Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements
Webcast-Catalyst9k
New Member

cisco 3548 switch is passing all traffic. How do I stop this ?

I have a couple of cisco switches ( that I know of I have not checked all of them ) that are passing both broadcast and non-broadcast traffic. This can be seen by doing a snoop from any device on the switch. Has anyone ever encountered this ? The IOS I am using is c3500XL-c3h2s-mz-120.5.2-XU.bin.

When I set up the switches I did it manually and not through the Cisco setup that starts on boot.

How do I prevent non-broadcast traffic from being seen on the switch by other devices on the switch ?

1 REPLY
New Member

Re: cisco 3548 switch is passing all traffic. How do I stop this

what percentage of the traffic is non-broadcast?.

If you snoop a port on a switch you will see non-broadcast traffic as normal. ie. When the switch receives a packet for a destination address not currently in it's CAM table, it will flood the packet out of all ports except the port on which it was received. Once the destination device responds it gains an entry within the switches CAM table and all further packets are directed to the specific port that the response was received on.

If your sniffer is on one of these ports, it will record non-broadcast frames while it populates it's CAM table.

hope this makes sense.

Best Regards,

Carl

266
Views
0
Helpful
1
Replies
CreatePlease to create content