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Re: Queries regarding LMP.
Hi Martin, comments in-line
Martin Dubuc wrote:
>
> Q1) a) & b) LMP is useful for auto-discovery of links and monitoring of
> control and data link health. To determine whether LMP is useful or not,
> one has to look at the operational aspect of product deployment and
> maintenance, i.e. what tools the vendor wants to implement to facilitate
> provisioning and maintenance of their customers network. In a small
> network, a vendor may be able to get away with manual configuration of
> links. In an opaque network, it is also easy to pinpoint link failures.
> However, in a truly optical network, there needs to be mechanisms to
> isolate faults (which LMP provides).
When you say "truly optical network", do you mean a network that has no
O/E/O (no 3R) at all? or is there some 3R at the edge?
As for mechanisms to isolate faults, I think this capability is already
part of networks. For example, SONET has mechanisms such as trace
identifiers, AIS/RDI signals, and tandem connection points for doing
this. OTN (G.709) also has these defined. In addition, OTN has defined 6
flexible layers for TCM and 2 fixed layer for TCM (section and path).
I think LMP is not necessary for fault isolation, but it could be
another mechanism that may be used (if one so chooses).
>
> Usefulness of LMP is not directly tied to use of link bundles. Link
> bundles are mostly used to reduce the flooding of link information
> generated by the routing protocol.
>
> Q3) Destination address can be multicast or any valid IP address of
> destination node (most likely the NodeID of the destination node).
>
> -----Original Message-----
> From: rajesh [mailto:rajesh@tejasnetworks.com]
> Sent: Wednesday, July 25, 2001 1:59 AM
> To: mpls@UU.NET; jplang@calient.net; kireeti@juniper.net;
> azinin@cisco.com
> Subject: Queries regarding LMP.
>
> Hi,
>
> Have a few queries regd LMP.
>
> Q1) Regd the applicability of LMP...
>
> draft-many-gmpls-architecture-00.txt states that
>
> " For instance, the traditional IP routing model assumes the
> establishment of a routing adjacency over each link connecting two
> adjacent nodes. Having such a large number of adjacencies is not
> scalable at all. Each node needs to maintain each of its adjacencies
> one by one, and link state routing information must be flooded in
> the topology for each link.
>
> To solve this issue the concept of bundling was introduced.
> Moreover, the manual configuration and control of these links, even
> if they are unnumbered, becomes totally impractical. The Link
> Management Protocol (LMP) was specified to solve these problems. "
>
> a) Can one assume that LMP makes sense ONLY in the case of a large
> number of parallel links and link bundling...
>
> and an implementation of GMPLS neednot have LMP if no link
> bundling is used ??
>
> The above maybe the case when using lower end SONET ADM,
> DXCs...
>
> b) Under what other conditions would one require LMP (ie other than
> link bundling) ?
>
> Q2) Suppose one does NOT need to use LMP but then one needs to use
> OSPF extensions to support TE
> (draft-kompella-ospf-gmpls-extensions-01.txt) ,
>
> then one may need to do a correlation of Link Ids between 2
> TE nodes.
>
> a) Is there a standard recommended way to do this correlation ??
>
> E.g OSPF - Link Local Signaling
> or OSPF - link scope LSA ?
>
> Q3) Section 9 of draft-ietf-mpls-lmp-02.txt says that LMP messages
> are encoded as IP packets and also suggests protocol number
> 140.
>
> What would be the destination IP address of an LMP packet ??
>
> A multicast or is it got from an IGP ??
>
> Q4) In LMP, if a Link Id correlation has been done, and If the link ids
>
> on one of the ends or both change... How is this change taken
> into
> account ??
>
> Eg for i = 1,2
> Port i, Node 1 connected to Port i, Node 2
>
> If one interchanges the connection then one has to recorrelate
>
> the Link Id mappings..
>
> Thanks in advance,
> Rajesh