All things related to multicast

[debbie fligor <>]

Well, they weren't all that quick on the answers, but I did specify  
this was a low-priority request.  Below is what I've heard back so far  
from Meru.  I was very specific that I needed non-NDA info, so you  
should be able to share this as needed.  I'm hoping to get the rest  
filled in over time, but wanted to pass on the parts I've gotten.



Q: How is multicast sent to AP from the controller?

A: Meru’s platform does not propagate L2 broadcast or L3 multicast  
frames to the wireless network. Instead Controllers send a unicast  
frame to the relative client. Meru can proxy all L2 broadcast and L3  
multicast frames, if needed, but this is not the default mode of  
operation. Streaming applications that require broadcast/multicast are  
supported per ESS, yielding industry-leading performance. To save  
power in phone applications, clients typically lock onto, and time  
synch with, a single beacon. This is a zero overhead feature of Meru’s  
single channel architecture.


3.5 Release (released in 1Q08)

AP200 Multicast Enhancement

Chooses transmission rate based on associated clients’ data rate


Q: Is multicast flooded to all APs in the SSID or just to AP with  
interest?


A: We proxy ARPs at the controller, thus not propagating ARP  
broadcasts and
mitigating against ARP floods.  On a per-application basis, we can allow
multicasts or broadcasts through to the APs that have clients in the
correct SSID to receive the multicast, and we prune this list by IGMP
snooping to only group members (with 3.6)  Independently for each AP, we
use the highest data rate that all associated clients in the group can
be reached at.

Q: Is IGMP snooping implemented?  What version(s)?


A: IGMP Snooping will be available in version 3.6 out later this year


Q: What about IPv6?  IPv6 requires multicast.


Multicast and IPv6 is supported per ESS.


Q: Is MLD snooping implemented?


Q: Can multicast base rate be set higher than the broadcast rate?   
What are the limitations?


Q:How does multicast work w/WPA2 security?  Broadcast group key?

Multiple unicast?


Q: How does this work with 802.11n multipath?

A: 802.11n is not a problem, so long as group rate selection is done
correctly.
Q: Is multiple unicast better due to retransmissions at 802.11 layer?


A: Converting to multiple unicasts is possible, and appropriate when the
particular application needs a higher level of assurance for packet
delivery and can afford the extra time the individual unicasts take.










On Apr 16, 2008, at 13:26, debbie fligor wrote:

> On Apr 16, 2008, at 11:59, Alan Crosswell wrote:
> > Questionnaire for vendors:
> > - please improve on these questions
> > - please volunteer to take to your vendor (or potential vendors) and
> > report back to the group
>
> I'm up for asking Meru -- I seem to recall seeing Multicast on a  
> roadmap somewhere.
>
> We're also doing a wireless technology review this June, so I can  
> hit a number of vendors up then.
>
>
> > - How is multicast sent to AP from the controller?
> > - Is multicast flooded to all APs in the SSID or just to AP with  
> > interest?
> > - Is IGMP snooping implemented?  What version(s)?
> > - What about IPv6?  IPv6 requires multicast.
> > - Is MLD snooping implemented?
> > - Can multicast base rate be set higher than the broadcast rate?   
> > What
> > are the limitations?
> > - How does multicast work w/WPA2 security?  Broadcast group key?
> > Multiple unicast?
> > - How does this work with 802.11n multipath?
> > - Is multiple unicast better due to retransmissions at 802.11 layer?
>
> -----
> -debbie
> Debbie Fligor, n9dn       Network Engineer, CITES, Univ. of Il
> email: 
>
>           <http://www.uiuc.edu/ph/www/fligor>
>                   "My turn."  -River Tam

-----
-debbie
Debbie Fligor, n9dn       Network Engineer, CITES, Univ. of Il
email: 

          <http://www.uiuc.edu/ph/www/fligor>
                   "My turn."  -River Tam