RouterGeek

When would you need this: When you connect two Cisco routers through a WAN connection, or back-to-back router setup.

Special Requirements: Both routers needs to be Cisco routers.

Cisco HDLC is not compatible with other vendors' HDLC, so you need to make sure that routers on both ends of the communication are Cisco routers.

There is no long procedure to do this. The configuration is actually a single command:

Router(config-if)#encapsulation hdlc

Usually, the default encapsulation on the out-of-the-box Cisco routers is HDLC.

For troubleshooting, you can use the following commands to check that it has been configured properly:

Router#show interface serial X/X

where X/X is the number of the interface to check.

You can also check the status and IP address of the interfaces using the following command:

Router#show ip interface brief

[sniplet adsense]

Find more about WAN protocols in the Router Geek Book: Guide to Cisco Routers Configuration