network infrastructure planning advice

[pollux1234567890]

I need to set up a new network: "Network A". It needs to have a t1 to "Network B", a backup t1 to "Network B", and a t1 to "Network C". In the near term future there will be a T1 to "Network C" and a T1 to "Network D".

What is a good router configuration for "Network A"? How many routers? What models? What T1s to what routers?

thanks

[a-vazquez]

In addition to ur stated requirements, I would also wish to know what type of connections(Long time, short time) and what is going to be the distance b/w ur Network A and other networks?

Here r the two main WAN connection :

1.For short Distances and long connection times - Leased line is far better.

2.If u want to use shared bandwidth and more efficient packet switching and for Long distances(Long connection times) - frame-relay is good.

Both these technologies provide more than T1 (1.544 mbps) speed connectivity.

Since, u need a T1 backup, ISDN PRI provides this T1 speed connectivity and so u can use it as backup line.It is a circuit switched n/w.