Re: [rbridge] [Isis-wg] Why is MTU discovery important?

[Donald Eastlake <[e-mail]>]

See below...

On Tue, Apr 14, 2009 at 2:55 PM, Hannes Gredler <[e-mail]> wrote:
> Robert Raszuk wrote:
>>
>> As Dave points out there is "significant amounts of shared code" between
>> L3 ISIS & TRILL-ISIS and IMHO it does make sense to keep isis-wg in the
>> loop.

The Quagga IS-IS implementation supports both.

> hehe, i was playing devils advocate here ;-) ... i'll find it worry some
> that
> the "significant" portion is shrinking for no good reason ...
>
> i am terribly sorry but i need to bring up an old question again:
>
> why are there separate PDUs for multicast LSPs and SNPs ? -

Answers to that question have been posted several times to the ISIS WG
mailing list. I gather the answers do not satisfy you...

> most implementation keep all sort of internal databases,
> so practically there is a already a separation between unicast
> and multi cast - why do we need to change the on-wire representation
> of multi-ast data (= new PDU) while the same stuff can be carried in
> vanilla LSPs as well. the latest version of the draft does not contain
> answers on that matter, although being promised ...

Which draft are you talking about? As far as I know, the additional
PDUs first showed up in draft-ward-l2isis. Because they were there, I
put them in draft-eastlake-trill-rbridge-isis and they are now in
draft-ietf-isis-layer2. But I don't think they have ever been
mentioned in any TRILL WG draft and I don't off hand recall much
discussion of them in the TRILL WG.

Thanks,
Donald

> why do we think that app. 375KB of LSP space to store multicast
> information is not enough, and if so why don't we reuse the LSP-ext
> draft for adding more space.
>
> /hannes

>>> Robert Raszuk wrote:
>>>>
>>>> It seems to me just like section 4.2.4.3 Hello Contents of the above
>>>> draft says there is sufficiently large number of optional information usable
>>>> for TRILL which could be added to today's ISIS header that perhaps it may
>>>> make sense to just define it as separate TRILL-Hello msg.
>>>> My point was that in the same time the padding issue would be solved yet
>>>> a lot of already available code for L3 ISIS could be reused.
>>>
>>> so we have now separate L2-encaps, separate IIH, separate LSP and
>>> separate SNP PDUs
>>> - all of that with changed semantics ...
>>>
>>> sounds to me much more like a new protocol, than something vendors can
>>> integrate
>>> in their existing IS-IS implementation.
>>>
>>> if we want to further walk down that road, we should name the beast
>>> TRILL-something
>>> and drop the isis-wg groups involvement, since this is not IS-IS any
>>> more.
>>>
>>> /hannes
-- 
=============================
 Donald E. Eastlake 3rd   [phone] (home)
 155 Beaver Street
 Milford, MA 01757 USA
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