Subject: Re: Out of Order

From: Bob Braden <[email-masked]>
Date: Sun, 28 Nov 1999 17:45:18 -0800 (PST)

*> 
  *> What guarantee is there that:
  *> 
  *> 1) Actual traffic goes out on the same egress i/f as the PATH message?

If it does not use the same egress interface, the implementation has a bug.
The protocol requires that a Path message go out the same interface
as the corresponding data.

  *> 2) The PATHTEAR goes out on the same egress i/f as the PATH message?

Ditto.

  *> 
  *> If you're doing load-balancing then surely it is necessary to duplicate the
  *> PATH messages across each route, and the corresponding RESV meassges will
  *> need to be duplicated in the reverse direction? Interesting question there
  *> as to how to split the Flowspec (e.g. half the traffic split 2-ways)....
  *> 

The load-balancing issue has been previously discussed on this list,
although you are raising an int-serv more than an RSVP issue here.

  *> 
  *> Regarding PATHTEAR, RFC 2205 states that the IP desitination address of the
  *> PATHTEAR is the session dest address. This may not go out on the same i/f
  *> as the PATH message. If instead it routed on N-HOP (from the RSB(s)) then
  *> it would.
  *> 
  *> 

There is no difference between the forwarding of a Path message or a
PathTear message with respect to the choice of interfaces.

Bob Braden

  *> 
  *> 
  *> Graham
  *> 
  *>

---

From: Bob Braden <[email-masked]>
Date: Sun, 28 Nov 1999 17:49:24 -0800 (PST)

*> 
  *> So in the RSVP implementation, you may want to record the ingress
  *> interface information for each PATH state, and only process the messages
  *> with the correct ingress interface. In this example, you should drop the
  *> PATHTEAR, and let the soft-state to remove the reservation eventually.
  *> 

PHOP for unicast, ingress interface for multicast.  This point is made
(perhaps somewhat obscurely) in section 3.1.3 of rfc2205, and given
more substance in rfc2209.

Bob Braden