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New Member

STP Disable

Hi all,

I have IBM router with 2 ethernet connect to Cisco Catalyst 3550. 1 of the ethernet got block from the Catalyst. As I need 2 ethernet port to be active when connect to the Cisco Catalyst. How to do this.

Thanks in advance.

HATO

8 REPLIES
Bronze

Re: STP Disable

no spanning -tree vlan

New Member

Re: STP Disable

Hi a.manosca first thank you for your quick response. But all the port are in vlan1 (so the switch is not configured).

Best Regards,

HATO

Re: STP Disable

Hi,

if the IBM router is configured correctly it should not participate in STP and the Catalyst should not block the port.

It seems like both Ethernet ports on the router are in one bridging group or something like that.

Are you really routing between the two Ethernet IBM router ports?

Regards,

Milan

New Member

Re: STP Disable

Hi Milan first thank you for your quick response. Maybe you need to know. The IBM router when connected to other switch is OK but when I replace with Cisco Catalyst 3550 the STP start working. Additionally there were no VLAN in the Catalyst 3550. Yes there are routing from one port to onother (one port with 10.xxx.xxx.xxx and the other 121.xxx.xxx.xxx). Hm.....do you have any idea??

Best Regards,

HATO

Re: STP Disable

Hi.

I'm confused now. What is your topology?

My understanding is:

You are connecting a router with two physical ports to one switch.

There is only one VLAN defined on the switch.

But different IP networks are used on router ports and you are routing between them.

When you replace the current switch with Cat3550 (factory config) one Ethernet port on the router gets blocked.

My questions:

1) What is the type of the current switch?

2) Why are you routing between two IP networks in one VLAN using two physical ports (If you don't want to separate IP traffic you can use secondary IP address on the same ethernet port)?

3) Do you see any syslog message (sh logging) on your Cat3550 in the time the port gets blocked?

Regards,

Milan

New Member

Re: STP Disable

HI Milan,

Yes you were right bout the topology. Current switch is IBM switch. So we have two network (10.xxx.xxx.xxx and 121.xxx.xxx.xxx), and 10.xxx.xxx.xxx need by other branch. I do not know whever the IBM router can be configure secondary IP address as Cisco router has.

Best Regards,

HATO

Re: STP Disable

OK,

what about any syslog message (sh logging) on your Cat3550 in the time the port gets blocked?

What is the output of show spanning-tree interface on the forwarding and blocked connection port?

Regards,

Milan

New Member

Re: STP Disable

Hi Milan,

Now it;s work. I just turn the STP off.

Thank YOu so much.

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