T1 Reliability

If you want true T1 redundancy, then a second T1 from a second provider would be the best thing. In the event the first went down due to ISP misconfiguration or hardware problems, the second would be available.

Depending on your needs or preferences, you can attach this to your current router and set up routing redundancy, or (if you're really ambitious) put in extra routers with dynamic routing enabled for full point-to-point redundancy in the event one of the routers or CSU/DSUs breaks.
If a second full T1 is not cost effective, then maybe a fractional T1 or ISDN from a second provider to provide some access during the outage. Depending on your agreement concerning line guarantees from your T1 provider, the line shouldn't be out long enough that a second, slower line would be too much of a burden for a short time.

Hope that helps,

To pick up on what "Some Guy" said...

It'd be quite easy to use a second router/T1 pair at each end, and then use another default gateway to do load balancing / fault tolerance between the two links (assuming the bandwidth "cost" [Routing distance/bandwidth, etc. depending on Routing protocols]

We use EIGRP and a total of six routers with two circuits to provide full load balancing and fault tolerance. The two leased lines are both the same number of hops, and the same speed, so EIGRP sees them as the same "cost". The default gateway (ethernet only, no serial links) exchanges routing information with the other two over EIGRP, and distributes the traffic according to which line is available and quietest.

Alternatively You could go for an ISDN-30 dial-on-demand solution, to give a similar speed link, and this could be terminated on your existing routers, but this doesn't give full fault tolerance. An improvement to this would be to use another router, and set them both up in an HSRP Pair, so the backup link is the "Standby" unit, which will activate if the line or router fails.

Hope this helps,

Jason.

This question was closed by the author