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

matthew zeier mrz at velvet.org
Wed Mar 19 23:13:43 EDT 2008


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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