HSRP load-balancing ?

[philth_123_2]

Hi,

I understand that when configuring HSRP for load-balancing we use two HSRP groups and subsequently have two different HSRP IP addresses for each of the groups. Therefore, from a PC's perspective there are two different gateway addresses to be configured.

My question is: Can a DHCP server be configured to supply 2 different gateway addresses to the PC's ?

If the PC's are allowed to receive two different gateway IP addresses what underlying method does the PC use to change from one gateway to the other ?

Cheers,

Phil.

[Roberto Salazar]

Actually, the load-balancing concept in HRSP is having the Active HSRP balanced between the two or more routers. for example, you have ten vlans, usually the one router is active for odd vlans and the otehr router for even vlans.

[sundar.palaniappan]

Another alternative to what Roberto stated above is to configure 2 HSRP groups for every VLAN and make one router the active for one group and standby for the 2nd group and the opposite on the 2nd router.

There's a good example at the following link.

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_configuration_example09186a0080094e90.shtml

Pls. rate all helpful posts.

HTH,

Sundar

[philth_123_2]

Sundar,

This alternative that you mention is what my original most was about. i.e using 2 HSRP groups for every Vlan would require 2 HSRP IP addresses.

Hence the PC's need to point to one of 2 different gateway addresses should one of the switches fail.

My original question was how this is achieved ?

Regards,

Phil.

[sundar.palaniappan · Accepted solution]

I don't know if you looked at the CCO link I had on my previous post.

Anyway, that example has 2 routers configured with 2 HSRP groups. R1 is the active router for 1 group with a standby IP of 171.16.6.100 and R2 is the active router for the 2nd group with a standby IP of 171.16.6.200. Half the hosts on the LAN will use 171.16.6.100 as their default gateway and the other half will use 171.16.6.200 as their gateway. Should one of the switches become unreachable the standby router should take over and route all the traffic.

This solution provides load balancing + redundancy for your LAN.

HTH,

Sundar

[dabels]

what are you using for DHCP? you will have to find out if that product supports any type of roundrobin type thing for giving out the default gateway.

in talking with the folks here that support our DHCP server it is not an option to load balance they just hand out the two address in the same order every time.

[philth_123_2]

I am in ageement with your statement concerning load balancing. To achieve an 'even' load balance with 2 different gateways you would want an equal number of conversations to traverse each of the uplinks. However, if you cannot control which PC's receive each gateway address then you cannot load balance in an 'even' manner.

I am thinking that GLBP is the solution here, utilising just one virtual gateway address but multiple MAC addresses are returned to the different PC's for this address.