IP Route Question

Unanswered Question
Aug 29th, 2007

We have two offices. My office has two T1 connections to the Internet. I've ordered Point-to-Point T1 (just the T1 port without Internet connection) to connect our other office to us and to the Internet.


I would like to subnet our class C IP like below:

198.78.142.1 255.255.255.128 (our office)

198.78.142.252 255.255.255.252 (For serial ports that are connecting our two offices)

198.78.142.128 255.255.255.192 (our other office)


I'm having a problem figuring out the "ip route" statements to accomplish the above:


IP route statement for my router here:

ip route 0.0.0.0 0.0.0.0 4.0.240.121

ip route 0.0.0.0 0.0.0.0 38.99.199.153

ip route 198.78.142.128 255.255.255.192 198.78.142.254


IP route statement for our other office:

ip route 0.0.0.0 0.0.0.0 192 198.78.142.253


Are the above ip route statements correct?

Are the Serial configuration for connecting our two offices correct?


-------------- Below is my Cisco router configuration----------

!

! Connection to Internet from Level3

description to-Internet-1

interface Serial0/0

bandwidth 1536

ip address 4.0.240.122 255.255.255.252

down-when-looped

service-module t1 timeslots 1-24

!

! Connection to Internet from Cogent

interface Serial1/0

description to-Internet-2

bandwidth 1536

ip address 38.99.199.154 255.255.255.252

ip access-group 111 in

encapsulation ppp

load-interval 30

down-when-looped

no fair-queue

service-module t1 timeslots 1-24

!

! Connection from our other office

! Point-to-Point - I need to connect them to our Internet

interface Serial0/1

description to-our-other-location

bandwidth 1536

ip address 198.78.142.253 255.255.255.252

encapsulation ppp

down-when-looped

no fair-queue

service-module t1 timeslots 1-24

!

!

! Our internal LAN

interface Ethernet0/0

description local_network

ip address 198.78.142.1 255.255.255.128

no ip redirects

ip route-cache flow

half-duplex

!

!

no ip http server

ip classless

ip route 0.0.0.0 0.0.0.0 4.0.240.121

ip route 0.0.0.0 0.0.0.0 38.99.199.153

ip route 198.78.142.128 255.255.255.192 198.78.142.254

!



-------------- Below is our other office router configuration----------

!

! Connection to main office

description to-our-main-office

interface Serial0/0

bandwidth 1536

ip address 198.78.142.254 255.255.255.252

encapsulation ppp

down-when-looped

no fair-queue

service-module t1 timeslots 1-24

!

! internal LAN

interface Ethernet0/0

description local_network

ip address 198.78.142.129 255.255.255.192

no ip redirects

ip route-cache flow

half-duplex

!

!

no ip http server

ip classless

ip route 0.0.0.0 0.0.0.0 198.78.142.253

!

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comentum Wed, 08/29/2007 - 18:55

Thanks for your reply.


Our Point-to-Point connection has not arrived yet. I'm getting the routers ready.


I wasn't sure if it was possible to subnet one class C address and use it in two locations:

198.78.142.1 255.255.255.128 (our office)

198.78.142.252 255.255.255.252 (For serial ports that are connecting our two offices)

198.78.142.128 255.255.255.192 (our other office)


I appreciate all your help - Thank you.

Edison Ortiz Thu, 08/30/2007 - 14:09

> I wasn't sure if it was possible to subnet one class C address and use it in two locations:


Definitely possible and you've done a great job at ip address preservation :)

Joseph W. Doherty Wed, 08/29/2007 - 19:31

I agree with Edison, didn't see any problems with the route statements, nor with the address block usage.


PS:

Some other suggestions.


If your router's and LAN hardware can support it, move to full-duplex (or auto).


Recommend fair-queue instead of FIFO on all your serial links.


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