[rbridge] Consensus Check: Hellos

[Eric Gray]

Anoop,

	As I recall, the reason for having this behavior was not at
all - or at least not primarily - for detecting missing connectivity.
As I recall, it was (primarily) about preventing looping as a result
of not detecting that there was more than one designated forwarder.

	See in particular Radia's discussion on "TRILL things" in the 
minutes at http://www.ietf.org/proceedings/08mar/minutes/trill.txt.

	Even if your assumption about why we might want to do it was
correct, I don't see how you could argue that we should have default
behavior that assumes the existence (and use) of some unspecified 
alternative for detecting connectivity issues.

	Hence the default should rely on the use of hellos as Donald's
note suggests.

--
Eric Gray
Principal Engineer
Ericsson  

> -----Original Message-----
> From: rbridge-bounces at postel.org 
> [mailto:rbridge-bounces at postel.org] On Behalf Of Anoop Ghanwani
> Sent: Wednesday, April 16, 2008 6:43 PM
> To: Eastlake III Donald-LDE008; Rbridge at postel.org
> Subject: Re: [rbridge] Consensus Check: Hellos
> 
> 
> I had a problem with the general wording and 
> had sent an email to the list about this a 
> while back.
> 
> While I think it's OK to have the designated
> forwarder send hellos on all VLANs, I would
> prefer it be worded such that:
> 
> (a) We clearly state that the intent for this
> is to detect connectivity issues.  In other
> words, this will not be used for forming 
> adjacencies (and there we will have something
> in the hello that distinguishes it from the
> hellos that are actually used to form adjacencies).
> 
> (b) That this behavior is optional because there
> are other ways to detect connectivity issues
> such as 802.1ag.  There is also the L2 Gateway
> Protocol defined in 802.1ah that we can look into.
> As such, I prefer that the default be to _not_ 
> send such messages unless explicitly configured
> to do so.
> 
> Anoop 
> 
> > -----Original Message-----
> > From: rbridge-bounces at postel.org 
> > [mailto:rbridge-bounces at postel.org] On Behalf Of Eastlake III 
> > Donald-LDE008
> > Sent: Tuesday, April 15, 2008 10:16 PM
> > To: Rbridge at postel.org
> > Subject: [rbridge] Consensus Check: Hellos
> > 
> > This is the last of the consensus checks via the mailing list 
> > to confirm or refute an apparent consensus at the 
> > Philadelphia meeting.
> > 
> > 
> > ******* The VLANs on which an Rbridge sends TRILL IS-IS 
> > Hellos is expanded to include those for which it is an 
> > appointed forwarder except to the extent that it is 
> > configured not to send these additional Hellos.
> > 
> > 
> > If no particular controversy arises over this in the next two 
> > weeks, we will declare it to be the working group consensus.
> > 
> > Thanks,
> > Donald & Erik
> > 
> > PS: There was not complete agreement on this although there 
> > did appear to be a rough consensus at the meeting. However, 
> > in light of the other consensus from that meeting to no 
> > longer require the "decapsulation check" (see
> > http://www.postel.org/pipermail/rbridge/2008-April/002939.html
> ) and the discussions of the trade-offs, perhaps the 
> consensus > should
> be that, by default, Rbridges MUST either (1) send 
> > these additional Hellos if they are an appointed forwarder or 
> > (2) perform the decapsulation check.
> > 
> > _______________________________________________
> > rbridge mailing list
> > rbridge at postel.org
> > http://mailman.postel.org/mailman/listinfo/rbridge
> > 
> 
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