[28027] in North American Network Operators' Group
Re: [nsp] IS-IS over IP?
daemon@ATHENA.MIT.EDU (Tony Li)
Wed Apr 5 05:49:26 2000
Message-ID: <38EAF284.F193F64B@home.net>
Date: Wed, 05 Apr 2000 01:00:04 -0700
From: Tony Li <tony1@home.net>
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To: danny@tcb.net
Cc: "Howard C. Berkowitz" <hcb@clark.net>, nanog@merit.edu
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> > I wasn't in Adelaide, but in earlier meetings, I had the impression
> > that there were at least some implementations using IPv4 as a
> > workaround both to lower layer specific problems (e.g., AAL SNAP/MUX)
> > as well as the hard MTU size limit due to lack of fragmentation
> > capability at the data link layer.
The specific problem that certain people were trying to address was the need to run
a multiprotocol encapsulation on top of ATM, thereby (further) lowering the
efficiency of ATM while still running IS-IS in their networks.
> I don't believe there were any meetings of the ISIS WG in Adelaide.
Correct.
> I'm not aware of any implementations of ISIS over IPv4, much less in production
> networks.
Neither am I. However, there is at least one obvious person that you should
consult directly.
> As for the MTU issue, most use maximum LSP size of 1492 bytes and
> even stop Hello padding after initialization.
There is no hard MTU issue. The problem that the spec both created and tried to
address was that in running IS-IS over IP, it would be necessary to perform IP
fragmentation to deal with IS-IS packets that would otherwise fit in the CLNP MTU.
Tony
