Technical Services

ACF Upgrades to 56K Modems

Melissa Whitney

Then the protocol war started. Two parties found ways past the 33.6 limit -- two significantly different ways. Modems with 56K emblazoned on their boxes arrived in stores. Unfortunately, these modems did not actually give you 56 Kbps connections. You might get close, but only if the phone lines running from your house to your phone company were very high quality; your Internet Service Provider used digital circuits to connect to the phone company; the modem you connected with at your ISP's end was also 56K; and it ran the same protocol as your modem.

The first issue will remain a problem as long as there are copper telephone wires buried in the ground; the second and third issues are settling themselves as more and more ISPs upgrade their modems and telephone connections. Here at NYU, we are addressing the fourth issue as we migrate our modems to 56K capable models.

The two competing protocols on the market are x2 and K56flex. We feel that the K56flex protocol is unfortunately named, because it can be confused with the connection speed. K56flex refers to a particular method of packaging data so it can be transferred over telephone lines. 56K refers to the maximum data rate achievable, whether it is by the x2 method of packaging data or the K56flex method.

As long as it was unclear which side would win out, ACF chose not to commit to either protocol. An x2 modem couldn't connect at the maximum rate to a K56flex modem, nor could a K56flex connect at the maximum to an x2.

Two developments led to our decision to upgrade our modems: the International Telecommunications Union (ITU) is expected to issue a standard for 56K communications early this year, and modem manufacturers have committed to issuing upgrades incorporating the new standard to existing customers.

The first step toward migrating the entire service to 56K modems was to upgrade one set of the DIAL service modems to K56flex protocol modems during the fall semester. This set of modems was monitored for compatibility with existing lower-speed modems and with x2 and K56flex 56K modems. People dialing in with modems ranging from 2400 baud to 33.6 Kbps made connections as they always had. Those dialing in with x2 protocol modems connected cleanly, though at a maximum rate of 33.6 Kbps.

Connections originating from K56flex modems attained significantly higher data rates. Due to the varying quality of the phone lines between the calling modem and ACF's modems, these rates were not the full 56K possible under perfect conditions. On average, the connection speed from a K56flex modem to an upgraded ACF modem was 40K, though rates as high as 52K were recorded. The highest-rate connections were placed from newer, high-quality local loops. (A local loop is the connection from your phone to your phone company's local office.)

With these results in hand, ACF upgraded the entire set of DIAL and LawDIAL modems over the winter recess. Now, when you connect to the DIAL service, you are reaching a K56flex protocol 56K modem. If you have a 33.6 Kbps or lower speed modem, you won't notice any difference in your service. With an x2 protocol modem, you'll see a maximum connection rate of 33.6 for the present time. With a K56flex modem, you'll get a much faster connection, but the exact speed will vary according to the phone lines between your computer and ours.

If you own a 56K modem, whether it is K56flex or x2, things will change slightly when the ITU standard is announced. With the new standard, new firmware will be written for 56K modems. Firmware is the programming within the modem which determines how it handles data. The DIAL and LawDIAL modems will incorporate the new standard as soon as the firmware upgrades are available. You will need to contact the manufacturer of your 56K modem to obtain the correct firmware upgrade for your modem.

If you are looking to purchase a 56K modem before the ITU standard is issued, choosing between the K56flex protocol and the x2 protocol is less important than choosing a modem manufacturer with a good reputation and a solid upgrade policy. ACF's modems are running the K56flex protocol only for the present time; after the ITU decision all modems will share a common protocol.

When buying a 56K modem, you should pay careful attention to the manufacturer's policy on upgrading to the ITU standard to avoid an additional charge.

Posted January 20, 1998