3Com 10014299 manual Configure Router B Select interface, Configure Router a a Select interface

224CHAPTER 16: CONFIGURING LAPB AND X.25

[Router-Serial0]lapb module 128

[Router-Serial0]lapb window-size 127

2Configure Router B:

aSelect interface

[Router]configure

[Router]interface serial 1

bSpecify IP address for this interface

[Router-Serial1]ip address 202.38.160.2 255.255.255.0

cConfigure the link layer protocol of the interface to LAPB and specify its working mode as DCE

[Router-Serial1]link-protocol lapb dce

dConfigure 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

Typical X.25

Configuration

Example

Back to Back Direct Connection of Two Routers via Serial Interface

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

	V.24/V.35 cable
Router A	Serial 0 Serial 1 Router B

III. Configuration Procedure

1Configure Router A: a Select interface

[Router]interface serial 0

bSpecify IP address for this interface

[Router-Serial0]ip address 202.38.160.1 255.255.255.0

cConfigure the link layer protocol of the interface to X.25 and specify its working mode as DTE

[Router-Serial0]link-protocol x25 dte

dSpecify X.121 address of this interface

[Router-Serial0]x25 x121-address 20112451