Dynamic load balancing

Unanswered Question
Mar 12th, 2007


I have 2 data pipes on Cisco 7206 Router.one is active and another one is standby.

What I require is to configure that another link on 2 nd 7206 router and do a dynamic load balancing.If one link goes down then traffic should switch dynamically to another link?

How can I do that?

Current scenario:Router1(with 2 links)--->Multiplexer-->csu/dsu---> router2(forgien location)


I have this problem too.
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spremkumar Mon, 03/12/2007 - 21:48

Hi Rohit

Are you trying to use the 2nd link on the router 1 to route your traffic when your primary link goes down ?

If thats the case then you can do it with normal floating Static routes configured with admin distance.

if you have something else in mind do post it out clearly..


rajivrajan1 Mon, 03/12/2007 - 22:24

hi rohit,

I do agree with prem kumar.

As per current scenario the second link is standby and not carrying any traffic until primary fails.

your requirement might be loadsharing between these two links.I.e you want to utlilize the second link and as well as a redundance of links.

For that you should post

1 your configuration,

2what routing protocol you are using

3the capacity of links

any other info what you feel important related to your circuit.

rohit_kulkarni Tue, 03/13/2007 - 12:05


I've configured my standby link on another 7206 router.Now I have two 7206 routers.

What I want is "Auto Load balancing" means if one link goes down then traffic should automatically switch to another link, not floating way with Ad.

I am using static routes no dynamic protocol.

I am thikin of PBR.But I've F/w in between the routers and Core switch.

I hope this will help.


Paolo Bevilacqua Tue, 03/13/2007 - 12:12

Can you post a diagram, even an ASCII one ?

Keep in mind that backup and load balancing can be tricky without using routing protocols, because in the case you have the circuit up, but the router is malfunctioning (so called black hole), you will keep sending data that is to be lost.

rohit_kulkarni Tue, 03/13/2007 - 12:36

Core 1--Core2-----------R2

| |--|____ |

| | |

F/W---->R1 |

| |

(Data Pipe1)|-- --|(Data Pipe 2)


(Multiplexer)--IPLC-Mplexer--dsu--router (Foreign place)

rohit_kulkarni Tue, 03/13/2007 - 12:40


I am sorry for that Diagram.

In that Second data pipe is connected to R2 and both the routers connected to Core 2(4003).

Core is connected to F/W, means it's behind the Routers.

Now if I configure PRB for Automatic load balancing , in case one link goes down the traffic should switch to another link.F/w comes in this picture.

I hope this will help.

Paolo Bevilacqua Tue, 03/13/2007 - 12:51

Yes diagrams can be tricky because this forum does not preserve spaces.

Much depends on the FW itself, if is able to run routing protocols or be traversed by a tunnel that would allow virtual direct communication between routers.

As I said I would try a traditional routing design first that is the easier to configure and monitor.

rohit_kulkarni Tue, 03/13/2007 - 13:04


Thank you.I caanot use Dynamic protocol.

What I think that if I put a addtional L3 device and terminate both the Router interface on that device like 2600 Router and configure PBR.

I need one smart serial to V.35 for that ,can you tell me how to convert smart serial to V.35?

Will it work?


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