Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

CAT2948G-L3 seeing traffic on switch ports that I shouldnt be??!!

Im running 2 CAT2948G-L3 with IRB and a gigabit trunk between them. They are both running IOS Version 12.0(18)W5(22b).

Snooping traffic from any host connected to one of the fast ethernet ports configured as a bridge port reveals traffic from other hosts in the same bridge group connected to the same switch/router?

Can anyone tell me why this is happening given the fact that it is a switch/router and the ports within a bridge group should be switching traffic?

  • Other Network Infrastructure Subjects
4 REPLIES

Re: CAT2948G-L3 seeing traffic on switch ports that I shouldnt b

I will assume this is unicast traffic. Is it consistent or one off traffic?

I would try a "clear bridge" (will cause a temporary flooding as L2 entries are re-learned and re-populated) and see if that clears it up.

Also do a "show epc patricia interface fast 1 (and 2) mac" on both ports that should communicate with each other directly (but in your case are not) to make sure they know each others mac addresses and where to send the frame. Do they see each other?

eg port 1:

MAC addr:0000.2222.2222 IF Number:5 Entry:Remote (mac address of PC on port 2)

MAC addr:0000.1111.1111 IF Number:4 Entry:Local (mac address PC on port 1)

port 2:

MAC addr:0000.2222.2222 IF Number:5 Entry:Local

MAC addr:0000.1111.1111 IF Number:4 Entry:Remote

Hope it helps.

Steve

New Member

Re: CAT2948G-L3 seeing traffic on switch ports that I shouldnt b

Thanks for the reply

Yes the traffic is unicast. E.g. if I snoop a port I see all the unicast bi-directional traffic for all other ports on the same switch which belong to the same bridge group

I recently upgraded the IOS and rebooted both switches

The IOS version I am using does not support the show command you mentioned?

Re: CAT2948G-L3 seeing traffic on switch ports that I shouldnt b

It used to be a hidden command (last I looked was version 18g, you are on 22b). But show epc is for L3 switches like the 2948g-l3 and the 8500, I am surprised it would be removed. I will look into it or find an equivalent.

Steve

New Member

Re: CAT2948G-L3 seeing traffic on switch ports that I shouldnt b

Sorry - found it! Didnt realise it was hidden.

The command does show the MAC addresses of the remote hosts which are showing in a snoop from that port? i.e.

sh epc patr int f9 mac

MAC addr:0003.ba0a.15ee IF Number:12 Entry:Local

MAC addr:0800.20c5.0b6c IF Number:14 Entry:Remote

and others......

sh epc patr int f11 mac

MAC addr:0003.ba0a.15ee IF Number:12 Entry:Remote

MAC addr:0800.20c5.0b6c IF Number:14 Entry:Local

and others........

197
Views
0
Helpful
4
Replies