Tranzeo TR-6019f initial semi-review

I just finished testing a link between two buildings located about
1/3 of a mile apart using a pair these beasties. First, I'd like
to thank Jeff Liebermann for the wonderful information and advice
to a wireless novice about equipment selection and other requirements.

The Tranzeos were *dead* easy to set up. Although the documentation was
a bit on the sparse (to put it kindly) side, the web-based interface
on the units was quite intuitive. Setting a few security parameters,
changing the network setup, and a few other minor tweaks was all that
was required. I then plugged them into one of my office networks
across a hall from each other to play with them.

Short shameful confession: I've never set up bridges before. Routers,
yes. Switches, yes. Bridges, no. It didn't occur to me that plugging
two bridges into the same LAN would cause problems. BAD problems.
Problems that made me run screaming around the office, clearing the
ARP tables from servers and routers, and briefly causing a few
fellow employees and a few thousand customers to lose internet access.
DON'T! DO! THAT!

Anyway, I finally had a chance yesterday to try out the Tranzeos in
the setting they will be used. One went on the roof of the building
we're currently in, and the other went inside the offices we're
moving to. I had roof access to the new building, but I wanted to
see if they would work with one side indoors to make setup easier.
Physical installation was a snap - all needed hardware is included.
The all-in-one units support power over ethernet, which also made
things MUCH easier.

Never having set up a wireless link before, I was unsure how to most
accurately aim the panels on either side. I wound up simply aiming the
roof mounted tranceiver by eyesight, and the indoor one using a pair
of nice binoculars with crosshairs in the lenses. The units were fired
up, and immediately linked at maximum speed. I was floored - I'd fully
expected to spend a great deal of time tweaking antenna direction.

I shoved a bunch of data back and forth over the link, and got speeds
comparable to a LAN connection. Latency was nice and low as well.
They won't be in actual production use for another week or so (delays
in finishing our new office space - who would've guessed?), but the
initial testing was extremely promising. They're a tad expensive,
having cost about U.S. $250.00 each from wirelessguys.com, but the
time savings from ease of setup makes the extra money spent well worth
it in my opinion. If there's any interest, I'll report how they work
under actual network load once the move begins.

JS

"John Schmidt" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
.. If there's any interest, I'll report how they work
> under actual network load once the move begins.
>
> JS

I would like to hear more. I just set up a TR-6019f access point at one end
and a TR-CPQ-19f customer premise at the other end of a 1.5 mile link. I
chose these units because at the one end we have to shoot through sparse
trees. Set up and install was easy. I don't need to send much data back and
forth it is just to share a high speed internet connection in a rural area.
I had trouble right away. The units were reporting -57 signal strength and
link quality of 45 which is excellent. So I went ahead and mounted the
units. The problem was that the internet speed at the CPQ end was down to
dial up speeds. Watching the CPE performance screen I could see the link
speed was constantly changing all they way from 1 to 11. I tried changing
channels, no difference. Locking the units a 2 Mbit/sec improved the speeds
to barely acceptable levels.

I got prompt response from Tranzeo support both via email and phone. About
all they could say was upgrade the firmware(there was just a new release)
and I must have a fresnell zone problem. Yes I have a fresnell zone problem,
sparse trees at one end but had hoped these radios would power through the
line of site issue. The signal strength and signal quality would seem to
indicate that they would. Well I upgraded the firmware on both units. With
the new firmware the units still reported the signal strength at -57 and
they removed the signal quality reporting feature in this release of the
firmware, so no numbers available. But still the same problem, speeds
constantly changing and very slow connection when set to auto, and had to
lock at 2Mbit.

The new firmware brought on another issue. The CPQ has 5 signal strenght
lights to aid in pointing. Before the firmware upgrade the signal lights
were on steady, after the upgrade the every 30 seconds or so the the radio
light and the signal lights go out, flash a couple of times and come back
on. Tranzeo has no suggestions for fixing this. I guess I will have to take
down the CPQ unit and bring it closer to the access point and see if the
problem is fresnell zone issue. If they work properly at close range I will
try switching to horizontal polarity.

Here are the details of my set up in case anyone has advice to offer.

TR-6019f access point connected to a linksys WRT54G V5 router. Mounted 20
feet AGL
TR-CPQ-19f customer premise equipment connected to a computer. Mounted 10
feet AGL.
Access point elevation approx 80 feet higher than customer premise.
Clear line of sight except for sparse trees 75 feet from the CPQ
Signal strength -57
Signal quality was reporting 45
Latest firmware on both units
Both mounted on wood structures

A quick question for anyone, if signal strength and quality are excellent
could the trees cause this problem or should I suspect radio problems? For
sure the issue with the signal and radio lights going out seems tied to the
firmware.

Ian

Just to add to my previous post. When trying to troubleshoot the link speed
I set the computer at the access point end to ping the CPQ 1000 times. The
results were one ping at 9 ms the rest at 2 ms and 0 packet loss.

Ian

John Schmidt <(E-Mail Removed)> hath wroth:

>I'd like
>to thank Jeff Liebermann for the wonderful information and advice
>to a wireless novice about equipment selection and other requirements.

Blush. I don't know if I can handle the praise. It doesn't happen
very often.

>the documentation was
>a bit on the sparse (to put it kindly) side,

You got documentation? All I get are a packing slip and a manifest.

>It didn't occur to me that plugging
>two bridges into the same LAN would cause problems. BAD problems.

Yeah, that's the problem with bridges. You can't just "move" users
from one switched path to another as easily as you can move them in a
router. Spanning tree protocol is suppose to be self-healing when a
path is lost, I've found that a limited number of bridges and switches
actually work. I don't think the Tranzeo bridges support spanning
tree protocol. So, when you pull the plug, the users conections are
reset rather than disconnected.

Suggestion: Do it often enough and the users will get used to being
disconnected.

>Problems that made me run screaming around the office, clearing the
>ARP tables from servers and routers, and briefly causing a few
>fellow employees and a few thousand customers to lose internet access.
>DON'T! DO! THAT!

Bah-humbug. That takes all the fun out of IT. If they lose work,
tell them it's their applications vendor that's really at fault in
that it should be able to tolerate a connection reset without missing
a beat.

>Never having set up a wireless link before, I was unsure how to most
>accurately aim the panels on either side.

It's in the data sheet. See:
http://tranzeo.com/uploaded_images/1...f%20Series.pdf
Beamwidth is about 15 degrees both horizontal and vertical. You can
be withing 7.5 degrees off and it will still work. However, there is
no guarantee that the mechanical boresight is also the peak in the
antenna pattern. Boresight alignment has its limitations with high
gain antennas. It's also a bad idea to be right at the bitter edge of
the 3dB beamwidth. The antenna pattern falls off rather rapidly
beyond the -3dB points. Therefore, make an effort to swing both
antennas back and forth, both vertical and horizontal, and try to find
the middle of the peak. My guess is anything withing +/- 3degrees
will work just fine.

>I shoved a bunch of data back and forth over the link, and got speeds
>comparable to a LAN connection. Latency was nice and low as well.

The big danger is interference from other systems. The high gain and
narrow beamwidth antennas will be a big help, but you should still
watch out for sudden drops in speed or link disconnections.

Congrats and good luck.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Ian" <(E-Mail Removed)> hath wroth:

>I would like to hear more. I just set up a TR-6019f access point at one end
>and a TR-CPQ-19f customer premise at the other end of a 1.5 mile link.

Running the numbers at 11Mbits/sec, I get a fade margin of 36.3dB.
This more an adequate for a 1.5 mile link.
http://en.wikibooks.org/wiki/FAQ_for...k_Calculations
However, trees are always an issue. Foliage attenuation varies
radically depending on the size of the leaves, degree of moisture, and
number of solid branches. How "sparce" are the trees?

>Watching the CPE performance screen I could see the link
>speed was constantly changing all they way from 1 to 11. I tried changing
>channels, no difference. Locking the units a 2 Mbit/sec improved the speeds
>to barely acceptable levels.

Oh-oh. Interference, moving trees, or reflections. Did you test the
units together at much shorter range to see if there are any problems?
I usually do that and then cover one antenna with a wet towel to
simulate a more distant connection.

>I must have a fresnell zone problem. Yes I have a fresnell zone problem,
>sparse trees at one end but had hoped these radios would power through the
>line of site issue.

It's difficult to predict foliage attenuation. Worse, it changes by
season and weather. During the winter, it's usually fairly mild as
the leaves have all fallen from the trees. During spring, when the
leaves come back, it's often fatal. I have one short (3000ft) link
that is super strong in the winter, and a marginal proposition during
the spring and summer. I can't move the antennas so I have the trees
trimmed. Fortunately, the tree has grown considerably in the last few
years and I can now shoot the beam under the foliage canopy.

>firmware, so no numbers available. But still the same problem, speeds
>constantly changing and very slow connection when set to auto, and had to
>lock at 2Mbit.

It will only change speed if it sees errors. However, those errors
can be caused by relfections, multipath, moving trees, Fresnel zone
diffraction, and interference. I can't tell from here.

>The new firmware brought on another issue. The CPQ has 5 signal strenght
>lights to aid in pointing. Before the firmware upgrade the signal lights
>were on steady, after the upgrade the every 30 seconds or so the the radio
>light and the signal lights go out, flash a couple of times and come back
>on.

That's what interference from another 802.11 system looks like. The
link disconnects and then tries to reconnect. Meanwhile, the signal
strength looks like a light show because it's trying to find a
suitable speed.

>Tranzeo has no suggestions for fixing this. I guess I will have to take
>down the CPQ unit and bring it closer to the access point and see if the
>problem is fresnell zone issue.

Yep. Also check for local interference with a spectrum analyzer or
Kismet passive sniffer (because it can also see clients and blank
SSID's).

>If they work properly at close range I will
>try switching to horizontal polarity.

That's usually a big help with interference. It doesn't do much for
reflections, foliage attentuation, or Fresnel zone problems.

>TR-6019f access point connected to a linksys WRT54G V5 router.

Argh. Methinks the WRT54G v5 is a loser. Be sure that the access
point and WRT54G are on widely seperated channels.

>Mounted 20
>feet AGL
>TR-CPQ-19f customer premise equipment connected to a computer. Mounted 10
>feet AGL.
>Access point elevation approx 80 feet higher than customer premise.
>Clear line of sight except for sparse trees 75 feet from the CPQ
>Signal strength -57
>Signal quality was reporting 45
>Latest firmware on both units
>Both mounted on wood structures

Any potential 2.4GHz RF sources in between or in line with the
antennas? Factories using 2.4Ghz microwave drying ovens are always a
problem.

>A quick question for anyone, if signal strength and quality are excellent
>could the trees cause this problem or should I suspect radio problems? For
>sure the issue with the signal and radio lights going out seems tied to the
>firmware.

Tough question. It is easily possible to have a very strong signal
and a lousy connection due to multipath and reflections. However,
that can usually be temporarily eliminated by simply moving the
antenna around somewhat. Eventually, you'll find some location that
is free of reflections (for the moment). However, this mess sounds
like continuous lousy connections which reeks of interference, not
reflections or trees.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Ian" <(E-Mail Removed)> hath wroth:

>Well I upgraded the firmware on both units. With
>the new firmware the units still reported the signal strength at -57 and
>they removed the signal quality reporting feature in this release of the
>firmware, so no numbers available.

Tranzeo Monitoring System
http://dev.webpipe.net/tranmon/
I haven't had time to try it.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> "Ian" <(E-Mail Removed)> hath wroth:
>
> Running the numbers at 11Mbits/sec, I get a fade margin of 36.3dB.
> This more an adequate for a 1.5 mile link.
> http://en.wikibooks.org/wiki/FAQ_for...k_Calculations
> However, trees are always an issue. Foliage attenuation varies
> radically depending on the size of the leaves, degree of moisture, and
> number of solid branches. How "sparce" are the trees?

I live in Canada. Right now there is no vegetation on the trees, you can see
the other end through the trees. There is one row of trees and once the
vegetation comes back I might not be able to see through them. I ran a test
with linksys stuff in the summer attached to 15dbi antennas and had a
connection, but of course wanted as much margin as possible so thats why I'm
using the Tranzeo 19 dbi units.
>
> Oh-oh. Interference, moving trees, or reflections. Did you test the
> units together at much shorter range to see if there are any problems?
> I usually do that and then cover one antenna with a wet towel to
> simulate a more distant connection.
>
I have checked it on calm days and with no vegetation on the trees I know it
is not a moving tree issue. As far as interference goes we are in a fairly
sparse area but a mile away I do have a 802.11 setup. The tranzeo CPQ picks
it up as a signal 0f -94. There is alot of oil field sacada equip around
running on 400 mhz I think and the ISP here runs aironet equipment on 900
Mhz. I did bench test them but it was more to get familiar with the setup
screens and to configure and test the encryption before installation. To be
honest I do not know if the units were hunting for a connection speed. I
like the wet towel idea.

>Fortunately, the tree has grown considerably in the last few
> years and I can now shoot the beam under the foliage canopy.

At the end with the trees the guy said we can cut down some brances in the
summer if we have to.

> That's what interference from another 802.11 system looks like. The
> link disconnects and then tries to reconnect. Meanwhile, the signal
> strength looks like a light show because it's trying to find a
> suitable speed.
>
> Yep. Also check for local interference with a spectrum analyzer or
> Kismet passive sniffer (because it can also see clients and blank
> SSID's).

> That's usually a big help with interference. It doesn't do much for
> reflections, foliage attentuation, or Fresnel zone problems.

I think I'll try moving the CPQ closer, they are close to where I live the
CPQ is easily accessable and it won't take long to do. Horizontal polarity
wouldn't take very long as well. I'll have to check if the wireless card I
have will work with Kismet - SMC2532W-B. I purchased it because it is 200mw
and can connect to an external antenna. When checking for local interference
is it best to attach an external antenna and do a sweep or just use the card
as is?

> Argh. Methinks the WRT54G v5 is a loser. Be sure that the access
> point and WRT54G are on widely seperated channels.

Yeah I got them the V5 before I knew of the issues with it because I have a
ton of V4's out there working flawlessly. Hopefully the WRT54GL will be
better. Anyone have any comments on it? At any rate it is easy to take it
out of the mix and try transfering files between PC's.

> Any potential 2.4GHz RF sources in between or in line with the
> antennas? Factories using 2.4Ghz microwave drying ovens are always a
> problem.

We are in a very sparsely populated area aprox 1 house every mile or so but
there is one house in a direct line in between at an elevation that should
be below fresnell problems but maybe I'm wrong. I don't think they are
running any equipment but you never know.

>However, this mess sounds
> like continuous lousy connections which reeks of interference, not
> reflections or trees.

If it is interference hopefully horizontal polarity will be the ticket.

> --
> Jeff Liebermann (E-Mail Removed)
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558

Thanks for you help Jeff, much appreciated. I'm not in a panic, the
connection seems to be hanging in there fast enough for the internet, but
I'll post back as soon as I get a chance to investigate further.

Ian

"Ian" <(E-Mail Removed)> hath wroth:

>I live in Canada. Right now there is no vegetation on the trees, you can see
>the other end through the trees.

Ok. So all you have is edge diffraction from the Fresnel Zone
problems. At 1.5 miles, the Fresnel Zone is 29ft. Do you have 29 ft
of clearance at midpoint including not hitting the ground? I don't
think so if you're 10 and 20 ft off the ground as you indicated.
http://www.terabeam.com/support/calc...esnel-zone.php
29ft clearance at midpoint would be nice, but I would settle for
perhaps 22ft. I should point out that objects in the Fresnel Zone do
not just cause attenuation by blocking part of the signal. They
create edge diffraction, which causes the signal level to vary in
peaks and nulls at the endpoints. Move a few inches one way or the
other, and the signal could easily be very strong, or very weak.

>There is one row of trees and once the
>vegetation comes back I might not be able to see through them. I ran a test
>with linksys stuff in the summer attached to 15dbi antennas and had a
>connection, but of course wanted as much margin as possible so thats why I'm
>using the Tranzeo 19 dbi units.

Tranzeo also transmits at +23dBm while most Linksys radios deliver
about +15dBm. Linksys also has the coax cable and connector losses,
which Tranzeo does not have with an integrated antenna. By all reason
and calculations, it should work.

>As far as interference goes we are in a fairly
>sparse area but a mile away I do have a 802.11 setup. The tranzeo CPQ picks
>it up as a signal 0f -94.

That's too low to have much of an effect.

>There is alot of oil field sacada equip around
>running on 400 mhz I think and the ISP here runs aironet equipment on 900
>Mhz.

Not Aironet but probably WaveRider. They use 900MHz because it goes
through the trees. It won't cause problems unless the ISP is using
2.4GHz as a backhaul from his central access point. Look for the
characteristic barbeque grill dish antennas.

A few years ago, we were having a local interference problem. None of
the 802.11 sniffers would show anything. I dragged a spectrum
analyzer and big dish around in the back of my pickup for most of day
until we found the culprit. It was a power company remote telemetry
link (SCADA) from a mountain top power switching station. For some
reason, copper data lines were not available so they used 2.4GHz
Proxim/Glenayre Lynx radios. These boxes transmit continuously even
though there is little or no data to send. They also occupy half the
2.4Ghz band in each direction (full duplex). It was difficult to find
because they had used solid dish antennas with every few side lobes. I
had to be practically under the antenna (on a 40ft telephone pole)
before the spectrum analyzer would see anything. PG&E was eventually
convinced to run some copper and replace the data link.

>I did bench test them but it was more to get familiar with the setup
>screens and to configure and test the encryption before installation. To be
>honest I do not know if the units were hunting for a connection speed. I
>like the wet towel idea.

It's difficult to simulate field conditions, but not impossible. I
like to set it up at close range and see what breaks. However, be
careful going too close. The 802.11 timing relys somewhat on the
speed-o-light time delay between endpoints. You'll need to put some
minimum distance between endpoints to do a proper test. I think about
3 ft is the minimum. Anything you can put between the antennas will
suffice as an attenuator. However, try to use absorbant material
rather than reflective. The reason I use a wet towel is that it's
easy to throw over a panel or dish antenna. Ideally, I should be
using black carbon foam, which is the same stuff used in RF anechoic
chambers.

>At the end with the trees the guy said we can cut down some brances in the
>summer if we have to.

Can you put the antenna in the trees and run a very long CAT5 cable?
I'm not sure how long a PoE CAT5 run can be with these units. The
data part of the CAT5 can be much longer than 300ft. I've done almost
1000ft without problems (using 10baseT-HDX). You can always run the
power over larger diameter copper cable such as Romex instead of CAT5.

>I think I'll try moving the CPQ closer, they are close to where I live the
>CPQ is easily accessable and it won't take long to do. Horizontal polarity
>wouldn't take very long as well.

Worth a try. Just remember that you're changing 3 things at once. The
Fresnel Zone, the folliage attenuation, and possibly the interference
pickup.

>I'll have to check if the wireless card I
>have will work with Kismet - SMC2532W-B. I purchased it because it is 200mw
>and can connect to an external antenna.

Prism2 (not sure) so it should work just fine.

>When checking for local interference
>is it best to attach an external antenna and do a sweep or just use the card
>as is?

External antenna pointed in the direction of the line of sight. You
want to pickup as much as possible. You can temporarily ignore
anything to the sides. Start at one end and point the antenna along
the line of sight in both directions. Repeat at the other end. If
that doesn't show anything interesting, find a high place nearby and
slowly spin the antenna 360 degrees. Anything that causes that much
trouble should show up with Kismet as a fairly strong signal. So, if
it really is 802.11 intereference, you should have no trouble finding
it. Don't be suprised if it's a client radio and not an access point
or repeater.

>Yeah I got them the V5 before I knew of the issues with it because I have a
>ton of V4's out there working flawlessly. Hopefully the WRT54GL will be
>better. Anyone have any comments on it? At any rate it is easy to take it
>out of the mix and try transfering files between PC's.

I've never seen a WRT54GL. It's my understand that it's a WRT54G v4
with a $20 higher price tag because Linksys had to re-negotiate the
contract with the vendor after the v5 problems.

>We are in a very sparsely populated area aprox 1 house every mile or so but
>there is one house in a direct line in between at an elevation that should
>be below fresnell problems but maybe I'm wrong. I don't think they are
>running any equipment but you never know.

Don't just consider the houses in between. Also anything that's along
the line of sight including beyond the end points. The signal doesn't
just magically stop when it hits the other end of the link.

Good luck.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...


> Ok. So all you have is edge diffraction from the Fresnel Zone
> problems. At 1.5 miles, the Fresnel Zone is 29ft. Do you have 29 ft
> of clearance at midpoint including not hitting the ground? I don't
> think so if you're 10 and 20 ft off the ground as you indicated.
> http://www.terabeam.com/support/calc...esnel-zone.php
> 29ft clearance at midpoint would be nice, but I would settle for
> perhaps 22ft. I should point out that objects in the Fresnel Zone do
> not just cause attenuation by blocking part of the signal. They
> create edge diffraction, which causes the signal level to vary in
> peaks and nulls at the endpoints. Move a few inches one way or the
> other, and the signal could easily be very strong, or very weak.

It looks like at mid point I have 19 ft. so could be a factor. I could go
higher than 10 feet at the CPQ end. The client wanted it installed at that
location. In the next county over from us an ISP uses Tranzeo radios and I
have seen lots installs with fresnel zone infractions working fine at
distances of 10 miles plus. I guess I just got lazy thinking if I use the
same radios at a much shorter distance it is bound to work. Lesson learned.

>
> Not Aironet but probably WaveRider. They use 900MHz because it goes
> through the trees. It won't cause problems unless the ISP is using
> 2.4GHz as a backhaul from his central access point. Look for the
> characteristic barbeque grill dish antennas.

Ooops not sure where I came up with Aironet, they are actually Alvarion
BreezeACCESS 900 units.

> Can you put the antenna in the trees and run a very long CAT5 cable?
> I'm not sure how long a PoE CAT5 run can be with these units. The
> data part of the CAT5 can be much longer than 300ft. I've done almost
> 1000ft without problems (using 10baseT-HDX). You can always run the
> power over larger diameter copper cable such as Romex instead of CAT5.

I asked Tranzeo support and they said the have tested the PoE CAT5 to 300
feet. That would be long enough to get past the trees.

> Worth a try. Just remember that you're changing 3 things at once. The
> Fresnel Zone, the folliage attenuation, and possibly the interference
> pickup.

Good point I guess it would only prove that there is nothing wrong with
radios.

> External antenna pointed in the direction of the line of sight. You
> want to pickup as much as possible. You can temporarily ignore
> anything to the sides. Start at one end and point the antenna along
> the line of sight in both directions. Repeat at the other end. If
> that doesn't show anything interesting, find a high place nearby and
> slowly spin the antenna 360 degrees. Anything that causes that much
> trouble should show up with Kismet as a fairly strong signal. So, if
> it really is 802.11 intereference, you should have no trouble finding
> it. Don't be suprised if it's a client radio and not an access point
> or repeater.

Thanks for the advice.

> I've never seen a WRT54GL. It's my understand that it's a WRT54G v4
> with a $20 higher price tag because Linksys had to re-negotiate the
> contract with the vendor after the v5 problems.

I hope they get it sorted out I've become quite comfortable with the WRT54G
routers.

> Don't just consider the houses in between. Also anything that's along
> the line of sight including beyond the end points. The signal doesn't
> just magically stop when it hits the other end of the link.

Again thanks for all your help. I 've learned some good lessons from this
little project. I had previously setup a couple of one mile links, one
using two WAP54G's in point to point mode and one with a WRT54G and WET54G
bridge and was getting a little cocky.

Ian