Network design / IP Addresing for local network

Posted on 2011-03-03
Last Modified: 2012-06-21
Hello Experts,

I'm looking at this trying to find ideas for simple ip scheme to be able to forward the public ip and access my end device over the net.

( 95.x.x.x /29 ) ----- ( T-1 ) ------pt to pt -------- (T-1)  -------- ( End Device)
   adsl modem           router                               router              router
      public ip
Question by:cisco20
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LVL 33

Expert Comment

ID: 35027992
For a private scheme you would want to use or  

I usually tell people to stay away from the low numbers that most people use by default on consumer routers. (i,e,

Is this for a home network with few hosts:
I would recommend, for a private scheme.  

the exact subnet you pick is really based on the number of hosts you need on 1 LAN.   Try to stay away from very large subnets to avoid alot of broadcast traffic if you will have many hosts....  

Author Comment

ID: 35028121
Mike, Thank you for quick response ! ! I agree with you on the most used ip's and the internal route forwarded will be an private.

My goal is to not complicate the routing portion of this config, so what would the t1  interaces and gateways be addressed to acheive this ?

adsl public ip : 95.x.x.x /29

router 1 ip :
router 1 gw :

router 2 ip :
router 2 gw:

end device ip :
end device gw:  

Thanks again.

LVL 33

Expert Comment

ID: 35029134
So you have 3 segments here
segment 1   Adsl to router 1
segment 2   router 1 to router 2
segment 3   router 2 to end-user devices

I would do something like this:

Segment 1 subnet  with
adsl internal ip:
router1 ip:  

Segment 2 subnet
router 1 ip:
router 2 ip:

Segment 3 subnet
router 2 ip:
end user devices get dhcp  using gw  

You will need to add routes to the adsl and router 1 so they know where to send packets bound for  


Author Comment

ID: 35031213
Very helpful Mike !

Does Telco normally provide the addressing for the point to piont circuit ? Haven't  dealt too much with these.

LVL 33

Accepted Solution

MikeKane earned 500 total points
ID: 35031442
You usually have 2 options.   For a telco managed router or a customer managed router.  

With a telco managed option, they install the router and work with you to address it on your subnet.   So essentially, the segment 2 in the example above would be fully handled by the Telco.    You just have to provide the subnets on each side of the router.  

If you opt for a customer managed router, they deliver the dmark and its up to you to configure the router.   If you haven't done this before, I suggest you get all the assistance from the Telco that you can for the config and such.  

Also, if there are any other LANs on segment 1, I would suggest using another 24 bit subnet, i.e. using as a sub interface on router 1 and let those clients use it as the gateway.  


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