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Versions: 00 01 02                                                      
Network Working Group                                              M. Xu
Internet-Draft                                                   S. Yang
Expires: January 16, 2014                                          J. Wu
                                                     Tsinghua University
                                                                F. Baker
                                                           Cisco Systems
                                                           July 15, 2013


            Traffic Class Routing Protocol in Home Networks
                   draft-xu-homenet-traffic-class-00

Abstract

   Home IT staff is generally unfamiliar with network operations, making
   it desirable to provide a configuration-free mode of operation.
   Policy-based routing (in the sense of configuring one router to
   redirect traffic to another based on access control) and multi-
   topology routing both require configuration, making them undesirable.

   In this document, we propose a configuration-free mechanism, in which
   packets will be routed towards the corresponding upstream ISPs based
   on both destination and source addresses.

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 January 16, 2014.

Copyright Notice

   Copyright (c) 2013 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



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   (http://trustee.ietf.org/license-info) in effect on the date of
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   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Router Behavior . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Egress Router Behavior  . . . . . . . . . . . . . . . . .   5
     4.2.  Interior Router Behavior  . . . . . . . . . . . . . . . .   5
   5.  TC-LSA Format . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Routing Table Structure . . . . . . . . . . . . . . . . . . .   7
   7.  Calculation of the Routing Table  . . . . . . . . . . . . . .   8
   8.  Matching Rule . . . . . . . . . . . . . . . . . . . . . . . .   8
   9.  Compatibility . . . . . . . . . . . . . . . . . . . . . . . .   9
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     12.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Home networks are growing both in device count and in complexity.
   Today they generally contain both wired and wireless components, and
   may require routing to place audio/visual entertainment traffic one
   one path, office services on another, and wireless LANs (both IEEE-
   style and 4G/LTE-style) on a third.  Traditionally, we have
   simplified networks using a single exit router and a default route.



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   Today, we might have multiple routers to wired upstream networks, and
   by separate paths LTE services, "Smart Grid" services, or health
   network services.  Increasingly, such networks are multihomed, and
   multihomed using diverse access network technologies.

   Traditionally, routing protocols make routing decisions solely based
   on destination IP addresses, packets towards the same destination
   will be delivered to the same next hop no matter where they come
   from.  These protocols work well with simple home networks that have
   only one egress router.  However, in the multi-homing scenario,
   packets may be dropped if forwarded only based on destination
   addresses [RFC3704].

   Although many patch-like solutions, like policy-based routing (PBR),
   multi-topology routing (MTR) and layer-3 VPN can solve the problem,
   they complex the configurations in home networks, and are not
   suitable for home IT staffs.  We need a configuration-free solution
   to help operators set up their home networks in the multi-homing
   scenario.

   In this document, we propose a configuration-free mechanism - traffic
   class routing, based on OSPFv3, such that home networks can route
   packets towards the corresponding upstream ISPs, according to both
   destination and source addresses.

2.  Terminology

   Terminology used in this document:

   o  Traffic Class (TC): Identified by (destination prefix, source
      prefix), all packets falling in the domain belong to the traffic
      class.

   o  TC-Route: Identified by (destination prefix, source prefix,
      value), where value is the administrative value applied to the
      traffic class (destination prefix, source prefix).

   o  TC-LSA: Link state advertisement that communicates the
      reachability for a traffic classes.

3.  Overview

   In a home network, traditionally, egress routers obtain delegated
   prefixes from upstream ISPs using DHCPv6 with prefix options
   [RFC3633].  The egress routers will then assign longer sub-prefixes
   to the other links in the home network.  Each router inside the home
   network will act as standard OSPFv3 router, and forward packets based
   on their destination addresses.



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   With traffic class routing, after obtaining delegated prefixes and
   assigning sub-prefixes, egress routers will populate traffic classes
   (with extended LSAs), rather than destination address only, into the
   home network.  Each router inside the home network will flood these
   traffic classes information.  When calculating the path towards a
   destination address, routers will take the traffic classes into
   considerations.  Intrinsically, in traditional routing model, the
   object being routed to is a destination prefix; in our routing model,
   the object being routed might be a destination prefix given that the
   packet sports a certain source prefix.

   Each traffic class is associated with a cost, which is a single
   dimensionless metric.

   For example, a site is connected to the Internet through two ISPs,
   ISP1 and ISP2.  ISP1 delegates prefix P1 to the site, and ISP2
   delegates prefix P2 to the site.  After being delegated with P1, the
   egress router E1 of the site will advertise a traffic class - {::/0,
   P1}, into the site.  After being delegated with P2, the egress router
   E2 of the site will advertise a traffic class - {::/0, P2}, into the
   site.  Receiving these advertisements, interior router I1 will
   compute two paths towards ::/0, one through router E1 for traffic
   from P1, the other through E2 for traffic from P2.


               +---------------+                  +-----------------+
               |               |                  |                 |
               |   ISP1: P1    |                  |    ISP2: P2     |
               |               |                  |                 |
               +--------+------+                  +-----+-----------+
                        |                               |
                     +--+---+                        +--+---+
                     |Router|                        |Router|
                     | BR1  |                        | BR2  |
                     +---+--+                        +---+--+
                   ------+----------          -----------+-----
                         |                               |
                     +---+--+                        +---+--+
                     |Router|                        |Router|
                     |  E1  |                        |  E2  |
                     +------+       +------+         +------+
                           -+-------+Router+---------+-
                                    |  I1  |
                                    +--+---+
                                    +--+---+  Address A in P1
                                    | Host |
                                    +------+  Address B in P2




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             Figure 1: Multi-homing Scenario in Home Networks

4.  Router Behavior

   All routers behave like traditional OSPFv3 routers, however, the
   following behaviors are different with traditional OSPFv3 routers.

4.1.  Egress Router Behavior

   After obtaining delegated prefixes using DHCPv6 with prefix options,
   an egress router should originate TC-LSAs, i.e., extended LSAs with
   source prefixes appended.  Egress routers then will advertise these
   TC-LSAs into the home network.

   Note that an egress router behaves like an interior router if it
   receives a TC-LSA from other egress routers.

4.2.  Interior Router Behavior

   Receiving TC-LSAs from egress routers, an interior router should
   store the TC-LSAs into its LSDB, and flood it to other routers.
   After calculating a path to an egress router advertising
   reachability, i.e., a destination prefix, the interior router should
   decide which traffic class can follow this path towards the egress
   router.  If a traffic class can travel through two different paths,
   then interior router should compare their costs, and select the path
   with the lowest cost.

   Interior routers contains a routing table that contains all necessary
   information to forward an IP packet following the path of a traffic
   class.  After computing the path towards a traffic class, interior
   routers should update the entry in the routing table if necessary,
   e.g., change the next hop towards the traffic class.  The routing
   table structure will be described in Section 6.  Calculation of
   routing table will be illustrated in Section 7.

   At last, interior routers should update the Forwarding Information
   Base (FIB), which will be discussed in the next version of this
   document.

5.  TC-LSA Format

   TC-LSA adds TLV extensions, which contains source prefix information,
   based on original OSPFv3 LSA.  We follow the TLV format in
   [I-D.baker-ipv6-ospf-dst-src-routing] and extended LSA format in
   [I-D.acee-ospfv3-lsa-extend].





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   Each extended LSA includes the traditional LSA part in [RFC5340], and
   one or more TLVs defined in [I-D.baker-ipv6-ospf-dst-src-routing].
   But we do not need all LSAs to be extended, the LSAs need to be
   extended are as follows:

   o  Intra-Area-Prefix-LSA: The extended LSA has type 0x2029.

   The extended LSA format for Intra-Area-Prefix-LSA in multi-homing is
   as follows:



          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
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |           LS Age              |0|0|1|       LSA Type          |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                      Link State ID                            |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                   Advertising Router                          |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                   LS Sequence Number                          |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |        LS Checksum            |          LSA Length           |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |       # Prefixes              |     Referenced LS Type        |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                  Referenced Link State ID                     |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |               Referenced Advertising Router                   |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |  PrefixLength | PrefixOptions |          Metric               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                        Address Prefix                         |
         |                             ...                               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                             ...                               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |  PrefixLength | PrefixOptions |          Metric               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                        Address Prefix                         |
         |                             ...                               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |           TLV Type            |        TLV Length             |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         | SPrefixLength | SPrefixOptions|               0               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                  Source Address Prefix                        |



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         |                             ...                               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                             ...                               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |           TLV Type            |        TLV Length             |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         | SPrefixLength | SPrefixOptions|               0               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |                  Source Address Prefix                        |
         |                             ...                               |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


             Figure 1: Multi-homing Scenario in Home Networks

   All LSA header fields are the same as defined in [RFC5340], except
   the following:

   o  LSA type: The LSA type value is 0x2029, according to
      [I-D.acee-ospfv3-lsa-extend];

   o  LSA length: The length of the whole LSA header, including the
      TLVs;

   o  TLV type: The type of IPv6 source prefix TLV, assigned by IANA;

   o  TLV length: The value is 20 as defined in
      [I-D.baker-ipv6-ospf-dst-src-routing];

   o  SPrefixLength, SPrefixOptions, Source Address Prefix:
      Representation of the IPv6 address prefix, which is delegated from
      the upstream ISP providers;

   In the extended LSA, suppose there are n destination prefix d1, d2,
   ..., dn, and m source prefix s1, s2, ..., sm, then the LSA carries
   n*m TC-route announcement, (d1, s1, v1), (d1, s2, v1), ..., (d1, sm,
   v1), (d2, s1, v2), (d2, s2, v2), ..., (dn, sm, vn), where vi is the
   metric associated with destination prefix di.

6.  Routing Table Structure

   For traditional routing, the routing table structure contains all
   needed information to forward IP packets to the right destination.
   For example, destination prefixes are commonly structured into a
   prefix trie, where each trie nodes contain the necessary information.
   Routers can lookup and update the prefix trie.





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   With traffic classes, the routing table structure must contain all
   needed information to forward IP packets following the right traffic
   class, i.e., towards the related destination and from the related
   source.  For each routing table entry, there are two additional
   fields other than the fields mentioned in [RFC5340]:

   o  Source IP Address: The IP address of the source in traffic class.

   o  Source Address Mask: If the source is a subnet, then it is
      referred to as the subnet mask.

   The routing table must provide interface for update and lookup in it.
   For example, traffic classes can be structured into a two dimensional
   (or two level) trie, where each trie node in the first dimension
   points to a sub-trie in the second dimension.  The trie nodes in the
   second dimension contain the necessary information to forward IP
   packets following the right traffic class.

7.  Calculation of the Routing Table

   The fundamental algorithm in OSPFv3 doesn't change.  The algorithm
   uses the SPF approach to calculate a path to the router advertising
   reachability, and then uses the reachability advertisement to decide
   what traffic should follow that route.  What we are changing is the
   reachability advertisement, in traiditional OSPFv3, the
   advertisements, which is one or several kinds of LSAs, represent
   destination prefixes; in this document, the advertisements, which is
   one or several kinds of TC-LSAs, represent traffic classes.

   Note that we do not have to change router-LSA and network-LSA in
   [RFC5340].  Thus, the first stage of Section 4.8.1 in [RFC5340]
   remains the same in this document.  However, the second stage of
   Section 4.8.1 in [RFC5340] should change by a little bit.  Instead of
   examining the list of the intra-area-prefix-LSAs, the list of
   extended intra-area-prefix-LSAs is examined.  The cost of any
   advertised traffic class is the sum of the class' advertised metric
   plus the cost of the transit vertex (either router or transit
   network) indentified by extended intra-area-prefix-LSAs' referenced
   LS type, referenced link state ID, and referenced advertising router
   field.

8.  Matching Rule

   We also adopt the LMF (longest match first) rule when a packet
   matches multiple routing entries.  However, traffic class has two
   dimensions, there might exist ambiguity.  For example, if there
   exists two routing entries, (d1, s1, nexthop1), (d2, s2, nexthop2),
   where d1 is longer than d2 and s2 is longer than s1, then none entry



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   is longer than the other in both dimensions.  In this situation, we
   must insert an additional entry into the routing table, e.g., (d1,
   s2, nexthop1) in the above example.  The entry directs to nexthop1
   rather than nexthop2, because we must guarantee reachability
   according to the destination prefix.

9.  Compatibility

   Routers can also announce the traditional destination-based LSAs at
   the same time.  In this case, routers have to keep two routing
   tables, one for destination prefix only, and the other for traffic
   classes.  When a packet arrives, routers first lookup in the routing
   table storing traffic classes; If none entry matches, then routers
   lookup in the routing table storing destination prefixes.

10.  IANA Considerations

   The newly LSA types and TLVs should be assigned by IANA, please refer
   to [I-D.baker-ipv6-ospf-dst-src-routing] and
   [I-D.acee-ospfv3-lsa-extend].

11.  Acknowledgments

   Zheng Liu and Gautier Bayzelon provided useful input into this
   document.

12.  References

12.1.  Normative References

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, March 2004.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, July 2008.

12.2.  Informative References

   [I-D.ietf-homenet-arch]
              Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
              "Home Networking Architecture for IPv6", draft-ietf-
              homenet-arch-07 (work in progress), February 2013.

   [I-D.baker-ipv6-ospf-dst-src-routing]



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              Baker, F., "IPv6 Source/Destination Routing using OSPFv3",
              draft-baker-ipv6-ospf-dst-src-routing-02 (work in
              progress), May 2013.

   [I-D.acee-ospfv3-lsa-extend]
              Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3
              LSA Extendibility", draft-acee-ospfv3-lsa-extend-00 (work
              in progress), May 2013.

   [I-D.baker-fun-routing-class]
              Baker, F., "Routing a Traffic Class", draft-baker-fun-
              routing-class-00 (work in progress), July 2011.

Authors' Addresses

   Mingwei Xu
   Tsinghua University
   Department of Computer Science, Tsinghua University
   Beijing  100084
   P.R. China

   Phone: +86-10-6278-5822
   Email: xmw@csnet1.cs.tsinghua.edu.cn


   Shu Yang
   Tsinghua University
   Department of Computer Science, Tsinghua University
   Beijing  100084
   P.R. China

   Phone: +86-10-6278-5822
   Email: yangshu@csnet1.cs.tsinghua.edu.cn


   Jianping Wu
   Tsinghua University
   Department of Computer Science, Tsinghua University
   Beijing  100084
   P.R. China

   Phone: +86-10-6278-5983
   Email: jianping@cernet.edu.cn








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   Fred Baker
   Cisco Systems
   Santa Barbara, California  93117
   USA

   Email: fred@cisco.com













































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