HSRP for LAN Fail-over

[CSCO11776584]

Hello Everyone!

I am Prashant. Planning to implement HSRP in layer 3 switch. This is the first time I am trying this out. So I am little bit nervous at the moment. Wanted your suggestion to implement this protocol. Here are the details:

We have two numbers of Cisco 4900 ME Switches. Basically want LAN failover from these devices. There are about 400 users in our network. I have attached rough network topology for your reference(Please excuse since I am not good at Microsoft Visio). Please let me know implementation of the HSRP in these switches. Two distribution switches(Cisco 4900 ME Switches) are connected to 4 Access switches and these are connected to the LAN. Please elaborate the configuration for the HSRP.

Thanks in advance!!!!!

[Vivek Ganapathi]

Hi,

Below is a topology & set of configuration which may help you

Configuration (Assumption)

====================

There are 3 VLANs in your network. VLAN 10, VLAN 20, VLAN 30.

ME4900-SW1 config

interface vlan 10

ip address 192.168.10.2 255.255.255.0

ip helper-address

standby 10 ip 192.168.10.1

interface vlan 20

ip address 192.168.20.2 255.255.255.0

ip helper-address

standby 20 ip 192.168.20.1

interface vlan 30

ip address 192.168.30.2 255.255.255.0

ip helper-address

standby 30 ip 192.168.20.1

Now on Switch-2

ME4900-SW2 config

interface vlan 10

ip address 192.168.10.3 255.255.255.0

ip helper-address

standby 10 ip 192.168.10.1

standby 10 priority 90

interface vlan 20

ip address 192.168.20.3 255.255.255.0

ip helper-address

standby 20 ip 192.168.20.1

standby 20 priority 90

interface vlan 30

ip address 192.168.30.3 255.255.255.0

ip helper-address

standby 30 ip 192.168.20.1

standby 30 priority 90

Verification Commands

show standby

show standby brief

show standby interface vlan

NOTE : This configuration is to always have Switch-1 routing / switching the traffic. i.e Primary Gateway. The best design would be to have traffic equally load-shared between two switches. For that adjust the priorities accordingly. Remember, the default HSRP priority is 100. So, lower one would be standby. Also, you may have to play around with spanning-tree root bridge priorities.

For example : Assume that, you need only Switch-1 to be catering the traffic (always). Then you need to have the root bridge priority configured as below

On Switch-1

spanning-tree vlan 10, 20 , 30 priority 4096

On Switch-2

spanning-tree vlan 10,20,30 priority 8192

Remember, lowest priority is BETTER

Now, lets assume you have configured VLAN 10's gateway as Switch-1 (HSRP priority) & other vlan 20 & 30 as Switch-2 (HSRP priority), you may now need to adjust your spanning-tree root bridge as well. Below is the config

On Switch-1

spanning-tree vlan 10 priority 4096

spanning-tree vlan 20,30 priority 8192

On Switch-2

spanning-tree vlan 10 priority 8192

spanning-tree vlan 20,30 priority 4096

Do some reading before your begun to understand better. Hope i was clear in answering your question.

Thanks

Vivek

*Please rate if helpful

[Latchum Naidu]

Hi Prashant,

When you say 400 users, I am guessing you must have vlans.
So you need HSRP (virtual default gateway) for all the vlans. Which means say you have two switches and configured vlan-10 in both switches, untill you configured per vlan hsrp there is only default gateway availabile in one switch if that switch goes down then the default gateway will be unavailable.
So you need to configure per vlan HSRP, which give you virtual or standby default gateway for each vlan.

This is what called per vlan HSRP.

See the below link for more informaiton.
http://www.firstdigest.com/2009/04/cisco-how-to-configure-hsrp-for-load-balancing-traffic/

Please rate all the helpfull posts.
Regards,
Naidu.

[skotalanwan14]

Hi Vivek,

Thanks For explaining. I have very similar config as above. I shut the vlan 10 on switch 1 but on the switch 2 the vlan 10 is still up but when my client tries to ping the 10.133.10.1 for vlan 10 is not able to ping. My question is when i shut the vlan 10 down on switch 1 the HSRP should failover to switch 2 and i still should be able to ping the HSRP gateway rt ? I also cant ping the 10.133.10.1 from switch 1. Can you please help ?

please see below config. 

switch 1

Vlan10 - Group 10
  State is Init (interface down)
    16 state changes, last state change 1d06h
  Virtual IP address is 10.133.10.1
  Active virtual MAC address is unknown
    Local virtual MAC address is 0000.0c07.ac15 (v1 default)
  Hello time 3 sec, hold time 10 sec
  Preemption enabled
  Active router is unknown
  Standby router is unknown
  Priority 130 (configured 130)
  Group name is "hsrp-Vl10-10" (default)

Show standby

Vlan10 - Group 10
  State is Init (interface down)
    16 state changes, last state change 1d06h
  Virtual IP address is 10.133.10.1
  Active virtual MAC address is unknown
    Local virtual MAC address is 0000.0c07.ac15 (v1 default)
  Hello time 3 sec, hold time 10 sec
  Preemption enabled
  Active router is unknown
  Standby router is unknown
  Priority 130 (configured 130)
  Group name is "hsrp-Vl10-10" (default)

sh standby brief 

Interface   Grp  Pri P State   Active          Standby         Virtual IP
                     
Vl10        10   130 P Init    unknown         unknown         10.133.10.1
 

switch 2

Vlan10 - Group 10
  State is Active
    28 state changes, last state change 1d06h
  Virtual IP address is 10.133.10.1
  Active virtual MAC address is 0000.0c07.ac15
    Local virtual MAC address is 0000.0c07.ac15 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 0.432 secs
  Preemption enabled
  Active router is local
  Standby router is unknown
  Priority 120 (configured 120)
  Group name is "hsrp-Vl10-10" (default)

Sh standby

Vlan10 - Group 10
  State is Active
    28 state changes, last state change 1d06h
  Virtual IP address is 10.133.10.1
  Active virtual MAC address is 0000.0c07.ac15
    Local virtual MAC address is 0000.0c07.ac15 (v1 default)
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 0.128 secs
  Preemption enabled
  Active router is local
  Standby router is unknown
  Priority 120 (configured 120)
  Group name is "hsrp-Vl10-10" (default)

sh standby brief 
                     P indicates configured to preempt.
                     |
Interface   Grp  Pri P State   Active          Standby         Virtual IP
Vl10        10   120 P Active  local           unknown         10.133.10.1

[Madhukrishnan Gopinathan Nair]

Hello,

Check whether the standby switch learns the ARP for the host address

sh ip arp

Then check it learns for mac. 

Also please unshut vlan 10 and check 

sh standby brief to ensure both knows about each other. Else there could be some topology issues.

Thanks,

Madhu.

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