[Search] [txt|pdf|bibtex] [Tracker] [Email] [Nits]

Versions: 00 01                                                         
                                                       Hormuzd Khosravi
   Internet Draft                                           Intel Corp.
   Document: draft-khosravi-forces-tcptml-00.txt         Furquan Ansari
   Expires: May 2005                                       Lucent Tech.
   Working Group: ForCES                                      Jon Maloy
                                                               Ericsson


                                                         November 2004


        TCP/IP based TML (Transport Mapping Layer) for ForCES protocol


  Status of this Memo

   By submitting this Internet-Draft, I certify that any applicable
   patent or other IPR claims of which I am aware have been disclosed,
   and any of which I become aware will be disclosed, in accordance
   with RFC 3668.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as ``work in
   progress.''

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.


  Conventions used in this document

   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 [2].

   Abstract

   This document defines the TCP/IP based TML (Transport Mapping Layer)
   for the ForCES protocol. It explains the rationale for choosing the
   transport protocols and also describes how this TML addresses all





Khosravi, et al            Expires May 2005                   [Page 1]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

   the requirements described in the Forces [3] requirements and ForCES
   protocol [7] document.


                             Table of Content

   1. Definitions.....................................................2
   2. Introduction....................................................3
   3. Protocol Framework Overview.....................................3
   4. TCP/IP TML Overview.............................................5
   4.1. Rationale for using TCP/IP....................................5
   4.2. Separate Control and Data channels............................5
   4.3. Reliability...................................................6
   4.4. Congestion Control............................................6
   4.5. Security......................................................6
   4.6. Addressing....................................................6
   4.7. Prioritization................................................7
   4.8. HA Decisions..................................................7
   4.9. Encapsulations Used...........................................7
   5. Example Scenarios...............................................7
   5.1. Establishment of Association..................................7
   5.2. Steady State Communication....................................7
   6. Security Considerations.........................................7
   6.1. TLS Usage for this TML........................................7
   7. IANA Considerations.............................................8
   8. References......................................................8
   8.1. Normative References..........................................8
   8.2. Informative References........................................9
   9. Acknowledgments.................................................9
   10. Authors' Addresses.............................................9


1. Definitions

   The following definitions are taken from [3], [5]

   ForCES Protocol - While there may be multiple protocols used within
   the overall ForCES architecture, the term "ForCES protocol" refers
   only to the protocol used at the Fp reference point in the ForCES
   Framework in RFC3746 [RFC3746].  This protocol does not apply to
   CE-to-CE communication, FE-to-FE communication, or to communication
   between FE and CE managers.  Basically, the ForCES protocol works in
   a master-slave mode in which FEs are slaves and CEs are masters.


   ForCES Protocol Layer (ForCES PL) -- A layer in ForCES protocol
   architecture that defines the ForCES protocol messages, the protocol
   state transfer scheme, as well as the ForCES protocol architecture





Khosravi, et al            Expires May 2005                   [Page 2]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

   itself (including requirements of ForCES TML (see below)).
   Specifications of ForCES PL are defined by this document.

   ForCES Protocol Transport Mapping Layer (ForCES TML) -- A layer in
   ForCES protocol architecture that specifically addresses the
   protocol message transportation issues, such as how the protocol
   messages are mapped to different transport media (like TCP, IP, ATM,
   Ethernet, etc), and how to achieve and implement reliability,
   multicast, ordering, etc.  This document defines a TCP/IP based
   ForCES TML.


2. Introduction

   The ForCES (Forwarding and Control Element Separation) working group
   in the IETF is defining the architecture and protocol for separation
   of control and forwarding elements in network elements such as
   routers.  [3],  [4]  define  both  architectural  and  protocol
   requirements for the communication between CE and FE. The ForCES
   protocol layer [7] describes the protocol specification. It is
   envisioned that the ForCES protocol would be independent of the
   interconnect technology between the CE and FE and can run over
   multiple  transport  technologies  and  protocol.  Thus  a  Transport
   Mapping Layer has been defined in the protocol framework that will
   take care of mapping the protocol messages to specific transports.
   This document defines the TCP/IP based TML for the ForCES protocol
   layer. It also addresses all the requirements for the TML including
   security, reliability, etc.


3. Protocol Framework Overview

   The reader is referred to the Framework document [RFC3746], and in
   particular sections 3 and 4, for architectural overview and where
   and how the ForCES protocol fits in.  There may be some content
   overlap between the ForCES protocol draft [7] and this section in
   order to provide clarity.

   The ForCES protocol constitutes two pieces: the PL and TML layer.
   This is depicted in Figure 1 below.

            +------------------------------------------------
            |               CE PL layer                     |
            +------------------------------------------------
            |              CE TML layer                     |
            +------------------------------------------------
                                      ^
                                      |




Khosravi, et al            Expires May 2005                   [Page 3]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

                         ForCES       |   (i.e. Forces data + control
                         PL           |    packets )
                         messages     |
                         over         |
                         specific     |
                         TML          |
                         encaps       |
                         and          |
                         transport    |
                                      |
                                      v
            +------------------------------------------------
            |              FE TML layer                     |
            +------------------------------------------------
            |               FE PL layer                     |
            +------------------------------------------------

                          Figure 1: ForCES Interface

   The PL layer is in fact the ForCES protocol.  Its semantics and
   message layout are defined in [7].  The TML Layer is necessary to
   connect two ForCES PL layers as shown in Figure 1 above.

   Both the PL and TML layers are standardized by the IETF.  While only
   one PL layer is defined, different TMLs are expected to be
   standardized.  To interoperate the TML layer at the CE and FE are
   expected to be of the same definition.

   On transmit, the PL layer delivers its messages to the TML layer.
   The TML layer delivers the message to the destination TML layer(s).
   On reception, the TML delivers the message to its destination PL
   layer(s).

   3.1.1 The PL layer

   The PL is common to all implementations of ForCES and is
   standardized by the IETF [7].  The PL layer is responsible for
   associating an FE or CE to an NE.  It is also responsible for
   tearing down such associations.  An FE uses the PL layer to throw
   various subscribed-to events to the CE PL layer as well as respond
   to various status requests issued from the CE PL.  The CE configures
   both the FE and associated LFBs attributes using the PL layer.  In
   addition the CE may send various requests to the FE to activate or
   deactivate it, reconfigure its HA parameterization, subscribe to
   specific events etc.

   3.1.2  The TML layer






Khosravi, et al            Expires May 2005                   [Page 4]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

   The TML layer is essentially responsible for transport of the PL
   layer messages.  The TML is where the issues of how to achieve
   transport level reliability, congestion control, multicast,
   ordering, etc. are handled.  It is expected more than one TML will
   be standardized.  The different TMLs each could implement things
   differently based on capabilities of underlying media and transport.
   However, since each TML is standardized, interoperability is
   guaranteed as long as both endpoints support the same TML.  All
   ForCES Protocol Layer implementations should be portable across all
   TMLs, because all TMLs have the same top edge semantics.


4. TCP/IP TML Overview

   The TCP/IP TML consists of two TCP connections between the CE and FE
   over which the protocol messages are exchanged. One of the
   connection is called the Control channel, over which control
   messages are exchanged, the other is called data channel over which
   external protocol packets, such as routing packets will be
   exchanged. The TCP connections will use unique server port numbers
   for each of the channels. In addition to this, this TML will provide
   mechanisms to prioritize the messages over the different channels.

   Some of the rationale of choosing this transport mechanism as well
   as explanation of how it meets the TML requirements is explained
   below.

4.1.Rationale for using TCP/IP

   TCP meets all the reliability requirements (no losses, no data
   corruption, no re-ordering of data) for the ForCES protocol/TML and
   also provides congestion control mechanism, which is important to
   meet the scalability requirement. In addition, it helps with
   interoperability since TCP is a well-understood, widely deployed
   transport protocol. Using TCP also enables this TML and the protocol
   to work seamlessly in single hop and multihop scenarios.

4.2.Separate Control and Data channels

   The ForCES NEs are subject to Denial of Service (DoS) attacks
   [Requirements Section 7 #15]. A malicious system in the network can
   flood a ForCES NE with bogus control packets such as spurious RIP or
   OSPF packets in an attempt to disrupt the operation of and the
   communication between the CEs and FEs. In order to protect against
   this situation, the TML uses separate control and data channels for
   communication between the CEs and FEs.






Khosravi, et al            Expires May 2005                   [Page 5]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

   The data channel carries the control protocol packets such as RIP,
   OSPF messages as outlined in Requirements [3] Section 7 #10, which
   are carried in ForCES Packet Redirect messages [7], between the CEs
   and FEs. All the other ForCES messages, which are used for
   configuration/capability exchanges, event notification, etc, are
   carried over the control channel. The data channel is set up only
   after the control channel is set up and the capability exchange has
   successfully taken place between the FEs and CEs. The CE signals the
   FE to establish the data channel at the appropriate time and
   provides it with the channel addressing information, such as, port
   number in case of TCP (see section 5.3). By default, the data
   channel is established on the CE control channel port number +1.

   The reliability requirements for the data channel messages are
   different from that of the control messages [Reqs] i.e. they dont
   require strict reliability in terms of retransmission, etc. However
   congestion control is important for the data channel because in case
   of DoS attacks, if an unreliable transport such as UDP is used for
   the data traffic, it can more easily overflow the physical
   connection, overwhelming the control traffic with congestion. Thus
   we need a transport protocol that provides congestion control but
   does not necessarily provide full reliability. Datagram Congestion
   Control Protocol (DCCP) [11], which is currently being defined, is a
   transport protocol that exactly meets this requirement. However
   since it is currently not an IETF standard RFC, and the authors are
   unaware of any existing implementations, this TML uses TCP as
   transport protocol for the data channel (for IP interconnect). TCP
   provides the congestion control mechanism required for the data
   channel and its wide deployment eases interoperability.


4.3.Reliability

   TCP provides the reliability (no losses, no data corruption, no re-
   ordering of data) required for ForCES protocol control messages.

4.4.Congestion Control

   TCP provides congestion control needed to satisfy this requirement.

4.5.Security

   This TML uses TLS [8] to provide security in insecure environments.
   Please see section 6 on security considerations for more details.

4.6.Addressing

   This TML uses addressing provided by IP layer.




Khosravi, et al            Expires May 2005                   [Page 6]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004


4.7.Prioritization

   This TML provides prioritization of messages sent over control
   channel as compared to the data channel. This has also been found to
   be useful in face of DoS attacks on the protocol. The details of
   this are TBD.

4.8.HA Decisions

   TBD

4.9.Encapsulations Used

   Other than the TCP/IP header, no other encapsulations will be added
   to the ForCES protocol messages.


5. Example Scenarios

5.1.Establishment of Association

   TBD

5.2.Steady State Communication

  TBD


6. Security Considerations

   If the CE or FE are in a single box and network operator is running
   under a secured environment then it is up to the network
   administrator to turn off all the security functions. This is
   configured during the pre-association phase of the protocol.

   When the CEs, FEs are running over IP networks or in an insecure
   environment, this TML uses TLS [8] to provide security. The security
   association between the CEs and FEs MUST be established before any
   ForCES protocol messages are exchanged between the CEs and FEs.


6.1.TLS Usage for this TML

   This section is applicable for CE or FE endpoints that use the TML
   with TLS [8] to secure communication.






Khosravi, et al            Expires May 2005                   [Page 7]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

   Since CE is master and FEs are slaves, the FEs are TLS clients and
   CEs are TLS server. The endpoints that implement TLS MUST perform
   mutual authentication during TLS session establishment process. CE
   must request certificate from FE and FE needs to pass the requested
   information.

   We recommend TLS-RSA-with-AES-128-CBC-SHA¶ cipher suite, but CE or
   FE may negotiate other TLS cipher suites. TLS must be used for all
   control channel messages. TLS is optional for the data channel since
   data channel packets are not encrypted externally to the NE.

   This TML uses TLS to provide security when the NE is in an insecure
   environment. This is because IPsec provides less flexibility when
   configuring trust anchors since it is transparent to the application
   and use of Port identifiers is prohibited within IKE Phase 1. This
   provides restriction for IPsec to configure trust anchors for each
   application separately and policy configuration is common for all
   applications.


7. IANA Considerations

   The TCP/IP TML needs to have a two well-defined TCP port numbers,
   which needs to be assigned by IANA.

8. References
8.1.Normative References

  1. S. Bradner, "The Internet Standards Process -Revision 3", RFC 2026,
     October 1996.

  2. S. Bradner, "Keywords for use in RFCs to Indicate Requirement
     Levels", RFC2119 (BCP), IETF, March 1997.

  3. Khosravi, et al., ¶Requirements for Separation of IP Control and
     Forwarding¶, RFC 3654, November 2003.

  4. L. Yang, et al., ¶ ForCES Architectural Framework¶, RFC 3746,
     April 2004.

  5. L. Yang, et al., ¶ ForCES Forwarding Element Functional Model¶,
     work in progress¶, July 2004,<draft-ietf-forces-model-03.txt>

  6. A. Audu, et al.,  Forwarding and Control Element protocol (FACT)"
     draft-gopal-forces-fact-06.txt, February 2004.






Khosravi, et al            Expires May 2005                   [Page 8]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

  7. A. Doria, et al., ¶ForCES protocol specification¶, draft-ietf-
     forces-protocol-00.txt, September 2004.


8.2.Informative References


  8. Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and P.
     Kocher, "The TLS Protocol Version 1.0", RFC 2246, January 1999.

  9. Jungmaier, A., Rescorla, E. and M. Tuexen, "Transport Layer
     Security over Stream Control Transmission Protocol", RFC 3436,
     December 2002.

  10.  R. Stewart, et al., Stream Control Transmission Protocol
     (SCTP)¶, RFC 2960, October 2000.

  11.  E. Kohler, M. Handley, S. Floyd, J. Padhye, Datagram
     Congestion Control Protocol (DCCP)¶, draft-ietf-dccp-spec-04.txt,
     June 2003.

  12.  Floyd, S., Congestion Control Principles¶, RFC 2914, September
     2000.

  13.  A. Doria, F. Hellstrand, K. Sundell, T. Worster, General
     Switch Management Protocol (GSMP) V3¶, RFC 3292, June 2002.

  14.  H. Balakrishnan, et al. The Congestion Manager¶, RFC 3124,
     June 2001.


9. Acknowledgments


10. Authors' Addresses

   Hormuzd Khosravi
   Intel
   2111 NE 25th Avenue
   Hillsboro, OR 97124
   Phone: 1-503-264-0334
   Email: hormuzd.m.khosravi@intel.com


   Furquan Ansari
   101 Crawfords Corner Road
   Holmdel, NJ 07733
   USA




Khosravi, et al            Expires May 2005                   [Page 9]


Internet Draft  TCP/IP based TML for ForCES protocol  November 2004

   Phone: +1 732-949-5249
   Email: furquan@lucent.com

   Jon Maloy
   Ericsson Research Canada
   8400 Boul Decarie
   Ville Mont-Royal, Quebec H4P 2N2
   Canada
   Phone: 1-514-345-7900
   Email: jon.maloy@ericsson.com

   Copyright Statement

   Copyright (C) The Internet Society (year).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.

   This document and the information contained herein are provided on
   an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
   REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
   INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.




























Khosravi, et al            Expires May 2005                  [Page 10]