Subject: [Capwap] The QoS-DTLS factor.

From: "Mani, Mahalingam (Mani)" <[email-masked]>
Date: Wed, 24 Jan 2007 00:05:16 -0700

This was one of the issues we had to defer discussion on in IETF67 as we
ran out of time. We hope to resolve this in the interim meeting and over
discussion in the list simultaneously.

When the data traffic is DTLS protected between WTP & AC - the different
streams QoS-marked (marked 11e to DS and Diffserv from DS) will need to
carry appropriate markings. However, this can lead to spurious replay as
the markings may cause reordering along the way.

This is a concern for both WTP-terminated 802.11i (as above). This is
perhaps a concern for AC-terminated 802.11i as well - given that the
encapsulation marks the packets per 11e-802.1q or 11e-diffserv
translation (without decryption at WTP).

What is the recourse?

1.	do not mark the encapsulation at all.
2.	entertain multiple DTLS streams - one per DSCP.
3.	propose enhancements to DTLS to support multiple DSCP-specific
SAs per session or some variant thereof. Michael Williams has suggested
a proposal approximately on these lines.

This may not be a concern for control path. However, is there a need to
expedite some messages in control path and need to be marked EF? If so -
that could give rise to the same problem in the control path as well.

Welcome discussions on this.

-mani

_________________________________________________________________
To unsubscribe or modify your subscription options, please visit:
http://lists.frascone.com/mailman/listinfo/capwap

Archives: http://lists.frascone.com/pipermail/capwap