[cisco-nas] PPP dialer -- "failover" routing

[Oliver Boehmer (oboehmer)]

Roth, Kevin P. <> wrote on Friday, May 22, 2009 17:08:

 
> We have a client machine at the POC which is originating 93+
> dialer-mapped IP connections to 93+ remote sites.  We want the 3845
> at the POC to dial-up the first 92 PPP connections, until all of the
> POC's T-1 channels are in use.  For the 93rd connection, we want a
> way for the BOC's T-1 channels to be used, which is completely
> transparent to the originating client machine.  Could the traffic be
> "re-routed" somehow to the BOC's 3845, where the BOC 3845 can dial-up
> the PPP connection?  Or is there a way for the POC's 3845 to "reach
> across the network" and utilize the BOC's T-1 channels?  This
> situation would be reversed if the originating client machine is at
> the BOC...          

I guess you need to look at L2TP dialout, where you decouple routing and
actial ISDN resources. You "terminate" the routing on the LNS (any box),
and instead of this machine dialing out directly, it uses L2TP to
forward the session to the 3845s' E1s/T1s. If one of the 3845 has no
more resources, L2TP takes care of failing over to the secondary. Never
used it with dialer maps, but it might work.

The dialin part is trickier (if you also need dial-in), you can't use
dialer-maps/DDR for this, so you might need to migrate your setup to a
dialer-profile design. If you do this, you could also look at
large-scale dial-out with SGBP, however this only works if the 3845s are
"close" to each other (best: adjacent). 

	oli