HSRP Between 3 COREs

[willard.hanada]

Hello all

I currently have 2 4506 CORE switch trunking each other 4GB channel, and the HSRP is working on them!

We´re studing a new site backup like 3km distance.. We decided to put a third CORE switch 6509 or any other!

At first, we´re studing a standalone solution... the CORE stay there as any other Switch from the LAN.. if something goes wrong we turn that CORE as VTP server and add the HSRP ...

And second, put the third CORE as part of VTP server and HSRP... so 3 COREs at same time...

My question for you experts, is if this is possible? I heard about GLBP? but Im trying to check first if its possible to add a third CORE using HSRP between them!?!?

thanks for any help!

-WH-

[rettuc_ccnp · Accepted solution]

Hello WH,

Here are my thoughts;

1. I wouldn't run L2 at the Core layer thus no need to be concerned with VTP configuration.  In any case if VTP is going to run at the Core layer you will want to ensure all 3 Core devices have the most current VLAN information prior to anything going wrong.  Meaning you should run all three devices in VTP server mode concurrently.  This is not really a "feature" that you turn off/on when problems arise.  Instead it's something that should be incorporated in your overall design strategy for minimizing network downtime by ensuring VLAN database consistency.  The different VTP modes also allows you to control which devices can add/remove entries to the VLAN databases environment.

2. HSRP configurations are defined by group numbers and use priority values (default = 100) to determine active and standby roles.  Each group can have multiple standby routers (e.g. Core1 HSRP group1, priority 140 | Core2 HSRP group1, priority 130 | Core3, HSRP group1, priority 120).  In this case Core1 is in the active state while Cores 2 and 3 are in the standby state.  When the subnet loses connecivity to Core1...Core2 will become the active router and when the subnet loses connectivity to Core2...Core3 then becomes the active router.  If you want Core1 to become the active router again once things are back in order you will need to ensure preempt is configured accordingly.

Hope this helps!

[willard.hanada]

Thanks rettuc for the answer!

[adamclarkuk_2 · Accepted solution]

Hi Willard

I concur with rettuc and have put together some outputs of what to expect.

R1 is the configured primary, R2 secondary and R3 tertiary. Note that that the state of R3 is listen until a failover occurs.

Pre failover

R1#

interface FastEthernet0/0

ip address 192.168.1.2 255.255.255.0

standby 10 ip 192.168.1.1

standby 10 priority 250

standby 10 preempt

end

R1#show standby

FastEthernet0/0 - Group 10

State is Active

   1 state change, last state change 00:03:33

Virtual IP address is 192.168.1.1

Active virtual MAC address is 0000.0c07.ac0a

   Local virtual MAC address is 0000.0c07.ac0a (v1 default)

Hello time 3 sec, hold time 10 sec

   Next hello sent in 2.704 secs

Preemption enabled

Active router is local

Standby router is 192.168.1.3, priority 200 (expires in 9.560 sec)

Priority 250 (configured 250)

Group name is "hsrp-Fa0/0-10" (default)

R2#

interface FastEthernet0/0

ip address 192.168.1.3 255.255.255.0

standby 10 ip 192.168.1.1

standby 10 priority 200

standby 10 preempt

end

FastEthernet0/0 - Group 10

State is Standby

Virtual IP address is 192.168.1.1

Active virtual MAC address is 0000.0c07.ac0a

   Local virtual MAC address is 0000.0c07.ac0a (v1 default)

Hello time 3 sec, hold time 10 sec

   Next hello sent in 1.988 secs

Preemption enabled

Active router is 192.168.1.2, priority 250 (expires in 9.156 sec)

Standby router is local

Priority 200 (configured 200)

Group name is "hsrp-Fa0/0-10" (default)

R3#

interface FastEthernet0/0

ip address 192.168.1.4 255.255.255.0

standby 10 ip 192.168.1.1

standby 10 priority 150

standby 10 preempt

end

FastEthernet0/0 - Group 10

State is Listen

Virtual IP address is 192.168.1.1

Active virtual MAC address is 0000.0c07.ac0a

   Local virtual MAC address is 0000.0c07.ac0a (v1 default)

Hello time 3 sec, hold time 10 sec

Preemption enabled

Active router is 192.168.1.2, priority 250 (expires in 8.360 sec)

Standby router is 192.168.1.3, priority 200 (expires in 8.196 sec)

Priority 150 (configured 150)

Group name is "hsrp-Fa0/0-10" (default)

Post Failover

R1#

FastEthernet0/0 - Group 10

State is Init (interface down)

   1 state change, last state change 00:07:21

Virtual IP address is 192.168.1.1

Active virtual MAC address is unknown

   Local virtual MAC address is 0000.0c07.ac0a (v1 default)

Hello time 3 sec, hold time 10 sec

Preemption enabled

Active router is unknown

Standby router is unknown

Priority 250 (configured 250)

Group name is "hsrp-Fa0/0-10" (default)

R2#

FastEthernet0/0 - Group 10

State is Active

   1 state change, last state change 00:00:44

Virtual IP address is 192.168.1.1

Active virtual MAC address is 0000.0c07.ac0a

   Local virtual MAC address is 0000.0c07.ac0a (v1 default)

Hello time 3 sec, hold time 10 sec

   Next hello sent in 0.236 secs

Preemption enabled

Active router is local

Standby router is 192.168.1.4, priority 150 (expires in 8.228 sec)

Priority 200 (configured 200)

Group name is "hsrp-Fa0/0-10" (default)

R3#

FastEthernet0/0 - Group 10

State is Standby

Virtual IP address is 192.168.1.1

Active virtual MAC address is 0000.0c07.ac0a

   Local virtual MAC address is 0000.0c07.ac0a (v1 default)

Hello time 3 sec, hold time 10 sec

   Next hello sent in 0.068 secs

Preemption enabled

Active router is 192.168.1.3, priority 200 (expires in 9.092 sec)

Standby router is local

Priority 150 (configured 150)

Group name is "hsrp-Fa0/0-10" (default)

[Latchum Naidu · Accepted solution]

Hi Willard,

What I can suggest you is, you can run HSRP between three CORE's
you configure the 3 switches in HSRP, 1 will be active, the second will be standby and the third will stay in listening mode and will move to a different status if one of the other 2 disappears.

HSRP is meant to give full redundancy for 2 routers only, the third is in a kind of 'cold mode'.
Regarding the config is exactly the same for any other  IOS based router or switch.

Please rate all the helpfull posts.
Regards,
Naidu.

[Latchum Naidu]

Hi Willard,

Continue to my previous post....See the below link will help you...
http://www.yasirirfan.com/Configuring_HSRP_in_Cisco_6500_Switches.pdf

You can keep the active switch priority for example 150, standby 100 and listening 99 like that.

Please rate all the helpfull posts.
Regards,
Naidu.

[willard.hanada]

Thanks Adan, for the answer and example! this was really helpfull!!