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ISDN backup to multiple sites


I've been searching, but cannot find a solution to the following scenario:

I need to implement ISDN backup for a leased line from remote sites to the central site. Should the leased line go down, the ISDN must kick in. This is easy. The more difficult part is that should the central site go down (with all the leased lines connected to it), all the remote sites should dial the Disaster recovery site. The order of connecting is thus: leased line, ISDN to Main site, ISDN to Disaster site.

Thanks a million


Re: ISDN backup to multiple sites

I am not too knowledgable about disaster recovery setup, but read somewhere that the same IP address is used in the backup site also. If that is true, you can manipluate the admin distance or metrics or metrics of the routing protocols to prefer the order in which you want them to connect over the various links. Or, see if you can control the flow of traffic through policy routing.


Re: ISDN backup to multiple sites

Just add the number of the Disaster site to the Dialer that already has the number of the main site. The Dialer will try all the numbers in order, if the first one does not answer (Main site down) it will call the second one (Disaster site).

interface Dialer x

dialer string 55512345 ! main site

dialer string 55523456 ! disaster site