3Com 3032 Configuration Manual page 228

224 C 16: C
HAPTER ONFIGURING
Typical X.25
Configuration
Example
Back to Back Direct
Connection of Two
Routers via Serial
Interface
LAPB X.25
AND
[Router-Serial0]lapb module 128
[Router-Serial0]lapb window-size 127
2 Configure Router B:
a Select interface
[Router]configure
[Router]interface serial 1
b Specify IP address for this interface
[Router-Serial1]ip address 202.38.160.2 255.255.255.0
c Configure the link layer protocol of the interface to LAPB and specify its
working mode as DCE
[Router-Serial1]link-protocol lapb dce
d Configure other LAPB parameters (if the link quality is good, and a higher rate
is required, the flow control parameter modulo can be increased to 128, k to
127, but they must be the same for both ends in the direct connection)
[Router-Serial1]lapb modulo 128
[Router-Serial1]lapb window-size 127
I. Networking Requirement
As shown in the diagram below, two routers are to be directly connected back to
back; the X.25 protocol is used between the serial ports for IP data packet
transmission.
II. Networking Diagram
Figure 68 Direct connection of two routers via serial ports
III. Configuration Procedure
1 Configure Router A:
a Select interface
[Router]interface serial 0
b Specify IP address for this interface
[Router-Serial0]ip address 202.38.160.1 255.255.255.0
c Configure the link layer protocol of the interface to X.25 and specify its
working mode as DTE
[Router-Serial0]link-protocol x25 dte
d Specify X.121 address of this interface
[Router-Serial0]x25 x121-address 20112451
V.24/V.35 cable
Serial 0 Serial 1
Router A
Router B