load balancing multiple ISPs

[Microbyte]

Hi,

We have 4 ISP feeds into cat3750.
We need to distribute that over 20 different users.
What is basic configuration required for load balancing 4 ISPs?
Thanks in advance!


Microbyte

 

[brianinms]

1. Ensure all ISP's will run BGP with you.

2. Obtain IP block

3. Register for ASN.

4. Configure and test

 

[jneiberger]

You can relatively easily configure outbound load sharing but it's extremely difficult to reliably configure it inbound. You could end up with a good ratio on outbound but have most of your inbound traffic coming in on one link.

What is the speed of your links? Are they all the same speed?

 

[Microbyte]

All 4 links have same down speed.
All 4 IP addresses are dynamic.
And all 4 links have the same gateway.

Does setting up BGP really necessary for this to work? Is there other way to go?

Thanks,

Microbyte

 

[burtsbees]

Why not bond them?

Burt

 

[brianinms]

You can't bond 4 different circuits from 4 different ISP's

 

[jneiberger]

Ah, I think I see a miscommunication. You don't really have four ISPs, do you? I think you mean you have four connections to the same ISP. If that's the case, you could work with your provider to bond them. There are a few different ways to do that depending on what they offer.

 

[burtsbees]

That is the way I read it, anyway...

Burt

 

[volleyman]

you can load balance them using GLBP (gateway load balancing protocol), a relatively new cisco-specific protocol.

Zane D.
Systems Admin

 

[jneiberger]

There are lots of ways to load-share outbound. The greater problem is inbound. The best way to handle that, in this sort of case, is to bond all the circuits into one large virtual circuit. That is the best way to optimize both inbound and outbound in this configuration.