[c-nsp] Cisco 3020 blade switches hung, HLFM errors, network meltdown?

[Mateusz Błaszczyk]

As Fredrik said running "channel-group on" could be very dangerous:

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a008009448d.shtml

Best Regards,

-mat

On 20/03/2008, Fredrik Jacobsson <cisco-nsp at jacobsson.nu> wrote:
> In a stp troubleshooting paper on cco, I saw a recommendation to run
>  pagp (non-silent) due to it's ability to select/negiotiate which port
>  in the bundle to run stp on. Also to prevent that the configs differ
>  and shut down inconsistant ports.
>
>  (was a while and I dont have a photographic memory so please dont kill
>  me if I'm wrong)
>
>  Is that setup (desirable non-silent) still considered best practise?
>  (I've noticed that many use "on" nowadays, hence not using pagp/lacp)
>
>  Thanks
>  /Fredrik
>
>  2008/3/20, matthew zeier <mrz at velvet.org>:
>
> >
>  > On Mar 19, 2008, at 5:18 PM, Lincoln Dale wrote:
>  >
>  > > Hi Matthew,
>  > >
>  > > not a specific diagnosis to your problem, but i think this is a bit
>  > > of a warning here:
>  > >
>  > > matthew zeier wrote:
>  > >> Felt like a broadcast storm or even a spanning-tree loop but I'd be
>  > >> surprised if it was the latter and the upstream switches, two
>  > >> 6500s, didn't know how to do deal with that (heck, they deal with
>  > >> HP 2510s that default to not running spanning-tree).
>  > >>
>  > > if you had switches in your network NOT running STP, you've got a
>  > > pretty good opportunitiy for "bad things<tm>" to happen.
>  > >
>  > > were those switches connected with >1 link?
>  >
>  > Yes and for all the Vlans I have, one uplink is blocked :
>  >
>  > Interface        Role Sts Cost      Prio.Nbr Type
>  > ---------------- ---- --- --------- --------
>  > --------------------------------
>  > Po1              Root FWD 3         128.72   P2p
>  > Po2              Altn BLK 3         128.80   P2p
>  >
>  > Native Vlan on 0/16 was changed which broke the bundle and everything
>  > else.  One upstream switch is the other 3020 in the same chassis - the
>  > other is a 6500 which is also running pvst.   I would have figured
>  > something would have noticed a look at shut something down (if it was
>  > a STP loop anyways).
>  >
>  > interface Port-channel1
>  >  description to_core2:po100
>  >  switchport trunk encapsulation dot1q
>  >  switchport trunk native vlan 2
>  >  switchport mode trunk
>  >
>  > interface Port-channel2
>  >  switchport trunk encapsulation dot1q
>  >  switchport trunk native vlan 2
>  >  switchport mode trunk
>  >
>  > interface GigabitEthernet0/17
>  >  description to_core2:7/32
>  >  switchport trunk encapsulation dot1q
>  >  switchport trunk native vlan 2
>  >  switchport mode trunk
>  >  logging event bundle-status
>  >  logging event spanning-tree
>  >  channel-group 1 mode on
>  > !
>  > interface GigabitEthernet0/18
>  >  description to_core2:7/33
>  >  switchport trunk encapsulation dot1q
>  >  switchport trunk native vlan 2
>  >  switchport mode trunk
>  >  logging event bundle-status
>  >  logging event spanning-tree
>  >  channel-group 1 mode on
>  >
>  > interface GigabitEthernet0/23
>  >  switchport trunk encapsulation dot1q
>  >  switchport trunk native vlan 2
>  >  switchport mode trunk
>  >  logging event bundle-status
>  >  logging event spanning-tree
>  >  media-type internal
>  >  channel-group 2 mode on
>  > !
>  > interface GigabitEthernet0/24
>  >  switchport trunk encapsulation dot1q
>  >  switchport trunk native vlan 2
>  >  switchport mode trunk
>  >  logging event bundle-status
>  >  logging event spanning-tree
>  >  media-type internal
>  >  channel-group 2 mode on
>  >
>  >
>  >
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-- 
-mat