FW: [802-11TGS] Beacon issue during Mesh Link Estabilishment phase
Colleagues,
The active discussion of beacons and probe/responses for things like
neighbor discovery and capability information may resonate with the .21
information services or event delivery models. There was interest in
pursuing a dialogue on this in the past. Perhaps we should (at least
informally) stay in touch with these discussions to see if the .21
concepts might be useful during .11s standards development.
Best Regards,
Michael Williams
IEEE 802.21 WG Vice Chair
-----Original Message-----
From: ***** IEEE stds-802-11-tgs List *****
[mailto:STDS-802-11-TGS@LISTSERV.IEEE.ORG] On Behalf Of ext Yang, Lily L
Sent: Saturday, January 15, 2005 12:00 AM
To: STDS-802-11-TGS@LISTSERV.IEEE.ORG
Subject: Re: [802-11TGS] Beacon issue during Mesh Link Estabilishment
phase
--- This message came from the IEEE 802.11 Task Group S Technical
Reflector ---
Hi, Akira --
Yes, we have not updated this subsection for quite a while and I agree
that we can add a little more details in it.
So I took your suggestion and added a few more details in it. Here is
the new text for 3.1:
"Similar to active scanning and passive scanning defined in 802.11,
802.11s needs to define mechanism(s) to aid the mesh discovery process
for new Mesh Points. It is an open question whether TGs needs to define
both passive and active mesh discovery, but some discovery mechanism
must be defined in TGs so that a Mesh Point can discover the existing
WLAN mesh in its environment.
To support passive scanning, the WLAN Mesh should have a way to
periodically advertise its existence and its capability information, for
example, by Mesh Beacon Messages. Whether such mesh beacon messages
should be sent out by only a subset of the Mesh Points (e.g., elected
leaders among Mesh Points), or by all Mesh Points, needs to be
investigated. Issues to study also include the scheduling mechanism of
such periodic beaconing and appropriate time interval. If beacons are
sent by many or all of the Mesh Points in a dense mesh network, careful
consideration should be given to the bandwidth overhead consumed by
beacons. On the other hand, if beacons are sent only by a very limited
subset of Mesh Points in the network, service area covered by such
beacons might not be sufficient.
In addition to supporting passive mesh discovery, Mesh Beacon may also
be used for other purposes like time synchronization, neighbor
discovery, etc. Such additional requirements should also be carefully
examined and taken into accounts when designing Mesh Beacon protocol.
On the other hand, Mesh Probe Request and Response can be used to
support active scanning for fast Mesh discovery. A mechanism is needed
to determine which of the Mesh Point should respond to a particular Mesh
Probe Request."
While I am at it, I also revised 3.2 slightly to improve its
readability:
"Before any data forwarding service between Mesh Points can be provided,
a trusted mesh link must be established between two Mesh Points. This is
similar to the authentication and association service defined today in
802.11, but 11s needs to define a suitable Mesh Authentication and
Association framework that takes into account the inherent distributed
nature of mesh networks. Such framework belongs to the Mesh Security
component, and is outside the scope of this document. However, it is
only after such authentication and association, the secure link between
two Mesh Points is considered to be established for data forwarding."
I just uploaded v10 of this document to include these changes. Please
review and discuss it next week at the meeting.
Thank you all!
Lily
-----Original Message-----
From: ***** IEEE stds-802-11-tgs List *****
[mailto:STDS-802-11-TGS@LISTSERV.IEEE.ORG] On Behalf Of Akira Yamada
Sent: Friday, January 14, 2005 8:47 PM
To: STDS-802-11-TGS@LISTSERV.IEEE.ORG
Subject: [802-11TGS] Beacon issue during Mesh Link Estabilishment phase
--- This message came from the IEEE 802.11 Task Group S Technical
Reflector ---
Hi Lily and all on TGs:
"3.1:Mesh discovery by a new Mesh Point" in doc#968-07 says:
"Issues to study also include the scheduling mechanism of such periodic
beaconing and appropriate time interval."
I think we also need to study "Overhead by beacon" in a mesh network. In
the case of high density Mesh Point deployment, bandwidth used for
transmitting beacons becomes severe.
Best Regards
Akira Yamada NTT DoCoMo,Inc.
Communication Systems Laboratory, Wireless Laboratories.
TEL:+81-46-840-6527 FAX:+81-46-840-3789
yamadaakir@nttdocomo.co.jp,ayamada@mlab.yrp.nttdocomo.co.jp
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