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Latest MPLS Ping draft...

  • From: "Brian Hassink" <BHassink@HatterasNetworks.com>
  • Date: Mon, 21 Oct 2002 17:08:36 -0400
  • Cc: <mpls@UU.NET>
  • Thread-Index: AcJ5QYXPZ0ZROwHNQc+dqkso50GU4wAAcLrw
  • Thread-Topic: Latest MPLS Ping draft...
  • X-MIME-Autoconverted: from quoted-printable to 8bit by cell.onecall.net id g9LL3Y319103

Please see followup comments inline below...

Cheers,
Brian Hassink
---
bhassink@hatterasnetworks.com

-----Original Message-----
From: Kireeti Kompella [mailto:kireeti@juniper.net]
Sent: Monday, October 21, 2002 4:36 PM
To: Brian Hassink
Cc: mpls@UU.NET
Subject: Re: Latest MPLS Ping draft...



On Tue, 15 Oct 2002, Brian Hassink wrote:

> I'm wondering if it wouldn't be better to move the return code from the
> main header to the TLV header, or add a return code to the TLV header? I
> think there may be a couple of good reasons for doing this...

Read section 3.4, and the documentation for value 0 for the return code.

[BH] Ok, I'll buy that. I think that if this "protocol" evolves to support other inband OAM functions, that a more granular error reporting mechanism will be required. However the "error" TLV ends up getting defined, there will likely be a result per TLV, or set of associated TLVs, and I figured allowing for a return code within the TLV may result in less correlation and processing overhead.

> Also, couldn't a (optional) "timestamp" TLV be defined rather than
> having this information as mandatory fields in the main header?

Any particular reason?  One could make TLVs of all fields, not just the
timestamp fields.

[BH] I think that measuring delay/RTT is not necessarily something you want to combine with testing/validating connectivity. And again, if this "protocol" evolves to support other inband OAM functions, then it may become even less relevant to a given function. 

> Lastly, it's not clear to me which FEC applies to a tunnel that has
> been setup manually (i.e. static tunnels)?

There isn't one at present.  One could add one, if it is deemed useful.

[BH] Seems like at pretty useful thing to be able to do. Static tunnels are used in networks and I would think the reasons for monitoring them would be the same as if they were signaled.

As for checksums, UDP does have a checksum; most underlying transport
does as well.  If some new reply mode is introduced which doesn't have
a native checksum, a checksum TLV can be added -- however, I would wait
until a concrete reason is given, so that the figh ... um, discussions
about which particular checksum methodology be used can have a concrete
basis.

[BH] Fair enough.

Kireeti.