GLBP on Catalyst 6500 Switches

 

Distribution1

Distribution1(config)#interface vlan 10 Distribution1(config-if)#ip address 172.18.10.2 255.255.255.0 Distribution1(config-if)#glbp 10 priority 110 Distribution1(config-if)#glbp 10 preempt Distribution1(config-if)#glbp 10 authentication md5 key-string s!a863 Distribution1(config-if)#glbp 10 ip 172.18.10.1 Distribution1(config-if)#exit Distribution1(config)#interface vlan 20 Distribution1(config-if)#ip address 172.18.20.2 255.255.255.0 Distribution1(config-if)#glbp 20 priority 110 Distribution1(config-if)#glbp 20 preempt Distribution1(config-if)#glbp 20 authentication md5 key-string s!a863 Distribution1(config-if)#glbp 20 ip 172.18.20.1 Distribution1(config-if)#exit Distribution1(config)#interface vlan 30 Distribution1(config-if)#ip address 172.18.30.2 255.255.255.0 Distribution1(config-if)#glbp 30 priority 110 Distribution1(config-if)#glbp 30 preempt Distribution1(config-if)#glbp 30 authentication md5 key-string s!a863 Distribution1(config-if)#glbp 30 ip 172.18.30.1 Distribution1(config-if)#exit Distribution1(config)#interface vlan 40 Distribution1(config-if)#ip address 172.18.40.2 255.255.255.0 Distribution1(config-if)#glbp 40 priority 110 Distribution1(config-if)#glbp 40 preempt Distribution1(config-if)#glbp 40 authentication md5 key-string s!a863 Distribution1(config-if)#glbp 40 ip 172.18.40.1 Distribution1(config-if)#exit Distribution1(config)#interface vlan 100 Distribution1(config-if)#ip address 172.18.100.2 255.255.255.0 Distribution1(config-if)#glbp 100 priority 110 Distribution1(config-if)#glbp 100 preempt Distribution1(config-if)#glbp 100 authentication md5 key-string s!a863 Distribution1(config-if)#glbp 100 ip 172.18.100.1 Distribution1(config-if)#exit Distribution1(config)#interface vlan 200 Distribution1(config-if)#ip address 172.18.200.2 255.255.255.0 Distribution1(config-if)#glbp 200 priority 110 Distribution1(config-if)#glbp 200 preempt Distribution1(config-if)#glbp 200 authentication md5 key-string s!a863 Distribution1(config-if)#glbp 200 ip 172.18.200.1 Distribution1(config-if)#exit

Distribution2

Distribution2(config)#interface vlan 10 Distribution2(config-if)#ip address 172.18.10.3 255.255.255.0 Distribution2(config-if)#glbp 10 authentication md5 key-string s!a863 Distribution2(config-if)#glbp 10 ip 172.18.10.1 Distribution2(config-if)#exit Distribution2(config)#interface vlan 20 Distribution2(config-if)#ip address 172.18.20.3 255.255.255.0 Distribution2(config-if)#glbp 20 authentication md5 key-string s!a863 Distribution2(config-if)#glbp 20 ip 172.18.20.1 Distribution2(config-if)#exit Distribution2(config)#interface vlan 30 Distribution2(config-if)#ip address 172.18.30.3 255.255.255.0 Distribution2(config-if)#glbp 30 authentication md5 key-string s!a863 Distribution2(config-if)#glbp 30 ip 172.18.30.1 Distribution2(config-if)#exit Distribution2(config)#interface vlan 40 Distribution2(config-if)#ip address 172.18.40.3 255.255.255.0 Distribution2(config-if)#glbp 40 authentication md5 key-string s!a863 Distribution2(config-if)#glbp 40 ip 172.18.40.1 Distribution2(config-if)#exit Distribution2(config)#interface vlan 100 Distribution2(config-if)#ip address 172.18.100.3 255.255.255.0 Distribution2(config-if)#glbp 100 authentication md5 key-string s!a863 Distribution2(config-if)#glbp 100 ip 172.18.100.1 Distribution2(config-if)#exit Distribution2(config)#interface vlan 200 Distribution2(config-if)#ip address 172.18.200.3 255.255.255.0 Distribution2(config-if)#glbp 200 authentication md5 key-string s!a863 Distribution2(config-if)#glbp 200 ip 172.18.200.1 Distribution2(config-if)#exit

VERIFY :

Distribution1#show glbp
VLAN10 - Group 10
  State is Active   

!--- AVG for the group 10.

    2 state changes, last state change 06:21:46
  Virtual IP address is 172.18.10.1
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 0.420 secs
  Redirect time 600 sec, forwarder time-out 14400 sec
  Preemption enabled, min delay 0 sec
  Active is local
  Standby is 172.18.10.3, priority 100 (expires in 9.824 sec)
   Priority 110 (configured)
  Weighting 100 (default 100), thresholds: lower 1, upper 100
  Load balancing: round-robin
  Group members:
    000f.3493.9f61 (172.18.10.3)
    0012.80eb.9a00 (172.18.10.2) local
  There are 2 forwarders (1 active)
  Forwarder 1
    State is Active

!--- Primary Virtual Forwarder for the virtual MAC 0007.b400.0102.

      1 state change, last state change 1d01h
    MAC address is 0007.b400.0102 (default)
    Owner ID is 0012.80eb.9a00
    Redirection enabled
    Preemption enabled, min delay 30 sec
    Active is local, weighting 100
  Forwarder 2
    State is Listen

!--- Secondary Virtual Forwarder for the virtual MAC 0007.b400.0103.

    MAC address is 0007.b400.0103 (learnt)
    Owner ID is 000f.3493.9f61
    Redirection enabled, 598.762 sec remaining (maximum 600 sec)
    Time to live: 14398.762 sec (maximum 14400 sec)
    Preemption enabled, min delay 30 sec
    Active is 172.18.10.3 (primary), weighting 100 (expires in 8.762 sec)


!--- Output suppressed.

Distribution2#show glbp
VLAN10 - Group 10
  State is Standby

!--- Standby Virtual Gateway for the group 10.

    1 state change, last state change 02:01:19
  Virtual IP address is 172.18.10.1
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 1.984 secs
  Redirect time 600 sec, forwarder time-out 14400 sec
  Preemption disabled
  Active is 172.18.10.2, priority 110 (expires in 9.780 sec)
  Standby is local
  Priority 100 (default)
  Weighting 100 (default 100), thresholds: lower 1, upper 100
  Load balancing: round-robin
  There are 2 forwarders (1 active)
  Forwarder 1
    State is Listen

!--- Secondary Virtual Forwarder for the virtual MAC 0007.b400.0102.

    MAC address is 0007.b400.0102 (learnt)
    Owner ID is 0012.80eb.9a00
    Time to live: 14397.280 sec (maximum 14400 sec)
    Preemption enabled, min delay 30 sec
    Active is 172.18.10.2 (primary), weighting 100 (expires in 7.276 sec)
  Forwarder 2
    State is Active

!--- Primary Virtual Forwarder for the virtual MAC 0007.b400.0103.

      1 state change, last state change 02:02:57
    MAC address is 0007.b400.0103 (default)
    Owner ID is 000f.3493.9f61
    Preemption enabled, min delay 30 sec
    Active is local, weighting 100


!--- Output suppressed.

 

Troubleshooting:

%GLBP-4-DUPADDR: Duplicate address

The error message indicates a possible Layer 2 loop and STP configuration issue.

Note: GLBP members communicate with each other via Hello messages sent every 3 seconds to multicast address 224.0.0.102 and user datagram protocol (UDP) port 3222 (source and destination). When configuring the multicast limit command, allow the multicast address by permit 224.0.0.0 15.255.255.255