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ISP's switching

By sridhar.kamath ·
I have primary link from ISP A and for redundant purpose we are getting one more additional link from another ISP B. ISP A gives serial output and ISP B gives Ethernet output.

Can I implement the following?

1) I want to use both the links simultaneously
2) When ISP A fails ISP B should take over
3) When ISP B fails ISP A should take over

In this situation

1) How does the router decide to switch when there is a ISP?s failure

Is it when local loop is down or ISP backbone is down or slowness in the link?

Kindly advise the same?

Sridhar Kamath

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Topology and Setup Does Matter

by JIM-H In reply to ISP's switching

Well based on the details that you provided it is hard to explain what your load balancing and fail-over options are. Here are some thoughts that you may want to consider regarding Fail-over:

-If you are not running BGP and do not own your own IP space then your public IP will more than likely need to change during an ISP outage when connecting to separate ISPs. It is possible to have local gear handle this with NAT/PAT.
-You are not able to load balance using the same IP addresses between different ISPs nor would you want to. Asymmetrical routing to that length can cause problems in connections.

Again, depending on what you have or plan to get your options will vary. If you email me directly or reply to this discussion withmore details I might be able to provide a more focused solution for you.


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