I had lately to configure compressed real-time protocols (CRTP) over a Frame-relay link.
I thought that it will be good to make a tutorial about how to configure this on the Serial interfaces (with HDLC or PPP encapsulation) and on the Frame-relay interface. Another type of interface supporting this is and ISDN interface, but the configuration there is the same like in the Serial interface case.
If you were asking why I don’t configure this on a Ethernet interface, well this is because CRTP is not supported on the Ethernet interfaces. This was just an explanation for those of you who didn’t knew this. The role of CRTP is to improve communication over low bandwidth links like Serial interfaces, Frame-relay or ISDN, and that’s why is not supported on Ethernet links (who’s speed is starting at 10 Mbps).

In the following tutorial I will configure CRTP on a Serial interface with PPP encapsulation (I chose this randomly as is the same with HDLC and ISDN) and Frame-relay interface, limit the number of header compression connections and check CRTP with “show…” commands. Since the purpose of this tutorial is CRTP the connection will no be active.

See the tutorial below: