glbp configuraition with tracking serial link.

mohaneternal · ‎09-13-2011

Hi,

I am trying to configure GLBP for the attached diagram but no luck its not working. Can you please help me in configuring the GLBP settings.

I wanna track serial link and do load sharing.

R1 config:

interface FastEthernet0/0

ip address 172.16.1.2 255.255.255.0

duplex auto

speed auto

glbp 10 ip 172.16.1.1

glbp 10 timers 5 18

glbp 10 priority 250

glbp 10 preempt

glbp 10 weighting 50

glbp 10 load-balancing weighted

!

interface Serial1/0

ip address 200.100.50.5 255.255.255.0

serial restart-delay 0

R2 config:

interface FastEthernet0/0

ip address 172.16.1.3 255.255.255.0

duplex auto

speed auto

glbp 10 ip 172.16.1.1

glbp 10 timers 5 18

glbp 10 preempt

glbp 10 weighting 50

glbp 10 load-balancing weighted

!

interface FastEthernet0/1

no ip address

shutdown

duplex auto

speed auto

!

interface Serial1/0

ip address 200.200.50.5 255.255.255.0

Let me know what needs to be done for load sharing and tracking serial link using glbp.

Giuseppe Larosa · ‎09-13-2011

Hello Mohan,

be aware that GLBP has a two dimensions priority schema: priority is used to elect the AVG, weighting to keep the list of currently active AVF (forwarder).

trscking a WAN link acts on the weighting dimension only

another point is that GLBP achieves load sharing only when it is serving a population of end users devices like in a client Vlan.

The AVG performs load balancing by answering to ARP requests for the GLBP VIP IP address by providing the MAC address of an AVF.

if only one host exists for example a firewall GLBP cannot achieve load sharing unless shortening to few minutes the ARP timeout of that host.

see

http://www.cisco.com/en/US/docs/ios-xml/ios/ipapp_fhrp/configuration/12-4t/fhp-glbp.html#GUID-FFA459B3-479D-4749-8BB6-C2D64EF7E6B7

Edit:

indeed it is your case in your network schema R5 is the only client once that R5 gets an ARP reply for the GLBP VIP it will use until the ARP entry ages out from the ARP table. With default timers this happens after 4 hours !

Hope to help

Giuseppe