3com 3031 Instruccion De Instalación

Two routers are directly connected back to back via serial interfaces encapsulated 
with LABP that can transmit IP datagrams directly.

Figure 71   Direct connection of two routers via serial interfaces (LAPB)

As shown in the diagram above, perform the following configuration tasks to 
connect two routers via serial interfaces encapsulated with LABP that can transmit 
IP datagrams directly:

1 Configure RouterA:

a Select interface.

[3Com]interface serial 0/0/0

b Specify the IP address for this interface.

[3Com-Serial0/0/0]ip address 202.38.160.1 255.255.255.0

c Configure the link layer protocol of the interface as LAPB, and specify it to 

work in DTE mode.

[3Com-Serial0/0/0]link-protocol lapb dte

d Configure other LAPB parameters (If the link is sound enough and a higher rate 

is desired, you can increase the traffic control parameters modulo to 128, k to 
127. But the connected parties must always keep the configured parameters in 
consistency.

[3Com-Serial0/0/0]lapb module 128

[3Com-Serial0/0/0]lapb window-size 127

2 Configure RouterB:

a Select interface.

[3Com]interface serial 1/0/0

b Specify the IP address for this interface.

[3Com-Serial1/0/0]ip address 202.38.160.2 255.255.255.0

c Configure the link layer protocol of the interface as LAPB, and specify it to 

work in DCE mode.

[3Com-Serial1/0/0]link-protocol lapb dce

d Configure other LAPB parameters (If the link is sound enough and a higher rate 

is desired, you can increase the traffic control parameters modulo to 128, k to 
127. But the connected parties must always keep the configured parameters in 
consistency.

[3Com-Serial1/0/0]lapb modulo 128

RouterA

V.35 cable

Serial0/0/0

Serial1/0/0

RouterB

RouterA

V.35 cable

Serial0/0/0

Serial1/0/0

RouterB