Re: [trill] seeking help to understand a line from TRILL-ESADI draft
Radia Perlman <radiaperlman@gmail.com> Wed, 18 July 2012 19:25 UTC
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Date: Wed, 18 Jul 2012 12:25:53 -0700
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From: Radia Perlman <radiaperlman@gmail.com>
To: Donald Eastlake <d3e3e3@gmail.com>
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Cc: Thomas Narten <narten@us.ibm.com>, Swet kumar <swet.kumar@ipinfusion.com>, "trill@ietf.org" <trill@ietf.org>
Subject: Re: [trill] seeking help to understand a line from TRILL-ESADI draft
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Oh right! You just learn of your ESADI neighbors based on the core instance LSPs. Sorry about the confusion. Radia On Wed, Jul 18, 2012 at 12:23 PM, Donald Eastlake <d3e3e3@gmail.com> wrote: > Currently there are no Hellos in ESADI. Participation is determined > from the core IS-IS link state database. > > Thanks, > Donald > ============================= > Donald E. Eastlake 3rd +1-508-333-2270 (cell) > 155 Beaver Street, Milford, MA 01757 USA > d3e3e3@gmail.com > > > On Wed, Jul 18, 2012 at 3:12 PM, Radia Perlman <radiaperlman@gmail.com> wrote: >> Actually, perhaps ESADI shouldn't bother with CSNPs at all. If each >> RB participating in the ESADI instance included the sequence number of >> its own LSP in its Hello for that ESADI instance, wouldn't that work? >> We need to have each RB (in the ESADI instance) send Hellos >> periodically anyway. >> >> Radia >> >> On Wed, Jul 18, 2012 at 11:15 AM, Thomas Narten <narten@us.ibm.com> wrote: >>> Seems to me that the MAY sentence all by itself is not helpful. >>> >>> If sending occasionaly ESADI-CSNPs increases robustness, IMO, the spec >>> should say that and explain which scenarios its useful in. And then, >>> MAY doens't seem right either. SHOULD would seem to make more sense... >>> >>> The RFC 2119 defintion of MAY says: >>> >>> 5. MAY This word, or the adjective "OPTIONAL", mean that an item is >>> truly optional. One vendor may choose to include the item because a >>> particular marketplace requires it or because the vendor feels that >>> it enhances the product while another vendor may omit the same item. >>> An implementation which does not include a particular option MUST be >>> prepared to interoperate with another implementation which does >>> include the option, though perhaps with reduced functionality. In the >>> same vein an implementation which does include a particular option >>> MUST be prepared to interoperate with another implementation which >>> does not include the option (except, of course, for the feature the >>> option provides.) >>> >>> which doesn't seem to match the explanation for why the MAY sentence >>> is in the document. >>> >>> Thomas >>> >>> Donald Eastlake <d3e3e3@gmail.com> writes: >>> >>> >>>> Hi Swet, >>> >>>> On Tue, Jul 17, 2012 at 5:59 AM, Swet kumar <swet.kumar@ipinfusion.com> wrote: >>>> > Hi Authors, >>>> > >>>> > >>>> > I am not able to understand the meaning of the following line in this draft: >>>> > http://tools.ietf.org/pdf/draft-ietf-trill-esadi-00.pdf >>> >>>> Thanks for reviewing this document. It was just recently posted as a >>>> WG document and I think it does need some more work. >>> >>>> > “For robustness, if an ESADI instance has two or more ESADI neighbors >>>> > >>>> > and is not DRB and it receives no ESADI-CSNP PDUs for at least the >>>> > >>>> > CSNP Time (see Section 6.1) of the DRB, it MAY transmit an ESADI- >>>> > >>>> > CSNP.” >>> >>>> Do you really no understand what the sentence says? Or is it that you >>>> don't understand what the reason is for this behavior? >>> >>>> The idea is that if the DRB on an ESADI virtual link is being flakey >>>> or the virtual link is broken then, to maintain LSP synchronization, >>>> it would be good for some other TRILL switch on that ESADI virtual >>>> link to occasionally send a CSNP. The multi-hop ESADI pseudo-link is >>>> inherently somewhat less reliable that a link between adjacent TRILL >>>> switches. (You might think this could result in a flurry of CSNPs but >>>> note that, due to the jitter in the IS-IS reliable flooding mechanism, >>>> if there were several non-DRB TRILL switches on the link, as soon as >>>> one sends a CSNP it will inhibit the others for a while.) >>> >>>> Anyway, although it doesn't make much difference. It should probably >>>> say "one" instead of "two" in the text and it should not just be that >>>> it has not received a CSNP but that it has not received or sent a >>>> CSNP. So, I think the wording should be changes to: >>> >>>> "For robustness, if an ESADI instance has one or more ESADI neighbors >>>> and is not DRB and it does not receive or send an ESADI-CSNP PDU >>>> for at least the CSNP Time (see Section 6.1) of the DRB, it MAY >>>> transmit an ESADI-CSNP." >>> >>>> Thanks, >>>> Donald >>>> ============================= >>>> Donald E. Eastlake 3rd +1-508-333-2270 (cell) >>>> 155 Beaver Street, Milford, MA 01757 USA >>>> d3e3e3@gmail.com >>> >>>> > This line is a part of section 4.1 (Sending of ESADI PDUs) on page number >>>> > 12. >>>> > >>>> > Please explain me what this line tries to convey. >>>> > >>>> > >>>> > Regards, >>>> > >>>> > Swet >>>> _______________________________________________ >>>> trill mailing list >>>> trill@ietf.org >>>> https://www.ietf.org/mailman/listinfo/trill >>> >>> >>> _______________________________________________ >>> trill mailing list >>> trill@ietf.org >>> https://www.ietf.org/mailman/listinfo/trill >>>
- [trill] seeking help to understand a line from TR… Swet kumar
- Re: [trill] seeking help to understand a line fro… Donald Eastlake
- Re: [trill] seeking help to understand a line fro… Thomas Narten
- Re: [trill] seeking help to understand a line fro… Radia Perlman
- Re: [trill] seeking help to understand a line fro… Donald Eastlake
- Re: [trill] seeking help to understand a line fro… Radia Perlman
- Re: [trill] seeking help to understand a line fro… Donald Eastlake
- Re: [trill] seeking help to understand a line fro… Thomas Narten
- Re: [trill] seeking help to understand a line fro… Donald Eastlake