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4block of Staic IPs: Router Config Question??

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4block of Staic IPs: Router Config Question??

Guys,

I have been assigned a 4 block subnet of static IPs by PlusNet. I will to get an 8block subnet but before I do upgrade my account I am setting up a test network.

PlusNet have informed me they can provide no surport but I dont think I have all the configuation information required.

The block i have been assigned is:
80.229.133.124
80.229.133.125
80.229.133.126
80.229.133.127
Netmask: 255.255.255.252
Clearly within this small subnet the 124 address is the network ID and 127 is the Broadcast address - both being usable to assign to machines.

So I have assigned 80.229.133.125 subnet mask 255.255.255.252 to the internal ethernet interface of my Cisco 837 router and 80.229.133.126 subnet mask 255.255.255.252 to a PC on my internal network.
This is the subnet fully used up and the router and the PC can communicate fine as you would expect.

Now I need the IP address for the external ADSL interface of my router that connects the PlusNet Network and hence the internet.

They will not provide me this information and have informed me that all I need is those IP addresses. They have also recommended that i assign one address to one side of the router and the other address to the otherside, but as these addresses are on the same subnet I dont see how any routing will be done. Also there would be no IPs left for PCs

Has anyone successfully set up a internal network with static IP addresses?

I have included a rather rubbish network diagram to make it clearer

What do I assign the external interfaceHuh? Plus wont tell meHuh

Many Thanks
Lee

Picture Link Here

[Moderator's note by Tom (tomspcs): I have linked your picture instead as it was tretching the page too much.]
9 REPLIES
FireStorm
Grafter
Posts: 90
Registered: 12-08-2007

4block of Staic IPs: Router Config Question??

They have assigned you 4 IPS.. you need to remember only 2 of these are usable.

80.229.133.124 = Default Gateway
80.229.133.125 = Useable
80.229.133.126 = Useable
80.229.133.127 = Network
Community Veteran
Posts: 14,469
Registered: 30-07-2007

4block of Staic IPs: Router Config Question??

And one is specifically for your router (.125) leaving a single IP free (.126) for internal use.
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4block of Staic IPs: Router Config Question??

Thanks guys,

This is how I have configed my router (see my network diagram in first post). The question I have is what IP and subnet mask do I assign the external interface (the ADSL interface) of my router.

Thjs address will need to be on a differnt subnet to mine, so the router will route packets from my assigned subnet to the external world.

This external address will need to sit on the subnet PlusNet have assigned for their ADSL network.

Anyone has any idea what this address maybe, or how to obtain it?
Also If I'm being really dumb could this be pointed out to me aswell please Smiley

Hopfully my rubbish network diagram will make things clear....

Cheers
Lee
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4block of Staic IPs: Router Config Question??

Numbersix,

I am trying to figure out why you want to change the subnet if im honest.
If your pc is given an external IP due to you having a block of 4then I am assuming you would need to remian on the same subnet. The reason for this one again I am assuming is because you have a block of 4 ip's where as I have a block of 8 so my subnet would be err 248 as apposed to your 252.

Anyway I need to study subnetting a little more but I dont think it can be changed. But thats my humble opinion.

Regards,
N/A

4block of Staic IPs: Router Config Question??

Hi,
Dont know if this is any help, or even if its the correct way - but it works

I have an 8 ip block (so subnet of .24Cool

*.48 = external interface of router
*.49 = "internal" interface of router (with security !)
*.50 = dsl router for wireless lan (NAT enabled !)
*.51 = pc 1
*.52 = pc 2
*.53 = pc 3
*.54 = spare, but have used it before - so it does work
*.55 = cant use this one

everything is set to use the same subnet (255.255.255.24Cool - obvously the wireless lan is a normal 192.168.0.1 range with the standard 255.255.255.0 subnet.
FireStorm
Grafter
Posts: 90
Registered: 12-08-2007

4block of Staic IPs: Router Config Question??

Yep thats right the first ip is assigned to your external interface.

In the cisco config simply set the routing up... somthing like this (my IOS is a bit rusty since we swapped to Dell kit)

En
conf
Ip route 0.0.0.0 255.255.255.255 <interface> (i.e s0/0)

Cheers

Dave
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4block of Staic IPs: Router Config Question??

Thanks for your help!

So i set the first address, i my case 80.229.133.124 with a subnet of 255.255.255.252 to my external interface?

I shall try this and get back to you.

Thanks again
Lee
FireStorm
Grafter
Posts: 90
Registered: 12-08-2007

4block of Staic IPs: Router Config Question??

How did you get on lee?
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4block of Staic IPs: Router Config Question??

Cheers Guys,

I got it all working now thanks.

I set the router up in NAT config with .125 on the external using the auto config.
then in IOS i manuallyed changed the internal interface to .125 with a .252 subnet and turned off NAT.

This worked fine a server with .126 was able to gain full access.

Then I connected another NAT router as set that 126. So now I know it works I will apply for 8block.

Thanks again
Lee