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From: k2@charly.bl.physik.tu-muenchen.de (Klaus Steinberger)
Newsgroups: comp.dcom.lans
Subject: Re: Do multiport repeaters buffer packets?
Message-ID: <4162@tuminfo1.lan.informatik.tu-muenchen.dbp.de>
Date: 28 Aug 90 07:18:24 GMT
References: <65056@yarra.oz.au>
Sender: news@lan.informatik.tu-muenchen.dbp.de
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chris@yarra.oz.au (Chris Jankowski) writes:


>Most Ethernet and IEEE.802.3 LANs design guidelines recommend use
>of multiport repeaters to increase LAN robustness and manageability
>of fault finding.
>Assume an asymmetrical configuration in the sense that there is
>a large server on one segment and a large number of PCs talking to it.
>The PCs are distributed among the other ports hanging off the multiport
>repeater.
>Just consider the following example:
>Assume that N-1 PCs each on different Ethernet segment generates a packet
>directed to the server at the same time. Even if the server's Ethernet
>segment is quiet only one of those packets can be delivered at a time.
>What happens with the others? 
None of those packets will go through, you will get a collision,
same as if your PC's are on the same segment, and are sending at the same
time.

>Does the N port repeater buffer the remaining frames?
No.

>If not (and I believe that store and forward is a function of a bridge)
>what other strategy can a multiport repeater use?
>Or am I missing something important altogether?
A repeater is only a electrical amplifier (some simplification, because
it must handle bidirectional traffic), so it has no sense of the packets.

Sincerely,
Klaus Steinberger

Klaus Steinberger               Beschleunigerlabor der TU und LMU Muenchen
Phone: (+49 89)3209 4287        Hochschulgelaende, D-8046 Garching, West Germany
BITNET:  K2@DGABLG5P            Internet: k2@charly.bl.physik.tu-muenchen.de