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WAN Link Aggregation

Hi all,

I need professional inputs to a design problem. Sorry I don't know if this is the right forum, but I'm sure I'll have good professional inputs here.

Please see the attached document.
My company already has a WAN link from a Branch Office to the Head Office, but now we want to install another WAN link, to provide for LOAD BALANCING and REDUNDANCY.
I really need advice on how to design the topology to integrate and aggregate the two WAN links. Please look at the various design that came to my mind, and advise which is workable.
I'm in doubt of which configuration will work best, to provide for redundancy and load balancing, if possible.
Please note that I am not strict to the topologies in the attached document, any good idea and topology will be highly appreciated.
Please help me and be specific with respect to the technology and appropriate configuration.

Thanks all.




The prosed diag..,,, depends on you requiremnet..

Is it solely redundancy or it is loadbalacng.

If you want combination of both ,  you can use single ISP with two link connectivity.

As you need only connectivity from branch to headoffice , you do nt need to go for dual ISP connection.

Dual ISP is mostly use in case of Internet connectivity.

Also wht kind of connectivity do you need b/w branch & Head office :-  is is layer 2 or layer 3 ??

Thanks Shekhar,

What we need primarily is redundancy, but management want us to use two different ISPs in case of failure of one.

Please note that one of the ISPs will provide internet connectivity to Branch Office users, and at the same time provide WAN cnnectivity to the Head Office, while the other ISP only provides WAN connectivity.

Also, it's a L3 connectivity between the ranch and Head Office.

Just thinking of the best method or config to get the job done.

Your inputs will be highly appreciated.



On Proposal #3 all you need is to have 2 static routes to reach remote "Enterprise LAN" via ISPs next hop address:

ip route

ip route

You can also do IP SLAs but this one is applicable for failover cases.

My sugesstion is to use BGP in case of two ISP as BGP is more reliable protocol in case of two ISP connection :-

You need to do the following to achieve this :-

1)In proposal 2 , have a back to back connection also in branch& HQ routers. This is required for IBGP session.

2) At both ends run BGP with each ISP.

3) Advertise half of LAN subnets on ISP1 & other half on ISP 2 and advertise summary address to both the ISP.

4)Keep local prefrence of one ISP to be higher.

This will help to achieve redundany as well as load sharing.If any of the ISP link fails or whole ISP gets down., still you can use other ISP link for whole traffic.

Let me know if u need any othe rinformation to achieve this.