The MPLS WG Archive

["Bhaskara P" <bhaskarap@rediffmail.com>]

Hi Kireeti and Yokov,

Whenever I read RFC 3477(Signalling Unnumbered Links in Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)), it leaves me in more confusion than clarification.  If we have a simple topology of 3 node LSP like below,

     Interfaces    1         2        3         4
            Node A ----------- Node B ----------- Node C

RFC 3477 suggests one can do ERO signalling from ingress Node A in either of the following formats

  format 1:   ERO with Router ID and out going interface Id of Node

              <Router Id of A>, <Interface 1>
              <Router Id of B>, <Interface 3>

  format 2:   ERO with Router ID and in coming interface of the Node

              <Router Id of B>, <interface 2>
              <Router Id of C>, <interface 4>

1) If the above statement is true, how should RRO for this LSP be encoded  i.e., in format 1 or format 2?. 

2) Which format  should the ingress node A, receive RRO object?   

3) Is RRO always seen by ingress Node A, should be always in the format of ERO singalled by ingress.  i.e., if ingress node singalls ERO in format 1, then it should recieve RRO in same format. or RRO should follow always format 1 irrespective of ERO format.

These formats are very important to inter-op between vendors. Can any please clarify the above issues and how the RRO and ERO inerop between the vendors achieved?

thank you
bhaskara