Impressive list of Q&A. Not an issue, but I think the Questioner was asking
about a different topic than the answerer was thinking of on one question.
I added the "Q" & "A" to make it clear:
>Q Are there any known problems with over-polling an AP with SNMP?
>A We do not use polling. In our view it is less efficient than our
>implementation.
I believe the questioner was thinking about a recent thread regarding Canopy
where a couple wisps surprising observations were being discussed relative to
the product's recent major OS replacement release by Motorola (Release 8). In
the thread someone observed that his network traffic appeared to "slow down"
when his network management application began polling radios by SNMP.
Continuous ping window times climbed in curious coincidence with network
manager performance polling. That's why from the langugage (and mention of
SNMP) I don't think he was referring to polling as a means of bandwidth
allocation between APs & SMs. Changing OS (and consequently stacks) is a
significant change. There was a previous list of Canopy problems attributable
to the OS communications stacks that could not be addressed because the license
for the stacks did not provide source to the Canopy developers. Ultimately a
change to a different OS & license (where all communications stacks were
provided with source) was needed so that the developers had the means to work
on problems that had been long unaddressed. Motorola beta tested this Release
8 longer than typical because of the major impact such a change could
potentially create. However, it was eventually released (very recently), and
some strange stack behaviors have begun to be noticed.
If I'm interpreting correctly this is a very "different" question, indeed. It
likely has to do with how APs and BH units prioritize responding to management
communications over customer traffic. It might even involve issue with the
number of threads the OS can support. The questioner is simply wondering if
others have noticed "known problems" with SNMP polling of APs. Canopy may have
some issue, which could be significant to a wisp if he's become reliant upon
network performance monitoring (which is a good thing IMO).
Rich
----- Original Message -----
From: Marlon K. Schafer
To: WISPA General List
Sent: Saturday, March 10, 2007 11:01 AM
Subject: [WISPA] Fw: [WISP] Sort of OT: Long list of answers...
I found this thread interesting.
Enjoy,
marlon
----- Original Message -----
From: Patrick Leary
To: [EMAIL PROTECTED]
Sent: Friday, March 09, 2007 5:51 PM
Subject: [WISP] Sort of OT: Long list of answers...
So a gent on the P15 Moto list asked a huge number of questions about Canopy.
I thought it would be very interesting to attempt to answer them from a VL
perspective. Since it took a ton of time, I wanted to get some use out them.
Excellent questions actually. Pretty darned thorough.
Patrick Leary
AVP WISP Markets
Alvarion, Inc.
o: 650.314.2628
c: 760.580.0080
Vonage: 650.641.1243
[EMAIL PROTECTED]
Are modifications to the APs FCC legal?
No, but we numerous 3rd party sectors sectors certified that may e used.
Our sectors range from 60, 90, and 120 degrees, plus omni choices (God forbid!)
How wide are the 5.7 AP channels, is this adjustable? What would a SA
show the channel width to be?
Yes, 10 or 20 MHz wide. You can also change on the fly and all CPE will
adjust automatically.
What is the real-world distance achieved in a LOS situation without
reflector, with?
The CPE with VL comes with an integrated antenna which enables on the VL to
reach about 7 miles LOS at full capacity (32mbps net ftp), 16mbps at 5 miles,
29mbps at 2 miles and 32mbps at 1 mile. The answer BTW to your Canopy question
can be found on their doc CNPY-ADV-SUBMODFCT brochure produced in 2006. On that
doc it says the range of the 5.7 w/o reflector is 14mbps to 1 mile and 7mbps to
2 miles. Beyond that you must have a reflector. With the reflect you get 14mbps
to 5 miles and 7mbps to 10 miles.
Are there any tools or utilities that Motorola or other offers to assist
in the network development of Canopy products?
There are things like link calculators, channel plan docs, and plenty of
opportunity for direct consultation.
Can two SMs on the same AP talk to each other without special routing?
In VL it could be enabled via the many VLAN capabilities, which include
QinQ VLAN support, but VL intentionally does not allow this out of the box (it
is something the operator, i.e. you, should have control over.)
Explain how the Advantage 14MB/s (or 20MB/s) works, how is that
allocated, how true are those figures? Is the allocation dynamic? Can
you mix breeds of SM on the AP?
VL uses OFDM, which gives it some NLOS abilities (not so much with trees,
but it also helps a bit there). The OFDM we uses adaptive modulates (dynamic)
to maintain the best connection. Each mod level down is a lower rate. You can
also set the radio to fix on a modulation level if you wish. All VL CPE
versions work seamlessly together in any sector.
Can an SM access the AP it's on for management?
In VL the operator can assign multiple stations for management access.
Is there a feature to disable broadcast traffic?
Yes, VL has a "broadcast rate limiting" feature which can be set per
subscriber. It can also send you a trap if any set station nears its limit.
Why can't the APs use horizontal polarization? Doesn't this limit the
radio's ability to co-locate?
The CPEs now have an option (in the rev E version hardware) to be either H
or V pol mounted. The AUs can be mounted either way (by way of antenna choice).
Why is the latency so high for the APs (5-7ms)?
N/A, but looking in terms of a specific application, the delay with the
optional "WLP" (wireless link prioritization feature) feature is stable at 4 or
less ms.
What is the maximum PPS per AP?
Up to about 60000 downstream and 48000 upstream.
Are there any tools to prevent or reduce the impact from an end-user
launching a DoS attack?
Yes, the broadcast rate limiting feature was designed specifically because
of this threat.
How do the APs handle VoIP traffic? Is there anything that can assist
this?
Better, literally, than any other AP in unlicensed, with up 288 CONCURRENT
VoIP calls per AP (we call them AUs) with a MOS of better than 4.0. With the
WLP feature implemented, MOS is typically over 4.1 and many tests show over
4.4. (I have some great VoIP graphs). We can also run tons of concurrent data.
The graphs show this too.
What is a realistic number of concurrent VoIP sessions an AP can handle?
VL is the only product that can literally and dynamically prioritize VoIP
over the entire pipe and across the entire sector (versus just dedicating a
partition that must be allocated whether used or not). At the same time, VL has
a starvation prevention mechanism to prevent starvation of low priority traffic.
Are there any known problems with over-polling an AP with SNMP?
We do not use polling. In our view it is less efficient than our
implementation.
Are the SMs SNMP capable, or only the data from a SM through the AP?
Yes, if set to be one of the management consoles.
What improvements over the current APs does Motorola hope to achieve in
the next generation?
VL was launched in 2002. Then it only netted about 12mbps. It now nets
32mbps. Many features have been added, such as 4th gen CIR/MIR, broadcast rate
limiting, VoIP from 40 calls per sector to 288, pps from about 3,000 to what I
noted above, etc., etc. This has always been done with backward compatibility.
(I can't yet name specific new features as v4.0 and rev E are both already new.)
Since Canopy's inception has there been an upgrade to the AP that was
not backwards compatible with existing SMs?
Never. VL has always supported backward compatibility.
Is a Lite SM the same hardware as a regular SM?
We have no such animal. We have real VL CPE (rev E 3mbps version) for only
$285/ea (all inclusive) under the AlvarionCOMNET program (that's with a 25/CPE
per quarter commitment).
Can lite SMs be purchased individually?
All CPE can be bought individually or in packs.
What is the benefit to using a SM other than the lite?
N/A
Can a non-advantage AP be software upgraded to Advantage?
N/A. But we do offer a limited association AU (designed for rural markets).
It can be upgraded to a full AU.
What is the voltage pin out on Canopy equipment for PoE, is positive on
pins 7 and 8 or 4 and 5?
I'm not an engineer (or sales VP either actually), but I believe it is
54vDC. Off hand I'm not sure which pin, but I can found out if you really want
to know.
What voltage range can the Canopy accept? (Min, Max)
VL can be powered with -48vDC or AC (the IDU side - indoor unit - ranges
from 85-265 vAC with 50-60 Hz).
How does GPS sync work?
VL does not need sync in our view. Our channels do not bleed near the
extent of certain other brands (as per a large such user tells me). We also
have very high capacity so we do not need the kind of re-use some require on
the same tower and planning between cells is fairly straight forward. We also
use higher end antennas (MTI) on both ends and with some FCC-legal 3rd party
antenna options on the AU side. We also use dynamic ATPC so our radios do not
talk beyond their connections.
What benefits does the CMM offer over the syncpipe? Is the satellite
management necessary?
N/A
What level of tolerance is acceptable with GPS sync? Can the GPS sync
cable length add delay?
N/A
How many GPS units are required for a network? Can the GPS data be sent
via the wireless to other towers?
N/A
If my network is GPS synced, and my competitor's network is GPS synced,
are they in harmony or do we have to coordinate our efforts on GPS sync
specific settings to reduce interference?
N/A
How do the APs handle interference? What methods to they use?
VLs are hugely configurable, but some of the key things are use of smaller
channels, tighter antennas (10 degrees on the CPE). OFDM's adaptively sliding
modulations, adjustments to various parameters, etc.
Is there a RF receive threshold that can be set? How fine is the
adjustment of this setting? Does it exist on both the AP and SM or just
one?
20 - 4,032 byes (both ends) with a default of 60 for SUs and 4032 for AUs.
What is the process of changing a channel on the AP? How do the SMs
know the new channel to change to?
Simple, a few keystokes. SU's change automatically.
Are there broadcast commands that can be sent to all SMs on an
particular AP? Or all SMs on the network?
Yes and yes.
Does the Canopy support ARQ?
Yes, VL does ARQ.
Explain what Transmit Frame Spreading is, what are the pros and cons?
N/A
Explain the 1x and 2x options, what are the pros and cons?
N/A
Where are the SMs authentication information (MAC, etc.) stored at? AP
level? If an AP fails, what is involved with replacing that AP and
restoring the SMs? Are there any backup utilities to assist?
MAC table. If an AU fails and the "best AU" setting is enabled the CPEs
will automatically re-associate to the next best AU. All CPE and AUs have a
shadow flash and different firmware can be stored on each flash, this is
invaluable if for some reason an upgrade fails in process. We are the only ones
with shadow flash (that I know of). AUs can also be deployed stand alone or as
part of a chassis system with blades. In the chassis configuration supports
redundant power and you can swap IDUs should an IDU fail.
Explain how canopy (not db) RSSI value is calculated?
We do not do RSSI, we do SNR and it is hardcoded, but the 10 SNR LEDs on
the CPE directly correspond to a specific SNR number.
What exactly is the definition of Jitter? Explain how jitter is
calculated?
Jitter is just not something that we have to deal with in VL except with
respect to VoIP and other real time sensitive apps. Our VoIP jitter using WLP
is under 3ms. A good definition though can be found via this link:
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci213534,00.html.
Discussion of jitter is not in the manual and I have never heard it discussed
among VL users in any forums. I believe it is a non-issue on the data side.
Explain how the test link function works, why is it disruptive to the
entire AP?
N/A
What must be changed from default values on an SM to begin the survey
process?
N/A. Nothing, on AU or SU end. Once the survey is over the system will
revert to its previous configuration.
What is the suggested method of validating a new installation - what
parameters should be measured?
Again, I am not an engineer, but you'd certainly want to validate the
quality of the link relative to the pre-installed expectation, so you really
just need to pass traffic via your preferred test method (chariot, etc.). If
the quality is not as expected, then you delve into looking at the myriad of
counters. Of course, if you are tagging for VLANs you need to validate, as you
would anytime you affect any specific setting. Beyond that, I'd defer to my
engineers.
How often is firmware updated? What is the method of upgrading
firmware?
Periodically when we can come up some major new thing or per market
request. In addition, if needed we provide timely bug fixes to issues found by
customers after we can repeat and fix. All upgrades are just a few key strokes
and can be down network wide, sector wide or specific set of SUs, all with a
few keystrokes. Of course, as mentioned before we have shadow flash.
How long is the product's warranty, when does that warranty begin, how
is this proven?
One year, usually from the date it ships from our warehouse, but in
recognition of the channel reality, we also have a grace period (flexible).
How is the RMA process handled? What is the return time? Whom do I RMA
to?
RMAs are processed directly. One VAR is able to process his own I think. It
is initiated by online opening of a trouble ticket. It is generally a two-stage
process (unless we know the user is highly advanced, where the 1st stage is
bypassed). Once the ticket is placed we call back and talk through the issue.
We have found in most cases the unit is fine, but the operator had limited
knowledge. Should it be determined a return is required, we process it using a
credit card number to hold as we ship the new unit before we receive the old
unit. Since replacements come from stock, exact time span depends on inventory
actually, but most products are commonly kept in inventory.
If the Prizm is management software necessary for several functions, why
is there a charge for it?
Our BreezeCONFIG comes with the units and (I'm told) does the things that
some brands force payment for, as does other advanced tools. By the way AES is
also standard and is hardware embedded so there is no major performance
sacrifice to implement it.
If the Prizm software crashes, do SMs lose their license for the
duration of the outage?
N/A
Can the Prizm software only allocate licenses on certain APs with
licenses?
N/A
Why are floating licenses sold instead of just unlocking the unit's full
capabilities?
N/A
What is real-world throughput on a lite 2mb/s floating license? Is that
aggregate? Can that burst higher?
In our CPE, a 3mbps CPE will (all number here in ftp net) do 3mbps
down/2mbps up, a 6mbps CPE will do 6mbps down/4 up and the 54 is wide open to
32mbps should the link budget allow it.
What is the BAM?
Our "bandwidth allocation module" is not a separate thing. Our MIR and CIR
is in the firmware and does not coast extra, it is also dynamic and intelligent.
When is the WiMax equipment schedule to be delivered?
Which band? We have been shipping some bands since 2004. Maravedis (and no,
we don't pay them to say it) says in terms of real WiMAX deployments we have
65% market share. On Feb 14 Motorola said it had 4 WiMAX signed contracts and
23 trials. We have 140 commercial deployments and over 200 other trials as of
the end of 2006. The delivery time for UL WiMAX is still not firm, due to
complex issues (UL WiMAX may get hosed by other UL until the mechanism being
developed in the IEEE 802.16h task group can be ratified and implemented. We
chair this TG. Also, the UL WiMAX profile that was developed by the WiMAX Forum
is ONLY for 5.725-5.850 GHz, not 5.3 or 5.4. That's a problem. Also the profile
is only 802.16d and not 802.16e and that's a bigger problem since the entire
weight of the WiMAX ecosystem is being crafted around 16e. So there are things
to sort out. I can explain further. We are charter members of the WiMAX Forum
and we are number two in executive rank there (under Intel).
Will the current SMs be compatible with the new WiMax stuff? How will
this be possible?
When it finally happens, they will not be able to connect to the same
sectors. Don't believe anyone that says they will.unless they remind you it
also means a truck roll, which is something all can say. I'm from Missouri on
this one and we know WiMAX best (not a boast, just a fact of the market).
Can Advantage APs be software/hardware upgraded to the future WiMax?
No.
What are the main 5.7GHz types of SMs?
5700, 5750, 5760
3 meg/1 MAC, 6meg/full bridge. 54meg/full bridge - all with integrated
antennas (currently 21dBi MTI panel). We also have an "E" model with an N-type
connector for support of an external antenna; these are all 54meg full bridges.
The hardware rev E version, beginning to ship now (and yes, they live with the
others) has a slightly wider antenna (20dBi I think) and support H or V pol
mounting.
Can a 5700 SM be software upgraded to a 5750 SM?
N/A
Do you have any Canopy end-users I can contact telephonically to discuss
the advantages of Canopy over Trango?
Any day. If you want I can make e-mail intros, and I'm talking about users
who have done both or might even be large Canopy users now.
What other third party products can you tell me about?
VL does not need things like Stingers (very nicely done though by Chuck's
people at Beehive) or the Cyclone by the Last Mile guys (nice too). The VL
already does the things natively (i.e. the line did not have "holes" that 3rd
parties had to fill).
Does Canopy support OFDM?
VL is the market's first UL PMP OFDM product, originally launched in 2002.
It remains the most deployed in the world among UL OFDM products.
Is there a way to force the SM to stay at a certain power level?
We use ATPC (Moto does enable forced TPC). ATPC an also be disabled on ours
(though you rarely would).
Does the SM and AP's handle PPPoE traffic?
We can enable or disable. From the manual: The PPPoE Broadcast Override
Filter option enables or disables the broadcasting of PPPoE (Point to Point
Protocol over Ethernet) messages. Even if according to the selected option in
the Filter Options parameter, broadcast messages should be filtered, PPPoE
broadcasts are transmitted if this parameter is set to Enable. We have the
following options: Disable - PPPoE Broadcast messages are filtered or
transmitted according to the general filtering criteria in the Filter Options
parameter. OR: Enable - PPPoE Broadcast messages are transmitted regardless of
the selected value of the Filter Options parameter.
Do the SM and AP allow for firmware to be downgraded if necessary?
Yes.
Does Canopy have any plans to implement MPLS?
Not yet. We do pass jumbo frame sizes (for some reason I think this is
important with MPLS?)
How can we monitor the SNR (Live readout of noise level)?
By physically looking at the LEDs or via telnet or SNMP.
Are there any utility's or built in tools that the AP or SM have for
troubleshooting?
BreezeCONFIG has exhaustive trouble shooting means. New users from other
brands are usually blown away (again, you can talk to some)
Do the SM and AP have a log that we can see information about interfaces
and traffic?
There's a question I do not know the answer to, but I can find out.
Obviously not like a packet shaper though.
Is the throughput at the SM level effected by the RSSI value?
This is true of all wireless products - it is not a brand question and the
answer is "Yes."
Is the throughput at the SM level effected by distance?
Same as above.
Yea, that's it for now! (:
Whew, that took a while. But it was a good exercise for me anyway.
I'm happy to say I could answer most without looking at the manual. Not bad for
a non-tech.
Regards,
Patrick
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