Configuring X.25: Before You Begin

C H A P T E R 6
Configuring X.25
This chapter describes how to configure a Cisco 1600 series router to connect to
a central-site router over an X.25 line or over an Integrated Systems Digital
Network (ISDN) line and provides verification steps and troubleshooting tips.
This chapter contains the following sections:
• X.25
• X.25 Over ISDN B Channel
• How X.25 Works
Before You Begin

The configurations in this chapter are based on the following assumptions:
• The router is connected a central-site router.
• You are routing IP and IPX network traffic.
Before you begin configuration, be aware of the following:
• You need to enter the commands in the order shown in the task tables.
• The values shown in italics are examples. You should substitute the values
shown with values that are appropriate for your network.
• You should be familiar with Cisco IOS software and its conventions.
Cisco 1600 Series Software Configuration Guide

78-4486-01 B0 6-1
Chapter 6 Configuring X.25
X.25
Note In order to use the verification steps described in this chapter, you must be
familiar with Cisco IOS commands and command modes. When you use the
verification steps, you need to change to different command modes. If you are
not familiar with command modes, refer to the “Understanding Command
Modes” section in the “Cisco IOS Basic Skills” chapter.
X.25
This section describes how to your router for a point-to-point X.25 WAN
connection to the central-site router.
These are the major tasks when configuring your router:
• Configuring Global Parameters
• Configuring Security
• Configuring the Ethernet Interface
• Configuring the X.25 Interface
• Configuring Command Line Access to the Router
Figure 6-1 illustrates the configuration used in this example.
Figure 6-1 X.25 Example Configuration
Remote site Central site

X.25 interface addresses:
X.25: 5432 X.25: 2345
172.16.26.1 172.16.26.2
X.25 Router
1600
S6688
Ethernet network: 172.16.25.42
IPX network: 9876

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X.25
Configuring Global Parameters

Use this table to configure the router for some global parameters, including IPX
routing and how log and debug messages are timestamped.
Prompt Command
Step 1 Enter configuration mode. Router# configure
terminal
Step 2 Configure the router to show the date and time of all Router(config)# service
debug messages. timestamps debug
datetime msec
This command is optional, but recommended if you
use debug commands to troubleshoot your
configuration.
Step 3 Configure the router to show the date and time of all Router(config)# service
log messages. timestamps log
datetime msec
This command is optional, but recommended if you
use the verification steps described in this guide. This
feature is enabled for all the example command
output shown in this guide.
Step 4 Enable IPX routing and configure the router with an Router(config)# ipx routing
IPX address. 0060.834f.66dd
Configuring Security
Use this table to configure the router with some security measures, such as the
router host name and the password used to prevent unauthorized access to the
router.

78-4486-01 B0 6-3
X.25
Prompt Command
Step 1 Configure the router with a host name, which is Router(config)# hostname 1600
used in prompts and default configuration file
names.
For Point-to-Point Protocol (PPP) authentication,
the host name entered with this command must
match the username of the central-site router.
Step 2 Specify a password to prevent unauthorized 1600(config)# enable password
access to the router. 1600user
Configuring the Ethernet Interface

Use this table to configure the Ethernet interface (which connects the router to
your local network) for IP and IPX routing and network addresses.
Prompt Command
Step 1 Enter configuration mode for the Ethernet 1600(config)# interface Ethernet0
interface.
Step 2 Configure this interface with an IP address 1600(config-if)# ip address
and a subnet mask. 172.16.25.42
255.255.255.224
Step 3 Configure this interface with an IPX network 1600(config-if)# ipx network ABC
number.
Step 4 Enable the interface and the configuration 1600(config-if)# no shutdown
changes that you have just made on the
interface.
Step 5 Exit configuration mode for this interface. 1600(config-if)# exit

6-4 78-4486-01 B0
X.25
Configuring the X.25 Interface

Use this table to configure the X.25 interface for the following:
• IP routing parameters
• IPX routing parameters
• X.25 packet encapsulation
• X.25 mapping to IP and IPX addresses
Step Task Prompt Command

Step 1 Enter configuration mode for the 1600(config)# interface Serial0
serial interface.
Step 2 Configure this interface with an IP 1600(config-if)# ip address 172.16.26.1
address. 255.255.255.0
Step 3 Set the encapsulation type on this 1600(config-if)# encapsulation x25

interface to X.25.
Step 4 Enable IPX routing on this interface. 1600(config-if)# ipx network 9876
Step 5 Set the X.121 address of this interface. 1600(config-if)# x25 address 5432
Step 6 Set up the LAN 1600(config-if)# x25 map ip 172.16.26.2

protocols-to-remote-host mapping for 2345 broadcast
IP and X.25.
Step 7 Set up the LAN 1600(config-if)# x25 map
protocols-to-remote-host mapping for ipx 9876.0000.0c03.ecc6
2345 broadcast
IPX and X.25.
Step 8 Enable the interface and the 1600(config-if)# no shutdown
configuration changes that you have
just made on the interface.
Step 9 Exit configuration mode for this 1600(config-if)# exit
interface.

78-4486-01 B0 6-5
X.25
Verifying Your Configuration

You can verify your configuration to this point by
• Confirming Connectivity to the Central-Site Router Over IP.
• Confirming Connectivity to the Central-Site Router Over IPX.
• Confirming That the Serial Interface Is Functioning Correctly.
• Confirming That the X.25 Map Is Configured Correctly.
• Confirming Switched Virtual Circuit and Permanent Virtual Circuit
Information.
Confirming Connectivity to the Central-Site Router Over IP
Step 1 Confirm that the router is connected to the central-site router.

Step 2 From the privileged EXEC command mode, enter the ping command followed by
the IP address of the central-site router:
1600# ping 172.16.26.2
Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.39.41, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/20/20
ms
Step 3 Confirm that the success rate shown in the output (shown in bold in the example)
is 60 percent (3/5) or greater. This means that your router is successfully
transferring data to the central-site router.
Step 4 To continue configuration, re-enter global configuration mode.
Confirming Connectivity to the Central-Site Router Over IPX
Step 1 Confirm that the router is connected to the central-site router.

Step 2 From the privileged EXEC command mode, enter the ping command.
Step 3 Respond to the prompts shown in the following example:

6-6 78-4486-01 B0
X.25
Note Substitute the IPX address of your central-site router for the IPX
address shown in the example.
1600# ping
Protocol [ip]: ipx 9876.0000.0c03.ecc6
Target IPX address:
Repeat count [5]: <Return>
Datagram size [100]: <<Return>>
Timeout in seconds [2]: <<Return>>
Verbose [n]: <<Return>>
Novell Standard Echo [n]: <<Return>>
Sending 5, 100-byte IPX cisco Echoes to 9876.0000.0c03.ecc6, timeout
is 2 seconds: !!!!!
ms
Confirming That the Serial Interface Is Functioning Correctly
Step 1 From the privileged EXEC command mode, enter the show interface serial 0
command.
Step 2 Check that the “line protocol is up” and the “State CONNECT” messages (shown
in bold in the example) appear in the command output:
1600# show interface serial 0
Serial0 is up, line protocol is up

Hardware is QUICC Serial
Internet address is 172.16.26.1/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation X25, loopback not set
x25 DTE, modulo 8, k 7, N1 12056, N2 20
T1 3000, interface outage (partial T3) 0, T4 0 State CONNECT, VS 6, VR
1, Remote VR 6, Retransmissions 0

78-4486-01 B0 6-7
X.25
Queues: U/S frames 0, I frames 0, unack. 0, reTx 0 IFRAMEs 22/25 RNRs

0/0 REJs 0/0 SABM/Es 0/1 FRMRs 0/0 DISCs 0/0 X25 DTE, address 5432,
state R1, modulo 8, timer 0
Defaults: cisco encapsulation, idle 0, nvc 1
input/output window sizes 2/2, packet sizes 128/128 Timers: T10 60,
T11 180, T12 60, T13 60, TH 0 Channels: Incoming-only none, Two-way
1-1024, Outgoing-only none RESTARTs 1/1 CALLs 1+0/2+2/0+0 DIAGs 0/0
Last input 00:00:32, output 00:00:32, output hang never Last clearing
of "show interface" counters never Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input
rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0
packets/sec
40 packets input, 1903 bytes, 0 no buffer Received 0 broadcasts, 0
runts, 0 giants 2 input errors, 0 CRC, 2 frame, 0 overrun, 0 ignored,
0 abort 42 packets output, 2033 bytes, 0 underruns 0 output errors, 0
collisions, 11 interface resets 0 output buffer failures, 0 output
buffers swapped out 7 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
Step 3 If you do not see these messages, refer to the following “Troubleshooting X.25
Problems” section for suggestions.
Confirming That the X.25 Map Is Configured Correctly
Step 1 From the privileged EXEC command mode, enter the show x25 map command:
1600# show x25 map
Serial0: X.121 2345 <--> ip 172.16.26.2,

ipx 9876.0000.0c03.ecc6
PERMANENT, BROADCAST, 1 VC: 1*
Step 2 Confirm that your IPX network number and the central-site router IP address and
IPX address appear in the command output (shown in bold in the example). The
IP and IPX addresses shown in your output are different than those shown above.

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X.25
Confirming Switched Virtual Circuit and Permanent Virtual Circuit Information
Step 1 From the privileged EXEC command mode, enter the show x25 vc command, as
follows:
1600# show x25 vc
SVC 1, State: D1, Interface: Serial0
Started 00:04:10, last input 00:00:26, output 00:00:33 Connects 2345
<-->
ip 172.16.26.1
ipx 9876.0000.0c03.ecc6
multiprotocol cud pid, standard Tx data PID Window size input: 2,
output: 2
Packet size input: 128, output: 128
PS: 7 PR: 3 ACK: 3 Remote PR: 7 RCNT: 0 RNR: FALSE Retransmits: 0
Timer (secs): 0 Reassembly (bytes): 0 Held Fragments/Packets: 0/0
Bytes 1540/1724 Packets 15/19 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
Step 2 Look for the following messages in the output (shown in bold in the example):
• “SVC 1”—Means that the X.25 service is active for the X.25 interface.
• “State: D1”—Means that there is an active virtual circuit on the X. 25
interface.
• “Connects 2345 <-->...”—Means that the X.25 address is correctly associated
to the IP address and IPX address of the X.25 interface.
• “Packets 15/19”—Means that data is being transferred across the X.25
interface. The number shown in this message varies and shows the success
rate of data that is being sent.
Configuring Command Line Access to the Router

Use this table to configure some parameters that control access to the router,
including the type of terminal line used with the router, how long the router waits
for a user entry before it times out, and the password used to start a terminal
session with the router.

78-4486-01 B0 6-9
X.25
Prompt Command
Step 1 Specify the console terminal line. 1600(config)# line console 0
Step 2 Set the interval that the EXEC command 1600(config-line)# exec-timeout 5
interpreter waits until user input is
detected.
Step 3 Specify a virtual terminal for remote 1600(config-line)# line vty 0 4
console access.
Step 4 Specify a password on the line. 1600(config-line)# password lineaccess
Step 5 Enable password checking at terminal 1600(config-line)# login

session login.
Troubleshooting X.25 Problems

If you are having problems or the output that you received during the verification
steps is very different from what is shown, you can troubleshoot your router by
taking some or all of the following actions:
Caution If you are not familiar with Cisco IOS debug commands, you should read the
“Using Debug Commands” section in the “Cisco IOS Basic Skills” chapter
before attempting any debugging.
• If the ping command is unsuccessful, use the debug x25 packet command.
• If you cannot use the ping command to confirm connectivity to any device
beyond the central-site router, verify that your routing (static or dynamic) is
correctly configured.
• If you do not see the “line protocol up” message in the show interface
command output, use the debug x25 event command.
• If you do not see the “State CONNECT” message in the show interface
command output, use the debug lapb command.

6-10 78-4486-01 B0
X.25 Over ISDN B Channel

This section describes how to configure the router to encapsulate IP and IPX
packets as X.25 and route them over an ISDN B-channel connection.
In addition to the assumptions described in the “Before You Begin” section in this
chapter, this configuration is based on the assumption that you can only use one
of the two ISDN B channels for this type of configuration.
These are the major tasks when configuring your router:
• Configuring Global Parameters
• Configuring Security
• Configuring the Ethernet Interface
• Configuring the ISDN Interface for X.25
• Configuring Command Line Access to the Router
Figure 6-2 illustrates the configuration used in this example.
Figure 6-2 X.25 over ISDN B Channel Example Configuration
Remote site Central site

ISDN interface addresses:
X.25: 5432 X.25: 2345
IP: 192.168.41.41 IP: 192.168.41.40
IPX: 9876 IPX: 9876
ISDN Router
1600
S6689
Network IP address: Phone # 5558461

192.168.38.0 IPX network: 9876
Configuring Global Parameters

Use this table to configure the router for some global parameters, including the
ISDN switch type that the router is connected to through the ISDN line, IPX
routing, and how log and debug messages are timestamped.

78-4486-01 B0 6-11
Prompt Command
Step 1 Enter configuration mode. Router# configure terminal
Step 2 Configure the router to show the date and Router(config)# service timestamps
time of all debug messages. debug datetime msec
This command is optional, but recommended

if you use debug commands to troubleshoot
your configuration.
Step 3 Configure the router to show the date and Router(config)# service timestamps log
time of all log messages. datetime msec
This command is optional, but recommended

if you use the verification steps described in
this guide. This feature is enabled for all the
example command output shown in this
guide.
Step 4 Enable IPX routing and configure the router Router(config)# ipx routing
with an IPX address. 0060.834f.66dd
Step 5 Configure the type of central office switch Router(config)# isdn switch-type
being used on the ISDN interface. Use the basic-ni
keyword that matches the ISDN switch type
that you are using:
• basic-ts013 —Australian TS013 switches
• basic-1tr6 —German 1TR6 ISDN switches
• basic-nwnet3—Norway NET3 switches (phase
1)
• basic-net3—NET3 ISDN switches
• vn2—French VN2 ISDN switches
• vn3—French VN3 ISDN switches
• ntt—Japanese NTT ISDN switches
• basic-5ess—AT&T basic rate switches
• basic-dms100—NT DMS-100 basic rate
switches
• basic-ni—National ISDN-1 switches
• basic-nznet3—New Zealand Net3 switches

6-12 78-4486-01 B0
Step 6 Enter configuration mode for the ISDN Router(config)# interface bri0
interface.
Step 7 Enable the ISDN switch type configuration Router(config-if) no shutdown
for the ISDN interface. #
Step 8 Exit configuration mode for the ISDN Router(config-if) exit

interface. #
You can verify your configuration to this point by confirming the ISDN line status
as follows:
Step 1 From the privileged EXEC command mode, enter the show isdn status
command.
Step 2 Confirm that the “State = MULTIPLE_FRAME_ESTABLISHED” message
(shown in bold in the example) appears on the command output:
1600# show isdn status
The current ISDN Switchtype = basic-5ess
ISDN BRI0 interface
Layer 1 Status:
ACTIVE
Layer 2 Status:
TEI = 80, State = MULTIPLE_FRAME_ESTABLISHED
Layer 3 Status:
No Active Layer 3 Call(s)
Activated dsl 0 CCBs = 0
Total Allocated ISDN CCBs =
Note In some cases, you might see a “State = TEI_ASSIGNED” message instead of
the “State = MULTIPLE_FRAME_ESTABLISHED” message. This message
also means that the ISDN line is correctly configured.
Step 3 If you don’t see the message, do the following:

a. Make sure that the router is correctly cabled.
b. Make sure that any external NT1 is functioning correctly. Refer to the
documentation that came with the NT1.
c. Make sure the ISDN line is correctly configured by checking with the ISDN
service provider.

78-4486-01 B0 6-13
d. Refer to the following “Troubleshooting Problems with X.25 over ISDN B

Channel” section for additional suggestions.
Configuring Security
Use this table to configure the router with some security measures, including the
password used to access the router and the username and password used for
Challenge Handshake Authentication Protocol (CHAP) and Password
Authentication Protocol (PAP) authentication with the central-site router.
Prompt Command
Step 1 Configure the router with a host name, 1600(config)# hostname 1600
which is used in prompts and default
configuration file names.
For Point-to-Point Protocol (PPP)
authentication, the host name entered with
this command must match the username of
the central-site router.
Step 2 Specify a password to prevent 1600(config)# enable password 1600user
unauthorized access to the router.
Step 3 Specify the password used during caller 1600(config)# username HQ password
identification and CHAP and PAP guessme
authentication.
For CHAP and PAP authentication, the
username entered with this command must
match the host name of the central-site
router.

6-14 78-4486-01 B0
Configuring the Ethernet Interface

Use this table to configure the Ethernet interface with an IP address.
Prompt Command
Step 1 Enter configuration mode for the Ethernet 1600(config)# interface Ethernet0
interface.
Step 2 Configure this interface with an IP address. 1600(config-if)# ip address
192.168.38.42
255.255.255.0
Step 3 Enable the interface and the configuration 1600(config-if)# no shutdown
changes that you have just made on the
interface.
Step 4 Exit configuration mode for this interface. 1600(config-if)# exit
Configuring the ISDN Interface for X.25

Use this table to configure the ISDN interface for X.25 packet encapsulation and
IP and IPX routing parameters.
Prompt Command
Step 1 Enter configuration mode for the ISDN 1600(config)# interface BRI0
interface.
Step 2 Configure this interface with an IP 1600(config-if)# ip address 192.168.41.41
address. 255.255.255.0
Step 3 Set the encapsulation type on this interface 1600(config-if)# encapsulation x25
to X.25.

78-4486-01 B0 6-15
Prompt Command
Step 4 Enable snapshot routing. Because your 1600(config)# snapshot client 5 60
router is dialing into a central-site router, it
is considered the client router.
The first number is the amount of “active
time” (in minutes) during which routing
updates are exchanged between your
router and the central-site router.
The second number is the amount of “quiet
time” (in minutes) during which routing
entries are frozen and remain unchanged.
Step 5 Enable IPX routing on this interface. 1600(config-if)# ipx network 9876
Step 6 Set the X.121 address of this interface. 1600(config-if)# x25 address 5432
Step 7 Set up the LAN protocols-to-remote-host 1600(config-if)# x25 map ip 192.168.39.40

mapping for X.25 to IP. 2345 broadcast
Step 8 Set up the LAN protocols-to-remote-host x25 map

mapping for IPX and X.25. ipx 9876.0000.0c03.ecc6
2345 broadcast
Step 9 Configure this interface to place a call to 1600(config-if)# dialer map ip
multiple sites and to authenticate calls 192.168.39.40 name HQ
5558461
from multiple sites based on IP address
and dialer string.
The name you enter after the name
keyword in this command must match the
name entered with the username
command in the previous “Configure
Security” section.
Step 10 Configure this interface to place a call to 1600(config-if)# dialer map ipx
multiple sites and to authenticate calls 9876.0000.0c03.e336
name HQ 5558461
from multiple sites based on IP address
and dialer string.
The name you enter after the name
keyword in this command must match the
name entered with the username
command in the previous “Configure
Security” section.

6-16 78-4486-01 B0
Prompt Command
Step 11 Assign this interface to a dialer group. 1600(config-if)# dialer-group 1
Step 12 Define a DDR dialer list to control dialing 1600(config-if)# dialer-list 1 protocol
based on access lists and IP packets. ip permit
Step 13 Define a DDR dialer list to control dialing 1600(config-if)# dialer-list 1 protocol
based on access lists and IPX packets. ipx permit
You can verify your configuration to this point by:

• Confirming Connectivity with the Central-Site Router Over IP
• Confirming Connectivity to the Central-Site Router Over IPX
• Confirming That the X.25 Map Is Configured Correctly
• Confirming Switched Virtual Circuit and Permanent Virtual Circuit
Information
Confirming Connectivity with the Central-Site Router Over IP
Step 1 Confirm that your router X.25 connection is active.

Step 2 From the privileged EXEC command mode, enter the ping command followed by
the IP address of the central-site router:
1600# ping 192.168.39.40

Sending 5, 100-byte ICMP Echos to 192.168.39.40, timeout is 2 seconds:
!!!!!
ms

78-4486-01 B0 6-17
Confirming Connectivity to the Central-Site Router Over IPX
Step 1 Confirm that your router X.25 connection is active.

Step 2 Enter the ping command followed by the IPX address of the central-site router:
1600# ping 9876.0000.0c03.ecc6
Protocol [ip]:
Target IPX address: Repeat count [5]: <Return>
Datagram size [100]: <<Return>>
Timeout in seconds [2]: <<Return>>
Verbose [n]: <<Return>>
Novell Standard Echo [n]: <<Return>>
Sending 5, 100-byte IPX cisco Echoes to 9876.0000.0c03.ecc6, timeout
is 2 seconds: !!!!!
ms
Note Substitute the IPX address of your central-site router for the IPX address
shown in the example.
Confirming That the X.25 Map Is Configured Correctly
Step 1 From the privileged EXEC command mode, enter the show x25 map command:
1600# show x25 map
Serial0: X.121 2345 <--> ip 192.168.39.40,

ipx 9876.0000.0c03.ecc6
PERMANENT, BROADCAST, 1 VC: 1*

6-18 78-4486-01 B0
Step 2 Confirm that the following addresses (shown in bold in the example) appear in the
command output:
• Your router IPX network number
• Central-site router IP address
• Central-site router IPX address
Note The IP and IPX addresses shown in your output are different than those shown
in the example.
Confirming Switched Virtual Circuit and Permanent Virtual Circuit Information
Step 1 From the privileged EXEC command mode, enter the show x25 vc command.
1600# show x25 vc
SVC 1, State: D1, Interface: Serial0
Started 00:04:10, last input 00:00:26, output 00:00:33 Connects 2345
<-->
ip 192.168.39.40
ipx 9876.0000.0c03.ecc6
multiprotocol cud pid, standard Tx data PID Window size input: 2,
output: 2
Packet size input: 128, output: 128
PS: 7 PR: 3 ACK: 3 Remote PR: 7 RCNT: 0 RNR: FALSE Retransmits: 0
Timer (secs): 0 Reassembly (bytes): 0 Held Fragments/Packets: 0/0
Bytes 1540/1724 Packets 15/19 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
Step 2 Confirm that the X.25 address is associated with the correct IP and IPX addresses
(shown in bold in the example).

78-4486-01 B0 6-19
Configuring Command Line Access to the Router

Use this table to configure some parameters that control access to the router,
including the type of terminal line used with the router, how long the router waits
for a user entry before it times out, and the password used to start a terminal
session with the router.
Prompt Command
Step 1 Specify the console terminal line. 1600(config)# line console 0
Step 2 Set the interval that the EXEC command 1600(config-line)# exec-timeout 5
interpreter waits until user input is detected.
Step 3 Specify a virtual terminal for remote console 1600(config-line)# line vty 0 4
access.
Step 4 Specify a password on the line. 1600(config-line)# password lineaccess
Step 5 Enable password checking at terminal session 1600(config-line)# login

login.
Step 6 Exit configuration mode. 1600(config-line)# end
Troubleshooting Problems with X.25 over ISDN B Channel

If you are having problems or the output that you received during the verification
steps is very different from what is shown, you can troubleshoot your router by
taking some or all of the following actions:
Caution If you are not familiar with Cisco IOS debug commands, you should read the
“Using Debug Commands” section in the “Cisco IOS Basic Skills” chapter
before attempting any debugging.
• If the ping command is unsuccessful, use the debug x25 packet command.
• If you cannot use the ping command to confirm connectivity to any device
beyond the central-site router, verify that your routing (static or dynamic) is
correctly configured.
• If the show isdn status command is unsuccessful, use the debug isdn q931
command.

6-20 78-4486-01 B0
How X.25 Works
How X.25 Works

X.25 is a method of packet-switching that is used for communication between
user devices (such as routers, bridges, and host machines) and network devices
(such as switching nodes and modems). User devices are called data terminal
equipment (DTE) and network devices are called data circuit-terminating
equipment (DCE)
With X.25, one computer calls another to request a communication session. The
called computer can accept or refuse the connection. If the call is accepted, the
two computers begin full-duplex information transfer. Either computer can
terminate the connection at any time.
User devices communicate with a bidirectional association called a virtual circuit.
Devices on a network use virtual circuits to communicate through intermediate
nodes without being directly, physically connected to each other. Virtual circuits
are permanent or switched (temporary). Permanent virtual circuits (PVCs) are
typically used for the most-often-used data transfers and switched virtual circuits
(SVCs) are used for sporadic data transfers.
Basic Rate Interface (BRI) is an ISDN interface consisting of two B channels (B1
and B2) and one D channel. The B channels are used to transfer data, voice, and
video. The D channel carries signal and call setup information. IPX, AppleTalk,
transparent bridging, XNS, DECnet, and IP can all be encapsulated as X.25 over
the ISDN B channels.

78-4486-01 B0 6-21
How X.25 Works

6-22 78-4486-01 B0

Configuring X.25: Before You Begin

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C H A P T E R 6

Before You Begin

Cisco 1600 Series Software Configuration Guide

Figure 6-1 X.25 Example Configuration

Remote site Central site

Ethernet network: 172.16.25.42

IPX network: 9876

Cisco 1600 Series Software Configuration Guide

Configuring Global Parameters

Cisco 1600 Series Software Configuration Guide

Configuring the Ethernet Interface

Cisco 1600 Series Software Configuration Guide

Configuring the X.25 Interface

Step Task Prompt Command

Step 3 Set the encapsulation type on this 1600(config-if)# encapsulation x25

Step 6 Set up the LAN 1600(config-if)# x25 map ip 172.16.26.2

Cisco 1600 Series Software Configuration Guide

Verifying Your Configuration

Confirming Connectivity to the Central-Site Router Over IP

Step 1 Confirm that the router is connected to the central-site router.

Type escape sequence to abort.

Confirming Connectivity to the Central-Site Router Over IPX

Step 1 Confirm that the router is connected to the central-site router.

Cisco 1600 Series Software Configuration Guide

Confirming That the Serial Interface Is Functioning Correctly

Serial0 is up, line protocol is up

Cisco 1600 Series Software Configuration Guide

Queues: U/S frames 0, I frames 0, unack. 0, reTx 0 IFRAMEs 22/25 RNRs

Confirming That the X.25 Map Is Configured Correctly

Serial0: X.121 2345 <--> ip 172.16.26.2,

Cisco 1600 Series Software Configuration Guide

Confirming Switched Virtual Circuit and Permanent Virtual Circuit Information

Configuring Command Line Access to the Router

Cisco 1600 Series Software Configuration Guide

Step 5 Enable password checking at terminal 1600(config-line)# login

Troubleshooting X.25 Problems

Cisco 1600 Series Software Configuration Guide

X.25 Over ISDN B Channel

Figure 6-2 X.25 over ISDN B Channel Example Configuration

Remote site Central site

Network IP address: Phone # 5558461

Configuring Global Parameters

Cisco 1600 Series Software Configuration Guide

This command is optional, but recommended

This command is optional, but recommended

Cisco 1600 Series Software Configuration Guide

Step 8 Exit configuration mode for the ISDN Router(config-if) exit

Verifying Your Configuration

Step 3 If you don’t see the message, do the following:

Cisco 1600 Series Software Configuration Guide

d. Refer to the following “Troubleshooting Problems with X.25 over ISDN B

Cisco 1600 Series Software Configuration Guide

Configuring the Ethernet Interface

Configuring the ISDN Interface for X.25

Cisco 1600 Series Software Configuration Guide

Step 7 Set up the LAN protocols-to-remote-host 1600(config-if)# x25 map ip 192.168.39.40

Step 8 Set up the LAN protocols-to-remote-host x25 map

Cisco 1600 Series Software Configuration Guide