3Com Router User Manual

Configure X.25217
DCE equipment in X.25 networks to provide the function of load balancing for 
DTE equipment) then configuration of X.25 load balancing needs to be made on 
the routers.
The main configuration tasks of X.25 load balancing are as follows:
■Start X.25 switching
■Create X.25 hunt group
■Add interfaces and XOT Tunnels to hunt group
■Configure the X.25 switching route whose forward address is hunt group
■Configure other X.25 switching routes 
Hunt group addresses do not need separate...

218CHAPTER 16: CONFIGURING LAPB AND X.25
Ta b l e 263   Add/Delete X.25 switching route whose forwarding address is hunt group
5Configure other X.25 switching routes
Ta b l e 264   Add/delete other X.25 switching routes
Configure X.25 over 
Other Protocols
Configure X.25 over TCP 
(XOT)Introduction to XOT Protocol
XOT (X.25 Over TCP) is a protocol that is supported by TCP, and implements the 
connection of two X.25 networks through IP network. The practical application 
environment is shown in the...

Configure X.25 over Other Protocols219
protocol provides reliable data transmission link. Because TCP has the mechanism 
of error redirection and window flow controlling to guarantee the reliability of 
links, it can be used by X.25. XOT builds a TCP tunnel connection between the 
two X.25 networks, and the X.25 packets are supported by TCP as data of 
application layer, i.e., TCP serves as the “link layer” of X.25. You can regard the 
middle RouterB, RouterC and IP net as a big “X.25 switch”, and data...

220CHAPTER 16: CONFIGURING LAPB AND X.25
Ta b l e 265   Start X.25 switching
1By default, do not start X.25 switch.
2Configure IP side interface
Because the XOT implements the connection of two X.25 nets through IP net, first 
you should ensure that the IP net is expedite. For the specific configuration, refer 
to chapters of Operation Manual - Network protocol.
3Configure local switching (SVC)
For SVC, when it receives the packets from the remote side, it must send out the 
packets through local switch...

Configure X.25 over Other Protocols221
Ta b l e 268   Configure PVC XOT switching
5Configure Keepalive and xot-source attributes
After the TCP link is established, TCP will not be easily cleared even if the link is 
disconnected. But after configuring Keepalive, the router will send checking 
packets in time to check the usability of the link. If it cannot get confirmation after 
sending out packets several times, it will consider the link failure and clear it 
automatically.
Ta b l e 269   Configure...

222CHAPTER 16: CONFIGURING LAPB AND X.25
When configuring an Annex G DLCI, the user must explicitly configure it with the 
argument DCE or DTE. In addition, the configurations on the routers of a 
connection should not be the same. That is, if a router is configured to work as 
DTE, the other router must be configured as DCE.
Ta b l e 271   Configure the X.25 attributes for an Annex G DLCI
It is necessary to properly understand the differences between the Frame Relay 
address map configured in interface...

Display and Debug LAPB and X.25223
By default, X.25 template is not applied on DLCIs.
Display and Debug 
LAPB and X.25In the all views, perform the following tasks to enable real-time monitoring of the 
current status of LAPB and X.25.
Ta b l e 273   Display and debug LAPB and X.25
Ty p i c a l  L A P B  
Configuration 
ExampleI. Networking Requirement
Two routers are directly connected via serial ports with LABP protocol to transmit 
IP data packets directly.
II. Networking Diagram
Figure 67   Direct...

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...

Typical X.25 Configuration Example225
eSpecify address mapping to the peer
[Router-Serial0]x25 map ip 202.38.160.2 x121-address 20112452
fAs this is a direct connection, the flow control parameters can be increased 
slightly
[Router-Serial0]x25 packet-size 1024 1024
[Router-Serial0]x25 window-size
2Configure Router B:
aSelect interface
[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...

226CHAPTER 16: CONFIGURING LAPB AND X.25
II. Networking Diagram
Figure 69   Connect the router to X.25 public packet network
III. Configuration Procedure
1Configure Router A:
aConfigure interface IP address
[Router]interface Serial 0
[Router-Serial0]ip address 168.173.24.1 255.255.255.0
bConnect to public packet network, make the router as DTE side
[Router-Serial0]link-protocol x25 dte
[Router-Serial0]x25 x121-address 30561001
[Router-Serial0]x25 window-size 5 5
[Router-Serial0]x25 packet-size 512 512...