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I'm testing a HSRP configuration between two layer 3 switches and two layer 2 access switches.

The HSRP functionality between the two layer 3 switches appears to failover as expected but I appear to have a stp convergence issue.

I have one hsrp switch configured as the root primary and the other as the root secondary for all vlans.  When I failed over from the root primary to the root secondary, I lose about 70 packets during a ping test from an access switch to a device connected to the other access switch.  When I perform the same test during a failover from the root secondary to the root primary, I only lost 1 packet.

I'm currently using rapid pvst.  I'm assuming the additional packet loss is due to convergence?  Any ideas?

Thanks


Update:  One thing I didn't mention was how the switches are connected.  I have a trunk between the two layer 3 switches.  Then each access switch as a trunk to each layer 3 switch.

asked 09/19/2011 05:18

VSUTech's gravatar image

VSUTech ♦♦


8 Answers:
Hi,

What is the topology and where are the redundant links?
link
rochey2009's gravatar image

rochey2009

The red links are active links.  The connections between the switches are port channel links.
 
hsrp diagram
hsrp diagram
 
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VSUTech's gravatar image

VSUTech

How are you testing this? Are you powering off HSRP A?

can you post

show spanning-tree for one of the VLANs
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rochey2009's gravatar image

rochey2009

check with RSTP and tweaking timers for HSRP.
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Sanjeevloke's gravatar image

Sanjeevloke

I was able to figure out the issue pinging from the access switch.  I hadn't configured the native vlan in an hsrp group so the pings would fail because the default gateway was down.

One thing I did notice was a trunk to a router attached to one of the access switches goes into a learning state when the root primary goes down or comes back up.  I am testing this by reloading the root primary switch.  

Any ideas why this would happen?  I am running rapid pvst.
 
added router
added router
 
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VSUTech's gravatar image

VSUTech

Hi,

Does the router understand rapid spanning tree or is it using traditional spanning tree?

You could use spanning-tree portfast trunk on the trunk link to the router.
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rochey2009's gravatar image

rochey2009

no i dont think so router understand RSTP.
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Sanjeevloke's gravatar image

Sanjeevloke

Please post the following output:

HSRP A:
show span
show standby brief
show int status
show ip int brief

HSRP B:
show span
show standby brief
show int status
show ip int brief

Layer 2 switch under HSRP A
show span
show int status

Layer 2 switch under HSRP B
show span
show int status
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donjohnston's gravatar image

donjohnston

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Asked: 09/19/2011 05:18

Seen: 364 times

Last updated: 11/03/2011 07:14

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