Targeted LDP Hello Reduction
draft-pdutta-mpls-tldp-hello-reduce-03

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MPLS Working Group                                  Pranjal Kumar Dutta 
Internet Draft                                           Alcatel-Lucent 
Intended status: Standard                               
Expires: November 2012                                       Giles Heron 
                                                           Cisco Systems 
                                                                                 
                                                           Thomas Nadeau 
                                                         CA Technologies 
                                    
                                                           May 20, 2012 
                                      
                       Targeted LDP Hello Reduction  
                draft-pdutta-mpls-tldp-hello-reduce-03.txt 

Status of this Memo 

   This Internet-Draft is submitted to IETF in full conformance with the 
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   This Internet-Draft will expire on November 20, 2012. 

Abstract 

   Targeted LDP Hellos are used for establishing adjacencies with non-
   directly connected peers. After an LDP session is established to a 
   targeted peer, the session Keepalives are sufficient to notify the 
   intent of an LSR to maintain its adjacency with the peer. This 
   document proposes a mechanism to turn off Targeted LDP Hellos after 
   LDP session is established to a peer. 

 
 
 
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Internet-Draft          T-LDP Hello Reduction                  May 2012 
    

 

Table of Contents 

    
   1. Introduction...................................................2 
   2. Conventions used in this document..............................3 
   3. Terminology....................................................3 
   4. Targeted LDP Hello Reduction Procedure.........................3 
   5. Security Considerations........................................5 
   6. IANA Considerations............................................5 
   7. Conclusion.....................................................5 
   8. References.....................................................5 
      8.1. Normative References......................................5 
      8.2. Informative References....................................5 
   9. Acknowledgments................................................6 
    
1. Introduction 

   LDP Hello messages are exchanged as part of the LDP discovery 
   mechanism [RFC5036]. There are two types of LDP discovery mechanism 
   described in [RFC5036] - Basic Discovery and Extended Discovery.  

   To engage in LDP Basic Discovery on an interface, an LSR periodically 
   sends LDP Link Hellos out the interface to the well-known LDP 
   discovery port for the "all routers on this subnet" group multicast 
   address. Receipt of an LDP Link Hello on an interface, identifies a 
   hello adjacency with a potential LDP peer reachable at the link level 
   on the interface. Thus an LSR may establish hello adjacency with 
   multiple peers discovered over a single interface and must continue 
   to transmit hellos at regular intervals even after hello adjacency is 
   established to a peer. 

   Extended discovery is used to support LDP sessions between non-
   directly connected LSRs. An LDP Targeted Hello is sent to a specific 
   address rather than to the "all routers" group multicast address for 
   the ongoing interface. Receipt of a LDP Targeted Hello indentifies a 
   hello adjacency with a potential LDP peer at network level. 

   In Extended discovery there can be only one Targeted Hello Adjacency 
   between two peers. Note that throughout this document "peer" means 
   the LDP LSR designated by a unique LDP Identifier. Once the LDP 
   session is operational between two targeted LDP peers, periodic 
   session Keepalives are used to maintain the LDP session. After the 
   session is operational the periodic Targeted Hellos between the LSRs 
   become redundant, as session Keepalives in turn serves the intent of 
   each LSR to maintain its adjacency to its peer.  
 
 
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