Working through INE Voll II lab 14 this evening I came across a task where they require you to discover the hardware address of EIGRP.
The reason for this is with the hardware address you are then able to block this address to certain ports on a vlan
To do this you need to convert the multicast address to a hardware address.
There is a block of addresses reserved by IANA for this requirement.
The range is 0100.5e00.0000 through 0100.5e7f.ffff
Convert Multicast Address to Hardware Address
In the example I am working on you need to work out the corresponding mac address for EIGRP 18.104.22.168
- First use the first 6 digits of the IANA assigned range 0100.5e
- Then add on 0.0.10
So the final Mac address of EIGRP 22.214.171.124 is 0100.5e00.000a
You are then able to map the mac-address to certain receiver ports
mac-address-table static 0100.5e00.000a vlan (vlan number) interface (receiver ports)
mac-address-table static 0100.5e00.000a vlan 100 interface fa0/11 fa0/12
This command will only allow EIGRP to be sent out of those ports
For this feature to work you need to disable igmp snooping on vlan 100
no ip igmp snooping vlan 100
Original credit for the information in this post: www.hep.ucl.ac.uk/~ytl/multi-cast/addresstranslation_01.html