[c-nsp] Port-Channel Problem

[Dan Armstrong]

These were just 2 ports on the same blade of a WS-X6724 blade at both 
sides... nothing at all strange.

I never thought of not using PAgP or LACP - perhaps I should try it.

I am too nervous to bring the GEC back up - both links out of the 
Etherchannel have been testing fine for days... maybe I should just suck 
it up and try it to see if it fails again.



Mike Lydick wrote:

> 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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>
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