Today’s post is part 4 of the solution to ICND2 Lab 1. Today’s installment: EIGRP configuration. Enjoy! Ask questions if you have them, and offer alternatives as well.
This lab requires very little for EIGRP configuration. However, it does ask that you make passive any interface that can “reasonably” be made passive. So I’ll spend most of today’s post discussing what’s reasonable before getting to the configuration.
First, making an interface passive means to configure EIGRP such that EIGRP is enabled on the interface, but EIGRP does not form neighborships on the interface. EIGRP still advertises about the subnet connected to the interface.
In the figure for this lab (repeated below), on which interfaces could you reasonably make the interfaces passive? Well, the short version is that all the LAN interfaces could be passive, because none of the routers have any potential EIGRP neighbors on those interfaces. However, all the WAN interfaces cannot be made passive, because that would prevent EIGRP neighborships, and those will be needed between the routers on the WAN.
Enabling EIGRP with ASN 1 takes very little work based on the IP addressing scheme. All interfaces use addresses in class A network 10.0.0.0, so every router needs both a router eigrp 1 command and a network 10.0.0.0 command. This enables EIGRP on every interface shown in the figure. Then, to make some interfaces passive, just add the passive-interface router subcommands, referencing the correct interfaces. In fact, because all four routers use the same LAN interface number (interface F0/0), all four router’s EIGRP configurations will be identical, as shown in Example 1-5:
This lab requires very little for EIGRP configuration. However, it does ask that you make passive any interface that can “reasonably” be made passive. So I’ll spend most of today’s post discussing what’s reasonable before getting to the configuration.
First, making an interface passive means to configure EIGRP such that EIGRP is enabled on the interface, but EIGRP does not form neighborships on the interface. EIGRP still advertises about the subnet connected to the interface.
In the figure for this lab (repeated below), on which interfaces could you reasonably make the interfaces passive? Well, the short version is that all the LAN interfaces could be passive, because none of the routers have any potential EIGRP neighbors on those interfaces. However, all the WAN interfaces cannot be made passive, because that would prevent EIGRP neighborships, and those will be needed between the routers on the WAN.
Enabling EIGRP with ASN 1 takes very little work based on the IP addressing scheme. All interfaces use addresses in class A network 10.0.0.0, so every router needs both a router eigrp 1 command and a network 10.0.0.0 command. This enables EIGRP on every interface shown in the figure. Then, to make some interfaces passive, just add the passive-interface router subcommands, referencing the correct interfaces. In fact, because all four routers use the same LAN interface number (interface F0/0), all four router’s EIGRP configurations will be identical, as shown in Example 1-5:
