198 CHAPTER 16: CONFIGURING LAPB AND X.25
Figure 61 Relations among LAPB, X.25 and X.25 switching
Configure LAPB LAPB configuration includes:
■Configure the link protocol of the interface to LAPB
■Configure LAPB protocol parameters
1Configure the Link Layer Protocol of the Interface to LAPB
Perform the following command in the interface view.
Tabl e 229 Configure the link layer protocol of the interface to LAPB
If not specified, the working mode of LAPB is DTE by default.
2Configure LAPB Protocol Parameter
aConfigure LAPB operating mode (also called modulo)
There are two LAPB modulus: Modulo 8 and Modulo128. Each data frame (I
frame) is numbered by sequence, the number can be any from 0 to modulo
minus 1, and the sequence number is selected periodically within the range of
the modulo.
In the interface view, configure as follows:
Tabl e 230 Configure LAPB frame numbering mode
By default, the LAPB modulus is Modulo 8.
bConfigure LAPB parameter K
The parameter K in the LAPB window represents the maximum number of I
frames numbered in sequence that is to be identifie d by the DTE or DCE in any
specified time.
In the interface view, configure as follows:
Tabl e 231 Configure LAPB window parameter K
By default, k is 7.
c Configure LAPB N1, N2
Inter-network protocol
X.25
switching
X.25
LAPB
Operation Command
Configure the link layer protocol of the interface to
LAPB link-protocol lapb [ dte |
dce ] [ ip ]
Operation Command
Configure LAPB frame numbering mode (also called
modulo) lapb modulo { 128 | 8 }
Operation Command
Configure LAPB window parameter K lapb window-size k-value
Restore the default value of LAPB window parameter
Kundo lapb window-size