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Community Member

Redundant connection between two 2950 - troubles

hi,

I have strange problem - connection between two switches if lost forewer after reboot of the root switch.

Details:

It started with not formed Etherchannel and lost connection between the two switches

or with topology loop followed by broadcast storm.

After some investigations, I was able to reproduce the problem with following basic cfg:

Switch 1

- Cisco Catalyst WS-C2950-24

- SW: IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(12c)EA1, RELEASE SOFTWARE (fc1)

- HW: cisco WS-C2950-24 (RC32300) processor (revision H0) with 21002K bytes of memory

Switch 2

- Cisco Catalyst WS-C2950-24

- SW: IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(12c)EA1, RELEASE SOFTWARE (fc1)

- HW: cisco WS-C2950-24 (RC32300) processor (revision H0) with 21002K bytes of memory

port fa0/23 of Switch 1 connected by crossover cable to port fa0/23 of Switch 2

port fa0/24 of Switch 1 connected by crossover cable to port fa0/24 of Switch 2

all parameters set to defaults using

#write erase

management interface Vlan1

for debuging purposes:

#service timestamps debug datetime msec

#service timestamps log datetime msec

#debug spanning-tree events

under normal conditions the Switch 1 is becoming spanning tree root, as it has lower MAC address

now the problem:

when the Switch 2 (NOT root) is restarted (power off/on) then everything goes well:

Switch 1 is root, fa0/23 FWD, fa0/24 FWD

Switch 2 sees root on fa0/23, fa0/23 FWD, fa0/24 BLK

but when the Switch 1 (root) is restarted then there is no connection between them (ping) and:

Switch 1 is root, fa0/23 FWD, fa0/24 FWD

Switch 2 is root, fa0/23 FWD, fa0/24 FWD

seems to be a bug in how STP implemantation reacts to interface/link down events

but as I'm not expert, ...

any idea?

thanks

ps

2 REPLIES
Bronze

Re: Redundant connection between two 2950 - troubles

Check the Cisco's Bug tool kit for any known issues.

http://www.cisco.com/cgi-bin/Support/Bugtool/home.pl

Community Member

Re: Redundant connection between two 2950 - troubles

upgrade from IOS 12.1(12c)EA1 to IOS 12.1(14)EA1a makes it working with some minor issues like LEDs remaining in orange

I have to say, that the technically hardest part was to figure out, how obtain the fixed IOS from Cisco

ps

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