HSRP, BGP and load balancing

[raceman3]

We currently have two cisco router running hsrp. The primary router has a T3 into the internet and the backup router has a T1. We just purchased a T3 for the backup router and I would like to load balance traffic between them. Does that mean I delete the HSRP since the second router is no longer a backup? How do I go about load balancing since I'm only requesting a default route from the ISP's not a BGP routing table. Both routers are 3640s running 12.1 code.

 

[lambent]

use multiple groups of HSRP for load-sharing outbound traffic

you need to use BGP MED/AS prepend or summary address + longer prefixes to manually load-share the inbound traffic. Take a look at this URL for an example using HSRP and AS prepend:

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080093f2c.shtml

 

[raceman3]

What do you mean by multiple groups of HSRP. Every device behind the router points to the HSRP address assigned to the Ethernet interface so which ever router is the primary will get all the oubound traffic.

 

[NetworkGhost]

To balance the load before it hits the router seems to be what you want. I think you would either need an intelligent switch or load balancing device for outgoing traffic BEFORE it hits. If both T3's were on the smae route it would be easy. Since you wont really need HSRP anymore, I guess you have to ask the question which is more important? Load balancing or redundancy. Unless I am wrong with load balacning and 2 routers you are going to have a sincle point of failure.

 

[raceman3]

I'm thinking I'll need a load balancing switch sitting in front of the two routers. What routing protocol do you recommend between the switch and the router interfaces?

 

[NetworkGhost]

If you have a hardware load balancer you shouldnt need any special protocols. The Load balancer should take care of that for you and should be redundant if the router goes down. This will be for outbound only though for incoming traffic your ISP would have to do some sort of load balancing. If you just throw a router in front of your 2 routers for load balancing then you could do a per packet load balancing between the 2 routers. Not the best load balancing solution (compared to PPP multilink) but should do well.

 

[KiscoKid]

Traditionally to load-balance out of your network, you would use any of the usual LAN protocols such as OSPF. EIGRP etc.

Alternatively, if you want to retain static routing, how about GLBP? The following doc explains how to set it up

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a008042fb97.html

To load-balance into the network, as the previous poster said you would typically consider manipulating BGP to prefer certain paths over another by using MED, AS Path etc. This is very well documented on the CCO and the traditional way of achieving this.

Cisco have been trying to build in dynamic load-balancing for BGP (not before time) and you can run all kinds of interesting stuff such multipath eBGP, multipath iBGP etc. Unfortunately some of these offerings are aimed at emerging WAN technologies like MPLS. If your ISP is providing an MPLS VPN for you, this may be something you can consider. It's a big subject but you can read about it in the following link:

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a00804556a3.html

 

[raceman3]

I think I may have found a much simpler solution right in the cisco IOS called GLBP. Functions similiar to HSRP but different in the fact that it load balances the traffic between all the participating routers while still maintaining a single default gateway. Basically doing redirects from what I've read. I just need to find out if it poses any issues with the pix since the data might go out one ISP and return on another. I believe it was introduced in 12.2