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Community Member

Two different ISP's

Please help,

I have to links to different ISP's, and to different ip address ranges from them. I plan to load balance between them. Is it a good idea to use NAT for it, any suggestion. Can I conect these two serial links to one router? Thank you for any help.



Re: Two different ISP's

Since you have two address ranges, the amount of traffic you receive through each ISP will depend on the amount of traffic you originate (send to) each ISP. The good news is that it's farily easy to control your outbound traffic, since you are probably just using defaults to reach each ISP. The bad news is that the simple case will probably cause you to have problems with assymetric routing, which will cause your sessions to fail.

What you probably want to do is to use statics to block off sections of the IP address space, and send different sections of the IP address space to each provider. This probably sounds complicated, but it's really not--a few statics redistributed into your igp (ospf/eigrp/is-is) would do the trick, and using varying numbers of statics would allow you to 'balance' the traffic.

You will need to use nat, most likely, to get this to work, although if you have enough addresses to cover all of your hosts, you could work around it this way, too. Feel free to email me for more specific information on how to set this up.


Community Member

Re: Two different ISP's

There is only switch block - firewall - router, so no igp. All traffic goes through this router. Is this good idea to connect two ISP's links to one router? I can divide clients on ip address bases and translate addresses to different ISP ranges, as you proposed. What if ane link goes down, does the second takes the role. How to do this best? I can purchase second router, if it help. Thank you for your time.

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