PPP Error Recovery: LAPB

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.