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Community Member

Router in bridge mode, Spanning tree and uplinkFast question

Hello,

Here is the network architecture :

----------3660

--Fa0/0-/--\-Fa0/1

---------/----\

--------/------\

-------/--------\

------/----------\

-----/------------\

----/--------------\

4000A---------4000B

RootBridge

3660 with two interfaces fast ethernet bridged.

Two 4000.

This 3 networks equipments are in the same subnet -> loop -> spanning tree used.

4000A = root bridge.

Port 3660 - Fa0/1 : Blocking.

Spanning tree OK.

Normal convergence : 30 à 40 sec if interface 3660-Fa0/0 is shut.

Now i activate Uplinkfast on 3660.

Rout3660A#sh spanning-tree uplinkfast

UplinkFast is enabled

Station update rate set to 150 packets/sec.

UplinkFast statistics

-----------------------

Number of transitions via uplinkFast (all VLANs) : 0

Number of proxy multicast addresses transmitted (all VLANs) : 0

Name Interface List

-------------------- ------------------------------------

Bridge group 10 Fa0/0(fwd), Fa0/1

Rout3660A#

But the convergence stays at 30 - 40 secondes (like uplinkfast doesn"t exist ...)

For information, IOS of 3660 is : 12.2.(11).T2

All ideas are welcome.

Thank You.

5 REPLIES
Silver

Re: Router in bridge mode, Spanning tree and uplinkFast question

I don't see anything wrong with your setup but I do question your test. "shut" on the Fast E might cause STP to rerun (TGN), which would make sense with the times you are seeing, since this port might come out of STP. In the docs Uplink fast states that it will only function on a direct link failure (not shutting down). So, just to ensure all is good, can you unplug your FastE to test this failover rather than shutting this interface down just to ensure you're inline with what the docs say.

Here is a link to uplinkfast but I am sure you've seen this, but if not hope it helps clarify my comments:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_6_1/config/stp_enha.htm#xtocid24329

Hope this helps you,

Don

Community Member

Re: Router in bridge mode, Spanning tree and uplinkFast question

Thank you for your answer Don.

We have done both tests (shut of the interface and unplug the cable) to verify the failover but twice time it was the same result.

I will verify if there is no bug associated with this version and

if not, open a case.

Anyway others ideas are welcome.

Regards.

Community Member

Re: Router in bridge mode, Spanning tree and uplinkFast question

Well i have found this : CSCdy35333 Bug Details

That is exaclty what we have.

Silver

Re: Router in bridge mode, Spanning tree and uplinkFast question

It was marked U (unreproducible) due to not being able to occur in this image.

12.2(12.10)T. Did not know if you could see the comments from outside so thought I would add that in hopes it might help you if you need to upgrade to fix this issue.

Regards,

Don

Community Member

Re: Router in bridge mode, Spanning tree and uplinkFast question

Hello Don,

I have opened a case and wait the answer from Cisco about this issue.

I will inform you when i will have interesting result.

Best regards.

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