Load balancing / Multihoming between two ISPs without using BGP

gabrieloyeyemi · ‎06-30-2006

We currently have connection to two ISP.

ISP A is terminated on a 1760 while ISP B is terminated on another router (2611). Both routers were connected together through a cross-over cable. ISP A has uplink bandwidth of 512k and downlink bandwidth of 2M, while ISP B has uplink bandwidth of 1M and downlink bandwidth of 1M. I have two default routes that points to the two ISPs.

I notice from the bandwidth manager that uplink traffic goes out through ISP B while downlink traffic comes in through ISP A. No uplink traffic passess through ISP A and no downlink traffic on ISP B.

Can anybody please suggest how i can configure it so that uplink and downlink traffic can pass through the two ISPs without running BGP since we don't have an ASN now and our router's memory is not sufficient to run BGP.

Thanks.

Gabriel.

Network Engineer.

Swift Networks Limited.

mheusinger · ‎06-30-2006

Hello,

the only traffic you can influence is the traffic leaving your routers. How are your clients connected to those internet routers? Are you using HSRP? then all the traffic will pass through the active router.

Use GLBP instead to get a more even load distribution. If you are not using HSRP, then polease post additional info on your internal routing setup.

With respect to return traffic: there is no way to force anything. BGP is not designed for load sharing in that it will only announce the best path for a prefix to the neighbors. This most of the internet presumablky does not even know about the second uplink of yours. you can check this by telnetting into some route servers (found f.e. through traceroute.org).

The only known method is to split your address space in two subnets and get traffic destined to one subnet prefered through ISP A and the other subnet through ISP B. No idea whether you can achieve this, it depends on your addresses and ISPs.

Hope this helps! Please rate all posts.

Regards, Martin

anthony.f · ‎06-30-2006

Gentlemen, I would like to expand this problem and perhaps guide in the right direction. If we toss in a Firewall that becomes everyone's default gateway and give the outside IP of the firewall an IP on the ISP to which the primary default route points (from the ONE router connected to two ISPs - T1 + Ethernet handoffs) and NAT to the 2nd IP block through the router when the secondary default route kicks in, this should then work, correct? I have yet to try it.

Anthony

gabrieloyeyemi · ‎07-02-2006

Thanks for your help.

We are not using HSRP.All our clients are connected to another router through the MAN ntk. This router is connected to the internet router where static and dynamic natting is done for all clients. see details of the arrangement below.

From MAN router to Internet router to WCCP router to central router to SAT router.

The first ISP is on central router and the second is on SAT router. The central and SAT router are connected thru a crossed cable.

Also two default routes are in place on the central router as shown below to the two isps

ip route 0.0.0.0 0.0.0.0 serialx/x track 124(ISP A)

ip route 0.0.0.0 0.0.0.0 ethernet 0/0 (ISP B)

I was trying to implement policy based routing but the tracking is not working maybe the config was wrong.

we presently don't have an ASN and don't intend to run BGP now. How do i divide my address space so that i can send traffic both ways simultaneously.

Thanks for your help.

Gabriel.

anthony.f · ‎07-02-2006

Load balancing is tough. You CANNOT do it on incoming traffic; only outbound. Without BGP, you may need an external device; sorry. :(

Anthony