adsl query

alliasneo

I've got a question that I hope some of you guys have configured at home before.

I've got my ADSL line coming in and connected to my ISP router. I'm wondering, can I plug my ISP router in to a Fast Ethernet port on my Cisco lab routers and then create a default route to get out on the internet? How would you normally configure an ADLS connection from your home lab?

Thanks

SharkDiver

Probably the first thing to do is to set "ip address dhcp" on the FE port you are going to use. Then I would set your "ip route" statement to go out that port rather than an IP address.

ip route 0.0.0.0 0.0.0.0 fa0/1

That would be the fastest way to go, but if you know the IP address of your ISP router, you can statically set the "ip route" statement with the next-hop as well. You can also set your ip address on the FE port for an address that is high enough that no one else ever gets it from the DHCP pool on your ISP router. Just make sure that it is still in the same subnet.

alliasneo

Thanks for the response.

So If I connect one of my ADLS router's FE ports to my cisco router would I need to configure an ip address on the port? I was thinking that if I connected my ADSL router to a switch and then the switch to my cisco router I wouldn't need an address that way and that would work but can I bypass the switch completely and just plug in to the router without an ip address? how come I would need to dhcp it?

martell1000

where should your router route to without an ip address?

martell1000

or do you mean the ethernet ports on you adsl router? these act like a switch and dont need an ip address. but your cisco router needs to get an address, either via dhcp or a static one.

alliasneo

yeah I was thinking if I plug the ADSL port into my cisco router, so this will provide my cisco Fast Ethernet port with an ip address and then I can just route out of it back to the ADLS router? That makes sense

martell1000

what kind of router are we talking about here? do you have a router and an ADSL modem or a router with an integrated modem?

best practise would be to connect you cisco router to one of the integrated switchports of your adsl router and give it an ip address via dhcp as shark diver described.

you can also connect you cisco router directly to you modem, but then you would have to configure something like that:
Cisco DSL Router Configuration and Troubleshooting Guide - Cisco DSL Router Acting as a PPPoE Client with a Dynamic IP Address - Cisco Systems

alliasneo

cool I'll check out the link. Yeah it's a standard ISP ADLS router with switchport like interfaces on the back for connecting hosts so I will try and DHCP out one of those to my cisco router...

alliasneo

Hey guys, Still having problems with this. I've plugged my ADSL Modem in to R1 over fast ethernet and been able to assign a DHCP address from the ADSL modem. I can get out on the internet from R1 using a static adress 0.0.0.0 0.0.0.0 fast0/0.

As I only have one fast ethernet port on R1 I have had to add R2 via serial so I can connect my PC.

I can ping everything from R2---> R1 but can't get out on the internet. The same for my PC. I have added a static route on R1 back to my host so I can ping back and forth. Any ideas?

Is it because the ADSL modem does not have a route back to R2?

martell1000

give us some running configs please.

edit: and a "show ip route"