GLBP - Load balancing per-packet or per-dest?

[Aaron Harrison]

Hi

I've a customer with two 2MB point-to-point links between two sites - they currently want to have one link as primary, the second as secondary.

Expectations are nice and low so I'm going to use HSRP and OSPF to provider router and link redundancy today..

However I'm considering GLBP as a better solution - however I can't see any docs that describe how it load balances... For packets to arrive in sequence for VoIP (which runs between two non-Cisco phones systems over the WAN) I'd prefer that load balancing is done per-source&dest pair or something as opposed to per-packet... Does/Can GLBP do this?

Anyone have any experience of using this protocol?

[dgahm]

The default is to round robin the router's mac adresses. In other words, with 2 routers on a subnet configured for GLBP the first host that ARPs for the default gateway will get the MAC for router A, and the 2nd host would get router B. A host will continue to use the same router until it ARPs again. In your scenario the return packets would often use the opposite link. This asymetrical routing shouldn't cause any problems, but you should be aware it is happening.

[Aaron Harrison]

Thanks for the info...

Just found a command that looks like it will override this behaviour tho

glbp 1 load-balancing [weighted|round-robin|host-dependant]

Should give me something to play with should things not go according to plan...