1. RSC Pools for Mgmt Frames
Month Year
doc.: IEEE yy/xxxxr0
March 2006
RSC Pools for Mgmt Frames
Date: June 17, 2006
Author:
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K.Hayes
John Doe, Some Company

2. Replay Checking background
March 2006
Replay Checking background
With a single session flow, frames must be sent in an ordered sequence across the link – frames cannot be reordered within the session
For multiple sessions, the rule above still holds, but frames may be reordered across sessions (i.e. output scheduling may occur)
K.Hayes

3. March 2006
Crypto sequences
TKIP and CCMP require replay checking as receiver function
Verification is asserted with Packet Numbers derived from the IV, extended IV
Transmitter must allocate all Packet Numbers in the sequence received from the network stack, even for multiple sessions; gaps in the increasing Packet Number sequence are allowed
Packet Numbers must never be reused with the same RSN key
K.Hayes

4. Output Scheduling March 2006 Low Prio PN = 11 PN = 9
Priority Scheduler
PN = 13
PN = 12
Hi Prio
PN = 13
K.Hayes

5. March 2006
Crypto sequences (2)
Multi-session receiver cannot use a single Receive Sequence Counter (RSC) to do replay checks; it must have N, where N is the number of streams/sessions
Data frames are “steered” into a discrete RSC bin by virtue of their QoS Control Field’s 4-bit TID, or 0 (zero) if QoS Control Field is absent from frame header
K.Hayes

6. Management Frame Steering
March 2006
Management Frame Steering
Management frames have no QoS Control Field in their header
They have no “priority”. Some implementations may give them preferential output scheduling and others may not.
Their different frame type field (0x0) means they can be easily steered into a distinct RSC pool
K.Hayes

7. March 2006
TGw cipher suites
TKIP and CCMP use a QoS TID field in calculation of their respective MICs; they use 0 (zero) if the QoS TID field is absent
CCMP also uses the QoS TID field in the definition of the Nonce; again it uses 0 (zero) if the QoS TID field is absent
The field used here for mgmt frames for MIC and Nonce inputs must be 0 (zero)
The unique PNs guarantee keys will not be reused on a given payload
K.Hayes

8. March 2006
Management RSCs
If management frames are subject to preferential scheduling, then the implementation must use a separate management RSC for replay checking
This is a receive-side only operation
K.Hayes

9. March 2006
Questions?
K.Hayes