Spanning Tree Lopp Guard Query .!!!!!.

Dipesh Patel · ‎07-12-2010

Dear All,

I have one query.

If I will connect 3 nos of switch in triagle pattern.

A -------B

| /

C

Now All the switches have configured with Spaaning-Tree LoopGuard Default. Means Loopguard is enable on all the ports.

Will it work or if I will do this type of connectivity for redundancy than I need to remove loopguard from all the involved ports of this ring.

Pls Reply.

Regards

Nagaraja Thanthry · ‎07-12-2010

Hello,

By default, spanning tree should take care of the topology and block one of

the ports. Enabling loopguard will add a second layer of protection against

any kind of physical loops.

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a0080

094640.shtml#loop_guard

Hope this helps.

Regards,

NT

Dipesh Patel · ‎07-12-2010

Hi..

My scenario is like this.

Is it ok or should I change something ?

Regards,

arun kumar · ‎07-13-2010

Hi Dipesh,

Loop guard is primarily used in cases of unidirectional link failure where one end of the link is transmitting and the other end is not receiving the frames. This will result in bringing the non-desingated ports into listening, learning and eventually into forwarding state due to non-receipt of BPDU's and eventually this creates loops. Loopguard is enabled on root and alternate ports in redundant paths. So in your case, you can enable in the other end of the two links of center switch (which were not showing in the diagram).

You can also look for enabling UDLD which also does the same functionality with minor differences.

You can compare the functionalities between loop guard and udld:

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a0080094640.shtml

HTH...

thanks

Arun

pls rate if it is useful