IEEE task force settles on expanded Ethernet frame size

* IEEE 802.3as task force reaches key decisions

The IEEE task force weighing whether and how to expand the size of Ethernet frames met again last week and made a couple of key decisions.

Earlier this year, the study group looking at the possibility of tinkering with the maximum size allowed for Ethernet frames became a task force after it decided that yes, the frame size should be changed. In January, several frame lengths were still on the table.

Last week the 802.3as task force decided on a length of 2,000 bytes as the new maximum envelope frame size, up from the current standard of a maximum of 1,518 bytes. The additional space would be used for header and trailer information.

The specification would warn that some standards-compliant implementations might not be able to handle anything longer than 1,518 bytes.

The group also adopted a timeline - these timelines are always subject to later changes, mind you - of reaching a standard a year from now. The next step is to complete the first draft of the specification, and then it would go through several revisions before being considered by larger groups within the IEEE.

The IEEE 802.3as group had been considering frame sizes ranging from 1,650 bytes to 2,048 bytes. The request for a change had come from IEEE 802.1 - to support 802.1ad, 802.1AE, and other functions. That group had only asked for an additional 64 to 128 bytes for its work, but by raising the maximum frame size all the way to 2,000 bytes, the task force is acknowledging that there could be other unforeseen, future uses for the headroom.

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Frame expansion moves forward

Network World High Speed LANs Newsletter, 01/18/05


Copyright © 2005 IDG Communications, Inc.

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