1. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 1 Supporting Drop Eligibility in IEEE 802.11 MAC Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair stuart@ok-brit.com as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdf stuart@ok-brit.compatcom@ieee.org Date: 2007-05-01 Authors:

2. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 2 Abstract This contribution proposes a mechanism for supporting frame drop eligibility in IEEE 802.11 MAC

3. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 3 What Is Drop Eligibility? The ability of a system (a network node, a station, an access point) to selectively drop frames when congested. Frame drop eligibility information is included in the frame header.

4. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 4 How Can it be Used? In existing data networks, e.g. IP drop eligibility is used to differentiate between in-profile (low discard precedence) and out-of profile packets (high discard precedence) –In or Out of profile is determined according to some conformance definition usually based on token (leaky) bucket algorithm Some application, e.g. Video applications, generates frames with different importance –“Not all bits are created equal”  video over wireless tutorial –I, P, and B frames

5. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 5 Some Examples IP Networks –IP differentiated services defines a number of per hop behaviors (PHB) –Assured Forwarding defines 3 drop eligibility levels for each AF class –PHB information is included in the type of service (ToS) byte of the IP header Frame Relay Networks –Discard eligibility (DE) bit FECN DLCI C/REA BECN DEEA ToS Byte PHBECN

6. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 6 Nodal Scheduling Decisions Nodal scheduling decisions are working in two dimensions, urgency and importance Urgency is decided by the transmission scheduler (who goes first) Importance is decided by the discard precedence (whom to keep) Urgency Importance

7. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 7 What does IEEE 802.11e Have? IEEE 802.11e user priority (UP) is based on IEEE 802.1D –Defines 8 straight priority levls –No consideration for discard eligibility. IEEE 802.11e somehow convolute the 8 priority levels with the 4 access categories (AC) –IEEE 802.11e operates on one- dimension only (urgency) –Only 4 code points levels are needed to support the a AC. Urgency Importance

8. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 8 What Happened since then? IEEE 802.1 have updated the semantics of the UP bits with the approval of IEEE 802.1Qad (Provider Bridges) amendment. –Allows for multiple options to support discard precedence –There is also an update of the traffic classes table

9. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 9 How Drop Eligibility be Supported in IEEE 802.11 MAC? Only 4 code points are needed to define the 4 AC. –There are 4 other code points that can be used for discard eligibility Discard eligibility can be supported by changing the semantic of the UP bits –In the same way as IEEE 802.1 did.

10. doc.: IEEE 802.11-07/0693r0 Submission May 2007 Osama Aboul-Magd, Nortel Networks Slide 10 References “Virtual Bridge Local Area Networks, Amendment 4: Provider Bridges” IEEE Std 802.1ad-2005, May 2005.