The MPLS WG Archive

[neil.2.harrison@bt.com]

Some comments:

1	Where did the requirements in section 1 come (and is there a
reference?):
"In order to meet the needs of realtime applications such as Voice
   over IP, it is highly desirable to be able to repair LSP tunnels in
   10s of milliseconds. "?

I would suggest voice would be one application where 1-2s of outage was
tolerable, cf  someone not answering a question immediately, but instead
thinking for a short period of time before answering.  In general I do not
believe customers would close down a voice call for an outage of the order
of 10ms, but they might on the order >3s.

2	At the top of page 5 in section 2 it says:
" When a failure occurs and the backup comes into use,......"

All user-plane (and indeed control-plane) failure modes must be identified
and specified in terms of entry/exit criteria and consequent actions before
we can meaningfully proceed with this draft. 

For the user-plane, the failure modes which must be considered/defined are:
-	simple below MPLS fabric server layer connectivity breaks;
-	simple within MPLS fabric connectivity breaks (at or below the LSP
level considered);
-	swapped LSPs, ie instead of A1->A2 and B1->B2 a defect creates
A1->B2 and B1->A2;
-	mismerged LSPs, eg instead of A1->A2 and B1->B2 a defect creates
A1->A2 and A1+B1->B2 say (though there are potentially several variations on
this).

For the latter 2 defects it will be vital to suppress the traffic due to
potential security/censorship/misbilling implications for carriers and
customers.  Speaking as a carrier these issues are requirements that must be
addressed.  This is not optional, and rigorous definitions must be provided
(or referenced). 

Neil Harrison
BT/Ignite/CTO/Network Architecture
Tel +44 1 604 820 724
mail neil.2.harrison@bt.com
 

> -----Original Message-----
> From: George Swallow [mailto:swallow@cisco.com]
> Sent: 29 March 2001 00:04
> To: mpls@UU.NET
> Subject: Last Call on RSVP Label Allocation for Backup Tunnels 
> 
> 
> This message commences a workgroup last call on "RSVP Label Allocation
> for Backup Tunnels" <draft-swallow-rsvp-bypass-label-01.txt>.  This
> draft is informational.  The last call closes April 11, 12 PM GMT.
> 
> ...George
> 
> ======================================================================
> George Swallow       Cisco Systems                   (978) 244-8143
>                      250 Apollo Drive
>                      Chelmsford, Ma 01824
> 
> 
>