One document matched: draft-vasseur-isis-link-attr-00.txt

   ISIS WG                                                              
   Internet Draft                                 Jean-Philippe Vasseur 
                                                        Stefano Previdi 
                                                          Cisco Systems 
                                                                        
   Document: draft-vasseur-isis-link-attr-                              
   00.txt 
   Expires: August 2004                                   February 2004 
    
    
               Definition of an IS-IS Link Attribute sub-TLV  
                                      
                    draft-vasseur-isis-link-attr-00.txt 
    
    
Status of this Memo 
    
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026 [i].  
    
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Abstract 
    
   This document proposes the definition of a sub-TLV called ôlink-
   attributeö carried within the TLV 22 and used to flood some link 
   characteristics. 
    
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 [ii]. 
    
 
 
 
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Table of contents 
 
   1. Introduction...................................................2 
   2. Link-attributes sub-TLV format.................................2 
   3. Interoperability with routers non supporting this capability...3 
   4. Security considerations........................................3 
   5. Intellectual Property Considerations...........................3 
   6. Acknowledgments................................................4 
   7. References.....................................................4 
   Normative references..............................................4 
   Informative references............................................4 
   8. Author's Addresses.............................................4 
 
 
1. 
  Introduction 
    
   [IS-IS] specifies the IS-IS protocol (ISO 10589) with extensions to 
   support IPv4 in [IS-IS-IP]. A router advertises one or several Link 
   State Protocol data units which are composed of variable length 
   tuples called TLVs (Type-Length-Value). 
    
   [IS-IS-TE] defines a set of new TLVs whose aims are to add more 
   information about links characteristics, increase the range of IS-IS 
   metrics and improve the encoding of IS-IS prefixes.  
    
   This document defines a new sub-TLV named ôLink-attributesö carried 
   within the extended IS reachability TLV (type 22) specified in [IS-
   IS-TE]. 
    
2. 
  Link-attributes sub-TLV format 
    
   The link-attribute sub-TLV is carried within the TLV 22 and has a 
   format identical to the TLV format used by the Traffic Engineering 
   Extensions for IS-IS [IS-IS-TE]: 1 octet of sub-type, 1 octet of 
   length of the value field of the sub-TLV followed by a 16 set of bit 
   flags. 
    
   The Link-attribute sub-type is 19 (to be assigned by IANA) and has a 
   length of 2 octets bit mask. 
    
   This sub-TLV is OPTIONAL and MUST appear at most once. 
    
   The following bits are defined: 
    

 
 
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   0x01: ôLocal Protection Availableö. When set, this indicates that the 
   link is protected by means of some local protection mechanism (e.g 
   [FRR]). 
    
   0x02: ôLocal protection in useö. When set, this indicates that the 
   local protection for the link in question is currently active. 
    
   Such link characteristics has several applications such as 
   constrained shortest path computation for a Traffic Engineering Label 
   Switched (TE LSP) path, triggering of specific actions in the context 
   of IS-IS SPF computation. 
    
   0x04: ôLink excluded from local protection pathö. When set, this link 
   SHOULD not be included in any computation of a repair path by any 
   other router in the routing area. 
    
3. 
  Interoperability with routers non supporting this capability 
 
   There is no interoperability issue as a router not supporting the 
   link-attribute sub-TLV MUST just silently ignore this sub-TLV. 
    
4. 
  Security considerations 
 
   No new security issues are raised in this document. 
    
5. 
  Intellectual Property Considerations 
    
   The IETF takes no position regarding the validity or scope of any 
   intellectual property 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; neither does it represent that it 
   has made any effort to identify any such rights. Information on the 
   IETF's procedures with respect to rights in standards-track and 
   standards-related documentation can be found in BCP-11. Copies of 
   claims of rights made available for publication 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 implementors or users of this specification can 
   be obtained from the IETF Secretariat. 
    
   The IETF invites any interested party to bring to its attention any 
   copyrights, patents or patent applications, or other proprietary 
   rights which may cover technology that may be required to practice 
   this standard. Please address the information to the IETF Executive 
   Director. 
    
   The IETF has been notified of intellectual property rights claimed in 
   regard to some or all of the specification contained in this 
 
 
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   document.  For more information consult the online list of claimed 
   rights. 
    
    
6. 
  Acknowledgments 
    
   The authors would like to thank Mike Shand for his comments. 
 
7. 
  References 
 
Normative references 
 
   [RFC] Bradner, S., "Key words for use in RFCs to Indicate Requirement 
   Levels," RFC 2119. 
    
   [IS-IS] "Intermediate System to Intermediate System Intra-Domain 
   Routeing Exchange Protocol for use in Conjunction with the Protocol 
   for Providing the Connectionless-mode Network Service (ISO 8473)",       
   ISO 10589. 
    
   [IS-IS-IP] Callon, R., RFC 1195, "Use of OSI IS-IS for routing in 
   TCP/IP and dual environments", RFC 1195, December 1990. 
    
   [IS-IS-TE] H. Smit, T. Li, ôIs-IS extensions for traffic 
   engineeringö, draft-ietf-isis-traffic, work in progress. 
    
Informative references 
    
   [FRR] Ping Pan, et al, "Fast Reroute Extensions to RSVP-TE for LSP 
   Tunnels", draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt, December 2003. 
     
 
8. 
  Author's Addresses 
    
      Jean-Philippe Vasseur 
      CISCO Systems, Inc. 
      300 Beaver Brook 
      Boxborough, MA 01719 
      USA 
      Email: jpv@cisco.com 
    
      Stefano Previdi 
      CISCO Systems, Inc. 
      Via Del Serafico 200 
      00142 - Roma 
      ITALY 
      Email: sprevidi@cisco.com 
    
         
 
 
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