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Cisco HSRP question 6500's on ISO Version 12.2(18)SXF11.

Posted on 2009-07-10
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Last Modified: 2012-05-07
I've got two 6500's on ISO Version 12.2(18)SXF11.
I have 7 vlan's defined on each with HSRP between the two.  There is one cat6 cable connecting them together.
When I bring the systems up, the HSRP looks great with 6500-A being active for all the VLANS as designed.

I have active hosts plugged into switch ports on vlans 2, 4, and 9.  The cross-connect ports are set up as trunks.  I will have hosts on the other vlans on down-stream switches (with uplinks to each unit for redundancy).  There are no connections to those downstream switches yet - that's to be done.

I'm doing failover tests now and I've run into an issue that confuses me.

When I turn off 6500-B, and on 6500-A I would expect everything to stay just fine with pings from a laptop on VLAN2 to each of the HSRP IP's for the other VLANS to stay active.  Instead, I have found that VLAN's with no active hosts start failing.
Logs show the HSRP going from Active to Init:
 Apr 27 18:15:01: %STANDBY-6-STATECHANGE: Vlan3 Group 3 state Active -> Init The VLAN interface shows as down/down.
They never recover until I reboot 6500-B.  Once 6500-B is back up, all recover to normal state.

The same thing happens on both 6500's if I remove the cross connect cable between the two.

I proved my 'no active hosts' theory by adding a host on one of the VLAN's that fail, and when I do the test again that VLAN stays up.

I've included config bits for one of the vlans below.  The rest are all identical with just IP's and numbers changing.

I've also include a show stand br output from A when B is turned off.

Any clues/thoughts/ideas?  I'm worried that if hosts for the other VLANS are only on downstream switches and this behavior happens then, I have no real routing redundancy...

Thanks for any input.


6500-A:
interface Vlan6
 description IuPS Vlan
 ip address 10.10.6.1 255.255.255.0
 no ip redirects
 standby 6 ip 10.10.6.3
 standby 6 timers 5 15
 standby 6 priority 110
 standby 6 preempt
 standby 6 authentication provo2
!

6500-B:
interface Vlan6
 description IuPS Vlan
 ip address 10.10.6.2 255.255.255.0
 no ip redirects
 standby 6 ip 10.10.6.3
 standby 6 timers 5 15
 standby 6 priority 90
 standby 6 authentication provo2
!

Happy state:
6500-A#show stand br
                     P indicates configured to preempt.
                     |
Interface   Grp Prio P State    Active addr     Standby addr    Group addr    
Vl2         2   110  P Active   local           10.10.2.2       10.10.2.3      
Vl3         3   110  P Active   local           10.10.3.2       10.10.3.3      
Vl4         4   110  P Active   local           10.10.4.2       10.10.4.3      
Vl5         5   110  P Active   local           10.10.5.2       10.10.5.3      
Vl6         6   110  P Active   local           10.10.6.2       10.10.6.3      
Vl7         7   110  P Active   local           10.10.7.2       10.10.7.3      
Vl9         9   110  P Active   local           10.10.9.2       10.10.9.3      

6500-B-turned-off state (hosts on VLANS 2,4,6,9 plugged in to 6500-A):
6500-A#show stand br
                     P indicates configured to preempt.
                     |
Interface   Grp Prio P State    Active addr     Standby addr    Group addr    
Vl2         2   110  P Active   local           10.10.2.2       10.10.2.3      
Vl3         3   110  P Init     unknown         unknown         10.10.3.3      
Vl4         4   110  P Active   local           10.10.4.2       10.10.4.3      
Vl5         5   110  P Init     unknown         unknown         10.10.5.3      
Vl6         6   110  P Active   local           10.10.6.2       10.10.6.3      
Vl7         7   110  P Init     unknown         unknown         10.10.7.3      
Vl9         9   110  P Active   local           10.10.9.2       10.10.9.3

Thanks.

6500-a.conf.txt
6500-b.conf.txt
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Question by:KrisArmstrong
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that1guy15 earned 500 total points
ID: 24828358
So you are correct. A SVI will go down/down when there are no active devices connected to it. You are fine when all is up and running because the trunk is active for all vlans. but when the trunk is removed between switches then the switch has no active connections for those vlans. Thus the vlan goes down/down. The same is true when the other switch goes down, this causes the trunk link to go down.

HSRP is then unable to setup for those interfaces since they are down. That is why the hsrp groups are in int state.

So when you connect your downstream switches, then you will have multiple connections for each vlan (trunk between switches and the downstream connections).

So when all is connected and one of the 6500s goes down all vlans will stay up on the other 6500 because downstream switches are still connected to it. Thus HSRP will fail over to it and all will be good.

To test connect a couple switches to both 6500s as you would in production and test.
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