I don't think that that statement is correct, that a root with mac
addresses:   ##:##:##:##:##:A1 and ##:##:##:##:##:A2 the MBSS will always
choose the A1 node as root?  That wouldn't be very optimal given that A2
may be less hops to a particular node?

The way I understand it (and I may be wrong so correct me if I am) the MBSS
doesn't determine a single global root to use.  Mesh Roots continue to send
out RANN announcements regardless of how many other root nodes are in the
MBSS.  And STA's determine the Root node to use based on metrics, but still
retain proactive paths to each Root node.

After re-reading the draft for mesh roots, and mesh gates.  I
re-gleaned the following, please let me know if im correct.

1) a STA can be defined as a Mesh Root and will then send RANN (root
announcements)

2) a STA can be defined as a Mesh Gateway and will then send GANN (gate
announcements)

3) the Root and Gateway STAs can be the same or separate nodes and there
can be multiple of each if needed.

4.a) A non-root STA will create return paths to each Mesh Root after
receiving a RANN (using PREQ and PREP handshake)

Observation: so ideally (to reduce management traffic) unless some nodes
are not able to communicate with a Root or the network is very large
(geographically) so that nodes at each extreem have
problems communicating to the other side you should only define 1 Root.
 when defining root nodes make them your best reachable STAs, i.e. high up
on towers with excellent line of sight to majority of nodes.  And roots
should have good communications between each other if there are multiple.

4.b) A non-gateway STA will select a (default) gateway after receiving GANN
by comparing metrics for known gateways.

4.c) Gateways will propagate their proxied (learned) external addresses
with other Gateways and will forward externally destined communications to
the Gateway that is currently proxying that specific MAC address.

For example in 4.b above if the originating non-gateway STA sends its
external destined communication to the wrong gateway (i.e. a different
gateway is currently proxying the external address) the gateway will
forward the external traffic to the correct gateway, the new gateway will
then send a Proxy update to the originating non-gateway STA indicating to
use itself for future communication with that external MAC address.
If the external address is not known then the first Gateway will attempt to
find the destination on the external network, failing that will send a
Proxy error back to the originating STA.

??? at this point does the STA try alternate known gateways with worse
metrics, or does communications just fail ?


5) When a path to a destination mesh STAs is not known the originating STA
will select the best root path based on metric at that given time (based
on existing proactive paths) to initiate communications, then will follow
up with HWMP on-demand path mechanism to determine best route.


David Fulgham


On Tue, Nov 22, 2011 at 1:54 AM, Antonio Anselmi <[email protected]>wrote:

> Ss far as I know the HWMP theory says that in case there is more than one
> node configured as ROOT, a mesh node will receive proactive PREQs with
> different originator mac addresses.
> The mesh node then sets the lowest originator mac address as the ROOT. All
> mesh nodes configured to act as ROOT, upon receiving proactive PREQ with
> lower originator mac address, stop sending proactive PREQ and set the
> originator of the proactive PREQ with lower MAC address as the ROOT.
> So finally there remains a single ROOT node which sends proactive PREQs
> and has paths to all nodes within the MBSS.
>
> Antonio
>
> 2011/11/22 MingAnn Ng <[email protected]>
>
>>  Hi all,
>>
>> I had configured two mesh gate and 1 mesh point, they are connect
>> together under 1 subnet. From Wireshark, two root announcement had been
>> observed.
>>
>> How do we verify which mesh gate the mesh point used to ping the PC,
>> which i connect to the two mesh gates using a switch. Does both of the mesh
>> gate operates at the same time or only 1 of the mesh gate will operate at 1
>> time?
>>
>> Thanks,
>> Ming Ann
>>
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