NIO CommKit Host Interface Installation and System Administration Manual

3-4

Control Tables (from AT&T 255-110-127)

Data Switch Dialstrings

Understanding the purpose and format of the data switch dialstring, espe-

cially the user-dialstring, is helpful for setting up the interface tables. This

section gives an in-depth description of the dialstring and its use.

The dialstring is used to access other data switch devices (such as terminals,

printers, and other hosts) from your host system. Dialstrings are originated

by a sender (such as a terminal user or a program on the local host),

expanded by the data switch node, and interpreted by the receiver (such as a

server on the remote host). Dialstring refers to the sequence generated by

the sender and the sequence generated by the data switch node and made

available to the receiver.

The following dialstring format description assumes a Datakit II VCS or

BNS data switch.

The format of the expanded dialstring transmitted from the data switch node

to the host is as follows:

Chan.Token.Lflag.URPinit.Recbuf\n

User-dialstring\n

User-Id\n

Origin.Node.Mod.Ochan.Cflag[.Par1.Par2...]\n

Module Type Information \0

NOTE: The Datakit VCS dialstring is the same, except that it does not include the URPinit,

Recbuf, and Module Type Information fields.

The ﬁelds are:

• Chan - the channel number assigned to the incoming data switch call (such as a

call from the local to the remote host) by the data switch node.

• Token - a unique request identifier associated with the incoming call.

• Lflag - the local flag byte (L if the call originated on the local data switch node

and R from a remote data switch node).

• URPinit - the URP initialization byte (0 if the call originator handles URP initial-

ization, 1 if the local host is to send INIT1, 2 if the local host is to send INITREQ,