This story appeared on Network World Fusion at

'Net Insider:

Over specification?

By Scott Bradner
Network World, 09/04/00            

Standards are good things. Standards are good for customers and good for vendors. They are good for customers because they ensure that there are compatible alternative products. They are good for vendors because they can significantly increase the market for a technology. But there can be too much of a good thing.

There has certainly been a problem with some vendors deciding to "embrace and extend" standards, in the words of one, in a way that negates any reasonable standards process, but some of that can be fought in the marketplace. A more systemic problem is that standards organizations have a tendency to produce standards that overspecify, reducing the ability of vendors to develop innovative products that are still interoperable.

A few years ago I, with a bunch of help from Internet Engineering Task Force mailing list discussions, put together an IETF document that tries to give guidance about when to mandate features in standards. This document (RFC 2119, ostensibly defines some key words for use in standards documents, such as MUST, MAY and MUST NOT. But a key part of the request for comment is a paragraph of guidance in the use of the specific terms: "Imperatives of the type defined in this memo must be used with care and sparingly. In particular, they MUST only be used where it is actually required for interoperation or to limit behavior which has potential for causing harm (such as limiting retransmissions). For example, they must not be used to try to impose a particular method on implementers where the method is not required for interoperability."

This guidance came to mind yesterday when I took a look at a new TIA/ EIA interim standard on "Performance and Interoperability Requirements for Voice-over-IP Feature Telephones" (

This is a well-done document. It does an excellent job of how voice-over-IP phones need to work. It does so for three types of voice-over-IP technologies: the International Telecommunication Union's H.323, the IETF's SIP and megaco/H.248 which is the product of a joint IETF/ITU effort. But I think it goes a little too far.

The document has a table (Table 5.2) that is an overview of telephony features. It has a list of 23 features and subfeatures, each with a requirement level. These range from the "mandatory" ability to originate and accept calls to the "recommended" ability to encrypt calls. I see too many features that are labeled mandatory which are not needed for interoperability. I see no interoperability or harm-avoiding reason to mandate a message-waiting indicator, for example.

To steal from Einstein, standards should be as complete as they need to be and no more complete. Going over the fuzzy line is counterproductive and will ensure less innovate products.

Disclaimer: Harvard, like any good university, ensures that lines are rarely sharp, but the above worry is my own.

All contents copyright 1995-2002 Network World, Inc.