Cisco NM-4E & Cable Modem

[tsemorgan]

Hi, I have Cisco 2620 with a NM-4E module that I want to connect to a cable modem. Can I use the ip address dhcp cmd on the fastethernet port to dynamically acquire an IP from the ISP, and then connect multiple PCs to the NM-4E's 4 ethernet ports? If that's possible, would I need crossover cables for the PC connections? Thanks for the help!

[pkhatri]

Hi,

That depends on how your cable modem is setup. If the modem is set up as a DHCP server, and this functionality is enabled on its ethernet port, then what you are suggesting will work. You might just have to plug it and see if it works.

As for the other part of your question, you can indeed plug in your PCs into the NM-4E's ports... However, be aware that each of them will have to be in a separate network (the alternative is to bridge over the three interfaces). You can use private IP addressing for that purpose. In addition, you will need to run NAT on your router so that the private addresses get NAT'ed to the public IP you receive from your cable modem.

Hope that helps - pls rate the post if it does.

Regards,

Paresh

[tsemorgan]

Yes, the cable modem is set up as a DCHP server. I will try connecting the fastethernet port to use as the "external" lan connection. If I keep different subnets on each NM-4E port, do I need to define separate dhcp pools? Then, all internal ethernet interfaces should be configured for inside nat & have an ip nat overload statement (& access list) for each corresponding interface (subnet). That sound correct? Thanks!

[pkhatri]

That all sounds cool.. except the bit about the separate DHCL pools...If you have just a single PC plugging into each port, why do you need to use DHCP to assign them addresses ? You could just hard-code them in...

Paresh

[tsemorgan]

Paresh,

Yes, you're right, DHCP pools are unnecessary (unless I was connecting a switch to the ethernet port). So I'll give each PC an IP w/same subnet as their ethernet connection to the NM-4E module, as well as inputting the default gateway as being that corresponding ethernet int IP. Once that's done, do I just need default route statements pointing all traffic to the fastethernet port that's using ip address dhcp? Am I missing anything else?

[pkhatri]

Yeah, you need the default route and appropriate NAT config and all of that should work fine...

Hope that helps - pls rate the post if it does.

Regards,

Paresh