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Versions: (draft-martin-isis-admin-tags) 00 01 02 03 04 RFC 5130

      IS-IS Working Group                                    Christian Martin
                                                                       Verizon
      IETF Internet Draft                                     Stefano Previdi
                                                                 Cisco Systems
                                                                    Brad Neal
                                                      Broadwing Communications
      
      
      
      
      Expires: August 2005                                       February 2005
      
      
              A Policy Control Mechanism in IS-IS Using Administrative Tags
      
      
                      <draft-ietf-isis-admin-tags-03.txt>
      
      
      Status of this Memo
      
         By submitting this Internet-Draft, I certify that any applicable
         patent or 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.
      
         This document is an Internet-Draft and is in full conformance with
         all provisions of Section 10 of RFC2026. 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.
      
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         and may be updated, replaced, or obsoleted by other documents at any
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         material or to cite them other than as "work in progress."
      
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      Martin, Previdi, Neal.                                          [Page 1]


      Internet Draft    draft-ietf-isis-admin-tags-03.txt      February 2005
      
      
      Abstract
      
         This document describes an extension to the IS-IS protocol to add
         operational capabilities that allow for ease of management and
         control over IP prefix distribution within an IS-IS domain. This
         document enhances the IS-IS protocol by extending the information
         that a Intermediate System (IS) [router] can place in Link State
         Protocol Data Units (LSPs) for policy use. This extension will
         provide operators with a mechanism to control IP prefix distribution
         throughout multi-level IS-IS domains. Additionally, the information
         can be placed in LSPs that have TLVs as yet undefined, if this
         information is used to convey the same meaning in these future TLVs
         as it is used in the currently defined TLVs.
      
      
      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 RFC-2119.
      
      
      
      1. Introduction
      
      
         As defined in [2] and extended in [3], the IS-IS protocol may be used
         to distribute IPv4 prefix reachability information throughout an IS-
         IS domain. In addition, thanks to extensions made in [6] and [7], IS-
         IS may be used to distribute IPv6 reachability information.
      
      
         The IPv4 prefix information is encoded as TLV type 128 and 130 in
         [2], with additional information carried in TLV 135 as specified in
         [3] and TLV 235 as defined in [6].  In particular, the extended IP
         Reachability TLV (TLV 135) contains support for a larger metric
         space, an up/down bit to indicate redistribution between different
         levels in the hierarchy, an IP prefix, and one or more sub-TLVs that
         can be used to carry specific information about the prefix. TLV 235
         is a derivative of TLV 135, with the addition of Multi-Topology
         membership information [6]. The IPv6 prefix information is encoded as
         TLV 236 in [7] and TLV 237 in [6].
      
      
         As of this writing no sub-TLVs have been defined; however, this draft
         proposes 2 new sub-TLVs for TLV 135, TLV 235, TLV 236 and TLV 237
         that may be used to carry administrative information about an IP
         prefix.
      
      
      
      
      
      Martin, Previdi, Neal.                                        [Page 2]


      Internet Draft    draft-ietf-isis-admin-tags-03.txt      February 2005
      
      
      2. Sub-TLV Additions
      
      
         This draft proposes 2 new "Administrative Tag" sub-TLVs to be added
         to TLV 135, TLV 235, TLV 236 and TLV 237.  These TLVs specify one or
         more ordered, 32 or 64 bit unsigned integers that may be associated
         with an IP prefix. Example uses of these tags include controlling
         redistribution between levels and areas, different routing protocols,
         or multiple instances of IS-IS running on the same router, or
         carrying BGP standard or extended communities.
      
      
         The methods for which their use is employed is beyond the scope of
         this document and left to the implementer and/or operator.
      
      
         The encoding of the sub-TLV(s) is discussed in the following
         subsections.
      
      
         2.1. 32-bit Administrative Tag Sub-TLV 1
      
      
         The Administrative Tag SHALL be encoded as one or more 4 octet
         unsigned integers using Sub-TLV 1 in TLV-135 [3], TLV 235 [6], TLV
         236 [7] and TLV 237 [6]. The Administrative Tag Sub-TLV has following
         structure:
      
      
                 1 octet of type (value: 1)
                 1 octet of length (value: multiple of 4)
                 one or more instances of 4 octets of administrative tag
      
      
         An implementation MAY consider only one of the encoded tags, in which
         case the first encoded tag MUST be considered.  A tag value of zero
         is reserved and SHOULD be treated as "no tag".
      
      
         2.2. 64-bit Administrative Tag Sub-TLV 2
      
      
         The Administrative Tag SHALL be encoded as one or more 8 octet
         unsigned integers using Sub-TLV 2 in TLV-135 [3], TLV 235 [6], TLV
         236 [7] and TLV 237 [6]. The 64-bit Administrative Tag Sub-TLV has
         following structure:
      
      
                 1 octet of type (value: 2)
                 1 octet of length (value: multiple of 8)
                 one or more instances of 8 octets of administrative tag
      
      
      
      
      Martin, Previdi, Neal.                                        [Page 3]


      Internet Draft    draft-ietf-isis-admin-tags-03.txt      February 2005
      
         An implementation MAY consider only one of the encoded tags, in which
         case the first encoded tag MUST be considered.  A tag value of zero
         is reserved and SHOULD be treated as "no tag".
      
      
      
      3. Ordering of Tags
      
      
         The semantics of the tag order are implementation-dependent.  That
         is, there is no implied meaning to the ordering of the tags that
         indicates a certain operation or set of operations need be performed
         based on the order of the tags.  Each tag SHOULD be treated as an
         autonomous identifier that MAY be used in policy to perform a policy
         action.  Whether or not tag A precedes or succeeds tag B SHOULD not
         change the meaning of the tag set.  However, an implementation MAY
         wish to preserve tag ordering such that an ordered set of tags has
         meaning to the local policy.
      
      
         Each IS that receives an LSP with TLV(s) 135 and/or 235 and/or 236
         and/or 237, that have associated SubTLV(s) 1 and/or 2, MAY operate on
         the tag values as warranted by the implementation.  If an
         implementation needs to change tag values, for example, at an area
         boundary, then the TLV(s) SHOULD be copied to the newly generated
         Level-1 or Level-2 LSP at which point, the contents of the SubTLV(s)
         MAY change as dictated by the policy action.  In the event that no
         change is required, the SubTLV(s) SHOULD be copied in order into the
         new LSP, such that ordering is preserved.
      
      
      
      4. Compliance
      
      
         A compliant IS-IS implementation MUST be able to assign one tag to
         any IP prefix in any of the following TLVs: TLV 135, TLV 235, TLV
         236, TLV 237.
      
      
         A compliant IS-IS implementation MAY be able to assign more than one
         tag to any IP prefix in any of the following TLVs: TLV 135, TLV 235,
         TLV 236, TLV 237.
      
      
         A compliant IS-IS implementation MAY be able to rewrite or remove one
         or more tags associated with a prefix in any of the following TLVs:
         TLV 135, TLV 235, TLV 236, TLV 237.
      
      
      5. Operations
      
      
         An administrator associates an Administrative Tag value with some
         interesting property.  When IS-IS advertises reachability for some IP
      
      Martin, Previdi, Neal.                                        [Page 4]


      Internet Draft    draft-ietf-isis-admin-tags-03.txt      February 2005
      
         prefix that has that property, it adds the Administrative Tag to the
         IP reachability information TLV for that prefix, and the tag "sticks"
         to the prefix as it is flooded throughout the routing domain.
      
      
         Consider the network in figure 1. We wish to "leak" L1 prefixes [5]
         with some property, A, from L2 to the L1 router R1.  Without policy-
         groups, there is no way for R2 to know property A prefixes from
         property B prefixes.
      
      
      
                             R2--------R3--------R4
                      L2     /                    \
                      - - - /- - - - - - - - - - - - - -
                      L1   /                        \
                         R1----1.1.1.0/24 (A)       R5
                                                     |
                                                     |
                                               1.1.2.0/24 (B)
      
      
      
                                    Figure 1
      
      
      
         We associate Administrative Tag 100 with property A, and have R5
         attach that value to the IP extended reachability information TLV for
         prefix 1.1.2.0/24. R2 has a policy in place to "match prefixes with
         Administrative Tag 100, and leak to L1."
      
      
         The previous example is rather simplistic; it seems that it would be
         just as easy for R2 simply to match the prefix 1.1.2.0/24. However,
         if there are a large number of routers that need to apply some policy
         according to property A and large number of "A" prefixes, this
         mechanism can be quite helpful.
      
      
      6. Security Considerations
      
      
         This document raises no new security issues for IS-IS, as any
         annotations to IP prefixes should not pass outside the administrative
         control of the network operator of the IS-IS domain.  Such an
         allowance would violate the spirit of Interior Gateway Protocols in
         general and IS-IS in particular
      
      
      
      
      
      
      Martin, Previdi, Neal.                                        [Page 5]


      Internet Draft    draft-ietf-isis-admin-tags-03.txt      February 2005
      
      7. IANA Considerations
      
      
         The authors have chosen "1" as the type code of the 32-bits
         Administrative Tag Sub-TLV and "2" as the type code of the 64-bits
         Administrative Tag Sub-TLV. These values must be allocated by IANA.
      
      
      
      8. Intellectual Property Statement
      
      
         The IETF takes no position regarding the validity or scope of any
         Intellectual Property Rights or other rights that might be claimed to
         pertain to the implementation or use of the technology described in
         this document or the extent to which any license under such rights
         might or might not be available; nor does it represent that it has
         made any independent effort to identify any such rights. Information
         on the procedures with respect to rights in RFC documents can be
         found in BCP 78 and BCP 79.
      
         Copies of IPR disclosures made to the IETF Secretariat and any
         assurances of licenses to be made available, or the result of an
         attempt made to obtain a general license or permission for the use of
         such proprietary rights by implementers or users of this
         specification can be obtained from the IETF on-line IPR repository at
         http://www.ietf.org/ipr.
      
         The IETF invites any interested party to bring to its attention any
         copyrights, patents or patent applications, or other proprietary
         rights that may cover technology that may be required to implement
         this standard. Please address the information to the IETF at ietf-
         ipr@ietf.org..
      
         8.1. IPR Disclosure Acknowledgement
      
      
         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.
      
      
      
      9. Acknowledgments
      
      
         The authors would like to thank Henk Smit for clarifying the best
         place to describe this new information, Tony Li and Tony Przygienda
         for useful comments on this draft, Danny McPherson for some much
         needed formatting assistance, and Mike Shand for useful discussions
         on encoding structure of the sub-TLV.
      
      
      
      
      
      Martin, Previdi, Neal.                                        [Page 6]


      Internet Draft    draft-ietf-isis-admin-tags-03.txt      February 2005
      
      
      10. References
      
      
         10.1. Normative references
      
      
         [RFC] Bradner, S., "Key words for use in RFCs to indicate
         requirements levels", RFC 2119, March 1997.
      
         [RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78,
         RFC 3667, February 2004.
      
         [RFC3668] Bradner, S., Ed., "Intellectual Property Rights in IETF
         Technology", BCP 79, RFC 3668, February 2004.
      
         [1] "Intermediate System to Intermediate System Intra-Domain Routing
         Exchange Protocol " ISO 10589.
      
         [2] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and dual
         environments", RFC 1195, December 1990.
      
         [3] Li, T., Smit, H., "IS-IS extensions for Traffic Engineering", RFC
         3784, June 2004.
      
         [4] Adwuche, D., Malcolm, J., Agogbua, M., O'Dell, M. and McManus,
         J., "Requirements for Traffic Engineering Over MPLS," RFC 2702,
         September 1999.
      
         [5] Li,T., Przygienda, T., Smit, H., "Domain-wide Prefix Distribution
         with Two-Level IS-IS" RFC 2966, October 2000
      
         10.2. Informative References
      
      
         [6] Przygienda, T., Shen, N., Sheth, N., "M-ISIS: Multi Topology
         Routing in IS-IS", draft-ietf-isis-wg-multi-topology-03.txt, April
         2002.
      
         [7] Hopps, C., "Routing IPv6 with IS-IS", draft-ietf-isis-ipv6-
         05.txt, January 2003
      
      
      
      
      
      
      11. Editors' Address
      
      
          Christian Martin
          Verizon
          1880 Campus Commons Dr
          Reston, VA 20191
          Email: cmartin@verizon.com
      
      
      Martin, Previdi, Neal.                                        [Page 7]


      Internet Draft    draft-ietf-isis-admin-tags-03.txt      February 2005
      
      
          Stefano Previdi
          Cisco Systems, Inc.
          Via Del Serafico, 200
          00142 Roma - Italy
          email: sprevidi@cisco.com
      
      
          Brad Neal
          Broadwing Communications
          1835 Kramer Lane - Suite 100
          Austin, TX 78758
          USA
          Email: bneal@broadwing.com
      
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      Martin, Previdi, Neal.                                        [Page 8]
      

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