The MPLS WG Archive

["David Allan" <dallan@nortelnetworks.com>]

Title: RE: draft-chang-mpls-path-protection Comments

Vishal:

comments imbedded, and extraneous stuff removed...

<snip>

>       Agreed, however such things MAY exist, such as intercarrier
> boundaries inside a contiguous MPLS space. That would be my only
> observation. The boundary MAY not be technical and in the real world that is
> what frequently happens. If there is some form of pre-emption, then it is
> also useful to constrain the space to minimize the amount of traffic
> distrupted.

I got lost on the last sentence here. By pre-emption do you mean the
usual --- pre-emption of low priority traffic on the protection path by
working traffic once the protection path is brought into use?

Yes, and segmenting the recovery space usually means that the disruption of pre-empted traffic can be localized and minimized, I do not preempt the traffic along the entire backup path.

<snip>

Again, I have a question. Why do you say that conservative label retention implies
a knowledge of which LSPs are more optimal?

I have to assume that for it to be useful. Some intelligent filtering of implicit advertisments is required when doing the topology, even if simple, "this LSR advertisment came in on the optimal interface for this FEC according to my tables, so I'll keep this one". However I have not done enough "I-D archeology" in order to substantiate this in detail. This is an area I would like to understand better.

I like the concatenated protection idea. This is sort of what I had alluded
to in an earlier email where I'd said that one may do protection of
a multi-domain LSP (ie, an LSP that spans multiple MPLS domains
one after another) on a segment by segment basis. Of course, the
implication above is more general than that.

Good.

>       My summary would be:
>
>       1) We need to clarify overall the goals of MPLS restoration. Is it
> explicit black box behavior or are we seeking a broader base of solutions
> that dovetail into the overall network.

I think the recovery framework document encompasses the broader definition.
As before, if you feel something more is needed, let us know.

I'll review it accordingly. But I'm timing out for this week ;-)

<snip>

I would like to add, however, that with the recent on-going activity in
the MPLS + crossconnects area, we might have to think about coordination
at least across the MPLS and optical transport networks (since that may be
an important case in practice).

I think there is applicability and common requirements. But this is one I need to think about as there are differences in the space.

regards
Dave