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X.21 Kabel - Das muß man wissen

WAN-Verbindungen über X.21 laut CISCO

(mit Hilfe der Synchronous Serial Connection)

Before you connect a device to the synchronous serial port , you will need to know the following:

 

1. The type of device you are connecting to the synchronous serial interface. - That means : Is the router being connected to a data terminal equipment (DTE) or data communications equipment (DCE) device?

2. The type of connector, male or female, required to connect to the device.

3. The signaling standard required by the device.

 

DTE oder DCE

A device that communicates over a synchronous serial interface is either a DTE or DCE device.

A DCE device provides a clock signal that paces the communications between the device and the router.

A DTE device does not provide a clock signal. DTE devices usually connect to DCE devices. The documentation that came with the device should indicate whether it is a DTE or DCE device. (Some devices have a jumper to select either mode.)

Das sagt die ITU:

Die ITU ist aus "International Telephone and Telegraph Consultative Committee" (CCITT) hervorgegangen und legt weitgehend weltweit die Standards fest.

 

[X.21] Recommendation X.21 (09/92) - Interface between

Data Terminal Equipment and

Data Circuit-terminating Equipment

for synchronous operation on public data networks.

 

Und alle meinen dasselbe !!!! Übrigens soll X.21 und V.35 auch dasselbe sein.

Typical DTE and DCE Devices

  • DTE (Data Terminal Equipment) or DCE (Data Communication Equipment)
  • CSU/DSU = Channel Service Unit / Data Service Unit
Device Type Gender Typical Devices
DTE
(hat keine Clock,
bekommt Timing)
männlich Cisco Router;
Terminal, PC
DCE
(hat die Clock,
liefert das Timing)
weiblich X.21/G.703 Konverter,
CSU/DSU, Multiplexer

Erläuterungen :

 

1. wenn Du Pins am Stecker hast, the connector is male=männlich.

2. wenn der connector Löcher hat to accept pins, the connector is female=weiblich.

3. CSU/DSU = Channel Service Unit / Data Service Unit.

 

X.21 devices, that communicate over a serial interface, are divided into two modes: DTE and DCE. The most important difference between these types of devices is that the DCE device supplies the clock signal that paces the communications on the bus. The documentation that came with the device should indicate whether it is DTE or DCE (some devices have a jumper to select either mode).

Is a male or female connector required on the cable? (noch eine Tabelle)

Type DTE DCE Selectable DTE or DCE
Device
Stecker

DTE-Schnittstelle

(i.d.Regel männlich)

(Empfänger des Clock-Signales)

X.21 / V.11, 15-polige D-Sub Buchse (des Routers)

Pin Nr. X.21 / V.11 Richtung Funktion
1      
2 Txd(+) -> transmit data
3 Ctrl(+) -> control
4 Rxd(+) <- receive data
5 Ind(+) <- indicate
6 Set(+) <- signal element timing
7      
8 GND <-> signal ground
9 Txd(-) -> transmit data
10 Ctrl(-) -> control
11 Rxd(-) <- receive data
12 Ind(-) <- indicate
13 Set(-) <- signal element timing
14      
15      

DCE-Schnittstelle

(i.d.Regel weiblich)

(Sender des Clock-Signales)

X.21 / V.11, 15-polige D-Sub Buchse (des X.21 Wandlers =TA)

Pin Nr. X.21 / V.11 Richtung Funktion
1      
2 Txd(+) <- transmit data
3 Ctrl(+) <- control
4 Rxd(+) -> receive data
5 Ind(+) -> indicate
6 Set(+) -> signal element timing
7      
8 GND <-> signal ground
9 Txd(-) <- transmit data
10 Ctrl(-) <- control
11 Rxd(-) -> receive data
12 Ind(-) -> indicate
13 Set(-) -> signal element timing
14      

X.21 für CISCO

(Serielles Synchron Interface an den CISCO Routern)

 

CISCO X.21 Cable Assembly - Diese Kabel gibts bei CISCO fertig !!!

 

 

The cable itself identifies the Cisco router as a DTE or DCE device to other devices in the network. !!!!

An ASCEND router seems to be a DCE allways - why ?? currently no explanation.

X.21 DTE

Cable Pinouts (DB-60 male to DB-15 male=männlich ) Cisco Type CAB-X.21MT

60 Pin Signal Description Direction 15 Pin Signal
J1-48
J1-47
GND
MODE_2
Shorting group -- -- --
J1-51
J1-52
GND
MODE_DCE
Shorting group -- -- --
J1-46 Shield_GND Single -- J2-1 Shield GND
J1-11
J1-12
TxD/RxD+
TxD/RxD--
Twisted pair
no. 3
===>
===>
J2-2
J2-9
Transmit+
Transmit--
J1-9
J1-10
RTS/CTS+
RTS/CTS--
Twisted pair
no. 2
===>
===>
J2-3
J2-10
Control+
Control--
J1-28
J1-27
RxD/TxD+
RxD/TxD--
Twisted pair
no. 6
<===
<===
J2-4
J2-11
Receive+
Receive--
J1-1
J1-2
CTS/RTS+
CTS/RTS--
Twisted pair
no. 1
<===
<===
J2-5
J2-12
Indication+
Indication--
J1-26
J1-25
RxC/TxCE+
RxC/TxCE--
Twisted pair
no. 5
<===
<===
J2-6
J2-13
Timing+
Timing--
J1-15
Shield
Control_GND Twisted pair
no. 4
--
--
J2-8
Shield
Control GND

X.21 DCE

Cable Pinouts (DB-60 male to DB-15 female=weiblich ) Cisco Type CAB-X.21FC

60 Pin Signal Description Direction 15 Pin Signal
J1-48
J1-47
GND
MODE_2
Shorting group -- -- --
J1-46 Shield_GND Single -- J2-1 Shield GND
J1-28
J1-27
RxD/TxD+
RxD/TxD--
Twisted pair
no. 6
<===
<===
J2-2
J2-9
Transmit+
Transmit--
J1-1
J1-2
CTS/RTS+
CTS/RTS--
Twisted pair
no. 1
<===
<===
J2-3
J2-10
Control+
Control--
J1-11
J1-12
TxD/RxD+
TxD/RxD--
Twisted pair
no. 3
===>
===>
J2-4
J2-11
Receive+
Receive--
J1-9
J1-10
RTS/CTS+
RTS/CTS--
Twisted pair
no. 2
===>
===>
J2-5
J2-12
Indication+
Indication--
J1-24
J1-23
TxC/RxC+
TxC/RxC--
Twisted pair
no. 4
===>
===>
J2-6
J2-13
Timing+
Timing--
J1-15
Shield
Control_GND
--
Twisted pair
no. 5
--
--
J2-8
Shield
Control GND
--
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