Subject: Questions on draft-andersson-reroute-frmwrk-00.txt

From: Vishal Sharma <[email-masked]>
Date: Tue, 23 Nov 1999 11:28:50 -0500

Hi Loa and Billel,

As discussed during the MPLS WG meeting on Thursday at the DC
IETF, we are in the process of reconciling the terminology and descriptions
across the various drafts addressing protection and LSP recovery, and have
some questions in this context.

(i) Does the "primary path" refer to the entire working LSP or only to that 
portion
of the LSP that needs to be protected (similar to the "working path," as 
defined
in the Makam draft).

(ii) Under failure detection, in Section 1.2.2, the text says that "the 
notification
(of failure) could be explicit or data driven."  What is data driven 
notification?
Does this assume some OAM functionality in MPLS, along the lines of that
discussed in the Theimer draft at the D.C. meeting.

(iii) It is not clear why the fast reroute framework does not allow the primary 
path
to be taken into operation before being verified by the routing protocols. It 
is
also unclear why there is an assumption that the backup path is by definition
sub-optimal? (A routing change could have made the backup optimal and the
pinned primary path suboptimal.)

(iiv) In the recovery cycle in Section 1.2.3, does step 4 assume that the 
secondary
is pre-negotiated and pre-setup? If not, how does the entity performing the 
switchover
establish the secondary?

(iv) Section 2.4 on  Backup Capacity states that the backup capacity will be 
dependent
on the traffic characteristics of the network. In what sense? It would seem 
that the backup
capacity relates not to network traffic but to the capacity used on the primary 
path.

(v) Sections 2.6 (Failure Types) and 2.7 (Re-ordering) provide general
"descriptions" rather than "Requirements". Should a framework provide
requirements in this area or are descriptions more appropriate?

(vi) Sections 2.9 (State overhead) and 2.10 (Loss) provide general "Objectives" 
(one would aim to have minimum state infomation and low loss, for example)
rather than "Requirements." Should a framework provide requirements for this
area or are objectives more appropriate?

(vii) What does "Fast" in "fast reroute" mean (qualitative)? Is there some 
range
of times that "fast" implies?

(viii) What does the term "reroute" mean(Layer 2? Layer 3?)? Specifically,
how does reroute refer to Layer 2?

Thanks,

-Vishal

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