CIDR IP Block setup

Posted on 2013-12-17
Last Modified: 2016-05-31
I just ordered CIDR IP Block from Cox.
Before I had internet connection with 60 pubic IPs from XO Communication.
When I use internet from XO, to make all computer's internet work, I just assigned each public IP to the computer and that's it.
I have setup and installed many routers for the customer but I don't know how to setup CIDR  IP information to the router because CIDR IP Block is first for me.

Current my network is very simple.
No need firewall / No need special setting. / No servers.
All 60 computers are for computer gaming. (Lan / online game center)
All 60 computers need to be faced to out side internet with public IP.

For example)
On each computer, open the internet like "" and shows public IP of each computer - actually CIDR IP not Wan IP.

MY network info is below

*Wan info
dns 1/
dns 2/

*Cidr IP info / network id / subnet / gateway / usable IP range / broadcasting IP

My network layout is below
Cox Modem (bridge)
Router (Dlink dir165 or Linksys E900 or Ubiquiti ERLite-3 EdgeMAX EdgeRouter Lite)
HP 2848 switch * 2
60 Gaming Computers which need to have public Ip for each computer
* I have several router. which router do you recommand for CIDR IP Block?

I don't need NAT because I will assign each IP from Cidr Block to the each computer.

I just tried setting like below
1. open router's setup page
2. put Wan Ip info to the Wan section with static IP option on the router.
3. put and to the Lan section on the router.
4. assign each Ip from Cidr Block to the each computer / 60 times for the 60 computes.

And I found problem. testing with Dir615 with DD-Wrt firmware
1. Each computer represent public Ip on the ""
2. but the problem is internet is really slow.
3. I disable firewall and NAT and reboot modem and router but no difference.
4. For the testing I connect my laptop to Cox cable modem, and no problem and no issue.

And testing with Linksys E900
1. internet up and down speed is perfect but all computers represent Wan IP on the
internet side like " - it shows public IP which is connected to their system"

So I thought problems are from
1. my routers are not support CIDR  or
2. my concept of setting CIDR is wrong totally.

Would you check on my setting of CIDR to find out what is wrong?

Your solution will be deeply appreciated.
Question by:seoul1004
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LVL 22

Accepted Solution

Jody Lemoine earned 500 total points
ID: 39726835
You're setting it up correctly, but depending on the home Internet gateways you're using, it may be beyond the scope of what they were designed for. Turning off the firewall and NAT is a start as these will interfere with the raw forwarding speed of the router and hide your block, respectively. Are you finding that the Internet access speeds are the same with all three gateways in this configuration?


Sorry... just re-read that. The Linksys E900 seems to be your best bet on performance, but it needs to have its NAT turned off, which is why you're seeing the WAN IPv4 address represented in your speed tests.

Author Comment

ID: 39728446
Thank you for answering.
I have already turned off NAT and Firewall on the router.
But the still internet connection is really slow, almost looks like no internet connection.
(to load, takes over 10 sec or cannot display)
And each computer represent it's own public IP on IP).
Today I contacted Linksys and they said E900 doesn't support CIDR IP.
Do you know a router supprot CIDR IP block?
LVL 22

Expert Comment

by:Jody Lemoine
ID: 39728452
Just about any standard router (Cisco, Juniper, &c) will be able to handle it. Low-end home gateways made by companies like D-Link, Belkin and Linksys are geared to be NAT devices and have trouble in this sort of configuration.

Oh, for the record, the problem isn't your use if CIDR. Almost all IPv4 addresses are CIDR. The problem is that you need to route between two IPv4 subnets without NAT.
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Author Comment

ID: 39728475
HI Jodylemoine.
Today I ordered "Ubiquiti ERLite-3 EdgeMAX EdgeRouter Lite".
Somebody said it will support CIDR IP Block. I am not sure this will works or not. Now I feel I don't have many options so that I would like to try any solution I can try.
Anyway, you said "you need to route between two IPv4 subnets", what do you mean by this?
Would you explain more in detail?
LVL 22

Expert Comment

by:Jody Lemoine
ID: 39728483
As you've already indicated, you need to route between IPv4 subnet and IPv4 subnet without NAT being applied.

If you're using a home gateway product, most of them will use NAT and many will not permit this to be disabled.  You need to use something that is capable of routing between the two networks without NAT.

I'm unfamiliar with Ubiquiti products, but if they can do this, you should be fine.

Author Comment

ID: 39728573
Yes sir, as soon as I get a Ubiquiti router, I will set up the router as you explained.
And I will give you a feedback what would happen to the issue.
Thank you.

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