From: Michael Snyder (msnyder@xxxxxxxxxxxxxxxxxxxxxx)
Date: Thu Aug 22 2002 - 10:22:19 GMT-3
The only time I've seen multiple cam entries going to different ports is
with multicast mac addresses.
I think multiple unicast mac addresses would be a sign of a layer two
loop to a switch.
Set span enable does something like what you describe, but that's a
special case, where the switch is echoing the traffic on two ports.
About your question about if the workstations would be fuctional?
Maybe, but the number of problems, for example what if both machines
where using ftp at the same time, or both using the port 80 web services
at the same time. Any personal firewall is going to see this as a
spoofing attack.
I stand by my statement that two of the same unicast mac addresses in
the same subnet is a very bad thing.
On the a side note, if you wish to drive a network administrator nuts,
randomly set the mac address's (some nic cards allow mac's to be set) on
random computers in the office to the same value. I only know a few
administrators that could figure it out.
-----Original Message-----
From: Brian [mailto:signal@shreve.net]
Sent: Thursday, August 22, 2002 8:03 AM
To: msnyder@revolutioncomputer.com
Cc: ccielab@groupstudy.com
Subject: RE: Challenge Question
On Thu, 22 Aug 2002, Michael Snyder wrote:
> The two ip address with one mac address isn't a problem. You can go
> into the ip advanced settings on a w2k box, and setup as many
addresses
> as you like. As long as the machine responds to the arp ip lookup, it
> works.
>
> Two of the same mac addresses on the same subnet would be a bad thing.
> Might work if you are using a hub instead of a switch, but both
machines
> would get each others traffic.
Are you 100% convinced that a switch would not install 2 CAM entries and
just send data to both? As far as both machines receiving eachothers
traffic, do you believe this would create a problem where the function
is
lost, or just slow performance.........think about how that traffic
would
be handled.
Brian
> > -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Brian
> Sent: Thursday, August 22, 2002 6:34 AM
> To: ccielab@groupstudy.com
> Subject: Challenge Question
>
> I know this group likes these challenge questions, so I have one for
you
>
> and hopefully it has not been put to this group recently.
>
> You have two hosts each with identical MAC addresses on an ethernet
LAN.
> They also have identical IP addresses. Why or why not would this be a
> problem for the client communicating (assuming each of the dupe
machines
>
> doesnt need to communicate with eachother only to other hosts on the
LAN
> and through the gateway)?
>
> Ok, similar to above, same MAC addresses but different IP addresses.
> Why
> or why not would this create communications on the LAN or through the
> gateway?
>
> good luck!
>
> Brian
>
>
>
> -----------------------------------------------
> Brian Feeny, CCIE #8036 e: signal@shreve.net
> Network Engineer p: 318.222.2638x109
> ShreveNet Inc. f: 318.221.6612
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