Re: [16NG] Re: multicast and IPv6 over ETHCS

All,

My 2 cents:

We work with WiMax and Satellite providers (who have the same basic 
topology).  The issue we've seen is the contention for the RF channels. 
This can be avoided on the downlinks, but is critical on the uplinks.  The 
asymmetry between up and downlinks combined with the point-multipoint 
topology exacerbates the problem.  At this time, most WiMax vendors are 
trying to block uplink broadcast/multicast to maximize uplink bandwidth 
available to subscribers (and to maximize the number of subscribers).  While 
historically networks had more download traffic than upload, the trend 
towards more peer-oriented networking creates a challenge that will 
ultmately be addressed, but is currently one of the biggest problems in 
WiMax.

Steve
----------------------------------------------------------------
Steve Jackowski
President/CEO
Deterministic Networks, Inc.
1200 Pacific Avenue, Ste 280
Santa Cruz, Ca 95060

Office: (831) 421-0388 x18
Mobile: (408) 813-6294
Fax: (831) 421-0394
www.DeterministicNetworks.com
"Secure Network Acceleration"

----- Original Message ----- 
From: "Alexandru Petrescu" <alexandru.petrescu@motorola.com>
To: <pars.mutaf@int-evry.fr>
Cc: <v6ops@ops.ietf.org>rg>; <16ng@ietf.org>
Sent: Friday, January 12, 2007 8:43 AM
Subject: Re: [16NG] Re: multicast and IPv6 over ETHCS

> Hi Pars, I would like so see others' oppinions on this too.
>
> Pars Mutaf wrote:
>> Hi, sorry for popping up,
>>
>> On Fri, 2007-01-12 at 12:19 +0100, Alexandru Petrescu wrote:
>>> Hi Jihoon, thanks for reply,
>>>
>>> Jihoon Lee wrote:
>>>> Hi Alex,
>>>>
>>>> Let me jump into discussion. 1) 802.16/16e MAC has no capability to do 
>>>> uplink multicast. In DL, 802.16 provides multicast CIDs which is 
>>>> initiated by DSA messages. In UL, however, there is no way for an MS to 
>>>> access others' UL data fundamentally, in 802.16 PHY/MAC.
>>
>> Do you think this is an accidental design choice (i.e. no uplink 
>> multicast)? Or 802.16/16e MAC designers had very good fundamental 
>> reasons?
>
> I'm not a link-layer designer.  I think the choice for 802.16MAC to
> design multicast only downlink (not ul) is inline with the widespread
> usage of mobile terminals: clients download stuff, rarely upload.
>
> Multi-party video calls (not even IP) need however multicast to run
> bothways ok to gain in efficiency.
>
> And there are link-layers (802.11) that offer a multicast appearence to
> the IP stack, bothways, despite the lower layer packet being sent
> through the AP always.  This should happen over 802.16MAC ETHCS too,
> otherwise ND won't work.
>
> Alex
>
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