HSRP problems

michelcaissie · ‎06-05-2007

Hi,

we currently have an internet access with 2 ISP composed

of two routers 2821(Version 12.4(11)T) running BGP ( we have an ASN) .

We are running two HRSP groups on the pair of routers.

Once in a while we lose internet access for a couple of minutes and the

problem seems to

be related to HSRP.

**First MRTG shows that router 1 generates a lot of traffic ( 80 Mb/s)

for 5 minutes.

**Router 1 traps shows that HSRP is toggleing from active to standby

for group 2 only

2007-06-02 18:34:50 Local7.No-tice x.x.56.3 261: Jun 2 2007 18:34:49.249

EDT: %HSRP-5-STATECHANGE: GigabitEthernet0/1 Grp 2 state Standby -> Active

2007-06-02 18:34:53 Local7.Notice x.x.56.3 262: Jun 2 2007 18:34:52.301

EDT: %HSRP-5-STATECHANGE: GigabitEthernet0/1 Grp 2 state Active -> Speak

2007-06-02 18:35:03 Local7.Notice x.x.56.3 263: Jun 2 2007 18:35:02.301

EDT: %HSRP-5-STATECHANGE: GigabitEthernet0/1 Grp 2 state Speak -> Standby

2007-06-02 18:35:13 Local7.Notice x.x.56.3 264: Jun 2 2007 18:35:12.301

EDT: %HSRP-5-STATECHANGE: GigabitEthernet0/1 Grp 2 state Standby -> Active

2007-06-02 18:35:22 Local7.Notice x.x.56.3 265: Jun 2 2007 18:35:21.273

EDT: %HSRP-5-STATECHANGE: GigabitEthernet0/1 Grp 2 state Active -> Speak

2007-06-02 18:35:32 Local7.Notice x.x.56.3 266: Jun 2 2007 18:35:31.278

EDT: %HSRP-5-STATECHANGE: GigabitEthernet0/1 Grp 2 state Speak -> Standby

2007-06-02 18:35:35 Local7.Notice x.x.56.3 267: Jun 2 2007 18:35:34.262

***Router 1 - There is no state changes on Group 1 but 514 on group 2

GigabitEthernet0/1 - Group 1

State is Active

1 state change, last state change 16w5d

GigabitEthernet0/1 - Group 2

State is Standby

514 state changes, last state change 1d21h

***Router 2 - No state changes on either group

GigabitEthernet0/1 - Group 1

State is Standby

4 state changes, last state change 14w3d

GigabitEthernet0/1 - Group 2

State is Active

2 state changes, last state change 16w5d

*** Here is the Router 1 config

standby 1 ip x.x.56.1

standby 1 priority 140

standby 1 preempt

standby 1 track GigabitEthernet0/0 50 (WAN ISP1)

standby 2 ip x.x.56.2

standby 2 preempt

***And Router 2 config

standby 1 ip x.x.56.1

standby 1 preempt

standby 2 ip x.x.56.2

standby 2 priority 140

standby 2 preempt

standby 2 track Serial1/0.500 50 (WAN ISP2)

Does anyone have an idea why Router 1 HSRP is going crazy ?

It seems to lose contact with Router 2 but only for group 2 , group 1

still works.

And it happens like once every two weeks. always at different times , days

or weekends...

Any hints ?

Thanks

chrihussey · ‎06-05-2007

The fist thing that jumps out at me is that you have the "preempt" option on both the active and standby interfaces. Only use this on the interface where the IP priotity is set to 140. So remove:

R1:

no standby 2 preempt

R2:

no standby 1 preempt

Jon Marshall · ‎06-05-2007

Hi

Actually i think you do need the preempt on both routers if you are tracking interfaces otherwise if the tracked interface goes down and the priority is reduced (by 50 in this example) without the preempt the other router would never take over.

Jon

michelcaissie · ‎06-05-2007

Thank you both for your replies...

According to cisco doc , i need preempt on both , for the reason you say. But i just saw that i don't track the wan interface on both groups . I will add that .

And do you think that changing the hello/holdtime to something like 10sec / 30 sec might help ? or is it irrevelant for that type of problem ?

http://www.cisco.com/en/US/customer/tech/tk648/tk362/technologies_tech_note09186a0080094e8c.shtml

rafaelgarcia · ‎06-06-2007

Hi,

Just as a comment, if you want a much better solution try GLBP (Gateway Load Balancing Protocol). This protocol allows you not only to configure redundancy but also load balance your circuits.

Probably you are paying for one circuit just to have it as a backup.Well, with this protocol you can have both working at the same time and if one fails the other takes the traffic.

I hope it helps.

royalblues · ‎06-06-2007

I think you are loosing the hellos between the routers during peak load which is causing the state changes.

try increasing the hello/hold timer or prioritize the traffic to 224.0.0.2 using UDP port 1985

HTH, rate if it does

Narayan