Though you wouldn’t know it from the number of posts, I’m finally done.
I was asked to configure LAPB for error recovery on a PPP link the other day. I had two questions: 1) What’s LAPB? 2) How? The latter is pretty simple, the former much more complex.
First, in the interest of time, let’s talk about how this is done.
Router(config)#int s0/0/0
Router(config-if)#encapsulation ppp
Router(config-if)#ppp reliable-link
That’s it! Now, what exactly have we accomplished? By enabling LAPB we’ve inserted another layer of error-checking in our link that’s transparent to upper layers. NOTE: LAPB can only be used on unique PPP circuits, not multilinks. If you’re looking for a link quality solution for multilinks, check out LQM.
There are some situations where you just don’t want any traffic flowing through a particular router unless there are ABSOLUTELY NO other alternatives. How can we do that? Tell a particular router to advertise his/her LSAs with the maximum metric possible (0xFFFF).
If you’re looking for a ridiculously easy way to make your OSPF process more efficient, you’ve come to the right place. According to Cisco, many of the CPU cycles spent on evaluating Dijkstra’s algorithm are unnecessary. You can save your router a lot of work by performing incremental SPF calculations in many cases rather than full SPF calculations.
How do you do it? It’s easy:
R0(config)# router ospf 1
R0(config-router)# ispf
R0(config-router)#
That’s it! Best of all, it doesn’t cause the adjacency to drop and it doesn’t need to be enabled on all routers!