Cisco Support Community
Community Member

Designing backup scenario for new router


I am working with a client today in an attemtp to configure some new branch office routers to replace the older branch office routers.

The legacy branch office routers are model 2610.  The new routers we have purchased are model 1921.

The legacy routers are connected back to the HQ building via Frame Relay circuits.  The new routers will also be connected via Frame, but will use MPLS and are with a new provider.

The legacy routers also have ISDN backup.  The new 1921's will use cellular as their backup.  So the new routers have a T1 card (for the MPLS frame) and then have a 3G Verizon card.

What makes this all interesting is that I need to roll out the new routers starting next week.  In doing so, we will arrive at each branch office, and then go thru the following procedure:

1.Power up the new 1921's, and connect them to the new Verizon Frame.

2. Move the Inside Ethernet (private network) conection from the E0 on the legacy router to the G0 on the new router.  The IP address will be moved from the E0 on the legacy router to the G0 on the new 1921 router.

That being said, the client wants to be able to use the legacy ISDN on the legacy router as backup until such time as the cellular network is available, which based upon input from Verizon may be six weeks away.

So for an interim period of time, the cient wants both routers up.  They want to know if I can create a private network from the E1 interface on the new 1921 that will connect to the formerly used E0 on the legacy 2600 boxes. 

I dont see any problem with this specific components.  What is unclear to me is how I will be able to make the ISDN dial on the former router, if in fact the MPLS Frame is down on the new router.

I was under the impression that if the legacy AT&T frame is disconnected on the legacy router (and the plan is that it will be upon installation of the new routers), that this would make the ISDN dial home on the former router.  One engineer at the client site indicated that he was under the impression that

the ISDN dialer would dial on the legacy router only if a route was missing from the route table.

I need some advice as to how exactly to set all this up.  Obviously I can do statics or floating statics from one box to the other, or use an eigrp instance if necessary for the network connection between the two routers.  After that I am not clear how to proceed.

Thank You

CreatePlease to create content