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GigabitEthernet Trunk hangs when I add a subint to a bridge group

Hello all,

I ran into something unsettling yesterday, and I'm hoping that someone can tell me why this happened, or if indeed it's even supposed to...

We have a 7206 that has several ethernet customers attached to it, as well as having an ATM DS-3 module for DSL customers. We've got one ethernet customer that has been convincing people to order DSL through us, and he requests that they be bridged to his ethernet connection so that he can provide different kinds of services to them.

Here's a show ver from my router:

Cisco Internetwork Operating System Software IOS (tm) 7200 Software (C7200-IS-M), Version 12.2(4)BW1, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)

The relevant lines (AFAIK) from the config are these (summarized for example's sake):

! bridge irb ! interface GigabitEthernet0/1 description 802.1q Trunk to Network no ip address duplex full speed 1000 media-type gbic negotiation auto ! interface GigabitEthernet0/1.20 description Ethernet Customer encapsulation dot1Q 20 ip address X.X.X.X X.X.X.X ! interface GigabitEthernet0/1.30 description Bridge to DSL Customer on ATM2/0.123 encapsulation dot1Q 30 bridge-group 30 ! interface ATM2/0.123 point-to-point description DSL Customer Bridge to GigabitEthernet0/1.30 class-int 3.0-768-atm pvc 1/123 ! bridge-group 30 ! bridge 30 protocol ieee !

Brief description: The GigabitEthernet0/1 port goes into a 3550 via an 802.1q trunk, and the ethernet customer's stuff is hooked into one of the ports on that 3550. The port he's connected to is ALSO a trunk port, but I'm only allowing the VLANs associated with the bridges I'm creating. Gig0/1.20 is the ethernet customer's main subinterface, where he's got his equipment "connected". Gig0/1.30 is there to create another VLAN for the bridge 30 to the ATM2/0.123 interface. So essentially, the DSL customer is attached to ATM2/0.123, which is in a bridge group with Gig0/1.30, which passes over the trunks to his equipment.

Here's the prob. While I'm creating Gig0/1.30, as SOON as I type bridge-group 30, BLAMMO, the Gig0/1 interface goes down. 30 seconds later, it's back and fine. It's like spanning tree is putting it into blocking mode or something. At least that's my best guess.

Is my assessment correct? Other ideas? Is there a better way to do this?

Thanks in advance!

--Rick Kunkel

Reply to
Rick Kunkel
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- You can first of all enable logging on the interface, use this as extra statements in config for the interface params :

logging event link-status logging event spanning-tree status logging event trunk-status

Also in your global config , enable logging to an available syslog server as in :

logging ip-of-syslog-server

Then when the problem situation occurs , issue a :

# show log

on the switch, and check the syslog server's syslog file and lookup all entries from the switch.

This may provide extra info.

M.

Reply to
Marc Elsen

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