   In Figure 34, SPR4 sends the packet toward SPR1 with the following
   header through the Internet (ER2, CR, and ER1) who will simply relay
   the packet according to the information in word 5 (Destination Host
   Number):



















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |           Destination Host Number (69.41.190.110)             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (4)      |     No. (4)   |     No. (40)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |    End of     |
     7 | (Destination) | Option Length |  Destination  |    Option     |
       |    (0X9B)     |      (3)      |     No. (1)   |   (00000000)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |      Source Port (All 1's)    |    Destination Port (9N)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 34: TCP/EzIP Header: From SPR4 to SPR1

B.2.7.  SPR1 Sends the Packet to RG1

   In Figure 35, RG1 address is reconstructed from the Option number and
   the Extended Destination No.





















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (192.168.1.0)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (4)      |     No. (4)   |    No. (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |    End of     |
     7 | (Destination) | Option Length |  Destination  |    Option     |
       |    (0X9B)     |      (3)      |     No. (1)   |   (00000000)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |      Source Port (All 1's)    |    Destination Port (9N)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 35: TCP/EzIP Header: From SPR1 to RG1

B.2.8.  RG1 Forwards the Packet to T1z

   In Figure 36, T1z address is reconstructed from that of RG1 and the
   NAT state-table based on Destination Port (9N).





















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (69.41.190.148)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |            Destination Host Number (192.168.1.9)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     6 |   (Source)    | Option Length |    Source     |    Source     |
       |    (0X9A)     |      (4)      |     No. (4)   |    No. (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |    End of     |
     7 | (Destination) | Option Length |  Destination  |    Option     |
       |    (0X9B)     |      (3)      |     No. (1)   |   (00000000)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |      Source Port (All 1's)    |    Destination Port (9N)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 36: TCP/EzIP Header: From RG1 to T1z

B.2.9.  T1z Sends a Follow-up Packet to RG1

   In Figure 37, T1z sends a follow-up packet to RG1 with all fields
   filled with needed information.





















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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     1 |Version|IHL (7)|Type of Service|       Total Length (32)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     2 |        Identification         |Flags|     Fragment Offset     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     3 | Time to Live  |    Protocol   |        Header Checksum        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     4 |              Source Host Number (192.168.1.9)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     5 |          Destination Host Number (69.41.190.148)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |     No Op     |
     6 |   (Source)    | Option Length |    Source     |     Option    |
       |    (0X9B)     |      (3)      |    No. (1)    |   (00000001)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    EzIP ID    |      EzIP     |   Extended    |   Extended    |
     7 | (Destination) | Option Length |  Destination  |  Destination  |
       |    (0X9A)     |      (4)      |     No. (4)   |    No. (40)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     8 |      Source Port (9N)         |Destination Port (All 1's)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 37: TCP/EzIP Header: Follow-up Packets from T1z to RG1

B.3.  Connection Between EzIP-unaware and EzIP-capable IoTs

B.3.1.  T1a initiates a request to T4z

   Since T1a can create only IP header with conventional format, the
   SPRs will provide CGNAT type of services to the IP packets.  And,
   assuming SPR4 has a state-table set up by DMZ for forwarding the
   request to T4z, the packet will be delivered to T4z.  Seeing the
   incoming packet using conventional IP header, T4z should respond with
   the same so that the session will be conducted with conventional TCP/
   IP headers.

B.3.2.  T1z initiates a request to T4a

   Knowing T4a is not capable of EzIP header, T1z purposely initiates
   the request packet using conventional IP header.  It will be treated
   by SPRs in the same manner as the T1a initiated case above and
   recognizable by T4a.

   In brief, the steps outlined above are very much the same as the
   conventional TCP/IP header transitions between routers, except two




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   extra steps in each direction are inserted to encode and decode the
   additional SPR provided EzIP routing process.

   Note that when an IoT, such as T4a or T4z, is directly connected to a
   SPR, like SPR4, there is no RG in-between.  There is no corresponding
   TCP port number in word 8 of the above TCP/EzIP headers.  This spare
   facility in the header allows an RG be inserted if desired, thus re-
   establishing the private network environment.  When extension address
   is transported by a full TCP/EzIP header with four octet format,
   proper precaution must be exercised to avoid confusing the routers
   along the way due to the appearance of a full private network address
   although at a location in the IP header not intended for ordinary IP
   address.  When EzIP-7 is used, this is not of concern because the
   240/4 block does not belong to the three conventional private network
   address blocks.

Appendix C.  Internet Transition Considerations

   To enhance a large communication system like the Internet, it is
   important to minimize the disturbance to the existing equipments and
   processes due to any needed modification.  The basic EzIP plan is to
   confine all actionable enhancements within the new SPR module.  The
   following outlines the considerations for supporting the transition
   from the current Internet to the one enhanced by the EzIP technique.

C.1.  EzIP Implementation

C.1.1.  Introductory Phase

   a.  Insert an SPR in front of a web-server that desires to have
       additional subnet addresses for offering diversified activities.
       For the long term, a new web server may be designed with these
       two functional modules combined.

   b.  Insert an SPR in front of a group of subscribers who are to be
       served with the EzIP function.  The basic service provided by
       this SPR will be the CGNAT equivalent function.  This will
       maintain the same baseline user experience in accessing the
       Internet.

   c.  Session initiating packets with basic IPv4 header will be routed
       by SPRs to a business's existing server at the currently
       published IPv4 public address (discoverable by existing DNS).
       The server should respond with the basic IPv4 format as well.
       Essentially, this maintains the existing interaction between a
       user and a web server within an EzIP-unaware environment.  So
       far, neither the web-server nor any subscriber's IoTs needs to be
       enhanced, because the operations remain pretty much the same as



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       today's common practice utilizing CGNAT assisted connectivity.
       See Appendix B.1.  for an example.

   d.  Upon connected to the main web server, if a customer
       intentionally selects one of the new services offered by the
       primary web-server, the web-server will ask the customer to
       confirm the selection:

       1.  If confirmed, implying that the customer is aware of the fact
           that his IoT is being served by an SPR, the web server
           forwards the request to a branch server for carrying on the
           communication via an EzIP address.

       2.  The SPR at the originating side, recognizing the EzIP header
           from the web-server, replaces the CGNAT service with EzIP
           routing.

       3.  For all subsequent packets exchanged, the EzIP headers will
           be used in either direction.  See Appendix B.2. for an
           example.  This will speed up the transmission throughput
           performance for the rest of the session.

C.1.2.  New IoT Operation Modes

   a.  EzIP-capable IoT will create EzIP header initiating a session, to
       directly reach a specific web-server, instead of the lengthy
       steps of going through the DMZ port followed by manually making
       the selection from the main web server.This will speed up the
       initial handshake process.  See Appendix B.2. for an example.

   b.  To communicate with an EzIP-unaware IoT, an EzIP-capable IoT
       should purposely initiate a session with conventional IP header.
       This will signal the SPRs to provide just CGNAT type of
       connection service.  See Appendix B.3. for an example.

C.1.3.  End-to-End Operation:

   Once EzIP-capable IoTs become common for the general public, direct
   communication between any pair of such IoTs will be achievable.  An
   EzIP-capable IoT, knowing the other IoT's full EzIP address, may
   initiate a session by creating an EzIP header that directs the SPRs
   to provide EzIP services, bypassing the CGNAT process.  See
   Appendix B.2. for an example.








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C.2.  SPR Operation Logic

   To support the above scenarios, the SPR should be designed with the
   following decision process:

C.2.1.  Initiating a Session Request for an IoT or via a RG

   If a session request IP packet contains EzIP Option word, it will be
   routed forward by SPR accordingly.  Otherwise, the SPR provides CGNAT
   service by assigning a TCP port number to the packet and allowing the
   packet to masquerade with the SPR's own IP address while an entry to
   the state (port forward / look-up / hash) table is created in
   anticipation of the reply packet.

C.2.2.  Receiving a Session Request from the ER

   If a received IP packet includes a valid EzIP Option word or port
   number, SPR will utilize it to route the packet to an RG or an IoT.
   For a packet with plain IP header, it will be routed according to the
   Destination Host Number (IPheader word 5).

C.3.  RG Enhancement

   With IPv4 address pool expanded by the EzIP schemes, there will be
   sufficient publicly assignable addresses for IoTs wishing to be
   directly accessible.  The existing private networks may continue
   their current behavior of blocking session request packets from the
   Internet.  In-between, another connection mode is possible.  The
   following describes such an option in the context of the existing RG
   operation conventions.

C.3.1.  Initiating Session request for an IoT

   Without regard to whether the IP header is a conventional one or an
   EzIP type, a RG allows a packet to masquerade with the RG's own IP
   address by assigning a TCP port number to the packet and creating an
   entry to the state (port forward /look-up / hash) table.  This is the
   same as current NAT practice.

C.3.2.  Receiving a packet from the SPR

   The "Destination Port" value in the packet is examined:

   a.  If it matches with an entry in the RG NAT's state-table, the
       packet is forward to the corresponding address.  This is the same
       as the normal NAT processes in a conventional RG.





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   b.  If it matches with the address of an activeIoT on the private
       network, the packet is assigned with a TCP port number and then
       forwarded to that IoT.

   Note that there is certain amount of increased security risk with
   this added last step, because a match between a guessed destination
   identity and the above two lists could happen by chance.  To address
   this issue, the following proactive mechanism may be incorporated in
   parallel:

   If the "Destination Port" number is null or does not match with
   either of the above cases, the packet is dropped and an alarm state
   is activated to monitor for possible ill-intended follow-up attempts.
   A defensive mechanism should be triggered when the number of failed
   attempts has exceeded the preset threshold within a finite time
   interval.

   Alternatively, if the IP header of a session requesting packet
   indicates that the sender knows the identity of the desired
   destination IoT on a private network, the common RG screening process
   will be bypassed.  This facilitates the direct end-to-end connection,
   even in the presence of the NAT.  Note that this process is very much
   the same as the AA (Automated Attendant) capability in a PABX
   telephone switching system that automatically makes the connection
   for a caller who indicates (via proper secondary dialing or the
   equivalent) knowing the extension number of the destination party.
   Such process can effectively screen out most of the unwanted callers.

Authors' Addresses

   Abraham Chen
   Avinta Communications Inc.
   142 N. Milpitas Blvd., #148
   Milpitas, California  95035
   USA

   Email: AYChen@Avinta.com


   Ramamurthy Ati
   Avinta Communications Inc.
   142 N. Milpitas Blvd., #148
   Milpitas  95035
   USA

   Email: RamaAti18@gmail.com.com





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