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Re: Clearwire May Block VoIP Competitors

  • From: Jared Mauch
  • Date: Wed Mar 30 19:06:57 2005

On Wed, Mar 30, 2005 at 11:32:33PM +0000, Paul Vixie wrote:
> the bigger issue with 802.11 and VoIP is that wireless ethernet tends to be
> half duplex whereas codecs tend to run both directions at once.  who's getting
> good service over 802.11 using G.711 or G.729?  (no fair if your wireless
> handset has its own proprietary halfdup codec, i'm talking real SIP here.)

	you didn't ask for the size of the wireless network(1), in my
experience i've not had any (major) problems with this, the key is to
insure that the packets are somehow QoS'ed at the edge, even if your
provider won't do QoS to you, you can do some neat artifical QoS on
your upstream/uplink interfaces..

	What i've done is rate-limit TCP inbound to be around 75-80%
of the link speed to force things to back-off and leave space for
my UDP packet streams.

	I think one of the major problems is that very few people know
how to, or are capable of sending larger g711 frames (at increased
delay, but more data per packet) because they can't set these more granular
settings on their systems.. this means you have a lot higher pps
rates which I think is the problem with the radio gear, it's just not
designed for high pps rates..

	big thing i've noticed in operational experience is that
not all 802.11 handsets handle AP roaming seamlessly, some want to
disconnect then re-dhcp for what is the same ssid/network domain.

	- jared

(1) - i'm speaking for a single-ssid network with more than one AP that
covers long-distance clients at 1Mb/s speeds on 802.11b (250meter+ one way)

Jared Mauch  | pgp key available via finger from
clue++;      |  My statements are only mine.

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