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Date:      Mon, 29 Jan 1996 12:09:31 -0700 (MST)
From:      Terry Lambert <terry@lambert.org>
To:        jhay@mikom.csir.co.za (John Hay)
Cc:        terry@lambert.org, hackers@FreeBSD.ORG
Subject:   Re: NetBUI and/or IPX routing?
Message-ID:  <199601291909.MAA04198@phaeton.artisoft.com>
In-Reply-To: <199601270518.HAA09078@zibbi.mikom.csir.co.za> from "John Hay" at Jan 27, 96 07:18:16 am

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> > A "GetNearestServer" from "IPX client" will elicit a response both
> > from "FreeBSD Router" and "NetWare Server2".
> 
> No it should not. Server1 isn't the nearest anymore, so the router should
> not respond to a GetNearestServer SAP request from the IPX client.

Ah.  Here is the problem.

A GetNearestServer request is not propagated past the local subnet.  It
is a special case broadcast NCP.

If a router replies, it is not because it is non-local, it's because the
router is replying on behalf of the server.  That is, the router is
replying, Server1 is not replying through the router.

Note that if enough clients were already attached to Server2, then Server2
would ignore the request.

So it's an error for the router to truncate replies based on the existance
of a local server with a smaller hop count.  It is more important that
the client get a connection than the connection actually be the smallest
posible hop count.

> > A local server is preferaable to a routed serve because of negotiated
> > packet sizes through routers dropping to 512.
> 
> A bigger problem (performance wise) is the extra hop that is incurred for
> NCP. Burst mode isn't the whole answer to that.

Having 1/3 the packet size is a bigger hit than the additional latency
of the multiple hops.

I agree that packet-burst only minorly helps latency.  It is a fixed
window single response protocol.  I dislike it immensely, since its
intent is to allow a single client to monopolize the wire to improve
benchmark performance.  On a big net, it causes problems instead of
solving them.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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