Configure IT Quick: Configure EIGRP with IP and IPX on Cisco routers

Learn how to configure EIGRP

EIGRP is sometimes referred to as a hybrid routing protocol, but Cisco calls it an advanced distance vector routing protocol. Cisco makes this reference primarily due to the way EIGRP handles convergence. With EIGRP, convergence, the process in which all routers share and process the same routing tables and maintain that each router has the exact same information, is achieved by retaining the information sent by the EIGRP routers’ neighbors and building a topology table. With this table, the router doesn’t have to continually wait on full updates to converge the network topology. This Daily Drill Down will show you how to configure both IP and IPX using EIGRP on Cisco routers.

Conveniently, configuring EIGRP on Cisco routers is just as simple as configuring Interior Gateway Routing Protocol (IGRP), even though it is considerably more advanced. IGRP is a distance vector routing protocol used by routers to send all or a portion of their routing tables at regular intervals to each neighboring router on the internetwork. EIGRP is a classless routing protocol, which means that you can have different subnet masks in your network. Like IGRP, it uses bandwidth and delay of the line as default metrics. IGRP doesn’t allow different masks on your network. For example, if you are using, every device on the network must use the same mask. EIGRP, because it sends subnet mask information with the route updates, allows you to use Variable Length Subnet Mask (VLSM) on your network.

EIGRP provides more control over your network than IGRP because it uses the best attributes of both distance vector and link state routing protocols. This protocol will benefit your network by using very few network resources. EIGRP accomplishes this feat by:
  • ·        Only sending out routing table changes (not the entire table).
  • ·        Only sending hello packets when a change takes place.
  • ·        Allowing for rapid (and sometimes instantaneous) changes in network topology.

Configuring the internetwork
For this Daily Drill Down, the network shown in Figure A will be used to configure IP and IPX using EIGRP. Notice that, after each IP address assigned for each router, I have included the size of the subnet masks (for example,, where 29 is the size). This is called Classless Inter Domain Routing (CIDR).

Figure A
This network has five routers; 2500B (a 2520 router) has four serial interfaces. First, I’ll configure IP on all interfaces and then, after IP is up and running with EIGRP, I’ll configure IPX on all interfaces.

The 1005A router
The 1005A router has one serial and one 10BaseT Ethernet connection. Here is the configuration, which set the enable secret password, allowed a telnet session without a password, and then configured the IP addresses.

The 2500B router
The 2500B router has four serial interfaces, all with DCE connections. The configuration looks like this.


IP addressing and subnetting
If you are having trouble understanding the IP addressing techniques used in this Daily Drill Down, read my Daily Drill Downs on IP addressing and subnetting.

The 2500C router
The 2500C router configuration looks like this.

The 2500D router
The 2500D router configuration looks like this.

The 2500E router
The 2500E router configuration looks like this.

Configuring EIGRP on the internetwork
Configuring EIGRP is the same as configuring IGRP. All I have to do is turn on EIGRP, choose an Autonomous System (AS) number, and then configure the network number.

Here is an example of configuring EIGRP on the 1005A router:
1005#config t
1005(config)#router eigrp 10

Notice that the network address is a classful address, which makes it easy to configure on each router. Also, since the 1005 router is connected to two networks, I had to enter the network command twice (once for each interface).

The configurations of the other routers in the internetwork look like this:
2500B(config)#router eigrp 10

2500C(config)#router eigrp 10

2500D(config)#router eigrp 10

2500E(config)#router eigrp 10

Verifying EIGRP on the internetwork
A few commands should be used to verify the configuration of EIGRP on your routers. Two of the most important ones are:
  • ·        show ip route
  • ·        show ip protocols

Show ip route
The show ip route command is the best command to view the EIGRP configuration on a router.

The 1005 router is directly connected to two networks, and EIGRP is advertising seven networks to the 1005 router from the 2500B router. The IP routing table on the 2500B router looks like this. The 2500B router is directly connected to four serial links and has identified four networks via EIGRP.

Show ip protocols
The show ip protocols command gives you routing protocol information, including timers and administrative distance as well as known neighbors. The Administrative Distance (AD) is 90 for networks within the AS of 10 and 170 for any network that is outside the AS.

Configuring IPX with EIGRP
Adding IPX to the Cisco routers is pretty straightforward. I will assume a basic knowledge of IPX when discussing its configuration with EIGRP.

First, I need to configure IPX, which will automatically turn on IPX RIP routing. I’ll then turn off IPX RIP and configure IPX to be advertised with EIGRP.

I’ll use Figure B to configure IPX on the internetwork. Please note that to get the full IP address, including the IP subnet numbers, you’ll take the IP address from the corresponding router interface in Figure A, remove the subnet size, and attach the IPX number, which is included in Figure B.

Figure B
The IPX numbers are the IP subnet numbers—very simple and easy to understand.

The configurations are as follows:

1005A router:
1005#config t
1005(config)#ipx routing
1005(config)#int e0
1005(config-if)#ipx network 192
1005(config-if)#int s0
1005(config-if)#ipx network 64

2500B router:
2500B#config t
2500B(config)#ipx routing
2500B(config)#int s0
2500B(config-if)#ipx network 64
2500B(config-if)#int s1
2500B(config-if)#ipx network 68
2500B(config-if)#int s2
2500B(config-if)#ipx network 72
2500B(config-if)#int s3
2500B(config-if)#ipx network 76

2500C router:
2500C#config t
2500C(config)#ipx routing
2500C(config)#int s0
2500C(config-if)#ipx network 68
2500C(config-if)#int e0
2500C(config-if)#ipx network 80

2500D router:
2500D#config t
2500D(config)#ipx routing
2500D(config)#int s0
2500D(config-if)#ipx network 72
2500D(config-if)#int e0
2500D(config-if)#ipx network 88

2500E router:
2500E#config t
2500E(config)#ipx routing
2500E(config)#int s0
2500E(config-if)#ipx network 76
2500E(config-if)#int e0
2500E(config-if)#ipx network 96

I can check to make sure that IPX is working with the show ipx route command.

Notice that IPX RIP is advertising the IPX networks. I can fix this with two simple commands. A sample on the 1005A router (I’ll use an AS of 50) looks like this:
1005#config t
1005(config)#ipx router eigrp 50
1005(config-ipx-router)#network all

That’s all there is to it. Well, almost. I still have to turn off IPX RIP because, by default, it’s running in the background:
1005(config-ipx-router)#ipx router rip
1005(config-ipx-router)#no network 64

This will now stop IPX RIP from advertising out the serial0 interface. Notice I did not turn IPX RIP off for the Ethernet network because I need IPX RIP to communicate and support the Novell servers and clients on the LAN.

The configuration of the other routers looks like this:
2500B#config t
2500B(config)#ipx router eigrp 50
2500B(config-ipx-router)#network all
2500B(config-ipx-router)#ipx router rip
2500B(config-ipx-router)#no network all

Notice that since I have no LANs to support connected to the 2500B router, I turned off IPX RIP completely. The configuration of the other three routers looks like this:
2500C#config t
2500C(config)#ipx router eigrp 50
2500C(config-ipx-router)#network all
2500C(config-ipx-router)#ipx router rip
2500C(config-ipx-router)#no network 68

2500D#config t
2500D(config)#ipx router eigrp 50
2500D(config-ipx-router)#network all
2500D(config-ipx-router)#ipx router rip
2500D(config-ipx-router)#no network 72

2500E#config t
2500E(config)#ipx router eigrp 50
2500E(config-ipx-router)#network all
2500E(config-ipx-router)#ipx router rip
2500E(config-ipx-router)#no network 76

IPX RIP was only turned off for the serial links.

Verifying EIGRP with IPX
With all the configurations complete, it’s time to verify that EIGRP is working on the network. I’ll do this with the show ipx route command.

By enabling IPX EIGRP and then disabling IPX RIP on our serial interfaces, I’ll enjoy a huge bandwidth savings because routing updates are only sent incrementally instead of periodically.

EIGRP is a very efficient protocol that is easy to configure on most networks. It can be configured to work with IP and IPX and saves an enormous amount of CPU cycles and bandwidth by relying on its neighbors to update routing tables. Since any router (on a common network) that has seen a router’s hello packet is considered its neighbor, a router using EIGRP will have quick access to the topology information of your network. By using this protocol, you’ll tax your routing hardware less, thereby making your network run more efficiently and smoothly.

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