Subject: Re: TE-MIB and RSVP

From: [email-masked]
Date: Tue, 3 Jul 2001 07:31:44 +0200

Manasa,

As Suresh indicates it is possible to share resources between the working path and the path used for protection. However, when doing this a price is paid in terms of a reduced protection: if a link / node that is used by both the working path and the
protecting path fails, both paths are gone.

     Francis.

Suresh Katukam <[email-masked]> on 03/07/2001 01:52:58

 To:      Manasa M <[email-masked]>                        
                                                              
 cc:      [email-masked](bcc: Francis ARTS/BE/ALCATEL)           

 Subject: Re: TE-MIB and RSVP                                 

Manasa,

>
> 1)Can we have a parallel tunnels with same tunnel id but, with a different tunnel instances running and
> loading sharing traffic with different paths altogether from ingress to egress, not just for
> make before break or rerouting a part of the path.
> for example in the case of SONET/SDH ring, can we use it as one instance is for working path and 2nd instance is for protection path?

For Load Sharing, It does not have to be a same tunnel ID as long as
Source and Destination know that there are two LSPs for Load Sharing.

Anyways, Yes, You can have same Tunnel ID with different LSP ids. This
is possible and it is upto Source and Destination to use these LSPs the
way they want. If you do not use SE bit, then these are for all practical
purposes, are two different LSPs. You could use SE bit to avoid setting up
bandwidth twice on a common set of links.

For example, in SONET BLSR, I do not think that you need to set up
two instances of LSPs since standard BLSR mechanism takes care of protection.
Ofcourse, this results in adjacent nodes time out RSVP states etc. I
think you are not supposed to delete the LSP except indicate to Source
or Destination of the LSP that you lost connection with your neighbor.
Source or Destination can look into the health of LSP data traffic and
also realize that BLSR link went down, it could keep the LSP alive
until it sees the data on LSP is affected.

For Standard UPSR, similar mechanism applies.

For Virtual UPSR (Or 1+1 path Protection), you would set up two
LSPs with same Tunnel ID, but different LSP ids.

Thanks,
Suresh

---

From: David Charlap <[email-masked]>
Date: Mon, 09 Jul 2001 10:10:41 -0400

[email-masked] wrote:
> 
> As Suresh indicates it is possible to share resources between the
> working path and the path used for protection. However, when doing
> this a price is paid in terms of a reduced protection: if a link /
> node that is used by both the working path and the protecting path
> fails, both paths are gone.

The use of SE style does not change this fact.

SE style will allow common links to share resources.  It has no impact
over which links may or may not be common.  That is decided by the
ingress node when it generates the ERO objects.

-- David