[c-nsp] Odd Etherchannel behavior between 7507 and cat 4006

[Bill Wichers]

I have a strange problem getting an Etherchannel link betweek a 7507 and
a Cat 4006. Basically everything works, but the two FE interfaces on the
7507 (both in the same VIP) keep dropping their "full-duplex" config and
reporting "unknown duplex" instead. Traffic works across the link, load
is about the same on both member links, only the weird duplex problem -
which is causing some errors to show on the port.

 

Config on the switch is very simple:

 

set port speed      2/1-2 100

set port duplex     2/1-2 full

 

set trunk 2/1  on dot1q 1-1005,1025-4094

set trunk 2/2  on dot1q 1-1005,1025-4094

set port channel 2/1-2 mode on

 

Just two FE interfaces in the group.

 

Config on the router isn't very complicated either:

 

interface Port-channel1

 no ip address

 load-interval 30

 hold-queue 150 in

!

interface FastEthernet1/0/0

 description EC to core switch 2/1

 no ip address

 channel-group 1

!

interface FastEthernet1/1/0

 description EC to core switch 2/2

 no ip address

 channel-group 1

!

 

There are a few virtual interfaces on the port-channel using 802.1q tags
and they all seem to work, they're setup the usual way of "port-channel
1.123 / encap dot1q 123 ... etc.

 

Router is running 12.2(6a), cat is running 8.4(8)GLX. There is no fancy
L3 blade in the cat. It seems like the router is just loosing the
'full-duplex' part of the config of the two member links and aside from
that everything seems to work. Any ideas? 

 

   -Bill