Lets say that you have an MPLS network, and youre running Open Shortest Path First (OSPF) as your dynamic routing protocol. All sites have access to every other site. At the central site, you have an Internet circuit.

 

One day, you decide that you want a remote site to be able to access the Internet through the central sites Internet circuit.
That means you must put in a default route, which basically sends any destination not specifically found in the routing table to the specified next-hop router.In the case of a frame-relay network, this would be asy to do. On the remote router, you would enter your default route, as shown
below:

ip route 0.0.0.0 0.0.0.0 xx.xx.xx.xx

 

The xx.xx.xx.xx route is the IP address of your central routers frame-relay interface. From here, assuming DNS was in place,
everything should work. The remote routers would go to the central router, and the central router would connect to the Internet, bring the traffic back, and deliver it to the remote routers. All routing is working.

 

In the case of MPLS, however, this approach wont work. If you put the same default route on the remote router, the IP address of
the next-hop router is not the same because the carriers router is in the middle. When using MPLS, its no longer just your company running the network—you must take the carrier and its routers into account.

 

Think of the providers router as the "big" router in the cloud. All of your routers connect to its router, and youre routing the traffic together.

documentation very useful for my job

very useful document for my regular O& M activity. Thanks.

very useful document for my regular O& M activity. Thanks.