Date: Fri, 7 Jun 96 15:15:55 EDT From: Milan Merhar To: jlarsoon@fnal.gov Cc: p8021@hepnrc.hep.net Subject: 802.1p/D3 Ballot SUBJECT: P802.1p/D3 - Traffic Class and Dynamic Multicast Filtering Services in Bridged LANs _X___ I disapprove for the following reasons. Milan J. Merhar____________ ---------------------------------------------------------------------- I believe that the method specified for signalling the priority of unicast messages by registration of individual addresses is not practical under many conditions of expected usage. The specified method is quite reasonable, if an individual address identifies a device requiring a particular level of message priority for all its network communications. Unfortunately, the expected users of elevated priority (e.g. - control messages, video and audio data streams, etc.) commonly share the same network interface (and therefore, the same network address) as applications not requiring anything more than default network priority. If this potentially large amount of traffic is also introduced into the network with elevated priority, it may degrade the network performace seen by the intended users of elevated priority to unacceptable levels. The only alternative available within the specification as written is to assign one individual address per device per priority level to be supported. This is both administratively complex, and in many cases functionally intractible, given the existing capabilities of available LAN interface hardware. I suggest that the following changes be applied to p802.1p/D3: Remove all references to the ability to register an individual address for the purpose of assigning message handling priority. Permit use of the specified queueing model and priority-sensitive forwarding process for registered group messages and messages carrying priority signalling information using means other than the registration of individual addresses. (Stripped of weasle-wording, this would allow both existing 802.5 and future 802.1Q access to the multiqueue priority sensitive forwarding system.) --------------------- Milan J. Merhar, Consulting Engineer Whittaker Xyplex 295 Foster St. Littleton, MA 01460 USA Internet: milan@xyplex.com Phone:(508)952-4713 Fax:(508)952-4887