RE: Queries regarding LMP.

[Jonathan Lang <jplang@calient.net>]

Following up on Martin's comments...

> -----Original Message-----
> From: Martin Dubuc [mailto:martin.dubuc@edgeflow.com]
> Sent: Wednesday, July 25, 2001 8:59 AM
> To: rajesh@tejasnetworks.com; mpls@UU.NET; jplang@calient.net;
> kireeti@juniper.net; azinin@cisco.com
> Cc: ccamp@ops.ietf.org
> Subject: RE: Queries regarding LMP.
> 
> 
> 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).
> 
> 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.
To add further, when GMPLS labels map to physical resources (i.e., ports or
fibers), LMP can be used to exchange these labels so that there is a common
understanding of the mapping.  Even if man ual configuration is used, LMP
provides a mechanism to verify the accuracy (it is not uncommon for manual
configuration to be in error...).

> 
> Q3) Destination address can be multicast or any valid IP address of
> destination node (most likely the NodeID of the destination node).
Note that the protocol Id suggestion of 140 has been removed in the latest
version as this value MUST be assigned by IANA.  140 has been used in
interops for the time being, but this shouldn't be considered as the final
protocol id.

Q4) Recorrelation of Link Ids can be done by reverifying the link and/or
resending the LinkSummary message.

Thanks,
Jonathan 

> 
> -----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
>