[c-nsp] mpls ldp discovery transport-address

[Oliver Boehmer (oboehmer)]

Vikas Sharma <> wrote on Tuesday, September 02, 2008 6:25 AM:

> Hi,
> 
> Below is the output of sh mpls ldp discovery. Here LDP identifier and
> LDP discovery source are different. I can change discovery source
> using "mpls ldp discovery transport-address but my question here is
> what is the best practice and what are the benefits? is it using both
> LDP identifier and Discovery source same or different?

best practice is to use a loopback as LDP router-ID and advertise this
address as transport address (i.e. use the default behavior). This has
multiple advantages:

- less config
- if you have multiple links between two nodes, you don't have to worry
about advertising the same address on both links
- it allows you to keep the session established even if the link
supplying the transport address goes down (good for convergence)

Or where you thinking about using a dedicated loopback as transport
address? Not sure what the benefit of this would be.

I've seen the transport address being used in some cases where the LDP
router-ID is not advertised in IGP (for whatever reason), but these were
corner cases..

> One of the benefit I can see is if I use the same IP for both is I can
> reduce the number of labels. Any other benefit wrt security!!!

not sure what you mean by "reducing number of labels".. Number of IGP
labels is usually not a concern. Not sure about the security argument.

	oli