INTERNET-DRAFT                               Danny McPherson
                                              Arbor Networks
                                                Naiming Shen
                                               Cisco Systems
Expires: March 2008                       September 30, 2007
Intended Status: Proposed Standard

             Dynamic Hostname Exchange Mechanism for IS-IS
                  <draft-ietf-isis-rfc2763bis-00.txt>



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   Copyright (C) The IETF Trust (2007).






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                                Abstract


   Currently, there does not exist a simple and dynamic mechanism for
   routers running IS-IS to learn about symbolic hostnames. This
   document defines a new TLV which allows the IS-IS routers to flood
   their name-to-systemID mapping information across the IS-IS network.

   The intention of this document is to provide an update to [RFC 2763].










































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Table of Contents


   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .   4
    1.1. Specification of Requirements . . . . . . . . . . . . . . .   4
   2. Possible Solutions . . . . . . . . . . . . . . . . . . . . . .   4
   3. Dynamic Hostname TLV . . . . . . . . . . . . . . . . . . . . .   5
   4. Implementation . . . . . . . . . . . . . . . . . . . . . . . .   6
   5. Security Considerations. . . . . . . . . . . . . . . . . . . .   6
   6. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . .   6
   7. IANA Considerations. . . . . . . . . . . . . . . . . . . . . .   7
   8. References . . . . . . . . . . . . . . . . . . . . . . . . . .   8
    8.1. Normative References. . . . . . . . . . . . . . . . . . . .   8
    8.2. Informative References. . . . . . . . . . . . . . . . . . .   8
   9. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . .   8




































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.  Introduction


   IS-IS uses a variable 1-8 byte system ID (normally 6 bytes) to
   represent a node in the network.  For management and operation
   reasons, network operators need to check the status of IS-IS
   adjacencies, entries in the routing table and the content of the IS-
   IS link state database.  It is obvious that, when looking at
   diagnostics information, hexadecimal representations of systemIDs and
   LSP identifiers are less clear than symbolic names.

   One way to overcome this problem is to define a name-to-systemID
   mapping on a router. This mapping can be used bidirectionally. E.g.,
   to find symbolic names for systemIDs, and to find systemIDs for
   symbolic names. One way to build this table of mappings is by static
   definitions. Among network administrators who use IS-IS as their IGP
   it is current practice to define such static mappings.

   Thus every router has to maintain a statically configured table with
   mappings between router names and systemIDs. These tables need to
   contain all names and systemIDs of all routers in the network, and
   must be modified each time an addition, deletion or change occurs..

   There are several ways one could build such a table. One is via
   static configurations. Another scheme that could be implemented is
   via DNS lookups. In this document we propose a third solution. We
   hope the proposed solution is easier and more manageable than static
   mapping or DNS schemes, and wide-scale implementation and deployment
   of this capability has proved this to be the case.



1.1.  Specification of Requirements


   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 [RFC 2119].



.  Possible Solutions


   The obvious drawback of static configuration of mappings is the issue
   of scalability and maintainability. The network operators have to
   maintain the name tables. They have to maintain an entry in the table
   for every router in the network, on every router in the network. The



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   effort to create and maintain these static tables grows with the
   total number of routers on the network.  Changing the name or
   systemID of one router, or adding one new router introduced will
   affect the configurations of all the other routers on the network.
   This will make it very likely that those static tables are outdated.

   Having one table that can be updated in a centralized place would be
   helpful. One could imagine using the DNS system for this. A drawback
   is that during the time of network problems, the response time of DNS
   services might not be satisfactory or the DNS services might not even
   be available. Another possible drawback might be the added complexity
   of DNS. Also, some DNS implementations might not support A and PTR
   records for CLNS NSAPs.

   A third way to build dynamic mappings would be to use the transport
   mechanism of the routing protocol itself to advertise symbolic names
   in IS-IS link-state PDUs. This document defines a new TLV which
   allows the IS-IS routers to include the name-to-systemID mapping data
   in their LSPs. This will allow simple and reliable transport of name
   mapping information across the IS-IS network.



.  Dynamic Hostname TLV


   The Dynamic hostname TLV is defined here as TLV type 137.

         LENGTH - total length of the value field.

         VALUE - a string of 1 to 255 bytes.

   The Dynamic hostname TLV is optional. This TLV may be present in any
   fragment of a non-pseudo node LSP. The value field identifies the
   symbolic name of the router originating the LSP. This symbolic name
   can be the FQDN for the router, it can be a subset of the FQDN or any
   string operators want to use for the router. The use of FQDN or a
   subset of it is strongly recommended. The content of this value is a
   domain name, see [RFC 2181]. The string is not null-terminated. The
   systemID of this router can be derived from the LSP identifier.

   If this TLV is present in a pseudo node LSP, then it SHOULD NOT be
   interpreted as the DNS hostname of the router.








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.  Implementation


   The Dynamic Hostname TLV is optional. When originating an LSP, a
   router may decide to include this TLV in its LSP. Upon receipt of an
   LSP with the dynamic hostname TLV, a router may decide to ignore this
   TLV, or to install the symbolic name and systemID in its hostname
   mapping table for the IS-IS network.

   A router may also optionally insert this TLV in it's pseudo node LSP
   for the association of a symbolic name to a local LAN.



.  Security Considerations


   This document raises no new security issues for IS-IS.



.  Acknowledgments


   The original efforts and corresponding acknowledgements provided in
   [RFC 2763] have enabled this work.  In particular, we'd like to
   acknowledge Henk Smit as an author of that document.

   Others to be provided....






















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.  IANA Considerations


   This document specificies TLV 137, "Dynamic Name".  This TLV has
   already been allocated and reserved [RFC 2763].  As such, no new
   actions are required on the part of IANA.













































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.  References




8.1.  Normative References


   [ISO 8473] ISO, "Intermediate system to Intermediate system
       routeing information exchange protocol for use in conjunction
       with the Protocol for providing the Connectionless-mode Network
       Service (ISO 8473)," ISO/IEC 10589:1992.



8.2.  Informative References


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

   [RFC 2181] Elz, R., Bush, R., "Clarifications to the DNS
       Specification", RFC 2181, July 1997.

   [RFC 2763] Smit, H., Shen, N., "Dynamic Hostname Exchange
       Mechanism for IS-IS, RFC 2763, February 2000.



.  Authors' Addresses



   Danny McPherson
   Arbor Networks, Inc.
   EMail:  danny@arbor.net

   Naiming Shen
   Cisco Systems, Inc.
   EMail: naiming@cisco.com



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McPherson, Shen                                     Section 9.  [Page 9]