WAN load balancing

Unanswered Question
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Alejandro Corte... Mon, 01/07/2008 - 15:10
User Badges:
  • Silver, 250 points or more

Actually you can use several cisco router models from the 1800 series to the 7000 series every router support load balancing

chschroe Mon, 01/07/2008 - 17:11
User Badges:

Yes they can. It really isn't that easy, however.

If you have two T1s to the same place, then your routing protocol or static routes would be able to load balance you.

You're talking about two connections to the internet. I assume you'll be using NAT. That makes it way more complicated.

You need a way to make X users always go out through one NAT, and Y users always go out through the other. Having two static default routes of the same cost can give you some load balancing, but it isn't really dynamic or deterministic based on load - you could still overload one or the other.

OER is the way to do that. But for tiny little branch locations it may not be supportable - and you'd need a bigger router, as well as something to make a decision on.

Look over the OER information to see if that works for you, http://www.cisco.com/go/oer.


Rick Morris Tue, 01/08/2008 - 06:20
User Badges:
  • Silver, 250 points or more

In order to provide you with a solid answer we need to know how your set-up will look?

Are you going to have one provider with 2 connections?

Are you going to have 2 providers with 1 connection from each?

Are you talking about a NxT solution?

Sharing across the line is set-up by how you route your traffic, there are also load balancers that will do this for you too. It all depends on how you are setting it up?

Sorry for responding late. I had no idea people were still helping me with this issue. Thank you for responding, and I hope you respond to this request soon.

1. Are you going to have one provider with 2 connections?

No, we actually plan to have two different ISPs. These ISPs can be two DSL lines, 1 DSL and 1 Cable, 1 T1 and 1 DSL, or any 8 combinations between T1, DSL, or Cable.

2. Are you going to have 2 providers with 1 connection from each?


3. Are you talking about a NxT solution? I'm not sure what an NxT solution is. If an NxT solution describes a situation where User A goes to the Internet on WAN connection 1, but WAN connection 1 is being heavily used by other users, then the router allows User A to use WAN connection 2.

Rick Morris Mon, 01/28/2008 - 05:55
User Badges:
  • Silver, 250 points or more

NxT1 is N=the number of T=1's you are going to have.

If you are using 2 separate providers I would recommend getting your own IP space from ARIN. Then run BGP, but you will also need your own ASN too. This way you control your traffic out to your peers. You can receive routing table updates from your peers to make informed routing decisions. This will allow you to use load sharing. I believe this will do everything you want.

sreekanth sreedharan Fri, 12/10/2010 - 00:17
User Badges:

We have a setup with 2 isp's with 8mbps each terminating on 2 respective 2851 router, currently we are using bgp and hsrp to achieve the failover. In this scenerio only one isp link is utilized for incoming and outgoing traffice, is it possible to acieve loadbalancing in this scenerio such that two  8mbps link is utilized. I have also attached a diagram for the same. any advice will be highy appreciated.

Rick Morris Fri, 12/10/2010 - 08:46
User Badges:
  • Silver, 250 points or more

With your current set-up the answer is no.  You can attempt to split your traffic and send

half of the network out one side and half out the other.  This will need 2 standby groups.  Or you will need a load balancer inline.  The other config set-up is to use GLBP.  However, not all cisco devices can run GLBP.  I do not believe the 2960's support this.  GLBP uses a VIP just like HSRP, but instead of one link being used it will be 1 VIP but it will run an algorithm to send the traffic to one link or the other.

One other alternative would be run BGP to an internal device.  Bring one switch behind the routers and run ebgp to an ip.  This will allow the routing to flow accross both links.  Another would be to run one router at the edge and run bgp to a loopback ip with ebgp.

This link has 7 different topology layouts


Very good site.

sreekanth sreedharan Mon, 12/13/2010 - 05:17
User Badges:

Hi Engagerock,

                          That was very informative and the site is too awsome. Thanks a lot


Srekanth V.S


This Discussion