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Cisco Router Possible HSRP Issues - Out of Sync ??

I have two Cisco 2821 routers with HSRP configured.

On the primary, if I do a "sh standby" I get the same results on all of the interfaces - 1 state change, last state change 1w0d

If I do a "sh standby on the secondary box I get the last state change as 23:16, with each of the interfaces having a different number of state changes ranging from 13 to 45.

The two routers have different uptimes, so there's no surprise that the amount of state changes is only 1 on the primary. However, I have the following questions :

1. On the secondary box, wouldn't you expect the interfaces to have the same state change counts ?
2. Shouldn't the last state change time on the primary and the secondary router agree ?
3. Is it possible for HSRP to get out of sync and, if so, how and under what circumstances ?

Any help would be much appreciated.

TIA
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ccfcfc
Asked:
ccfcfc
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2 Solutions
 
Jim_CoyneCommented:
On the secondary box, wouldn't you expect the interfaces to have the same state change counts ?

>> This sounds like you have multiple standby groups on the same router, so the state changes would be independent. Could you post the configs?

Shouldn't the last state change time on the primary and the secondary router agree ?

>> They don't have to match, take this scenerio into consideration: Both routers loose communication with each other. This causes both routers to become "active". Communication between the routers is restored and the lower priority changes state to "passive", but the higher priority has not chaged state. It is still "active"

Is it possible for HSRP to get out of sync and, if so, how and under what circumstances ?

>> In the scenerio above, I would say they are "out of sync" since they both think they are the "active" router. This could also happen if authentication didn't match.

Sample sh standby:

Ethernet0/0 - Group 1 <-----Group number  (standby 1 ip 192.168.0.22)
  State is Active
    2 state changes, last state change 00:01:16
  Virtual IP address is 192.168.0.22
  Active virtual MAC address is 0000.0c07.ac01
    Local virtual MAC address is 0000.0c07.ac01 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 1.296 secs
  Preemption enabled
  Active router is local
  Standby router is 192.168.0.20, priority 100 (expires in 7.276 sec)
  Priority 110 (configured 110)
    Track object 3 state Up decrement 20
  IP redundancy name is "hsrp1" (cfgd)

Ethernet0/0 - Group 1
  State is Standby
    1 state change, last state change 00:07:58
  Virtual IP address is 192.168.0.22
  Active virtual MAC address is 0000.0c07.ac01
    Local virtual MAC address is 0000.0c07.ac01 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 2.784 secs
  Preemption enabled
  Active router is 192.168.0.21, priority 110 (expires in 7.772 sec)
  Standby router is local
  Priority 100 (default 100)
    Track object 3 state Up decrement 20
  IP redundancy name is "hsrp1" (cfgd)


Sample sh standby (with "out of sync" group)

Ethernet0/0 - Group 1
  State is Active
    2 state changes, last state change 00:11:05
  Virtual IP address is 192.168.0.22
  Active virtual MAC address is 0000.0c07.ac01
    Local virtual MAC address is 0000.0c07.ac01 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 2.144 secs
  Preemption enabled
  Active router is local
  Standby router is unknown
  Priority 110 (configured 110)
    Track object 3 state Up decrement 20
  IP redundancy name is "hsrp1" (cfgd)

Ethernet0/0 - Group 1
  State is Active
    2 state changes, last state change 00:01:08
  Virtual IP address is 192.168.0.22
  Active virtual MAC address is 0000.0c07.ac01
    Local virtual MAC address is 0000.0c07.ac01 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 0.792 secs
  Authentication text "test"
  Preemption enabled
  Active router is local
  Standby router is unknown
  Priority 100 (default 100)
    Track object 3 state Up decrement 20
  IP redundancy name is "hsrp1" (cfgd)

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Jim_CoyneCommented:
(now back in sync)

Ethernet0/0 - Group 1
  State is Standby
    4 state changes, last state change 00:00:11
  Virtual IP address is 192.168.0.22
  Active virtual MAC address is 0000.0c07.ac01
    Local virtual MAC address is 0000.0c07.ac01 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 0.912 secs
  Preemption enabled
  Active router is 192.168.0.21, priority 110 (expires in 9.920 sec)
  Standby router is local
  Priority 100 (default 100)
    Track object 3 state Up decrement 20
  IP redundancy name is "hsrp1" (cfgd)

Ethernet0/0 - Group 1
  State is Active
    2 state changes, last state change 00:12:59
  Virtual IP address is 192.168.0.22
  Active virtual MAC address is 0000.0c07.ac01
    Local virtual MAC address is 0000.0c07.ac01 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 2.904 secs
  Preemption enabled
  Active router is local
  Standby router is 192.168.0.20, priority 100 (expires in 7.876 sec)
  Priority 110 (configured 110)
    Track object 3 state Up decrement 20
  IP redundancy name is "hsrp1" (cfgd)
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Don JohnstonInstructorCommented:
1. On the secondary box, wouldn't you expect the interfaces to have the same state change counts ?
No. If the standby HSRP router has "issues" (a flapping interface, for example), it could change HSRP state everytime that interface goes down... and up. While the active HSRP router hasn't changed state at all.

2. Shouldn't the last state change time on the primary and the secondary router agree ?
No. See answer to #1.

3. Is it possible for HSRP to get out of sync and, if so, how and under what circumstances ?
Ifby "out of sync" you mean different number of state changes, then yes. See answer to #1.
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ccfcfcAuthor Commented:
Thanks for all the info. That's helped clear things up.
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