One document matched: draft-ietf-isis-link-attr-01.txt

Differences from draft-ietf-isis-link-attr-00.txt

   ISIS WG                                                              
   Internet Draft                                 Jean-Philippe Vasseur 
                                                        Stefano Previdi 
                                                          Cisco Systems 
                                                                        
   Proposed Status : Standard                                           
   Expires: November 2005                                      May 2005 
    
    
               Definition of an IS-IS Link Attribute sub-TLV  
                                      
                     draft-ietf-isis-link-attr-01.txt 
    
    
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Abstract 
    
   This document defines a sub-TLV called "Link-attributes" 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 [i]. 
    
 
    
 
 
 

draft-ietf-isis-link-attr-01.txt                               May 2005 

 
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. IANA considerations............................................3 
   6. Intellectual Property Considerations...........................3 
   7. Acknowledgments................................................4 
   8. References.....................................................4 
      8.1 Normative references.......................................4 
      8.2 Informative references.....................................4 
   9. Authors' Addresses.............................................5 
   Full Copyright Statement..........................................5 
 
 
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 optimize the encoding of IS-IS prefixes.  
    
   This document defines a new sub-TLV named "Link-attributes" 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 sub-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 the 
   value field in this case, a 16 bit flags field. 
    
   The Link-attribute sub-type is 19 (to be assigned by IANA) and has a 
   length of 2 octets. 
    
   This sub-TLV is OPTIONAL and MAY appear at most once for a single IS 
   neighbor. 
    
   The following bits are defined: 
    


 
 
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draft-ietf-isis-link-attr-01.txt                               May 2005 

   Local Protection Available (0x01). When set, this indicates that the 
   link is protected by means of some local protection mechanism (e.g 
   [FRR]). 
    
   Link excluded from local protection path (0x02). When set, this link 
   SHOULD not be included in any computation of a repair path by any 
   other router in the routing area. The triggers for setting up this 
   bit are out of the scope of this document. 
    
   Such link characteristics has several applications such as 
   constrained shortest path computation for a Traffic Engineering Label 
   Switched (TE LSP) path or the triggering of specific actions in the 
   context of IS-IS SPF computation. 
    
   Local maintenance required (0x04). When set, this indicates that the 
   link will be put out of service and will consequently be shortly 
   unavailable. The set of actions triggered by other nodes is out of 
   the scope of this document. An example of the usage of this bit is 
   provided in [GR-SHUT]. 
    
3. Interoperability with routers non supporting this capability 
 
   A router not supporting the link-attribute sub-TLV MUST just silently 
   ignore this sub-TLV. 
    
   Where the information in the link attributes sub-TLV is used to 
   affect the IS-IS SPF calculation, additional information indicating 
   which routers are using this information is required to insure such 
   usage does not result in loops or black holes. How this additional 
   information is conveyed is outside the scope of this document. 
  
4. Security considerations 
 
   No new security issues are raised in this document. 
    
5. IANA considerations 
 
   IANA will assign a new codepoint for the link-attribute sub-TLV 
   defined in this document and carried within TLV 22. Suggested value 
   is 19 (to be assigned by IANA). 
    
6. Intellectual Property Considerations 
    
   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 

 
 
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   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. 
    
7. Acknowledgments 
    
   The authors would like to thank Mike Shand and Les Ginsberg for their 
   useful comments. 
 
 
8. References 
 
8.1 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, "IS-IS extensions for traffic 
   engineering", RFC 3784. 
    
8.2 Informative references 
    
   [FRR] Ping Pan, et al, "Fast Reroute Extensions to RSVP-TE for LSP 
   Tunnels", draft-ietf-mpls-rsvp-lsp-fastreroute-07.txt. Work in 
   progress. 
     
   [GR-SHUT], Z. Ali et al, "Graceful Shutdown in MPLS Traffic 
   Engineering Networks", draft-ali-ccamp-mpls-graceful-shutdown-01.txt. 
   Work in progress. 

 
 
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9. Authors' 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 
    
Full Copyright Statement 
    
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   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 
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