I have a friend who is located in the US and his wife is located in
China. They communicate often--using Skype. His LAN is connected to
the Internet via Comcast Cable and his wife has two broadband
connections (I am not sure what type). This generally all works quite
well for my friend except when there are problems with his cable

We are both EEs and as a result we have chatted about some sort of
redundancy for his cable network connection. He would be open to
bringing in some other form of Internet connection (e.g. DSL) and to
buying a router if we could figure out how to make this work.

I have read about dual wan routers that can be used to connect a LAN to
the Internet via two different paths (e.g. cable and DSL). These
devices will apparently load share the traffic across both paths when
these paths are operating and will redirect all traffic to the
operating path if either path fails. Each of these paths would have
its own ISP supplied IP address at the router end.

This sounds like a nifty device but I don't think that it will work
with Skype (for seamless switchover in a path failure). It is my
understanding that a Skype session on his local LAN machine will
establish a P2P connection with its remote partner. The local router
would do NAT on the packets from the LAN machine before sending them
on. The remote Skype would be sending packets back to the IP address
of the local router. These packets would be port/address translated
before sending them on to the LAN machine. Since the remote Skype
machine would be targeting a particular IP address, things would quit
working if that path to the dual path router went down.

It seems like my friend needs only one IP address but multiple routes
to this address. I have checked to see if a person could register an
IP address and apparently this is possible. I have also read that it
is difficult to get packets routed to these individual addresses.
Understandably ISPs and network administrators don't want to clutter
their routing tables with individual addresses.

So, I don't see a clever solution-but maybe someone cleverer than I
might see one. Does anyone have any suggestions?

Greg Laird