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New Member

Establishing a subnet across a Wan Link

We have two unix boxes on a subnet that is needed

for a critical application. The software has these addresses hard coded into it. We currently have a unique subnet on either side of all our wan links and are running Cisco 7206 and 7507 products. We want to have one unix box in each site across the wan link with the same ip subnet for security reasons. Is there someone who has done this or some document out there that can explain how to do this?

7 REPLIES
New Member

Re: Establishing a subnet across a Wan Link

Don't think thats going to work. What sercuirty issue are you trying to resolve by doing this?

New Member

Re: Establishing a subnet across a Wan Link

In the event of a disaster where we lose the building these units are housed in. We want to put one of the units at a different site without re-writing the application.

New Member

Re: Establishing a subnet across a Wan Link

We use a radio link, using ISO layer 2. Acts like a bridge.

New Member

Re: Establishing a subnet across a Wan Link

What routing protocol(s) are you running?

New Member

Re: Establishing a subnet across a Wan Link

How far apart the IP addresses of the Unix boxes on the subnet? You can try using using Variable Subnet Masks (VLSM).

IOS Version 12.2.2T can use 31BIT VLSM. This gives you two hosts and only takes up two IP adresses per network.

You can use one for the Unix box and one for the IP address of the Ethernet port on the router.

UNIX SERVER1 Ethernet Port 10.1.1.1/24

Router Ethernet Port 10.1.1.2/31

UNIX SERVER2 Ethernet Port 10.1.1.3/24

Router Ethernet Port 10.1.1.4/31

-Evan

New Member

Re: Establishing a subnet across a Wan Link

You can configure bridging between the two site,just like bridging NetBEUI across WAN link.

!

bridge irb

!

interface FastEthernet0/0/0

bridge-group 1

!

interface Serial1/1/0

bridge-group 1

!

bridge 1 protocol ieee

!

New Member

Re: Establishing a subnet across a Wan Link

If you are running a routing protocol that supports VLSM, you should be able to create a host route

to access both boxes. The longest match rule should route the packets to the correct box.

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