Connecting switch to 3550

Unanswered Question
Jun 5th, 2007

What needs to be done (enabled or disabled) to connect a regular switch to a 3550 so a port listens to more than one mac address? Portfast & what else?

I have this problem too.
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I would not recommend to turn on portfast on port connected to other switch as this feature is to immediately put the port to forwarding state ignoring the listening, learning states which is used for STP convergence. Actually the switches are learning the MAC addresses dynamically and build the mac-address table based on the traffic going through that. I think you are confused with the port security but that is different thing and not enabled by default. Summarized you don't have to configure anything the switches will take care almost of everything :)

Hope it helps, rate if does,


sundar.palaniappan Tue, 06/05/2007 - 11:37

There's no special configuration required to have the port learn multiple MAC addresses. The switch would update the MAC address table based on the source MAC address of the ethernet frame(s) arriving on the interface. You can configure the port as an access or trunk depending on what you want to do. If the port needs to carry data for multiple VLANs then the port needs to be configured as a trunk. If the port is just an access port make sure the port is assigned to the correct access vlan 'switchport access vlan (vlan#)' command.

Moreover, you would want to enable portfast only on ports connected to end devices and not when it's connected to another switch. This mayn't create a problem if there are no redundant connections but it can create problems if any loop situation is created is unintentionally.




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