802.1p: Who's policing the police

It's easy to presume that implementing 802.1p prioritization on your network will make things run more smoothly, but how will you know? The answer isn't very appealing.

Traditionally, network analysis has involved tracing traffic profiles with a network analyzer. Even in switched networks, most LAN switches support a monitoring port that allows user to tap into network activity.

However, an analyzer is only helpful when it can properly diagnose a problem, and here's the rub: Many of the network analyzers on the market today don't decode 802.1p protocol information. Furthermore, those that do, often only identify one or two priority levels. That presents two problems:

First, users can't determine whether the priority tags are being applied to the traffic properly. One might be able to determine, for instance, that a switch or an adapter was configured to assign HTTP traffic to high priority. However, without proper network analysis, there is really no way to determine whether or not the priority was ever actually assigned.

The second problem is that lack of protocol analysis makes it nearly impossible to determine whether internetworking equipment is properly applying the traffic priority settings. For instance, if users can't determine which traffic is priority 1 vs. priority 7, then they can't determine how a switch is handling each traffic stream.

With the growing interest in 802.1p (and in its parent, 802.1q), expect to see growing support for 802.1p decodes among network analysis equipment. However, be forewarned that support is by no means universal, and it's very possible that you'll need to upgrade your analyzer if you want to decode 802.1p information.

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