ISDN Backup

karunesh · 10-31-2002, 02:08 AM

Hi.

I have Redhat Linux 7.2 which is working as a Router for my 4-5 PC network.Till now I had a ISDN Router ( I ISDN line & 1 LAN port) which I was using for my router as dial on demand.Now I got a DSL connection which I have terminated into my Linux box and my working if going fine.

Now I want to use that old ISDN router as a backup solution for my DSL line.So if my DSL lines goes down then my linux router will automatically sense it and divert the default route towards my ISDN router .Which on getting demand will dial to ISDN network and I have again my link working.Same time as when my DSL link comes up,my ISDN router will automatically disconnect the ISDN link.

Dos someone has any solution for this ?

daxy · 10-31-2002, 07:28 AM

I don't have any examples, but I can give you a suggestion. Use a dynamic routing protocol like RIP to check if there's a connection. If not, establish an ISDN connection.

Sorry, can't help you more with this one...

tarballedtux · 10-31-2002, 08:33 AM

Now when you say "terminated to you Linux box" do you mean that DSL modem is internal instead of an external/NIC setup? If it is external and along with the ISDN being external you may be able to setp some sort of dynamic protocol. I'm not sure if Linux understands RIP, it may if someone made a working 'hack' to do it. Otherwise the only way I can see that you could do it would be to have a smart router like a Cisco 1600 that can have an administrative cost applied to the interface of each Internet connection. So when the DSL link goes down the ISDN interafce is seen as a better route so they info gets sent across the correct link. Likewise when the DSL link is active again it is seen as a better alternative.

--tarballedtux

daxy · 10-31-2002, 08:59 AM

Take a look at http://www.zebra.org. You can configure RIP+, OSPF and BGP like a Cisco router. Advanced knowledge of networking is required I'm affraid but it could help you out.

karunesh · 10-31-2002, 10:46 PM

I know about Zebra(RIP,OSPF and BGP).But for such a small network I don't want to run some routing protocol.Becuase as I ma on DSL then running some routing protocol will unnecessary load my box with 'n' numbers of routing protocol.

Better if there is some sort of script that can monitor the DSL link and make autodial if DSL link goes down.