Operational efficiency wins

As we saw last week, one trend is clear: As raw bandwidth has become less expensive over the past two decades, the emphasis on using every possible bit-per-second of that bandwidth has likewise diminished. Instead, other considerations that relate more to the overall efficiency of network operations have taken precedence.

In recent articles, we’ve seen that protocol efficiency seems to have diminished in importance and has given way to multiple other issues. Take, for example, some interesting products recently introduced by General DataComm that would have totally defied all logic a few years ago. These products are designed for transporting legacy asynchronous and synchronous traffic over Ethernet and IP.

With GDC’s new SpectraComm ADT and SDT products, any older equipment that is not IP-enabled can be connected over an Ethernet and IP backbone. This is especially attractive in industrial environments, where process-control equipment has a considerably longer life cycle than your typical PC.

The ADT products are designed for transporting asynchronous traffic, while the SDT transports byte-synchronous High-level Data Link Control (HDLC) and Synchronous Data Link Control (SDLC) traffic. Additionally, contact closures can be monitored for telemetry applications.

From a bandwidth-efficiency perspective, this is a bit curious. You’re taking traffic from protocols like SNA and even frame relay that were designed to be quite efficient. Then you’re putting that traffic into an overhead-heavy IP packet. And then you’re putting that information into an Ethernet frame. So you end up with a two-ounce candy bar in five pounds of packaging.

Nevertheless, this is quite attractive in today’s environment. LAN bandwidth is already almost free, and WAN bandwidth is getting much less expensive. And legacy equipment, having been optimized for an earlier time, uses a relatively low amount of bandwidth – to the extent that the vast majority of the legacy traffic almost becomes background noise on current nets. 

What’s much more important is that the current data network can be used to transport the legacy traffic along with current applications, obviating the need for separate nets.