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Community Member

How to route public IP's

Sorry about the double-post but this seems like seperate question.

My question seems very trivial, but is something new to me.

 

The ISP normally gives out /29 subnets, but we are asking for something larger like a /27.

 

I've only dealt with NAT'd networks to this point and am wondering how to subnet/assign the /27 network to the internal tenants. We would like the tenants to use their own personal routers

 

For example...

 

ISP (66.67.68.1/27) ------ (66.67.68.2/27) CISCO2821 (66.67.68.5/30)---- (66.67.68.6/30) Tenant 1 (10.1.2.0/24)

                                                                                              (66.67.68.9/30)---- (66.67.68.10/30) Tenant2 (192.168.1.0/24)

 

The above does not seem logical to me?

 

Coule someone shed some light on the proper assignment of IP's & appropriate subnets?

 

Thanks!

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Accepted Solutions
Community Member

How to route public IP's

In my opinion the best thing is that your ISP give you two address blocks - one /30 (for point to your router) and second for tenants (/27)

You should have this:

ISP (66.66.66.1/30) ---- (66.66.66.2/30) CISCO and on this side all subnet (66.66.67.1/27) you should bind to your ethernet if it is to these network connect tenants routers (for natting). Separating for subnets /30 you are wasting many ip addresses which you can need later.

So give first tenant ip 66.66.67.2/27 with gateway 66.66.67.1 and mask /27, second

ip 66.66.67.3/27 with gateway 66.66.67.1 and mask /27 and so on

5 REPLIES
Community Member

How to route public IP's

In my opinion the best thing is that your ISP give you two address blocks - one /30 (for point to your router) and second for tenants (/27)

You should have this:

ISP (66.66.66.1/30) ---- (66.66.66.2/30) CISCO and on this side all subnet (66.66.67.1/27) you should bind to your ethernet if it is to these network connect tenants routers (for natting). Separating for subnets /30 you are wasting many ip addresses which you can need later.

So give first tenant ip 66.66.67.2/27 with gateway 66.66.67.1 and mask /27, second

ip 66.66.67.3/27 with gateway 66.66.67.1 and mask /27 and so on

Community Member

How to route public IP's

Thanks Adam. That makes perfect sense to me.

So... The ISP in effect does some subnetting for me initially and puts in place a route on their side stating something like.

Ip route 66.66.67.0 255.255.255.224 66.66.66.2

am I on the right page with this?

Community Member

How to route public IP's

No there is not needed.

This two subnets will be directly connected to your router so will be self routerd, one route as you need add is defult route to your isp:

ip route 0.0.0.0 0.0.0.0 isp_wan_ip

Community Member

How to route public IP's

Sorry my statement was a little misleading.

this route would exist on the ISP router--> Ip route 66.66.67.0 255.255.255.224 66.66.66.2

I understand that the default route for my 2821 would point to the ISP IP on the /30 side 66.66.66.1

I've never requested such a setup before. I assume the ISP will know exactly the scenario we're speaking of??

lots of googling has resulted in not too much information on this topic.

Thanks again!

Community Member

How to route public IP's

ISP will know this scenario i thing.

On the ISP side you address ip from /30 address space (separate from /27) and on ethernet you address your address space /27

and you need to add only one route - default to the ISP as i posted before, nothing more.  Tenats will setup gived adress by you and setup default router your ethernet ip and thats all.

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