Configuring a netblock on plusnet

Hey guys,

I had a static IP on my business line with plusnet, which I have had with them for years.

Recently I have needed an additional IP for to assign to other servers we have on-site, which couldn't be solved by using NAT.

I requested a 4 IP Netblock from plusnet, and at the time I knew that two of those IP addresses would be "lost", the broadcast and the gateway IPs.

My Range is:

212.159.64.216 <- Gateway
212.159.64.217 <- First IP
212.159.64.218 <- Last IP
212.159.64.219 <- Broadcast

Now currently I'm using a linksys AM200 which, as far as i know, I have no way to configure without the modem stealing an IP, unless i get one of our servers to do the PPP authentication and get the IP directly.

Am I right in thinking that if I get one of these: http://www.broadbandbuyer.co.uk/Shop/ShopDetail.asp?... then I will be able to have to connect a standard switch, not router, to that modem and assign xxx.xxx.xxx.217 to one server and xxx.xxx.xxx.218 to the other, using a netmask of 255.255.255.252 on both.

I understand that if I then wanted nat, due to the lack of a router, I would have to get one of the servers with a routable IP to perform NAT for the rest of the network.

My second problem is the gateway....

I am having weird issues. Currently I am letting the modem just get standard dhcp and it gets the following config:

IP: 212.159.64.217
Gateway: 195.166.128.184

This is strange because on my plusnet control panel it specifically states that 212.159.64.216 is my gateway, and when I have configured proper dedicated connections in the past the usual rule of thumb is that the first IP is the gateway, although sometimes they configure the last usable ip as the gateway. I understand that it can be any ip, apart from the broadcast, but usually it is the first or last routable ip.

Now I have an issue setting the gateway on my connection, if on any of my linux servers i configure 212.159.64.218 as an IP then set the gateway as 212.159.64.216 i get:

inet addr:212.159.64.218 Bcast:212.159.64.219 Mask:255.255.255.252

route add default gw 212.159.64.216
SIOCADDRT: No such process

I'm a bit confused as to why I can't set the 216 address as the gateway

When I had an 8-block with Zen, three were assigned to WAN, LAN (gateway) and broadcast, with five for local nodes.

With a 4-block, one is useable by nodes, with the same three allocated to WAN, LAN, Broadcast. Or that's how I see it.

http://www.plus.net/support/service/policies/IP_bloc...

4 IP block provides 2 usable IP addresses (1 for the router and 1 for servers, PC, etc.)

I presume you could setup DHCP for one IP, and the PCs could use it, while you configure the other IP for a server. Either that, or it's fine for using a non-NAT setup.

Edited by camieabz (Wed 25-Jul-12 10:41:27)

A /30 allocation is not really suitable for what you are looking to do.

How many servers and PCs do you have?