How to configure HDLC on Cisco IOS Router

This topic is to discuss the following lesson:

H Rene

I set up similar set up in my GNS3 lab, R1 and R2. Set R2 with a clock rate for the serial interface but R1 is not showing as a DTE. I assigned the IP address and I can ping the interfaces but DTE is not showing on R1. Any reason can you think of? How can I troubleshoot this issue?

R1#sh controllers s0/0
Interface Serial0/0
Hardware is PowerQUICC MPC860
DCE 530, no clock
R2#sh controllers s0/0
Interface Serial0/0
Hardware is PowerQUICC MPC860
DCE 530, clock rate 64000

Thanks
Palani

Hi Palani,

Setting the clock rate is for the physical interface. In GNS3, there’s no need to set the clock rate since they emulate everything. If you want to test this, you will have to use real hardware.

Rene

Hi Rene,

Is HDLC encapsulation only for serial interfaces ? I have seen it on Ethernet interface as well

Hello Aniket

HDLC is an encapsulation method that provides layer 2 functionality almost exclusively for point to point connections. Point to multipoint connections are also possible but are rarely used. Ethernet on the other hand is a layer 2 technology based on a multiple access philosophy. These are two very different and incompatible technologies, both of which operate at layer 2, so HDLC cannot operate on an Ethernet interface.

Do you have an example of what you have seen concerning HDLC and Ethernet? Maybe that will help to clarify the confusion. If you do, share it with us so we can continue the conversation.

I hope this has been helpful!

Laz