Re: GTTP and LSP PING

[Kireeti Kompella <kireeti@juniper.net>]

On Sat, 6 Mar 2004, Ronald Bonica wrote:

> At IETF 59, an issue regarding the relationship of GTTP to LSP PING was
> raised and redirected toward the list. I am posting this message in order to
> initiate discussion.
>
> One might argue that GTTP should invoke LSP PING when tracing though an MPLS
> LSP. (In fact, previous versions of the GTTP draft stated that GTTP would
> invoke LSP PING.) I'm not sure that this is a good idea.

LSP ping traces through the data plane, which is not always possible
with GTTP.  One thing to consider is to reuse some of the formats and
objects from LSP ping.

> GTTP has a requirement to trace through multiple levels of heterogenous
> tunnels. For example, GTTP might be required to discover IP over MPLS over
> IP. If GTTP were to invoke LSP PING to discover LSP details, I fear that it
> would miss the IP tunnel at the bottom of the stack.
>
> This assumption could be wrong. Comments?

LSP ping uses TTL for tracing.  TTL-hiding tunnels present a problem.
Also, at present, LSP ping doesn't address IP tunnels, although it
could (and this has been suggested).

Kireeti.
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