I just installed a link using CM9, Station Server, WRAP board, about 300
yards away LOS, with only a single client so far on AP to SU mode. The
radios associated at 54 mbps, and about -70 db, with a quality of 24/29.
All speed enhancement features enable, and encryption turned off.
Using Station server throughput test, testing from AP, the RX was 13.6
mbps,
and the TX was 9.1 mbps.
I thought that was odd, because I thought the TX would be faster. (AP to
SU)
This supported my estimates that 54 mbps Atheros card's top real
throughput
(for 54 mbps) was about 14 mbps, in a best case scenario. Then through
in
longer range links, interference, hidden node (or CTS/RTS to cure),
retransmissions, heavy use links, and before you know real throughput can
be
much less than 10 mbps. Asumming of course Turbo Mode won't be used to
hog
up channels.
My tech question is... Is this being limited by the Atheros chipset, or
the
WRAP motherboard? If using the Mikrotik RB532 board with higher processing
speed, can a single Atheros card transfer at a higher rate?
For those interested....
My business decission question is:
1) If Atheros can't go higher than 10 mbps in real world PtMP and...
2) Trango has fixed its short range packet loss problem (which they have)
3) Trango has new low pricing on Fox-D2 CPE (dropped $100 or so)
4) Trango has better testing tools
5) Trango avoids all the problems of 802.11 standard and home brew that
cost
ISPs aggrevations (accept large packets 1600b, pre-assembles, consistent
availabilty, security, better remote management, ARQ, etc),
What reason would there be to use anything but Trango broadband, even for
small community projects?
802.11 Atheros gives you...
1) Mesh designs
2) Relay radio designs, multiple antennas/links per single unit, with only
a
$50 cost per radio card added.
3) HotSpot, compatible with laptops built-in config.
4) Built in VLAN switch, when used with Mikrotik RB532&daughter card.
5) OMNI support, when 6 sector design not needed.
6) One radio to stock, that supports ALL Freqs, for easy on the fly
adaptabilty (pending antenna swap).
#2 was good to reduce roof top colocation costs, by not needing to discuss
the need to install two radios with a landlord for roof top approval.
My recent interest, was for #4 and #5 for a small multi-building /
multi-tenant complex.
I reduce AP costs, by using only one AP w/ OMNI (OK for short range),
apposed to Trango sector model. In a worse case scenario, where a Trango
60
degree, would cover all MTUs based on edge of complex placement, Mikrotik
802.11 would still save about $400 on the AP side. On the MTU side, I
would
normally pay $385 for 802.1q VLAN switch (24 port) for EACH building,
apposed to $99 additional for Mikrotik RB daughter card (total of 9 ports
including RB532). Many complexes have less than 8 subscribers per
building.
But if we use an example of a 4 building project, the savings for a VLAN
switch would add up quick to around $1100, and adding simplicity with
maintenance of only one device (the CPE/Router/VLAN combo) instead of two
devices (VLAN switch and CPE Router). It also reduces costs for remote
reboot devices, as the Mikrotik has a hardware watch dog, where as a
typical
VLAN switch would not. We use WDS to accomplish VLAN support. We use
VLAN
support for several reasons. 1) it protects end users from seeing other
end
users for security. 2) It allows us to more easilly centrally bandwidth
manage and route via VLAN (per customer), apposed to paying attention to
IPs
and MACs which may have the need to change over time, or may not be known
in
advance. 3) Prevents customer's misconfigurations from effecting other
users' links or router configs. Because the traffic doesn't cross paths,
it
can't conflict. The misconfigured client only gets effected.
I will say, after all the time it has taken me to order, deploy, figure
out
how to configure, and wait for equipment stalling reocurring revenue, I'd
argue I would have saved by just deploying Trango and VLAN switches to the
project.
Another problem, is that if VLAN is used, its no longer possible to use a
Trango sector for both VLAN and non-VLAN customers at the same time,
because
large VLAN packets would get their would be no VLAN device on the Non-VLAN
custoemrs to untag
In summary...
1) If Trango would add a third external connector option to their 5830AP
line, like the 900APs, it would drastically reduce the justification of
home
brew wifi, making it much more affordable to use Trango for these type
projects. It still wouldn't fix the VLAN cost reductions, but then again
so
what.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
