doubt abt proected ports in 3550

Unanswered Question
May 23rd, 2007

hi all i am having a silly confusion abt the protected ports.

in the documentation they have mentioned that 2 protected ports cannot talk to each other.they can only talk via layer-3 device.

does it mean that 2 protected ports should be in the different vlans.

blocking of unknown unicast and multicast traffic for protected ports.

when we are having vlans unknown mac-address are only flooded to the ports in which the traffic was originated.then it will flood to protected ports.

can someone pls explain me or clear my doubts.



I have this problem too.
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Anonymous (not verified) Wed, 05/30/2007 - 06:03

Some applications require that no traffic be forwarded by the Layer 2 protocol between ports on the same switch. In such an environment, there is no exchange of unicast, broadcast, or multicast traffic between ports on the switch, and traffic between ports on the same switch is forwarded through a Layer 3 device such as a router.

If you want to know more please click following URL:

Amit Singh Wed, 05/30/2007 - 06:10


Protected ports can be in the same vlan. In any case if the ports are in different vlans they cannot talk to each other without a Layer-3 device.

Protected ports will restrict sending the unknown unicast,broadcast and multicast traffic to each other. But the traffic originated from the unprotected ports can be flooded to protected ports and you have to use " port block " command to block flooding od excess traffic on the protected ports.

HTH,please rate if it does.

-amit singh


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