Showing results for 
Search instead for 
Did you mean: 

4006 not passing broadcasts

Here's a good one I'm stuck on.

Most of my buildings are divided up by VLANs. In one particular building, no one else in the buildings VLAN can communicate with devices on the third floor. From what I can gather so far from my troubleshooting, the switch doesn't appear to be passing incoming broadcasts. I'm fairly certain both L2 and L3 broadcasts are effected. Devices connected to the 4006 appear to be able to use broadcasts, as they are getting their addresses via DHCP. ARP packets sent from within the VLAN from other parts of the building never reach the third floor. I can ping the devices from the core and other networks, as the core does have ARP entries for the other devices.

The switch on the third floor is a 4006 with a SUPII running CatOS. The next upstream switch is a 375012S, which is the distribution switch. From there it goes to our core router. The uplink between the 4006 and the 375012 is multimode fiber (SX transcievers). There are no port errors on any of the uplinks. The 4006 does show one of the Ethernet line cards as faulty, but client communtications appear to be working and I have confirmed that clients on the other cards can not be contacted as well.

I'm really grasping at straws at this point. I have scheduled after hours maintenance this week, any thing I should try? I was going to take another switch over to confirm/deny the problem lies in the 4006, possibly reboot the 4006.

Any suggestions would be helpful.



Hard to say the truth, but a reboot is always a good thing to do when weird things happen .

Anyway, good that it solved the issue, and hopefully it will be permanent.


Bruno Silva.