IP helper

We all are familiar with the IP helper command to allow DHCP requests (broadcast) passthrough a router to get as a unicast packet to a DHCP server. Pretty easy and simple.. But the IP helper can do more!

When there is a network with multiple vlans and you need the use the good old “net send” command from Windows computers on all computers on all the VLAN’s, you have to configure the IP helper.

Bridging / IRB

This is just a summary about the bridging and IRB functions in Cisco routers and switches. The configuration on routers and switches is identical, but only the interfaces are different (real interfaces on routers, vlan interfaces on switches).

If you have a network and a router splits this network, you’ll need the bridging functionality.