3Com 3031 Command Reference Manual page 365

Example
Configure LAPB as the link layer protocol of the interface Serial 0/0/0, and enable
it to work in DCE mode.
[3Com-Serial0/0/0] link-protocol lapb dce
link-protocol x25 Syntax
link-protocol x25 [ dte | dce ] [ ietf | nonstandard ]
View
Interface view
Parameter
Description
Using the link-protocol x25 command, you can encapsulate X.25 protocol to the
specified interface.
By default, the link-layer protocol for interface is PPP. When the interface uses
X.25 protocol, it works in DTE IETF mode by default.
If the X.25 switching function is not used, and two Routers are directly connected
back to back via the X.25 protocol, one Router shall work in DTE mode, while the
other shall work in DCE mode. When two Routers are connected via the X.25
public packet network, they shall generally work in DTE mode. If the X.25
switching function is used, the Router shall generally work in DCE mode.
In practice, select the IETF format of datagram if there is no special requirement.
For the related command, see display interface.
Example
Specify X.25 as the link layer protocol of the interface Serial 0/0/0 that works in
DTE IETF mode.
[3Com-Serial0/0/0] link-protocol x25 dte ietf
pad
Syntax
pad x121-address
dte: Indicates that the interface works in DTE mode.
dce: Indicates that the interface works in DCE mode.
letf: Based on the standard stipulation of the IETF RFC 1356, encapsulate IP or
other network protocols on the X.25 network.
nonstandard: Encapsulates IP or other network protocols on the X.25 network
with nonstandard.
LAPB and X.25 Configuration Commands 365