Internet Load Balancing - Routing Issue

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Nov 3rd, 2007
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Dear all, good day...

in our ministry we are going to contract with 2 ISPs to provide us with the internet service (one of them will be the main line 16 MB, and the other line will be working as a backup line). Now, here is my question, is there any router that can holds the 2 ISPs lines at the same time and have the fail over property and load balancing, or i have to use 2 different routers (we have CISCO 2821) to do the load balancing between the 2 internet lines. Thankx

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thotsaphon Sun, 11/04/2007 - 03:31
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Hi Tareq

There are many ways you can do.But depending on your requirement.If you are using 2 ISPs and all of ISPs are willing to do BGP then that is the right way you should do. For doing load-sharing.please check this link out.

Just my thought.In case one of your ISPs can't do BGP then you can use the policy-based routing feature to do out-bound load-sharing(inside to ISPs) by classifying traffics you want.

Try to understand technology first.

Hope this helps


Richard Burts Sun, 11/04/2007 - 04:10
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There are several aspects of the network environment that impact how to load share which we do not yet know about your situation, such as whether you will be using public IP address space inside your network or using private address space and translating at the outbound router.

But as Thot suggests many people do want to use BGP when they are connecting to 2 separate ISPs.

I do not see any need to use 2 separate routers and believe that your 2821 should be able to handle the load sharing and the failover. The failover will be easier if just 1 router connects to both ISP.



intelide3 Sun, 11/04/2007 - 18:02
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just to be clear : there is a little differences between load balancing and HA failover redundancy.

for load balancing (active-active) you can just put 2 equally static routes for the router to the internet.

for example :

ip route 0/0 int e0, and

ip route 0/0 int e1.

that will create an automatic load-balancing (and failover as well).

but for HA (active-passive) - you can just put the route a higher metric for the other interface.

example :

ip route 0/0 int e0 metric 1 (default will be use this connection),

ip route 0/0 int e1 metric 10 (backup).

that second line wont route traffic until something trigger it.

you can do that in single router such as yours.



william.caban Sun, 11/04/2007 - 19:18
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If you want load-balancing and you manage to get BGP, you can try Cisco Optimized Edge Routing (OER).

(Even when in some documentation it states it can work without BGP, I recommend it with BGP)

I don't recommend OER for carriers or certain huge enterprise, but for the rest of the deployments, it is a very good feature.


(If this helps, please, rate post)


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