Athena supports dial-in connections via digital phones. In order to
take advantage of this capability, your computer should be connected
to the port on the back of your black ISDN 7506, or 7507, digital
phone set with a "hardware-handshaking" serial cable. This allows your
computer and digital phone to use special signals to control data flow
when communicating at high speeds.
1. Once your digital phone is hooked up to your computer, start your
communications software, and make sure that you have set the following
parameters:
8 data bits
1 stop bit
No parity
Full duplex
19.2Kbps speed
At this point, you will be talking to your digital phone.
You should see a prompt like this:
CMD:
The very first time you want to make a digital data call, you should
type the following commands at the "CMD:" prompt:
set mode dx25
set parity space
set rec.flow eia
set trans.flow eia
These commands place the phone into packet-switched mode, set the
parity to "space," and enable hardware flow control between the
computer and digital phone. If you are not using a
"hardware-handshaking" serial cable, you will not be able to (and
should not) turn on hardware flow control. If you do not use hardware
flow control, you run the risk of losing characters at high speeds.
After configuring these settings on the digital phone, you can dial up
to Athena by typing the following at the "CMD:" prompt:
d 700-7000
This will connect you to one of the cisco protocol translators (CPTs).
Continue with the instructions in step 2, below.
2. At this point, you should be greeted by the CPT box. If you see
nothing, hit return once, and you will get a prompt like this:
ZITI.MIT.EDU>
or LASAGNE.MIT.EDU>
or TORTELLINI.MIT.EDU>
or CANNELLONI.MIT.EDU>
or RAVIOLI.MIT.EDU>
or LINGUINE.MIT.EDU> (They're named after pastas.)
To see a list of possible commands, type "?". In most cases, though,
you will simply want to connect to a dialup machine. Typing:
athena
at the aforementioned prompt will open a telnet connection to an
Athena dialup machine. Currently, there are eleven dialup machines
supported by Athena. They also do load balancing (a calculation based
on a combination of CPU load, number of users, and available disk
space), so you will automatically be connected to the least loaded
dialup server. Because of this, you may be connected to a VAX or DEC
workstation. If you absolutely must be connected to one of the two
architectures, you can type:
athena-vax
or athena-dec
to be connected to the appropriate type of machine. Again, load
balancing is in effect, so you will be connected to the least loaded
machine of that type architecture.
At this point, log in to Athena as usual. When you log out, you will
be returned to the CPT prompt. To disconnect, type "exit," "quit," or
just "q" -- or simply hang up the phone. The system will disconnect
cleanly if you just hang-up.
Much of this information was taken from the Athena document "Dialing
Into Athena," available free from the Graphic Arts centers in the
basements of building 11 and the Student Center, or in Online Help.
To see this information online, just type the following at your
athena% prompt:
help @dialup:main_menu
You may also wish to consult the IS publication "IS-9: Dial-up Access
to MIT Computers and Others," available free from the MIT Computer
Connection in the Student Center basement or by sending email to
sendpubs@mit.edu or by calling 253-5150.
DIGITAL PHONE CONFIGURATION. You can set the digital phone options from
the phone's dial pad. The handset must be in the cradle and the speaker
must be turned off to set options from the dial pad. Take the following
steps (in order):
1. Press the Shift/Select button (7506 models), or the Select button
(7507 models).
2. Press the Data/Send/Off button.
If you have a model 7506 or 7507 digital telephone, follow the
instructions on the phone's display at this point, pressing * to change,
0 to skip, and # to save the settings specified below.
Data Mode: DX25
Data Rate: 9600
Parity: space
Local Mode: CMD
(Note: Some software/devices cannot keep up with such a high data rate.
If you notice lost characters in your connection, try using a lower
speed.)
Or you may continue with these steps:
3. Press the 3 key to set the phone to DX25 packet-switched mode.
4. Press the 5 key to set the data transmit/receive rate to 9600 bps
(for lower speeds, press 4 for 4800, 3 for 2400, 2 for 1200, or 1 for
300).
5. Press the 1 key to set no parity ("space").
6. Press the 1 key to set local mode to CMD.
The telephone automatically stores your selections and exits program
mode after the last step.
ISDN digital telephones support flow control. If your terminal and
RS232 cable support hardware flow control, enter the following commands
at the CMD prompt on your terminal:
CMD: set rec.flow eia
CMD: set trans.flow eia
If your terminal does not support flow control, enter the following
commands at the CMD prompt:
CMD: set rec.flow off
CMD: set trans.flow off
If you want your selections to be the default settings next time the
phone resets, enter this command at the CMD prompt:
CMD: copy active to p1
Step 2: Connecting to a CPT Gateway
When your device is properly configured, you can connect to the gateway
by dialing in to the appropriate number:
---------------------------------------------------
Modem Speed Number Modem Type
---------------------------------------------------
2400 and lower 258-7000 V.22bis, 212A,
103/113
9600 258-7096 V.32
14400 258-7096 V.32bis
19200 (on-campus only) 700-7000 ISDN
---------------------------------------------------
(Note: If you have call-waiting service installed on your analog phone,
you should disable this service during a dialin session or run the risk
of being disconnected if someone calls you. In some cases, you can
disable the service for the duration of a call by prefixing the special
code *70 before the phone number; for example, you might want to include
it as part of your modem's dialup command. Check with your phone
company about how to temporarily disable call-waiting for your own
phone.)
The phone numbers listed connect you to a CPT (Cisco Protocol
Translator) gateway. The CPT allows you to make a connection over a
network to a machine that accepts remote logins -- in this case, one of
the Athena dialup servers. Several CPTs serve dialup users.
When you first connect to the system, the CPT you reach displays its
message of the day, then displays its command prompt. For example:
LINGUINE.MIT.EDU>
The exact prompt differs slightly depending on the CPT you reach, but
all of the CPT machines at MIT are named after various kinds of pasta.
Once you reach the CPT prompt, you are ready to log into a dialup server.
GENERAL
The MIT campus is served by an on-site AT&T 5ESS time-division digital
switching system or PBX. The system was placed into service in
two phases. MIT initiated telephone service to some of its
residential community on August 12, 1988, and to its institutional
or business community on October 28, 1988. Ownership and
administrative control of the switch shifted from AT&T to MIT on
February 10, 1989.
The MIT 5ESS is a state-of-the-art switching system, currently
equipped with 5E5.1 generic software, that provides advanced call
processing features, such as Calling Line Identification (CLID).
Currently MIT is exploring distributed trunking as well as future
generic software enhancements.
Of the 15,244 lines installed in the 5ESS, 5542 are ISDN (Integrated
Services Digital Network) lines, and 5606 lines could be readily
converted to ISDN.
ISDN
MIT's 5ESS is one of the largest ISDN (Integrated Services Digital
Network) systems in the country. All of the ISDN digital
telephones at MIT are equipped with asynchronous data modules (ADMs)
with an RS232 connector and a visual display indicator.
The 5ESS supports connectivity for both ISDN interfaces and
conventional analog and digital technologies. Each
5ESS digital subscriber line (DSL) is a ISDN Basic Rate
Interface (BRI) that provides two "B" channels and one "D" channel
(2B+D) on twisted-pair wire. The 64Kbps B channels provide two
independent channels for either voice or data services. All
signaling is done on the 16Kbps D channel, which also supports
X.25 packet data at up to 9.6Kbps.
MIT uses ISDN technology to address a number of applications.
For example, MIT's voice mail system uses digital signaling between
the 5ESS and the voice mail system over one DSL, employing a 0B+D
scheme. ("0B+D" means that only the D channel of the DSL is used.)
Another example is the use of multi-line hunt groups over which B channel
packet data is transported (at speeds up to 64Kbps) through Cisco CPT
(Cisco Protocol Translators) boxes (that convert X.25 to TCP/IP, the
protocol of choice of MITnet) to MITnet. By using the 5ESS modem pool,
analog telephone users either on- or off-campus can originate Telnet
sessions on hosts connected to MITnet at speeds up to 14.4 Kbps.