CCNP Route EIGRP Challenge Lab

skwira001

I was just doing the EIGRP Challenge lab where they don't spoon feed you with the commands. On the list of the criteria was to disable multicast between 2 neighbors. I went into router eigrp 1 configuration mode and set the neighbors statically. Does that send unicast hells to that neighbor when I do that then? I was trying to think of another command but couldn't recall any.

billyr

Yes, if you use the neighbor command on the interface this will disable multicast. If you were to use passive interface instead this would stop multicast but hellos would not be able to be sent or received, so no neighbour relationship.

From Cisco Website wrote:

Q. What does the neighbor statement in the EIGRP configuration section do?


A. The neighbor command is used in EIGRP in order to define a neighboring router with which to exchange routing information. Due to the current behavior of this command, EIGRP exchanges routing information with the neighbors in the form of unicast packets whenever the neighbor command is configured for an interface. EIGRP stops processing all multicast packets that come inbound on that interface. Also, EIGRP stops sending multicast packets on that interface.

The ideal behavior of this command is for EIGRP to start sending EIGRP packets as unicast packets to the specified neighbor, but not stop sending and receiving multicast packets on that interface. Since the command does not behave as intended, the neighbor command should be used carefully, understanding the impact of the command on the network.

Full article here: EIGRP Frequently Asked Questions  [IP Routing] - Cisco Systems