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Having a strange issue here.. I replaced a stack member (2 members in a stack of Cisco 3750x). Both switches have a 10Gb card and I had a perfectly working LAG/etherchannel between to 10Gb ports.

After replacing a stack member the portchannel can't bundle due to flow-control mismatch. It says that flow-control is of on the interface of the new member but in the config it is clearly on, consistent with the config on the other interface and the portchannel.

The error: %EC-5-CANNOT_BUNDLE2: Te1/1/2 is not compatible with Te2/1/2 and will be suspended (flow control receive of Te1/1/2 is off, Te2/1/2 is on) (ISCSI-MER2-1)

sh run:

interface TenGigabitEthernet1/1/2
 flowcontrol receive on
 channel-protocol lacp
 channel-group 1 mode active
end

interface TenGigabitEthernet2/1/2
 flowcontrol receive on
 channel-protocol lacp
 channel-group 1 mode active
end

interface Port-channel1
 flowcontrol receive on
end

I want to try to add another port to the channel but not sure if this causes disruption on the portchannel?

I could also try to disable flow control on the interfaces and on the port channel, but I need to now if this can be done during production?

5
  • Both ports have to link in the same mode as well as be configured the same. I bet, if you look, on port will be up with out flow-control. Barring that, remove and re-add the ports to the port-channel. – Ricky Dec 23 '13 at 9:41
  • True, flow control is of when doing sh interface te 1/1/2. Can i remove the failing interface from the port channel in a live environment and then add it again? I hate to shut down all vmware host and the san... – user209 Dec 23 '13 at 9:48
  • Update.. tried a couple of things.. removing and adding the failing interface.. result: no bundle.. Adding a new interface to the channel result: no bundle No matter what i try the interface keeps in suspended mode.. all config is consistent... driving me insane.. – user209 Dec 23 '13 at 15:55
  • Did you check the other devices to make sure flow control is enabled on that end? – longneck Dec 26 '13 at 3:31
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 8 '17 at 16:24
3

Sadly portchannels on Cisco are a pain when adding new interfaces. Sometimes the only way to "recover" a Port-Channel is to completeley deconfigure and reconfigure it. Steps to do so:

Reset all channel interface members to their default config

default interface TenGigabitEthernet1/1/2
default interface TenGigabitEthernet2/1/2

Remove the channel interface

no interface Port-channel1

Add interfaces to Channel

interface TenGigabitEthernet1/1/2
 channel-group 1 mode active

interface TenGigabitEthernet2/1/2
 channel-group 1 mode active

Configure all interface parameters on channel

interface Port-Channel1
 flow-control receive on

It is important to configure all interface-relevant information on the Port-Channel (except stuff that only works on physical interfaces like cdp).

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  • 1
    Always configure all of the individual interfaces as minimally as possible. Port-channels are notably picky to configuration mismatches. – Ryan Foley Mar 26 '14 at 20:48
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You might also try to disable flow control on t2/1/2 and then interface range t1/1/2, t2/1/2 and re-add the flowcontrol statement.

I know I might be stating the obvious, but I didn't see it in your steps.

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