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RE: Your "favorite" network faults

2009-04-14 10:30:52
-----Original Message-----
From: ietf-bounces(_at_)ietf(_dot_)org 
[mailto:ietf-bounces(_at_)ietf(_dot_)org] On Behalf Of
Lars
Eggert
Sent: Tuesday, April 14, 2009 8:16 AM
To: Ole Jacobsen
Cc: IETF discussion list
Subject: Re: Your "favorite" network faults

Daisy-chaining a small number of hubs also causes interesting issues.
Doesn't happen much anymore, now that switches have become prevalent.

Exactly, was replaced with daisy-chaining large numbers of switches (where
large == "more than 7 or so")
:)

On 2009-4-13, at 4:49, Ole Jacobsen wrote:
OK, I'll chime in: I got one of those key-chain sized Ethernet
loopback connectors. The idea is that you attach one end to a patch
cable and the other to the hub and if all is well the link light goes
on on the hub. So, I am sitting there admiring this wonder when all my
telnet sessions (OK, maybe SSH sessions) go away, webpages won't load
and AIM/Jabber disconnects. Of course the loopback device is causing a
broadcast storm and the hub isn't working well.

This supposedly does not happen on a switch... I haven't bothered to
try.

Actually, I am not sure a switch would be immune ... broadcast (and
multicast, sans snooping) still gets flooded ...
(IIRC it also triggers bpdu-guard to disable the ports, if the config is
just right (or just wrong)).

/TJ

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