Multiple IP address with eircom

Blaster99

I have gotten a chunk of IP addresses assigned by eircom, along the lines of x.y.z.192/29. I have a router that's capable of dealing with multiple IP addresses on the WAN side. I currently using PPPoE bridging over the ADSL modem. This is how I currently get the WAN IP address and initialise the connection on the router.

The last time I called eircom support I talked to somebody who couldn't speak English and/or didn't know what a static IP address was, so before I get the pleasure of that experience again I wouldn't mind getting to know some of the basics of this stuff.

I'm guessing that I should not be doing PPPoE anymore and that I should simply tell my router that the inbound interface has IP address x.y.z.192/29. I'm guessing that one of those addresses is the gateway? Eircom didn't indicate which one so I might call them ask about that and I'll setup a static route to it. Should that do it basically? Or is PPPoE required for some kind of authentication?

watty

You would need to explain more about what you are trying to achieve. Needing more than one WAN static IP for an enormuse LAN with 1000s of private static IPs these days given the cleverness of NAT, Proxies and port forwarding is UNUSUAL.

But not unheard off. You can PM if you are shy to explain publically.

The "Gateway" is usually the IP on your LAN that connects to the WAN. If you are not using NAT/Proxies etc but simple Static IPs and non-NAT router, then the Gateway IP is NOT any of your bunch of IPs at all, but the IP of the next EIRCOM router.

Sometimes you don't need a gateway IP at all (like if all the IPs that talk to each other are in same SUB net).

The gateway IP is essentially the IP of a device that connects two differing subnets (the Internet and a Private LAN 192.168.n.x SN 255.255.255.0 is just ONE example).

I use proxy based routing so my GW is the Static LAN IP on the PC dedicated as a proxy based Firewall with two Ethernet cards in it, the other Ethernet is DHCP WAN address, but it will work just the same if it is a STATIC WAN IP. The internal LAN GW IP wont change as it can't see the WAN IP range I get

cgarvey

You still do PPPoE, which will always assign you with the one IP out of your subnet. In my case it's the first usuable IP, so I presume it'll be the same for yours. All the other usable IPs are then routed to that first one, so it's up to your router/firewall to be able to do NAT, 1:1 NAT or routing of those additional IPs. In the case of a linux box, it's as simple as adding aliases to the PPP device.

.cg

Blaster99

Yeah I talked to an eircom support rep there earlier who said much the same. I've gotten it to work now. In my router, one sets the interface IP to the subnet and it then looks after the lot. The only problem was that I needed to add a static route to eircom's gateway and I didn't know what the gateway IP was, so I configured it as you describe and then I picked up the DHCP'd gateway and hardcoded it in the route table and switched back the subnet configuration. Mucho cool to have multiple external addresses.

iano

Be aware that Eircom occasionally assign addresses other than your static addresses during the PPPoE exchange.

It happens infrequently and a reboot or drop/re-establish the PPPoE will normally correct the problem and give you back your correct addresses.
It is something to check if you have connectivity problems.