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From: Naidu, Venkata (Venkata.Naidu_at_MARCONI.COM)
Date: Thu Aug 29 2002 - 18:10:18 CDT

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    Link Bundling comments:

    -> This is to initiate a last call for the
    ->
    -> <draft-ietf-mpls-bundle-04.txt>

       All component links in a bundle must begin and end on the same pair
       of LSRs, have the same Link Type (i.e., point-to-point or multi-
       access), the same Traffic Engineering metric, and the same set of
       resource classes at each end of the links.

       A Forwarding Adjacency may be a component link; in fact, a bundle can
       consist of a mix of point-to-point links and FAs.

    Link Types Restriction
    ----------------------
    *** Only beginning & ending of the link types are restricted or
    *** all the links along the path (from beginning router to end router)
    *** are restricted to the same link type?

    *** I didn't not understand why we need same link type at the
    *** beginning and at the end of the link? Link Type TLV will cover
    *** whatever link type at the advertising router side of the link.
    *** I didn't see any issue if we have different link types at each
    *** side of the link.

    *** I request to elaborate these restriction a little bit with
    *** a single appropriate diagram (if possible).

    *** The use of bundling has very large scope. For example, one can
    *** bundle all the VCs in a VP (where each VC is viewed as a different
    *** link with its own resources). All such VPs can be bundled/unbundled
    *** (depending on the requirements). Still all those VPs will have
    *** a same risk-factor (i.e. SRLG). I think, it will be
    *** better to mention few example of such uses of link bundling.

    Metric Restriction
    ------------------
    *** Why is the same metric restriction? Can a router have
    *** the flexibility to decide a different metric for the bundled
    *** link (may be independent of all the component links)?

    *** For example, a router chooses the largest metric of all
    *** component links (just like OSPF area aggregation). Just a
    *** a matter of flexibility. If the metrics are different and
    *** if we bundle those links did you see any problem?

    *** Let is explain an example scenario, where router starts
    *** advertising the largest of all links metric as bundled
    *** link metric. One the largest component link resources (bw)
    *** are completely consumed (crossed some threshold ) then
    *** bundled link metric will become the next highest component
    *** link metric.

    Link Protection consideration
    -----------------------------
    *** There is no mention about link protection type of the bundled
    *** link when component links are of different type?

    SRLG consideration
    ------------------
    *** There is no mention about SRLGs of bundled link w.r.t component
    *** links. In some situations, failure of one component link may or
    *** may not affect other component links. I think, it will be better
    *** to mention something about SRLG - that is, all component links
    *** in bundled link must have same SRLG (in order to benefit most
    *** from bundling). Even if the component links risk factor is independent
    *** from each other (ie. different SRLGs) still we can use bundling.
    *** Please mention something like that...

    Switching Capability consideration
    ----------------------------------
    *** I think the switching capability should be same for all component
    *** links in order to use bundling?! Please mention.

    DiffServ consideration
    ----------------------
    *** There is no mention about BCs and TE Classes applicability
    *** to Link bundling? Do you see any issues w.r.t to the recent
    *** diffserv draft (esp interpretation of unserverved bws etc)?

      Thank You.

    --
    Venkata.