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Same MAC address on 3550

 
 
Network_Guru
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      06-04-2007
I am attempting to set up a Cisco 3550 with an HP 760wl Access
Controller. The problem I am having is all the clients connected to
the 3550 show to have the same MAC address when it leaves port 48 of
the 3550 and gets to the 760wl.

When the first client authenticates, the 760 allows all other clients
traffic from the same mac-address through.

Is it possible to configure the 3550 to where it does not show the
same mac address in packets leaving the 3550 and force it to show the
actual mac of the client?

Thank You

 
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Walter Roberson
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      06-05-2007
In article <(E-Mail Removed) om>,
Network_Guru <(E-Mail Removed)> wrote:
>I am attempting to set up a Cisco 3550 with an HP 760wl Access
>Controller. The problem I am having is all the clients connected to
>the 3550 show to have the same MAC address when it leaves port 48 of
>the 3550 and gets to the 760wl.


Do you have the 3550 acting as a switch or a router for the purpose
of the clients reaching the 760wl? If it is configured as a router
to reach the 760wl then it -must- use its own MAC; the 760wl would
not be able to reply if it received original MACs in that case.
 
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Network_Guru
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      06-05-2007
On Jun 4, 8:41 pm, (E-Mail Removed) (Walter Roberson) wrote:
> In article <(E-Mail Removed) om>,
>
> Network_Guru <(E-Mail Removed)> wrote:
> >I am attempting to set up a Cisco 3550 with an HP 760wl Access
> >Controller. The problem I am having is all the clients connected to
> >the 3550 show to have the same MAC address when it leaves port 48 of
> >the 3550 and gets to the 760wl.

>
> Do you have the 3550 acting as a switch or a router for the purpose
> of the clients reaching the 760wl? If it is configured as a router
> to reach the 760wl then it -must- use its own MAC; the 760wl would
> not be able to reply if it received original MACs in that case.


It is being used as a router. I have 8 separate networks plugged into
the the 3550 with port 48 going to the 760, which then of course is
connected to the firewall. What you are telling me is it doesn't
matter what the mac address is on any of the clients, the 3550 will
strip it from the outbound packet and place the mac address of port 48
in the packet before forwarding it to the 760. From the 760 point of
view, the packets it gets may have different source ip addresses, but
the source mac address will always be the same. Am I correct?

 
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Walter Roberson
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      06-05-2007
In article <(E-Mail Removed) om>,
Network_Guru <(E-Mail Removed)> wrote:
>It is being used as a router. I have 8 separate networks plugged into
>the the 3550 with port 48 going to the 760, which then of course is
>connected to the firewall. What you are telling me is it doesn't
>matter what the mac address is on any of the clients, the 3550 will
>strip it from the outbound packet and place the mac address of port 48
>in the packet before forwarding it to the 760. From the 760 point of
>view, the packets it gets may have different source ip addresses, but
>the source mac address will always be the same. Am I correct?


Yes, that is correct. That is the way routing works.

If you for some reason -need- the original MACs on the 760wl, then
the 760wl will have to be on the same segment as those other hosts,
and some way would have to be found to allow the 760wl to talk
directly to the hosts. -Potentially- you could do that by giving
all those hosts a static ARP for the IP address of the 760wl.
If all of the clients are Windows 2000 or later windows, then if
the 760wl were defined as their default gateway, they could talk
(through a MS hack) talk directly to the 760wl even though it was
on a different subnet. If the 760wl needed to initiate conversations
with the clients, you'd run into problems, though.

Getting original MACs through both ways across multiple subnets is
not always impossible, but it isn't the way networks are designed,
and solutions tend to be fragile. Could make a mess of internal
communications, for example.

 
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