Re: draft-ietf-mpls-rsvp-te-p2mp-06.txt [P2MP ID]

[Yakov Rekhter <yakov@juniper.net>]

Lou,

> Yakov,
>          Thank you for the concise response to a question that has 
> been outstanding for some time.  Now there are two specific aspects 
> to the proposed response (Rahul's) to the issues you raise below:
> 
> 1) Tunnel ID
> [From rahul's mail]
>   > 4.
>   > 19.1.1
>   >
>   > "Tunnel ID
>   >
>   >       A 16-bit identifier used in the SESSION object that remains
>   >       constant over the life of the P2MP tunnel."
>   >
>   > to
>   >
>   > "Tunnel ID
>   >
>   >       A 16-bit identifier used in the SESSION object that remains
>   >       constant over the life of the P2MP tunnel. It SHOULD be set to 0
>   >       by the ingress LSR and be ignored on receipt."
>   >
> 
> I don't see how this change, setting the ID to zero, relates to the 
> issue you raise.  Can  justify why this change is required?

This is orthogonal to the issue of P2MP ID uniqueness scope. 
  
> 2) Extended Tunnel ID
> [again from rahul's mail]
> 
>   > 5.
>   >
>   > "Extended Tunnel ID
>   >
>   >  A 32-bit identifier used in the SESSION object that remains
>   >       constant over the life of the P2MP tunnel.  Normally set to
>   >       all zeros. Ingress nodes that wish to narrow the scope of a
>   >       SESSION to the ingress-PID pair may place their IPv4 address
>   >       here as a globally unique identifier [RFC3209]."
>   >
>   > to
>   >
>   > "Extended Tunnel ID
>   >
>   >       A 32-bit identifier used in the SESSION object that remains
>   >       constant over the life of the P2MP tunnel. This identifier
>   >       MUST be set to the ingress LSR's IPv4 address."
> 
> So the original text, allowed for global uniqueness and included a 
> "well-established procedures for assigning (globally) unique" P2MP IDs.

Could you please point me to the text that spells out procedures
for assigning P2MP IDs that are globally unique *on their own* (not
in a combination with the Extended Tunnel ID).

> It seems to me that the -05 text covered the issue you raised.  So 
> now we come to the heart of the matter:  Why is a change in the -05 
> definition of the IDs needed?
> 
> It seems to me that at most the text needs to replace a "may" with a 
> "MUST", as in "Ingress nodes that wish to narrow the scope of a 
> SESSION to the ingress-PID pair MUST place their..."

That is necessary, but not sufficient. Here are the changes that
need to be made:

1. Section 4.1:

   A P2MP TE Tunnel comprises one or more P2MP LSPs. A P2MP TE Tunnel is
   identified by a P2MP SESSION object. This object contains the
   identifier of the P2MP Session which includes the P2MP ID, a tunnel
   ID and an extended tunnel ID.

   The fields of a P2MP SESSION object are identical to those of the
   SESSION object defined in [RFC3209] except that the Tunnel Endpoint
   Address field is replaced by the P2MP Identifier (P2MP ID) field.

   The P2MP ID provides an identifier for the set of destinations of the
   P2MP TE Tunnel.

The last sentence above has to be deleted.

2. Section 19.1.1 replace:

 P2MP ID

      A 32-bit identifier used in the SESSION object that remains
      constant over the life of the P2MP tunnel. It encodes the
      P2MP ID and identifies the set of destinations of the P2MP
      Tunnel."

with the following:

 P2MP ID

      A 32-bit identifier used in the SESSION object that remains
      constant over the life of the P2MP tunnel. It encodes the
      P2MP Identifier that is unique within the scope of the Ingress LSR
      whose IP address is carried in the Extended Tunnel ID.

3. Section 19.1.1 replace

  Extended Tunnel ID
 
       A 32-bit identifier used in the SESSION object that remains
       constant over the life of the P2MP tunnel.  Normally set to
       all zeros. Ingress nodes that wish to narrow the scope of a
       SESSION to the ingress-PID pair may place their IPv4 address
       here as a globally unique identifier [RFC3209]."

with the following:
 
  Extended Tunnel ID
 
       A 32-bit identifier used in the SESSION object that remains
       constant over the life of the P2MP tunnel.  Ingress nodes
       that use the locally scoped  P2MP ID MUST place their IPv4
       address here; a combination of this address and P2MP ID
       provides a globally unique identifier for the P2MP tunnel.
  
4. Make similar changes in 19.1.2

Yakov.