AB 143A I N F O R M A T I O N R E L E A S E
To provide a "Dial on Demand" ISDN solution using Specialix ITA 1000 ISDN Terminal Adapters and Cray 818 Multiplexes.
To interconnect to a remote site EDP has always recommended the use of kilostream links and multiplexes.
For remote sites with very low device populations and anticipated low daily useage then this can be an expensive option.
For sites with upto 4 peripherals who do not expect the aggregate usage time to exceed 3 hours per day then an ISDN solution will probably be more cost effective than the kilostream solution.
Apart from installations and quarterly rental charge, users pay standard call rates whilst there is a connection in a similar manner to making a telephone call.
The advantages of ISDN over analogue circuits is that the time to establish the connection is less than a second and the link is noise free.
CRAY 818
Information about the Cray 818 has already been issued. Therefore this release will only provide configuration changes necessary to enable the 818 to support a dial up on demand configuration.
The Specialix ITA1000 Terminal Adapter
The Specialix ITA1000 is, effectively, an ISDN modem. It can be used to connect any serial computing device to an ISDN Basic Rate Interface, (BRI), for long distance digital communications.
An ISDN BRI provides 2 x 64Kbps bearer (B) channels plus 1 x 16Kbps (D) data channel.
The two 64K bearer channels enable the connection of two separate circuits, operating independently. Each channel is configurable for X.21, V.24, V35 or V36.
The ITA1000 supports synchronous data transfer at speeds from 9.6Kbps to 64Kbps. Using CCITT V.110/V.120 rate adaption enables asynchronous data transfers, (V24), at speeds from
2.4Kbps to 38.4Kbps.
Other features include:-
-Six methods of dialling.
-A dedicated configuration port for connection to a P.C or VDU.
The next two pages are extracts from the manual showing connectors and indicators.
You should note that some functions alter depending on individual configurations.
The ITA1000 can be used in numerous configurations. The only tested configuration is "dial up on demand". Further configuration guides will be issued as they are tested.
`Dial on Demand'
The theory behind `dial up on demand' is that a Cray 818 multiplexor is interfaced onto the ITA1000 at the system end and at a remote site.
At the system end the multiplexor is interfaced into the host system.
At the remote site, VDU, other input devices or printers are interfaced onto the Cray 818.
A standard composite cable is used to interface the Cray to the ITA1000.
The Cray is configured for defaults except:-
(1)The composite link speed is set to 19K2. (This is the fastest speed that the ITA1000 will support through the composite RS232 interface).
(2)The X.21 option is enabled .
(3) Data timeout is set for 10 seconds.
The composite link cable for the Cray is connected to link 1 on the ITA1000.
Connect the ISDN connector to the BRI and a suitable VDU or P.C. to the ITA1000's configuration port. This device should be set for 9600, 8, N and 1 stop bit.
On the ITA1000 set the protocol selection rotary switch to `A'. This configures both ports for V.24.
Power on the ITA1000 and allow it to complete it's self test sequence.
On the VDU you should see a banner and >1
To configure the ITA1000 enter:-
set answer auto (CR)
set call control V25 direct (CR)
note 1set name (site identifier) (CR)
set speed 19K2 (CR)
note 2set remote address [ISDN telephone number of the opposite end of the link] (CR)
save (CR)
Notes
(1)Site identifier should be a name which identifies the physical location of the ITA. eg SISHEFF.
(2)ISDN number should be entered as it is a standard telephone number including the STD code.
To test the configuration:-
(1)Ensure that the opposite end of the link has been properly configured and is ready for a test connection.
(2)Press any key on a VDU keyboard which is connected to the remote Cray 818.
You should see the ACTIVE and CONN lights on both ITAS light up. All lights on the Cray 818 light up.
You should be able to display the Unix prompt on terminals at the remote site.
Functionally test all VDU's at the remote site.
(3)Test any printers at the remote site by sending long prints to them, checking for missing data or corruption.
(4)Once all printing has completed, wait for 10 seconds. The link should automatically disconnect.
All the lights on the front of the Cray 818 will extinguish.
The active and CONN lights for channel 1 on the ITA1000 will extinguish.