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EIGRP checks its topology table for a suitable new route to the destination. If a route exists in the
table, EIGRP updates the routing table with the new route and purges the old route from the table.
Unlike other routing protocols, EIGRP saves WAN−link bandwidth by sending routing updates only
when routing information changes. It also takes into account the available bandwidth between the
paths to determine the rate at which it transmits updates.
Open Shortest Path First—OSPF is an IP−based link−state routing protocol designed to overcome the
limitations of RIP. It sends link−state advertisements (LSAs) to all other routers within the network.
Information is included in the LSAs about the interfaces on which OSPF is running and the metrics
used. As routers collect the link−state information, they use the Shortest Path First (SPF) algorithm to
calculate the shortest path to each node.
Routing Information Protocol—RIP is another distance−vector routing protocol that works well in
small networks. However, in larger, more complex internetworks, RIP has many limitations, such as a
maximum hop count of 15, lack of support for variable−length subnet masks (VLSMs), slow
convergence, and inefficient use of bandwidth.
Routing Protocol Assignment
All devices communicate with each other through a path or route. If the destination interface does not reside
in the same network segments as the sender, a route to the destination must be found using a dynamic routing
protocol or a static route. If you have stacks of cash to spend on IOSs for your internal route processors, you
can support any number of the following routing protocols:
Enhanced Interior Gateway Routing Protocol (EIGRP)
Hot Standby Routing Protocol (HSRP)
Interior Gateway Routing Protocol (IGRP)
NetWare Link Services Protocol (NLSP)
Open Shortest Path First (OSPF)
Routing Information Protocol (RIP)
Routing Table Maintenance Protocol (RTMP) for AppleTalk
To use a dynamic protocol, you must first assign a routing protocol to the route processor being configured
just as you would an external router. Then, you identify the network and, in some cases, an area ID and an
autonomous system number.
Supervisor Engine Modules
The Supervisor Engine (SE) is basically the brains of the Cisco 4000, 5000, and 6000 families of switches.
There are three series of Supervisor Engines; each has its own individual features and the newer ones add
features that go beyond those of their predecessors. Let's take a look at the features of each Supervisor
Engine.
Supervisor Engines I and II
As shown in Figure 6.1, the SE I and SE II provide a switching engine using a 25MHz Motorola MC68EC040
Network Management Processor (NMP). The processor's ability to switch more than one million packets per
second (pps) provides data path and data control for all the switch's network interfaces, including two
on−board integrated Fast Ethernet interfaces that can support redundancy using the Spanning−Tree Algorithm
or load sharing. Other features supported by these SEs are:
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Troubleshooting
