WAN Link

I am horribly new to the whole wireless thing (PACKETS ARE SUPPOSED TO TRAVEL OVER COPPER!!!), and am a bit overwhelmed with the available information. I need to set up a point to point WAN link, and would appreciate pointers in the right direction - I don't expect anyone to "do my homework" for me. The requirements for the link are pretty simple.

It has to be reasonably priced, as it'll only be operating for approximately a month during a facility move, so there's *no*

*way* I'm going to get a real budget. A simple bridging setup is desired - routing would complicate network migration more than necessary. The two buildings are approximately 1/4 mile apart, I have rooftop access to both, and there's lovely unobstructed line of sight between them.

Any tips and/or usable resources would be greatly appreciated!

Thanks, JS

Really? I thought it was all magic :-)

Pretty well any wireless router that permits an external antenna to be connected, and any wireless device that will act as a bridge (and take an external antenna) to it will do the job.

I'd recommend something like my setup - two linksys WRT54Gs (< $70 ea), two small FAB-corp dishes ($30-40 ea) with pigtails for the Linksys (< $30ea) and sveasoft firmware ($20), except that you may have trouble finding WRT54Gs that you can install the new firmware on (if the V4.x/V5.x WRT54s can do bridging natively, they'll be fine). The whole thing should cost under US$300 including your time.

Yeah, I forget about fiber. With the advent of GigE, I really don't have a use for it anymore.

Which is precisely the scenario I'm looking for. Being forced into a routed solution would mean a god-awful amount of extra work, given my current network topology.

Agreed - by "simple", though, I meant "not complex from a networking standpoint".

There are also integrate radio/antenna solutions that might be worth

Thanks for your patience. I'm so new at this I don't even know the proper questions to ask.

Dead sure - that's the one thing I do know.

10 Mbs would make me ecstatic. I can get away with 2 or 3 Mbs, as long as it's pretty much constantly available.

I have 110v AC readily available on both roofs.

A maximum of 2 dozen - after migration is complete, there will be a lot more, but I can tweak the schedule to minimize what will need to be carried over the wireless link.

That question is a *great* example of how ignorant I am, BTW. I'm used to dealing with powerful enough Cisco routers and switches that MAC address count has simply never been an issue I've had to deal with.

None of one roof, nor any in between. On the other roof, I'm not sure. I know a bit about ham antennas, but I wouldn't know the difference visually between a 2.4GHz and a microwave (or pretty much any other type) of antenna.

I guess a chat with the owner of the new building is in order to find out what the couple of antennas (antennae?) are.

Price limit is tricky. The way my boss normally works for this kind of stuff is I give her a close cost estimate for a given project, and it's either accepted or rejected. I have to be a bit of a mind reader.

Again, I *really* appreciate the advice. If I knew just a bit more about the subject, I'd know enough to be able to recognize a good resource (web site, book) to answer my questions. But this is absolutely virgin territory for me...

JS

Bridging is about as simple as you can get. As long as you aren't trying to glue together two giant networks, bridging should work. The bottom of the line wireless bridges will do 32 MAC addresses. The better ones will do 256. The overpriced stuff will typically do 2048.

As a rule of thumb, you'll get slightly less than half your connection speed. At 1500 ft (1/4 mile) with 802.11g, you'll get at least a

12Mbit/sec connection, which will yield about 6Mbit/sec thruput. It will probably be higher but that really depends on the gain of the antennas and the local RF noise pollution. I'll try to grind the numbers to go faster later.

This is too easy. Can't you offer some kind of complication to add to the challenge? Ideal installations like this just never seem to happen to me. I NEVER seem to have AC power anywhere near where it's needed. (Hint: Don't run sensitive electronics on the same power that runs the elevator or rooftop HVAC motors. The power tends to be really glitchy).

24 MAC addresses is doable with literally anything you can buy. However, note that this is the total number of MAC addresses for both sides of the bridge.

I know the feeling. The first time I slammed into a 32 or 256 MAC address limit, I was amazed that it could be so limited. However, with bottom of the line cost cutting, even cheap RAM is considered fair game for the bean counters. The bad news is that many of the cheap bridges and routers do not recover gracefully from overflowing tables. Some hang, some crash, some reboot, and some actually do the right thing and impliment a least recently used algorithm and expire the oldest MAC's.

Also, check if there are any funny looking antennas on the rooftops along the line of sight and beyond the target building. You may find it expedient (or convenient) to mount the antenna in a window rather than on the roof top. You'll pickup much less interference that way. The idea is to see the other end of the link and not the entire city. Unlike lower frequency land mobile installs, higher is not necessarily better for point to point.

Just look for dish antennas. The 2.4Ghz variety are usually barbeque grill types of dish antennas. The 5.7GHz variety are usually solid dish antennas. See:

typical antennas. The narrow 0.5ftx3ft fiberglass panel antennas are usually for cellular or paging. There are some 2.4Ghz sector antennas that look very much like cellular antannas but those are only for WISP (Wireless ISP) service and are usually easy to discover with a laptop access point scanner (Netstumbler for Windoze or Kismet for Linux). If you're near a University, you may be in trouble as they tend to deploy huge numbers of hot spots.

If you find the roof occupied with 2.4GHz hardware, all is not lost. There are 3 non-overlapping channels (1, 6, and 11). Just pick the one that's hopefully unoccupied. Also, you might wanna read: | ftp://download.intel.com/business/bss/infrastructure/wireless/deployment/hotspot.pdf It's really made for hotspot deployment, but all the terms, technology and buzzwords are relevent to anything that uses 802.11a/b/g. Well worth a reading, methinks.

Well, I was hopeing for order of magnitude. Since this is allegedly temporary, methinks maintaining resale value is also a consideration. Therefore, I suggest an integrated unit with antenna, radio, and power all in one package, with a minimum of configuration and installation issues.

Tranzeo TR-6015 or TR-6019 point to point bridge: |

about $300/each end is methinks ideal, but possibly expensive.

If you want to do 5.6GHz instead, the TR-5a-21f will also work for a bit more money: |

At the low end of the scale, there's a pair of Linksys WAP54G bridge radios for about $50/ea. Add two antennas of about 15dBi gain for about $40/ea and two coax pigtails for about $15/ea. Total is slightly over $200.

You can also use a pair of WRT54G radios, and install alternative DD-WRT firmware to give it bridging capeabilities. However, this solution requires considerable tinkering and will involve considerably more effort. I think the WRT54G give 256 MAC addresses, while the WAP54G only gives 32 MAC addresses. You have one of the simplest installations possible. All you need to do is configure the:

1. Channel numbers
2. SSID (system name)
3. MAC address of destination bridge for security.
4. Encryption level (WPA if possible) and pass phrase (20 chars minimum).

That's it. There are some issues with proprietary enchancements (Turbo, Super G, etc) but you probably won't run into those.

Ouch. I've helped with minor moves and found that even if we get 99% of the changes correct, the remaining oversights will burn most of the next week. I learned that it's best to assume that literally everything will need to be tweaked, tested, and documented. Trying to get the telco monopoly to fix their provisioning on a weekend is impossible.

What nearly killed me was physical access. We had done a successful dry run on a 200 desk move. But on the day of the move, the high command had decided that this would be a great time to take a vacation so as not to get blamed if it failed. They took the keys and codes with them and literally disappeared. I had to pick locks and do some password bypass games on the network boxes. I got lucky and only set off one alarm. Suggestion: Get keys and codes to the people that need them BEFORE the move.

Also, T1 and even OC3 are considered commodity bandwidth by most telco monopolies. Getting them to fix the inevitable errors in the provisioning over a weekend is impossible. 3 days is about right. We also covered ourselves on one move by anticipating that the T1 PRI, the DID lines, and the rotarty would get mangled during the transition. (Always happens). We had pre-arranged for a VoIP provider to handle the company voice traffic. When the PRI didn't work, I just cut over the phone system to the WAN connection. Internet access was a bit constipated for a while, but it bought me the necessary time to get the telco untangled.

Suggestion: Read some Dilbert cartoons and books before proceeding. It will put you in the right frame of mind. Also, if you're in charge, plan on practicing some sleep deprivation and practice living off delivered junk food (pizza, donuts, etc).

On the roof? Surely these buildings must be IT heaven. I've had to install ferroresonant transformers on rooftop power to keep the building garbage out of the power. On one rooftop, I was blessed with

90VAC on one phase, and 160VAC on the other.

I don't think so. The short product life of the bottom of line wireless products do not lend themselves to long term quality and testing. Many of the vendors involved literally do not have any high end gear to promote.

> for about $300/each end is methinks ideal, but possibly expensive.

Well, if the $600-$700 total price is too high, there are cheaper versions with the same form factor.

YDI was purchased by Terrabeam which was recently bought by bankrupt Proxim. The original product was called "Etherant" and is available in versions I through III. There is also "Bridge in a box". They can still be found at various wireless dealers and on eBay.

are 802.11b only which will give you about 4Mbits/sec maximum thruput. Make sure you get the wireless bridge and not the client or access point version. Not great, but useable. I would spend the money on 802.11g Tranzeo units as the cost savings for 802.11b only is not very large.

< loads of great information snipped throughout >

The entire migration is going to be challenging enough. Try to remain sane while co-ordinating moving the local loops for a dozen or so data lines ranging in size from T1 to OC3.

I'm going to put one of my therapist's kids through college by the time this is done...

Added bonus - it's filtered, clean, reliable power from UPSes. I guess *something* had to go right.

The cynic in me thinks that behavior might be (at least a bit) intentional. Vendors would rather sell high end gear than entry level. That cynicism isn't solely directed at wifi vendors, but rather the networking industry as a whole.

for about $300/each end is methinks ideal, but possibly expensive.

That looks like a *great* solution. Just a touch more than I wanted to suggest spending, but the time savings from an all-in-one solution should more than make up for it.

Thanks again, Jeff. You have been a _HUGE_ help.

JS