nanog mailing list archives

Re: Some very strange network behaviors


From: Crist Clark <crist.clark () globalstar com>
Date: Thu, 11 Sep 2003 14:49:56 -0700


Gregory Hicks wrote:

Date: Thu, 11 Sep 2003 13:35:37 -0700
From: Crist Clark <crist.clark () globalstar com>

Mike Lewinski wrote:

[...snip...]
OS's IP stack is misbehaving badly, Zone Alarm should not see the traffic
on the LAN that does not have his MAC address on it.

How would a switch/router be deciding that these other IP addresses
should go to his PC's NIC (MAC address)?

Unless the switch got confused when the MAC address changed as it
did...?  Then the switch would go into "broadcast" or "flood" mode
where every packet is delivered to evey port because the switch doesn't
know where to send it.

Even if a switch floods all ports, it does not change the fact the packet
will not have the correct MAC address and his NIC should never pass it
up the stack. Switches do not rewrite the Ethernet addresses on packets.
-- 
Crist J. Clark                               crist.clark () globalstar com
Globalstar Communications                                (408) 933-4387


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