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tim
New Member

Strange IP problems after etherchannel has been implemented

Having successfully set up a four port etherchannel between a Cisco 3524 and a 5505 switch, I find that when I telnet into the 3524 and try to ping another 3524 (that was set up as a 2 port etherchannel previously) I cannot ping its IP address. However, when I try and ping a PC attached to this other 3524 from the recently etherchanneled Switch, I can ping it succesfully. Help!!! Any ideas??

1 REPLY
New Member

Re: Strange IP problems after etherchannel has been implemented

First of all, check the channel for correct configuration. Notice that each device has its own implementation limitations due to the port grouping by separate Ethernet Bundle Controllers. Check the documentation for this.

I can remember that 5000s can group 2 or 4 contiguous ports starting at port 1, 5, or 9 for the 12 port modules. (It has 3 EBCs)

The 24 port module that I know also has 3 EBSc., grouping 8 ports each.

Once you are sure your phisical configuration is supported by both switches, chech the CAM (sh cam dynamic) to see where your MAC address is learnt. Test connectivity between other devices using the same physical link (port).

I´ve had a sad disappointment with something around this problem. I´m not sure which was the platform, but the problem was that the channel information should be hidden when "building" the forwarding database, and I found that the command for showing this DB shows the physical port, not the port group!!!

This means that if that port fails, although there are other channeled ports, I had to wait for the DB aging or manually clear it! I already tested this and compared it in a 1900, 2900XL, and 5000. Sorry I don´t remember which was the conflicting one. (I think it was the 5000, and the XL shows the port group for the sh mac-address-table command, as it should)

Input for this will be very apreciated.

Patricio

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