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| 1. What is the difference between IGRP and EIGRP? | EIGRP supports VLSM and CIDR, it has faster convergence times, it’s more scalable, and handles routing loops better than IGRP does. |
| 2. Why is EIGRP referred to as a hybrid protocol? | Because it primarily is a distance vector protocol, but also has some characteristics of a link state protocol, such as sending hello packets, sending only partial updates (instead of entire table exchanges), and using neighbor discovery. However, it’s easier to configure than OSPF. |
| 3. Can IGRP and EIGRP routers “talk” to each other? Why or why not? | Yes, they can talk because EIGRP is simply an enhancement of IGRP; they’re still basically the same protocol. |
| 4. List the three tables that EIGRP maintains and briefly describe each one. | Topology – lists all routing tables in the AS; all learned routes are in this table |
| 5. List the five pieces of information found in the topology table and briefly describe each one. | · Feasible distance – The feasible distance (FD) is the lowest calculated metric to each destination. |
| What is DUAL? | The EIGRP distance vector algorithm is called the Diffusing Update Algorithm (DUAL). DUAL tracks all the routes advertised by neighbors. Composite metrics of each route are used to compare them. DUAL also guarantees that each path is loop free. DUAL inserts lowest cost paths into the routing table. These primary routes are known as successor routes. A copy of the successor routes is also placed in the topology table |
| 7. What is the difference between a “feasible successor” route and a :successor” router? | The successor route is the route in the routing table; in other words, the route considered the best to the destination. The feasible successor is the back-up route, or the next-best route. |
| 8. What makes EIGRP able to support IP, IPX, and AppleTalk? | It uses PDMs (protocol dependent modules). Also, for AppleTalk, it can actually act as the primarily protocol and AppleTalk doesn’t even have to be running. |
| 9. What is RTP? What does it do? | Reliable Transport Protocol is a transport-layer protocol that can guarantee ordered delivery of EIGRP packets to all neighbors. This means EIGRP does not rely on TCP/IP to exchange routing information the way that RIP, IGRP, and OSPF do. To stay independent of IP, EIGRP uses RTP as its own proprietary transport-layer protocol to guarantee delivery of routing information. |
| What are the five EIGRP packet types? Briefly describe each one. | · Hello - discover, verify, and rediscover neighbor routers |
| What are the commands used to start EIGRP running on a router? | router(config)# router eigrp [autonomous-system-number] |
| If you do not want to summarize routes, what is the command to turn it off? Why might you not want to summarize (aggregate) routes? | router(config-router)#no auto-summary |
| List some of the show commands you can use to verify that EIGRP is running correctly. | show ip route |
| Which table built by EIGRP is considered the most important? List the fields of information contained in this table and briefly describe each one. | The neighbor table.· Neighbor address –network layer address of the neighbor router |
| What is the most common problem that keeps RIP tables from updating? | The use of VLSM and RIP v. 1, which doesn’t support it. |
| What is the most common type of networking problem? | Layer 1 issues (cabling is the most prevalent) |
| Hold Time is? | The interval to wait without receiving anything from a neighbor before considering the link unavailable |
| Diffusing Update Algorithm (DUAL) | EIGRP routers coverge quickly because they rely on a state-of-the-art routing algorithm called he Diffusing Update Algorithm (DUAL). DUAL guarantees loop-free operation at every instant thoughtout a route computation and allows all routers involved ina topology change to synchronize at the same time. |
| Feasible Distance | The lowest calculated metric to each destination. |
