Cisco Hands On Training Podcast

"Ships in the night" routing refers to two routing protocols which do not interact with each other. We can migrate from one routing protocol to a more believable one by simply turning on the new protocol then turning off the old protocol. Bug be careful to turn the new protocol on in the entire routing domain before turning off the old protocol.

IGRP is a Cisco-proprietary routing protocol. It is a classful distance vector protocol with a metric based on bandwidth and delay. This is superior to RIP, whose metric is based on hop-count. IGRP's classfulness makes it a bad choice for new deployments, but its advanced metric is worth study.

RIP distribute lists deny specific route advertisements. RIP offset-lists increase the metric (hopcount) for specific route advertisements.

RIP version 1 route advertisements do not include a field for the netmask. This means receiving routers have to gess the netmask based on whatever information they have available. That includes the "natural" netmask of that classful network. That also includes the receiving routers own configuration.
This means that variable length subnets and discontiguous classful network have problems with RIP version 1. The lack of the netmask field in the route advertisement is a real problem.

RIP version 1 is a classful routing protocol. We cover the RIP packet format and configuration. We see examples of split horizon and triggered updates using the RIP debug commands.

Routing protocols (and static routing) update the route table. The route table is used to forward packets. Cisco Express Forwarding (CEF) is a special route table optimized to forward packets more efficiently.

We cable and configure ethernet and synchronous serial point-to-point links. In the next session these will be the "legs" of our triangle.

Routers route packets based on the destination IP address: a 32-bit number included in the header of every IP packet. Historically, "large" sites were allocated IP address blocks starting with 0 (binary). Medium sites were allocated address blocks starting with the bits 10. "Small" sites were allocated address blocks starting with the bits 110.

Every network engineer needs to be able to deal with a router with an unknown password. Whether you are taking over a site where the previous engineer was "hit by a bus", or scrounging routers from the storage closet, good network engineers can deal with routers with unknown passwords.