HDLC synchronous or asynchronous??

[echipbk12]

In my Accessing the WAN book, it says "HDLC uses synchronous serial transmission to provide error-free communition between 2 points". And on Wikipedia it says "HDLC frames can be transmitted over synchronous or asynchronous links". So does HDLC use synchronous or asynchronous transmission?? Thank you.

[tobyarnett · Accepted solution]

HDLC can be used on both synchronous and asynchronous links. Your book is likely specifying how the protocol is used on a standard WAN link (is DS3 or T1) in which case both of these links are synchronous. There are other implementations of HDLC though that is used across asynchronous links. I believe wiki is accounting for all uses and your book is tar getting common usage on a WAN circuit.

Toby


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