Magnet fibre and Cisco 871 for NAT

gavdbyrne · 11-12-2008 12:28PM #1

Hi all,

I am thinking of getting a Cisco 871 for my home, mainly to do NAT but enough horsepower to do it at up to 24Mbps.

My problem has been that magnet give out public IP addresses through DHCP on various /24 subnets and most of the time my PC's are on totally different ones to my NAS, causing Microsoft networking features like mapping a network drive to fail (I'd need to have domain controllers and WINS servers I think to make this work, I've tried alot of workarounds unsuccessfully).

So I am looking at getting this as to me it looks straightforward enough, but I just want to check whether anyone spots a problem?? I assume I can connect the Ethernet WAN port on the 871 to one of the Ethernet ports on the switch provided by Magnet and that it will get a public IP address by DHCP just like my PC does. Then I can configure the 871 to do NAT and connect further switches, wireless access points, and PC's in behind it. I can leave the phone and tv connections plugged into the Magnet switch.

I was looking at some of the lower end netgear/linksys routers and they don't seem to be able to handle anything near the speeds possible with Magnet.

I've configured cisco routers before so the config side shouldn't be a problem, just not that familiar with Magnet's setup and whether there'll be any protocol conflicts that I haven't thought of.

Thanks!

ntlbell · 11-12-2008 12:33PM

Not really sure I understand.

Assign all internal private addressing to pc's + nas...

static private on inside of cisco

cisco nat's random assigned ip to internal

am i missing something?

gavdbyrne · 11-12-2008 01:00PM

Thanks for the reply.

Yes, I guess what I'm really asking/confirming is that there should be no problems getting the 871 to play nice with Magnet in obtaining a public DHCP IP address (is there any PPPoE config to be done or would the switch provided by magnet be looking after all of that?). Has anyone done anything similiar with a Magnet fibre connecction?

After that it's straightforward, was just providing the extra info as to the why I want to do this...

DjDangerousDave · 11-12-2008 11:04PM

Where are you thinking of buying said device? I'm looking into getting an 871 to use with magnet business broadband. I wont get the swanky speeds your getting but I will have a concurrent block of IP's to play with.

Dave.

15-12-2008 01:05PM

gavdbyrne wrote: »

Thanks for the reply.

Yes, I guess what I'm really asking/confirming is that there should be no problems getting the 871 to play nice with Magnet in obtaining a public DHCP IP address (is there any PPPoE config to be done or would the switch provided by magnet be looking after all of that?). Has anyone done anything similiar with a Magnet fibre connecction?

After that it's straightforward, was just providing the extra info as to the why I want to do this...

It doesn't care about the public IP address. It will get assigned by the dialer.

There will be a bit of configuring of PAT/NAT overloading. Thats all really.
I'm not sure why you would assign the public IP address(s) directly to the stuff on your internal network. You much better off using a form of NAT.
I'm not sure if magnet gives you more than one public IP but if they do you are perhaps better off using plain old NAT. It will defiantly be easier on your router as it won't have to keep a huge port translation table this can be a problem on cheaper routers and p2p traffic.

Are you familiar with the cisco IOS? If not it can be quite difficult to configure. I think this might be overkill for your needs to be honest.
This migth be worth a look:
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_q_and_a_item09186a00800e523b.shtml
Edit:Ok I just see you have used them before

gavdbyrne · 19-12-2008 01:39PM

Thanks for the replies. So sounds like this would work.

I intend to have all my internal devices configured with private addresses by DHCP, my problem is they currently get assigned random public addresses with only 1 hour DHCP leases by magnet which leads to different appliances having addresses in different /24 subnets (and therefore the resulting problems I outlined in my first post). Magnet said there's no way to ensure that my machines always get assigned addreses in a particular subnet but if I was a business customer I could get static ip addresses

Thanks for the help, I'll update if I go ahead with it

21-12-2008 10:07PM

gavdbyrne wrote: »

Thanks for the replies. So sounds like this would work.

I intend to have all my internal devices configured with private addresses by DHCP, my problem is they currently get assigned random public addresses with only 1 hour DHCP leases by magnet which leads to different appliances having addresses in different /24 subnets (and therefore the resulting problems I outlined in my first post). Magnet said there's no way to ensure that my machines always get assigned addreses in a particular subnet but if I was a business customer I could get static ip addresses

Thanks for the help, I'll update if I go ahead with it

I don't see the issue here.

Whatever interface you choose will get the assigned address from magnet.

Why does it matter that the public address jumps between subnets? It shouldn't break anything apart from the usual issues caused by dynamic addresses.

Magnet fibre and Cisco 871 for NAT

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