Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

STP-Problem with CIGESM (Blade) Mgmt-Ports

We use 4 IBM-Blades with internal Cisco CIGESM-Switches in our LAN.

Our 2 Core-Switches (c6513) are connected via Gigabit Etherchannel (8 ports) and every Core ist connected to one of the internal Blade-Switches via one Gigabit uplink.

The internal switches are connected to each other via 2 internal management ports (Gi0/15 and Gi0/16).

Here is where our problem starts:

1. Those Ports can not be disabled:

(config-if)#shut

% Shutdown not allowed on this interface.

2. VLAN 1 can not be removed:

User prevented from modifying mode for Gi0/16

Command rejected: not allowed on this interface.

! oh, how nice :-(

The crazy thing is, that those ports act like "hard-coded" spanning-tree bpdufilter. That means:

Internal switch A:

#show spanning-tree int gi0/16 detail

...

BPDU: sent 1177157, received 0

Internal switch B:

#show spanning-tree int gi0/16 detail

...

BPDU: sent 1177220, received 0

-> they do not recognize BPDUs from their neighbor but -because in fwd state- sent traffic (e.g. broadcasts) across those interfaces.

Unfortunately we use VLAN 1 as our management-VLAN and here is where the loop occurs.

Of cause we could remove VLAN 1 from the uplink-trunks and use a different VLAN for managing this switches but I'd prefer find a solution with VLAN 1 for management. I don't understand why the interfaces Gi0/15 and 0/16 act like this - it seems to be imposible to prevent loops when using VLAN1 ?!

We'd be thankful for any help.

Rolf Fischer

1 ACCEPTED SOLUTION

Accepted Solutions
Purple

Re: STP-Problem with CIGESM (Blade) Mgmt-Ports

It depends on how things are setup . I believe we only use 1 port to manage the switch . This is managed thru the management module and does not travel up thru the etherchannel . This is a separate connection that is not part of the etherchannel . Vlan 1 in G0/15 and 16 can be connected to any vlan you want on the other end as long as you don't try to trunk them , STP should then take care of any built in loop for whatever vlan you decide to manage it with and you should see either 15 or 16 as a blocked port if there is truly a loop in your design , if not then both ports will show forwarding . How do you know you have aloop ?

Not knowing how your blades are setup we can only speculate . We use only 1 port to manage the switch with for each management module. Vlan 1 on g0/15 is for management only I think which connected thru a separate connection thru the bladeserver management module not the switch module itself. Your etherchannels then should run on ports 17-20 only .

2 REPLIES
Purple

Re: STP-Problem with CIGESM (Blade) Mgmt-Ports

It depends on how things are setup . I believe we only use 1 port to manage the switch . This is managed thru the management module and does not travel up thru the etherchannel . This is a separate connection that is not part of the etherchannel . Vlan 1 in G0/15 and 16 can be connected to any vlan you want on the other end as long as you don't try to trunk them , STP should then take care of any built in loop for whatever vlan you decide to manage it with and you should see either 15 or 16 as a blocked port if there is truly a loop in your design , if not then both ports will show forwarding . How do you know you have aloop ?

Not knowing how your blades are setup we can only speculate . We use only 1 port to manage the switch with for each management module. Vlan 1 on g0/15 is for management only I think which connected thru a separate connection thru the bladeserver management module not the switch module itself. Your etherchannels then should run on ports 17-20 only .

New Member

Re: STP-Problem with CIGESM (Blade) Mgmt-Ports

Thanks for the reply.

I should have mentioned that we only administrate the switches - we don't have access to the blade management.

To be honest, I don't understand the purpose of the ports 0/15 and 0/16.

We provide redundancy by connecting each switch to the core and we don't need the internal connection via this ports.

But, like mentioned, I cannot shut them down or remove VLAN 1 from this ports.

We realized the loop after an IOS-Update; the cpu utilization went to 80% and we disconnected the backup-links to the core.

Maybe I can ask one of our server-admins to show me the blade-management GUI, I think I read in documentation that there are some options for using the internal management-ports.

541
Views
0
Helpful
2
Replies