Configuring PAD Service Directory of X25
The
List of Configuration Tasks
The complete introduction of PAD commands can be referred to the chapter “The Commands for Linking PAD and X25 in the book “The Reference for WAN Commands” If the location of other commands needs to be known, the master index for commamds shall be used or on-line search shall be conducted.
PDA configuration is used to
activate the X25 linkage between network equipments. PAD is a kind of equipment
receiving character stream transmitted from one or multiple terminals. It
divides the character stream into groups and transmitted the group data to host
computer. PAD also can do its work reversely, that is, it can receive the data
transmitted from network host and translate the data package into character
stream acceptable to the terminal. PAD is defined on X3, X28 and X29 under the
suggestion of CCITT.
Chart 1 Standard
X. 25 Linkage between Dumb Terminal and X.25
PAD can be configured by changing the application program on protocol to make it work. In Chart 2, a computer at remote terminal sets up simulation modem calling with IP network, link to 1700 router and allow IP to divide data to achieve the conversion from IP to X.25 protocol. It first communicates with PAD equipments inside the router, then links to X.25 host computer.
Chart 2 Dialing up to X.25 Host Computer through protocol conversion
The
List of Configuration Tasks
X.28 emulation is the standard user interface between DTE
and PAD. The router of the Compnay offers X.28 user emulation model (PAD model),
which enable uers to interchange with PAD and control PAD. During the periond of
controlling information exchange, the message or command sent from DTE to PAD is
called PAD command signal. The message sent from PAD to DTE is called PAD
service signal. These signals and transmitted data are the coded character
stream defined on IA5.
Chart 3 Dialing up to asynchronous device of X.25 host
computer on X.25 Network
PAD
uses X.28 standard user interface to enable PAD system administrator to dial up
to x.25 network or set PAD parameters. The interface is commonly used in many
European countries. It complies with ITU-T standards for X.25.
PAD interface is designed for
accessing the remote or local asynchronous device or the asynchronous device
applied by asynchronous host computer through X.25. For example, dial-up
application program uses X.28 interface to access remote X.25 host computer.
Banks often employ X.28 PAD calling support, such as ATM, the background
application of point of sale of authorizied equipments and alarming system. ATM
can be linked to a alarming computer and a router in an asynchronous manner.
After the alarm is trigged, the warner sends a alarming calling through router
and X.28 PAD.
The PAD calling through router of the Company can be transmitted on
public group network, Internet, special X.25 network, special network based on
IP and FR network. It can be used to convert ptotocol. The protocol conversion
and VTY asynchronous
interface enable the users to use the PAD services and other protocols, such as
the local area transmission of Digital Equipment Corporation (DEC) and
Transmission Control Protocol (TCP), to access X. 25 application in both
directions.
The
List of Configuration Tasks
This part describes the following optional tasks:
l
Setting
up and Clearing Calling
l Customizing
Local X.3 Parameters
l Mornitoring X.25 FAD Linkage
l
X.
25 PAD Access Limitations
By
using user’s command “EXEC”, pad accesses to X.28 model.. The pad
model is accessible when Ctrl-p is pressed. The prompt of default PAD model is
“pad” and “(>)”. When pad> appears, the standard user’s
interface can be used and PAD can be configured under this model.
Setting
up and Clearing Calling
Manay function related to X.25 can be realized under PAD model, such as
resetting and clearing calling. Table 20 lists the executable and usable command
signals.
Under PAD model, the various PAD command signals can be used, the
standars can be selected or the command syntax can be expanded. For example, the
command “clr” or “clear” is entered to clear calling. The
commands designated on the standard command syntax are only the short ones of
expanded command syntax. The role of these
two command syntaxes are same in essence.
Command |
Functions |
Clr |
Clearing virtual call |
Help |
Showing help
information |
Int |
Transmitting
interrupted group data |
par? Par |
Showing current value
of local parameter values |
Prof filename |
Install a standard
outline value |
Reset |
Resetting Calling |
Set |
Changing local
parameter values |
set? |
Changing then reading
parameter values |
Stat |
Request the state of
linkage |
Quit |
Quiting PAD linkage |
Setting
up Calling
To set up calling with another X.25 information destination, X.121 address shall be designated and enter “command” under user’s mode or management mode.
pad svc
address [profile-number
[r|w]] |
Dialing
up remote interface address through SVC. If dial-up succeeds, X.28 mode
is avaible and the prompt “>” appears |
pad pvc interface
pvc# [profile-number
[r|w]] |
Dialing
up remote interface address through PVC. If dial-up succeeds, X.28 mode
is available and the prompt “>” appears. |
Clearing
Calling
After the linkage to the remote X.25 equipment is set up, the following command can be used to clear the linkage,
Steps
|
Command
|
Function |
1 |
ctrl-p
|
Retreating from
remote host computer to local router PAD model. |
2 |
Clr |
Clearing virtual
calling |
Customizing
Local X.3 Parameters
X.3 PAD parameters is set at the local terminal and the following commands are used under user’s mode or management mode:
Steps |
Command |
Function |
1 . |
pad svc
address |
Entering X.28 model |
2 |
Ctrl-p |
Retreating from X.28
model to PAD model. |
2 . |
par |
Showing current X.3
PAD parameters |
3 . |
set
parameter-number: new-value |
Changing parameter
value |
4 . |
par |
Verifying
the PAD parameters are correctly set. |
To show the information of current open linkage, the following command shall be used under the management mode:
Command |
Function
|
Show x25 |
Showing the
information of current open X.25 linkage |
The configuration can
limit the access to source X.121 address of router
Command
|
Function |
X25 map pad x121addr
|
Configuring static PAD-accessible source X121 address of
router |
X25 pad-access |
Starting
the access limitation of PAD and examing the access limitation through
list item configured by the previous command. If there is no
configuration, all the PAD access will be prohibited. |
l Demonstration
of Customizing X.3
l Demonstration
of X.3 Outline Value
l Demonstration
of Obtaining Help
l
Demonstration
of Monitoring X.25 Network
Route
A#pad svc 123456
COM
router-B>
exit
CLR(cause=0x0,diag=0x0)
Router
A#
The following example shows that the linkage to remote X.25 host computer is cleared. The command “clr” under X.28 model is used to disconnect the linkage between rounter A and router B.
router-A#
pad svc 123456
COM
router-B>按Ctrl-p
pad>clr
CLR
CONF
Pad>
Demonstration
of Customizing X.3
Router
A# pad svc 12345678
Router
B>按ctrl-p
pad>par
PAR
1:1 2:1 3:126 4:0 5:1 6:2 7:2 8:0 9:0 10:0 11:14 12:1 13:0 14:0 15:0 16:127
17:24 18:18 19:2 20:0 21:0 22:0
pad>
set 9:1
pad>
par
PAR
1:1 2:1 3:126 4:0 5:1 6:2 7:2 8:0 9:1 10:0 11:14 12:1 13:0 14:0 15:0 16:127
17:24 18:18 19:2 20:0 21:0 22:0
pad>
Demonstration
of X.3 Outline Value
router-A#
pad 3333
router-B>按ctrl-p
pad>prof
0
pad>par
PAR
1:1 2:1 3:126 4:0 5:1 6:2 7:2 8:0 9:2 10:0 11:14 12:1 13:0 14:0 15:0 16:127
17:24 18:18 19:2 20:0 21:0 22:0
Note: If X.29 outline value is default value, this outline value will ba applicable to all X.25 calling, including the calling used for protocol conversion.
Demonstration
of Obtaining Help
pad>
help
CLR
- clear X.25 connection
HELP
- this help
INT
- send interrupt packet over X.25 connection
PAR?
- show X.3 parameters as wanted
PROF
- use X.3 profile 0 or 1
QUIT
- quit PAD and clear connection
RESET
- send RESET packet over X.25 connection
SET
- set X.3 parameters
SET?
- set X.3 parameters and show it
STAT
- show X.25 connection status
Demonstration
of Monitoring X.25 Network
router
A# pad svc 123456789
COM
Router
B> ent
Router
B#show x25
X.25/IP
state
Serial1/0=UP
=====================================================================
No.Port
VC I/O
State X.121addr
IPaddr hostname
=====================================================================
01
Serial1/0 16
in work
1111
Router
B#