[c-nsp] Port-Channel Problem

[Mike Lydick]

I had a similar issue when trying to turn up port channels that span across stack 3750. TAC recommends not using PAGP or LACP. Have not gotten it work since. Is this similar to your scenerio? Any resolution?

----- Original Message ----
From: Dan Armstrong <dan at beanfield.com>
To: "Collins, Richard (SNL US)" <rich.collins at siemens.com>
Cc: cisco-nsp at puck.nether.net
Sent: Tuesday, May 8, 2007 7:31:17 PM
Subject: Re: [c-nsp] Port-Channel Problem

I did exactly that, and managed to get it to go into LACP mode.

The Etherchannel ran for about 3 hours without a problem, then all of a 
sudden started losing pings all over the place.  I took one channel out 
of service, and it was fine.

I tested both physical links separately, and they're both perfect.  I'm 
scared to put them back into the Etherchannel now for fear that they'll 
fail again.

I am using the single fibre SFPs (the GLC-BX-Us and GLC-BX-Ds) for both 
of these links.

Anybody seen an Etherchannel lose it when the two underlying physical 
links are seemingly perfect on their own?




Collins, Richard (SNL US) wrote:
> So I suppose the opposite side was set at the same time to either
> channel-group 10 mode [active or passive] for LACP?
>
> What about additionally setting..
> metro2.tor-Front[760(config-if)#channel-protocol lacp 
> I can't test this myself but saw the configuration option.
>
> -Rich
>
>
>   
>> Date: Sat, 05 May 2007 02:39:04 -0400
>> From: Dan Armstrong <dan at beanfield.com>
>> Subject: [c-nsp] Port-Channel Problem
>> To: cisco-nsp at puck.nether.net
>> Message-ID: <463C2688.8060909 at beanfield.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Riddle me this.
>>
>> I have 1 physical link, and a port-channel interface operating in PAgP
>>     
> mode.
>   
>> interface GigabitEthernet1/21
>> no ip address
>> switchport
>> switchport trunk encapsulation dot1q
>> switchport trunk allowed vlan
>>     
> 50,80,119,300-304,349,412,420,440,444,446,447
>   
>> switchport trunk allowed vlan add 449,500,503,616,620,900
>> switchport mode trunk
>> channel-group 10 mode desirable
>> end
>>
>> interface Port-channel10
>> no ip address
>> switchport
>> switchport trunk encapsulation dot1q
>> switchport trunk allowed vlan
>>     
> 50,80,119,300-304,349,412,420,440,444,446,447
>   
>> switchport trunk allowed vlan add 449,500,503,616,620,900
>> switchport mode trunk
>>
>>
>> metro2.tor-Front[7609]#sh int po10
>> Port-channel10 is up, line protocol is up (connected)
>>  Hardware is EtherChannel, address is 0015.f91d.5c8e (bia
>>     
> 0015.f91d.5c8e)
>   
>>  Description: GEC to metro1.tor-Mowat [Port-channel10]
>>  MTU 9216 bytes, BW 1000000 Kbit, DLY 10 usec,
>>     reliability 255/255, txload 104/255, rxload 202/255
>>
>>
>> Life was good, then:
>>
>>
>> 2 problems.  I first tried to change to LACP:
>>
>> metro2.tor-Front[760(config-if)#channel-group 10 mode ?
>>  active     Enable LACP unconditionally
>>  auto       Enable PAgP only if a PAgP device is detected
>>  desirable  Enable PAgP unconditionally
>>  on         Enable Etherchannel only
>>  passive    Enable LACP only if a LACP device is detected
>>
>> metro2.tor-Front[760(config-if)#channel-group 10 mode active
>>
>>
>> The interface bounced, and went straight back into PAgP mode..... 
>>
>> I tried it several times.  #$S%E$@#$, always back to PAgP..... 
>> "channel-group 10 mode desirable"
>>
>>
>> Second problem:
>>
>> I tried a second link anyway, and when I added a second link into the 
>> PAgP group, the rely on the port-channel interface started dropping
>>     
> like 
>   
>> a stone,  packets were dropping all over the place and even though 
>> everything seemed to be up, speed, duplex, vlans, configuration 
>> perfectly matched between the underlying physical interfaces & the 
>> port-channel interface.... the po interface was a mess.  The new 
>> physical link on it's own is clean as a whistle when I setup a test 
>> vlan, or set both sides up as routed interfaces....
>>
>> Anybody have any light to shed?
>>
>>     
>
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