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Community Member

Internet multiple routes

I subscribe for 2 high-speed internet connections from the same ISP provider.

Is it possible for the provider to configure my setup for both links to accept Source IP address in either block of IPs assign to me:

I want to implement Policy based routing using source-sensitive routing, without using IP NAT translations. In our own experience we are having problems if the provders are different for they do not allow IP Spoofing, IP address of other ISP networks to passthru their links..

Thanks..

1 ACCEPTED SOLUTION

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Silver

Re: Internet multiple routes

What you are asking for is certainly possible. Whether or not your ISP is willing, however, is up to the ISP. There are multiple ways to set this up. Which is best will depend upon the relative importance of load sharing versus availability versus simplicity. Because most approaches require the cooperation of your ISP, you should talk over your needs with them and see what approaches they prefer (hint, most ISPs tend to prefer the solutions they are best able to support, which generally translates into fewer mistakes causing downtime).

There is a very brief white paper on my web site discussing various approaches to redundant ISP connectivity. Just be aware that its emphasis is on availability and not load sharing. As always, YMMV.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

3 REPLIES
Silver

Re: Internet multiple routes

What you are asking for is certainly possible. Whether or not your ISP is willing, however, is up to the ISP. There are multiple ways to set this up. Which is best will depend upon the relative importance of load sharing versus availability versus simplicity. Because most approaches require the cooperation of your ISP, you should talk over your needs with them and see what approaches they prefer (hint, most ISPs tend to prefer the solutions they are best able to support, which generally translates into fewer mistakes causing downtime).

There is a very brief white paper on my web site discussing various approaches to redundant ISP connectivity. Just be aware that its emphasis is on availability and not load sharing. As always, YMMV.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

Community Member

Re: Internet multiple routes

Thanks, Vincent,

One more thing, since I have dual links from the same ISP provider they claim that they route both my IP blocks to the same links.

So I do not have to bother with IP NAT. Is this correct?

Regards,

Regie

Silver

Re: Internet multiple routes

IF - You are not using NAT for any other purposes AND the ISP will send traffic for either IP block over whichever link is up, then you do not need NAT for the purposes of getting outgoing traffic to have a working source address. Shut down one of your links and verify that the ISP detects the outage and routes around it (and that you do) and that addresses in both your blocks are still reachable from the outside.

Remember, there must be both an outbound route and an inbound route before communications can occur. For redundancy to work, you need both the ability to detect an outage and the ability to direct traffic to use a still functional route. Routing protocols do this automatically, if they are correctly configured. Again, you will find that there are three key design factors in a redundant path scenario: availability, load sharing, and complexity. You only get to choose two of the three.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

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