HSRP redundancy issue

jdechiaro · ‎01-17-2008

Hello,

I am having a strange problem with our HSRP configuration. I have 2 7206VXR and a 3750 stack (3 switch). The problem being experienced is whenever switch 1 is unplugged all connectivity is lost. If switch 2 or 3 are unplugged there is no loss of connectivity.

It appears that when switch 1 is removed from the stack the servers cannot find their default gtw of 172.28.20.129, which is the standby address of the HSRP group. 7206-01 is the active router. Both routers have ethernet-channel configured to each switch in the stack. running-cfgs and are attached.

7206-01#show standby

Port-channel1 - Group 0

State is Active

7 state changes, last state change 1d14h

Virtual IP address is 172.28.20.129

Active virtual MAC address is 0000.0c07.ac00

Local virtual MAC address is 0000.0c07.ac00 (default)

Hello time 3 sec, hold time 10 sec

Next hello sent in 0.352 secs

Preemption enabled

Active router is local

Standby router is 172.28.20.132, priority 90 (expires in 8.644 sec)

Priority 100 (default 100)

Track interface FastEthernet2/0 state Up decrement 20

IP redundancy name is "hsrp-Po1-0" (default)

7206-01#

7206-02#show standby

Port-channel2 - Group 0

State is Standby

16 state changes, last state change 1d14h

Virtual IP address is 172.28.20.129

Active virtual MAC address is 0000.0c07.ac00

Local virtual MAC address is 0000.0c07.ac00 (default)

Hello time 3 sec, hold time 10 sec

Next hello sent in 1.032 secs

Preemption enabled

Active router is 172.28.20.131, priority 100 (expires in 9.700 sec)

Standby router is local

Priority 90 (configured 90)

Track interface Serial2/0 state Up decrement 10

IP redundancy name is "hsrp-Po2-0" (default)

3750#show switch detail

Current

Switch# Role Mac Address Priority State

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

1 Slave 0014.a9c3.b080 1 Ready

2 Slave 0015.2b2d.c080 1 Ready

*3 Master 000a.b801.4580 1 Ready

Stack Port Status Neighbors

Switch# Port 1 Port 2 Port 1 Port 2

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

1 Ok Ok 2 3

2 Ok Ok 3 1

3 Ok Ok 1 2

3750#

3750#show switch neig

Switch # Port 1 Port 2

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

1 2 3

2 3 1

3 1 2

rsamuel708 · ‎01-17-2008

jdechiaro,

How do you have your uplinks setup? Does switch one have both uplinks, or do you have it set up with an uplink to router1 from switch1, and the other uplink to router2 from switch3? Sorry if this is an obvious question.

Also, the HSRP decrement value is 10 when a link goes down, which in your case would set them to equal at 90. Would it still fail over with both at the same value?

I'm not the expert by any means, but I thought I'd give it a shot at helping you think through the problem.

/rls

jdechiaro · ‎01-18-2008

Thanks for your reply.

The uplinks are an via ether-channel to each switch: On the port-channel the HSRP decrement has been set to 20, via standby track FastEthernet2/0 20 command, so link failure would decrement to 80 and standby would then have higher value at 90.

phyiscal wiring is:

7206-01 FE0/0 - 3750-02 2/0/23

7206-01 FE4/0 - 3750-01 1/0/23

7206-01 FE3/0 - 3750-03 3/0/23

7206-02 FE0/0 - 3750-03 3/0/8

7206-02 FE3/0 - 3750-02 2/0/4

7206-02 FE4/0 - 3750-01 1/0/7

rsamuel708 · ‎01-18-2008

jdechiaro, I'll have to leave this one up to the pros. I have several theories, but I wouldn't want to muddy the waters. Hopefully the experts can chime in here with some things to look at to help with troubleshooting.

/rls