Best Practice Network Design for Multiple Backhaul Routing using Wireless, MLPPP, and PPP T1s.

Posted on 2008-10-03
Last Modified: 2012-05-05
I'm looking for input pertaining to best practice for establishing a redundant backhaul system.

We have a primary wireless link from the office to the first tower. That tower then links to two other towers and those link to others creating a ring of linked Wireless towers which then backhaul from Tower 1 to the main office before being sent out the OC3.

We are attempting to create a sonet type routing solution so that when a wireless backhaul link fails, it reroutes the traffic over the second wireless link. Some towers would also have tertiary T1 links available when it or it's segment gets isolated from the rest of the ring. The T1 links terminate to the core router at the office.

We use Cisco routers at each tower location and we are looking for assistance in determining the best routing protocol to accomplish this and how to implement it.

Initial thoughts were leaning to weighted static routing or possibly OSPF.  I've also included an image for further clarification.
Question by:semonet

Author Comment

ID: 22680209
If someone could point out the critical details as to what is missing, I would appreciate it.

More details below that will hopefully spur a comment.

OSPF is currently established on the T1 links from the core to the towers and is being used as the primary backhaul. We want to force the T1s to be the last choice of backhaul, using the wireless links when possible.

Right now all OSPF is configured to use Area 0, and includes the network statement for the link as well as the following lines:

router ospf 1
 redistribute connected subnets
 redistribute static subnets

OSPF was configured by a previous employee on R0-R3
LVL 15

Accepted Solution

bkepford earned 500 total points
ID: 23315369
The best thing to do is to not use static routes let OSPF learn about all network segments.(the more you keep it in one routing protical the better. As long as these are not pay per use T1s or backups then they can be up at all times and exchange routing updates.
You should not be redistributing any links or any static routes. Each router should be configured like below. When you redistribute it treats the routes as external and you do not get the proper cost on each route.
router ospf 1
 network area 0
 network area 0

Now on your slower links make sure the bandwidth command  is configured on each link and ospf should always pick the faster link when available. Just do a "show ip route" on each link to verify that this is so.
Now for your default connection to the Internet instead of using a redistribute static. You should enter your static route and then under the ospf process use the command

default-information originate

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