[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 draft-ietf-mpls-ldp-ipv6

MPLS Working Group                                       Vishwas Manral
Internet Draft                                          IPInfusion Inc.
Intended status: Standards Track
Expires: April 2011                                         Rajiv Papneja
                                                                Isocore

                                                            Rajiv Asati
                                                           Cisco Systems

                                                          October 13, 2010


                          Updates to LDP for IPv6
                       draft-manral-mpls-ldp-ipv6-04


Status of this Memo

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

   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

   This Internet-Draft will expire on April 15, 2011.



Copyright Notice

   Copyright (c) 2010 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



Asati, et. al           Expires April 15, 2011                    [Page 1]

Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010


   (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 to this document. Code Components extracted from this
   document must 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 BSD License.





Abstract

   The Label Distribution Protocol (LDP) specification defines
   procedures to exchange label bindings over either IPv4 or IPv6 or
   both networks. This document corrects and clarifies the LDP behavior
   when IPv6 network is used.



Table of Contents


   1. Introduction...................................................3
   2. Specification Language.........................................3
   3. LSP Mapping....................................................4
   4. LDP Identifiers................................................4
   5. Peer Discovery.................................................5
      5.1. Basic Discovery Mechanism.................................5
      5.2. Extended Discovery Mechanism..............................5
   6. LDP Session Establishment......................................6
      6.1. Transport connection establishment........................6
      6.2. Session initialization....................................7
   7. IANA Considerations............................................7
   8. Security Considerations........................................7
   9. Acknowledgments................................................7
   10. References....................................................8
      10.1. Normative References.....................................8
      10.2. Informative References...................................8
   Author's Addresses................................................9








Asati, et. al           Expires April 15, 2011                  [Page 2]

Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010


1. Introduction

   The LDP [RFC5036] specification defines procedures and messages for
   exchanging label bindings over either IPv4 or IPv6 or both (e.g.
   dual-stack) networks.

   However, RFC5036 specification has the following deficiencies in
   regards to IPv6 usage:

   1) LSP mapping: No rule defined for mapping a particular packet to a
      particular LSP that has an Address Prefix FEC element containing
      IPv6 address of the egress router

   2) LDP identifier: No details specific to IPv6 usage

   3) LDP discovery: No details for using a particular IPv6 multicast
      address (with or without IPv4 co-existence)

   4) LDP Session establishment: No prescription for handling both IPv4
      and IPv6 transport address optional objects in a Hello message,
      and subsequently two IPv4 and IPv6 transport connections.

   This document addresses the above deficiencies by specifying the
   desired behavior.

   Note that this document updates RFC5036.



2. Specification 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 [RFC2119].

   LDP   - Label Distribution Protocol

   FEC   - Forwarding Equivalence Class

   TLV   - Type Length Value

   LSR   - Label Switch Router

   LSP   - Label Switched Path





Asati, et. al           Expires April 15, 2011                  [Page 3]

Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010


3. LSP Mapping

   Section 2.1 of [RFC5036] specifies the procedure for mapping a
   particular packet to a particular LSP using three rules. Quoting the
   3rd rule from RFC5036:

     "If it is known that a packet must traverse a particular egress
     router, and there is an LSP that has an Address Prefix FEC element
     that is a /32 address of that router, then the packet is mapped to
     that LSP."

   Suffice to say, this rule is correct for IPv4, but not for IPv6,
   since an IPv6 router may not have any /32 address.

   This document proposes to modify this rule by also including a /128
   address (for IPv6). In fact, it should be reasonable to just say
   IPv4 or IPv6 address instead of /32 or /128 addresses as shown below
   in the updated rule:

     "If it is known that a packet must traverse a particular egress
     router, and there is an LSP that has an Address Prefix FEC element
     that is an IPv4 or IPv6 address of that router, then the packet is
     mapped to that LSP."



4. LDP Identifiers

   Section 2.2.2 of [RFC5036] specifies formulating at least one LDP
   Identifier, however, it doesn't provide any consideration in case of
   IPv6 (with or without dual-stacking).

   This document preserves the usage of 32-bit LSR Id on an IPv6 only
   LSR and allows the usage of a common LDP identifier i.e. same LSR-Id
   and same Label space id for IPv4 and IPv6 on a dual-stack LSR. This
   rightly enables the per-platform label space to be shared between
   IPv4 and IPv6.

     Editor's note: The possible conflict with last paragraph of
     section 2.5.2 of RFC5036 needs to be addressed or clarified.

   Additionally, this document reserves 0.0.0.0 as the LSR-Id, and
   prohibits its usage.






Asati, et. al           Expires April 15, 2011                  [Page 4]

Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010


5. Peer Discovery

5.1. Basic Discovery Mechanism

   Section 2.4.1 of [RFC5036] defines the Basic Discovery mechanism for
   directly connected LSRs. Following this mechanism, LSRs periodically
   sends LDP Link Hellos destined to "all routers on this subnet" group
   multicast IP address.

   Interesting enough, per [IANA-IPv6] [RFC4291], IPv6 has three "all
   routers on this subnet" multicast addresses:

         FF01:0:0:0:0:0:0:2   = Interface-local scope

         FF02:0:0:0:0:0:0:2   = Link-local scope

         FF05:0:0:0:0:0:0:2   = Site-local scope

   [RFC5036] does not specify which particular IPv6 'all routers on
   this subnet' group multicast IP address should be used by LDP Link
   Hellos.

   This document specifies the usage of link-local scope e.g.
   FF02:0:0:0:0:0:0:2 as the destination multicast IP address for IPv6
   LDP Link Hellos. An LDP Hello packet received on any of the other
   addresses should be dropped. Also, the LDP Link Hello packets must
   have their IPv6 Hop Limit set to 1.

   More importantly, if an interface is a dual-stack interface (e.g.
   enabled with both IPv4 and IPv6 LDP), then the LSR must periodically
   send both IPv4 and IPv6 LDP Link Hellos and must separately maintain
   the Hello adjacency for IPv4 and IPv6. This ensures LDP peerings on
   a multi-access interface (even if there are IPv4-only, IPv6-only and
   dual-stack routers).  Needless to say, the IPv4 and IPv6 LDP Link
   Hellos must carry the same LDP identifier (assuming per-platform
   label space usage).



5.2. Extended Discovery Mechanism

   Suffice to say, the extended discovery mechanism (defined in section
   2.4.2 of [RFC5036]) doesn't require any additional IPv6 specific
   consideration, since the targeted LDP Hellos are sent to a pre-
   configured destination IP address.




Asati, et. al           Expires April 15, 2011                  [Page 5]

Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010


6. LDP Session Establishment

   Section 2.5.1 of [RFC5036] defines a two-step process for LDP
   session establishment:

     1. Transport connection establishment
     2. Session initialization

   Next two sections discuss the LDP consideration for IPv6 and/or
   dual-stacking.

6.1. Transport connection establishment

   Section 2.5.2 of [RFC5036] specifies the use of an optional
   transport address object (TLV) in LDP Link Hello message, however,
   it does not specify the behavior of LDP in case of both IPv4 and
   IPv6 transport address objects (TLV) are sent in a Hello message.
   Additionally, it does not specify whether both IPv4 and IPv6
   transport connections should be allowed, if there were Hello
   adjacencies for both IPv4 and IPv6.

   This document specifies that:

     - An LSR should not send the Hello containing both IPv4 and IPv6
        transport address optional objects. In other words, there would
        be at most one optional Transport Address object in a Hello
        message. An LSR should include only the transport address whose
        address family is the same as that of the IP packet carrying
        Hello.

     - An LSR should accept the Hello message that contains both IPv4
        and IPv6 transport address optional objects, but use only the
        transport address whose address family is the same as that of
        the IP packet carrying Hello.

     - An LSR should not create (or honor the request for creating) a
        TCP connection for a new LDP session with a remote LSR, if they
        already have an LDP session (for the same label spaces)
        established using whatever IP version. This means that only one
        transport connection is established, even if there are two
        Hello adjacencies (one for IPv4 and another for IPv6), as
        highlighted in the last paragraph of section 2.5.2.

     - An LSR should close the lagging TCP connection for a new LDP
        session with a remote LSR, if they attempted two TCP
        connections using IPv4 and IPv6 transports simultaneously.



Asati, et. al           Expires April 15, 2011                  [Page 6]

Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010




6.2. Session initialization

   No additional consideration needed.



7. IANA Considerations

   None.



8. Security Considerations

   The extensions defined in this document only clarify the behavior of
   LDP, they do not define any new protocol procedures. All the
   security issues relevant for the [RFC5036] are relevant for this
   document as well.

   Moreover, this document allows the use of IPsec [RFC4301] for IPv6
   protection, hence, LDP can benefit from the additional security as
   specified in [RFC4835].



9. Acknowledgments

   A lot of the text in this document is borrowed from [RFC5036]. The
   authors of the document are acknowledged. The authors also
   aknowledge the help of Manoj Dutta and Vividh Siddha. Thanks to Bob
   Thomas for providing critical feedback to improve this document
   early on.

   This document was prepared using 2-Word-v2.0.template.dot.













Asati, et. al           Expires April 15, 2011                  [Page 7]

Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010


10. References

10.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5036] Andersson, L., Minei, I., and Thomas, B., "LDP
             Specification", RFC 5036, October 2007.

   [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
             (IPv6) Specification", RFC 2460, December 1998.

   [RFC4291] Hinden, R. and S. Deering, "Internet Protocol Version 6
             (IPv6) Addressing Architecture", RFC 3513, April 2003.





10.2. Informative References

   [RFC4301] Kent, S. and K. Seo, "Security Architecture and Internet
             Protocol", RFC 4301, December 2005.

   [RFC4835] Manral, V., "Cryptographic Algorithm Implementation
             Requirements for Encapsulating Security Payload (ESP) and
             Authentication Header (AH)", RFC 4835, April 2007.

   [IANA-IPv6] http://www.iana.org/assignments/ipv6-address-space.



















Asati, et. al           Expires April 15, 2011                  [Page 8]
Internet-Draft        draft-manral-mpls-ldp-ipv6         Oct 13, 2010


Author's Addresses

   Vishwas Manral
   IP Infusion Inc.,
   Bamankhola, Bansgali,
   Almora, Uttarakhand 263601
   Email: vishwas@ipinfusion.com


   Rajiv Papneja
   ISOCORE
   12359 Sunrise Valley Dr, STE 100
   Reston, VA 20190
   Email: rpapneja@isocore.com


   Rajiv Asati
   Cisco Systems,
   7025-6 Kit Creek Rd, RTP, NC, 27709-4987
   Email: rajiva@cisco.com


Html markup produced by rfcmarkup 1.107, available from http://tools.ietf.org/tools/rfcmarkup/