Subject: Re: simple questions

From: Tony Li <[email-masked]>
Date: Fri, 9 Apr 1999 00:58:56 -0700 (PDT)

|          1) What is dataLinkBlockSize?
|                  (hypothesis: MTU of interface)

Correct.

|          2) Does the protocol allow for sending PDU's larger than
|          the MTU of the interface?

Nope.  And there's no need, either.

Tony

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From: [email-masked] (Christian E. Hopps)
Date: 09 Apr 1999 02:23:07 -0400

I have some simple is-is questions, hopefully you won't find
them too bothersome.

I'm reading through my copy of ISO 10589 and a couple of things,
so far, are not to clear to me:

        1) What is dataLinkBlockSize?
                (hypothesis: MTU of interface)

        2) Does the protocol allow for sending PDU's larger than
        the MTU of the interface?

Thanks,
Chris.

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From: [email-masked] (Christian E. Hopps)
Date: 09 Apr 1999 04:19:59 -0400

> Nope.  And there's no need, either.

The main reason for asking was that I didn't know and wanted to;
however, I suspected the answer and was contemplating that the
restriction seems to limit the number of possible adjacencies.

Assuming you have a MTU of 1497 (e.g., ethernet) and idlen of 6.
The size of the fixed header is 27 octets.  Next assume 1 area
address which is 13 octets long, so the area option adds 16
octets.  That leaves 1454 octets, which if I calculate correctly
is enough room for 5 full neighbor options and 1 remaining
neighbor option with 30 in it for a total number of neighbors of
240.

This certainly doesn't seem too restrictive to me by itself;
however, in light of the recent > 255 circuits per router draft,
I thought this was a similarly small number.  Perhaps its just
much more common to have many circuits rather than many neighbors
on a circuit.

Thanks,
Chris.

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From: Tony Przygienda <[email-masked]>
Date: Fri, 09 Apr 1999 10:21:35 -0400

> neighbor option with 30 in it for a total number of neighbors of

240 routers on a single ether could be a serious riot ;-) 

I have to admit my  mind wasn't sick enough to try 
to break the protocol that way ;-) 

> much more common to have many circuits rather than many neighbors

		thanks 

	== =tony