HSRP, VRRP and GLBP - Part I
December 4th, 2008 in CCIE, IP and IOS Features | tags: , ,

Here a quick reference for first hop redundancy protocols :

HSRP VRRP GLBP
Port UDP 1985 IP protocol 112 UDP 3222
Multicast address 224.0.0.2 224.0.0.18 224.0.0.102
Hellotime Timer 3 seconds 1 seconds 3 seconds
Mac address 0000.0c07.ac<standby group nr> 0000.5e00.01<vrrp group nr> 0007.b4yy.yyyy
Default priority 100 higher preferred 100 higher preferred 100 higher preferred

Let’s do a configuration-example of HSRP and VRRP.
See below the diagram with the network used

HSRP_VRRP


R6 :


interface FastEthernet0/0
 ip address 150.1.61.6 255.255.255.0
 speed auto
 full-duplex
 standby 1 ip 150.1.61.1
 standby 1 priority 95
 standby 1 preempt

R13 :


interface FastEthernet0/0
 ip address 150.1.61.13 255.255.255.0
 duplex auto
 speed auto
 standby 1 ip 150.1.61.1
 standby 1 preempt

As you can see router R13 is the active router for standby group 1 since router R6 has a priority of 95 specified which is lower than the default priority of 100 on router R13.

If we take a look at the “sh standby” on router R13 output we get :

R13 :


R13#sh standby
FastEthernet0/0 - Group 1
  State is Active
    5 state changes, last state change 00:00:11
  Virtual IP address is 150.1.61.1
  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 0.624 secs
  Preemption enabled
  Active router is local
  Standby router is 150.1.61.6, priority 95 (expires in 8.680 sec)
  Priority 100 (default 100)
  IP redundancy name is "hsrp-Fa0/0-1" (default)

As you can see the Mac-address is 0000.0c07.ac01 where 01 stands for the standby group 1.

Now let’s replace the HSRP with VRRP :

R13 :


interface FastEthernet0/0
 ip address 150.1.61.13 255.255.255.0
 duplex auto
 speed auto
 vrrp 1 ip 150.1.61.1
end

R13 :


R13#sh vrrp
FastEthernet0/0 - Group 1
  State is Master
  Virtual IP address is 150.1.61.1
  Virtual MAC address is 0000.5e00.0101
  Advertisement interval is 1.000 sec
  Preemption enabled
  Priority is 100
  Master Router is 150.1.61.13 (local), priority is 100
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.609 sec

R6 :


interface FastEthernet0/0
 ip address 150.1.61.6 255.255.255.0
 duplex auto
 speed auto
 vrrp 1 ip 150.1.61.1
 vrrp 1 priority 95
end

R6 :


R6#sh vrrp
FastEthernet0/0 - Group 1
  State is Backup
  Virtual IP address is 150.1.61.1
  Virtual MAC address is 0000.5e00.0101
  Advertisement interval is 1.000 sec
  Preemption enabled
  Priority is 95
  Master Router is 150.1.61.13, priority is 100
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.628 sec (expires in 2.880 sec)

As you can see router R13 is the master since 100 is the default priority and we specified a priority of 95 on router R6. Also notice the MAC address of 0000.5e00.0101 where the last 01 stands for the VRRP group.

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