18 CONFIGURING HDLC
This chapter contains information on the following topics:
■Configure HDLC
■Display and Debug HDLC
Configure HDLC HDLC (High Data Link Control) is a bit-oriented link layer protocol. Its most
prominent feature is that it can transparently transmit any kind of bit flow without
the restriction that the data must be character set. Protocols of standard HDLC
protocol group operate upon the synchronous serial lines, e.g., DDN. The address
field of HDLC is 8 bits, its control field is 8 bits, and the protocol field is 16 bits,
which are used to represent all kinds of control information of HDLC protocol and
to mark whether they are data. The 3Com Router supports the HDLC protocol and
can connect with HDLC protocol of other popular devices.HDLC configuration
includes:
■Configure the link layer protocol of the interface to HDLC
1Configure the Link Layer Protocol of the Interface to HDLC
In synchronous interface view, perform the following task.
Tabl e 318 Configure the link layer protocol of the interface to HDLC
By default, the link layer protocol of the interface is PPP.
Only when the interface operates in the synchronous mode, can the link layer
protocol be configured to HDLC.
When the interface link layer protocol is SLIP, its physical attribute cannot be
changed to synchronous mode. At this time, you should first change the link layer
protocol of the interface to PPP before you change the interface attribute to
synchronous mode.
Display and Debug
HDLC Tabl e 319 Display and debug HDLC
Operation Command
Configure the link layer protocol of the interface to
HDLC link-protocol hdlc
Operation Command
Enable all the debugging of HDLC protocol debugging hdlc all [ interface
type number ]
Enable HDLC event debugging debugging hdlc event [
interface type number ]