09-17-2007 08:00 AM - edited 03-05-2019 06:31 PM
I have a 3750 stack in one of my MDFs, this stack connects to 4 additional 3750 stacks via redundant fiber connections (2 connections to each IDF). I have bundled each of the fiber connections, but I just noticed that when I do a "show etherchannel detail" on the core stack there is only 1 port active in each etherchannel. When I remove the channel-group configuration at the interface level and then put it back, one port in the bundle immediatly leaves the group. The interface configuration is as follows:
!
interface GigabitEthernet1/0/1
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 1 mode on
!
interface GigabitEthernet2/0/1
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 1 mode on
!
The "show etherchannel 1 detail" gives the following:
Group state = L2
Ports: 2 Maxports = 8
Port-channels: 1 Max Port-channels = 1
Protocol: -
Minimum Links: 0
Ports in the group:
-------------------
Port: Gi1/0/1
------------
Port state = Up Mstr In-Bndl
Channel group = 1 Mode = On Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = -
Age of the port in the current state: 0d:00h:07m:29s
Port-channels in the group:
---------------------------
Port-channel: Po1
------------
Age of the Port-channel = 10d:18h:27m:21s
Logical slot/port = 10/1 Number of ports = 2
GC = 0x00000000 HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = -
Port security = Disabled
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Gi1/0/1 On 0
Time since last port bundled: 0d:00h:07m:29s Gi2/0/1
Time since last port Un-bundled: 0d:00h:09m:53s Gi1/0/1
09-17-2007 08:09 AM
Is it possible that the problem lies at the other end of this channel link? Are the two corresponding ports on the other end of the link correctly configured and bundled? This is the sort of behavior I might expect if the two ports making the bundle at the other end are mismatched and therefore unable to form a bundle.
Maybe they are crossed between different distribution switches. At the core switch, if you show cdp neighbors, are these two ports connected where you think they are connected?
Kevin Dorrell
Luxembourg
09-17-2007 08:13 AM
It doesn't appear that is the case, i have confirmed the ports are correctly configured and bundled, at least the configuration is exactly the same on the interfaces. In fact a "show etherchannel detail" on the other side shows a good bundle. They are connected where I think they are.
09-18-2007 10:32 PM
What is IOS Release? 12.2(40)SE?
09-19-2007 10:15 AM
Yes, in fact we had recently upgraded to the 12.2(40)SE
Have you seen the same problem?
09-19-2007 10:38 PM
>Yes, in fact we had recently upgraded to the 12.2(40)SE
>
>Have you seen the same problem?
Yes it is.
09-19-2007 12:49 PM
Check that you are using a LACP trunk. PAgP is not supported for etherchannels across chassis.
"PAgP cannot be enabled on cross-stack EtherChannels while LACP is supported on cross-stack EtherChannels from Cisco IOS Software Release 12.2(25)SEC and later. "
09-19-2007 04:10 PM
No he is forcing the etherchannel on which is ok on crosstack etherchannel. that is the problem when you force on a etherchannel it can look like it is working like on one side like you are seeing , you might want to try and use lacp instead and see what happens.
09-20-2007 12:25 AM
It is not helping! =). I tested Cross-Stack Etherchannel in both mode. Result was the same. I changed even Stack Master (from switch 1 to 2) and after election the bundled port Gi1/0/1 is displayed in the Etherchannel only through 'remote command 1 sh etherchannel 1 port', but all is working. =)
It is IOS Release 12.2(40)SE bug. I am fully confident.
09-20-2007 05:53 AM
I did the same last night and came to the same conclusion. Thank you for your help with this.
09-21-2007 03:55 AM
Make sure you have both ports on both switches configured to "on" mode if you want to run etherchannel without using LCAP for cross-stack etherchannels.
HTH,
Leo
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