Secure Wireless Site to Site Bridge - Aironet 1300 or 1252?

[nathan.boisse]

Hi there,

We're planning to connect a building no more than 50m away to our network via wireless (after careful research. The builing will only house 2 people, one requiring just internet and email access for ordering materials, the other will be doing document scanning - currently scanning files of roughly 15Mb every 3-5 minutes to an SQL server in the main building. They will also need to retrieve similarly sized files from said server within the same timescale. The solution would need to offer WPA2 security and a hidden SSID.

I have been pointed in the direction of the Aironet 1100 which now appears to be discontinued, so the Aironet 1300 was suggested instead. Will this 54g device be sufficient for the activities above and if so, I guess I will just need to configure each unit as a bridge (1 per building?)

I have also been looking into N type devices and found the Aironet 1252 but I believe that this is an internal device? I have the facility to locate it by a window/ very close to the outside of the building on both sites but not sure if this would be cost effective. Am I right in thinking the 1252 would require me to purchase additional antenna to go with it? If so, what type would be suitable as there are several listed on the site.

Finally. I'd like the solution we go with to be expandable (if it allows) as another building within the same area is also being looked at and would benefit from having a similar connection to it. Whether the bridging would allow for this, or another 2 units would need to be purchased is something I am unsure of.

I'd really appreciate some feedback from someone with experience of both units or experience in setting up a similar configuration as I am quite new to this side of wireless

I have included a basic Visio diagram of my proposed configuration; I hope it is of some use.

Thanks in advance.

[Nicolas Darchis]

Hi,

the 1310 will offer sufficient throughput. But if you add buildings, maybe you will start reaching the limit ...

The problem with the 1250 is that it's not meant to go outdoor as it is, apart from that it's perfect for the job.

The type of antennas strongly depend on the location of the building.

If the 3 buildings are in a line with the main building in the center, you will need an omnidirectional antenna. The point is that your bridges should all hear each other, so their coverage zone should include all other bridges. Then it's possible to have one AP at each site, the main site AP being "root" and the other being "non-root". If too hard, you could also go with 2 APs at the central site and then you can go with directionnal antenna toward each building.

And the 1310 can come either with an internal antenna that is very directionnal or with external antennas connector. The 1250 is always for external antennas.

Note also that the 1250 requires a bit more power than normal PoE allows.

I hope this helps,

Regards,

Nicolas

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[nathan.boisse]

Thankyou very much for your advice. I am putting through a proposal for the Aironet 1300. I have few follow up questions I'd like to ask if you don't mind?

1. Can I hide the SSID on the 1300 to improve security?

2. Can I setup MAC Address filtering if needed?

3. Does the 1300 come with an external mains power supply as PoE will not be available on the switches it will connect to.

With regards to the expansion to an additional unit, this looks like its going ahead. Would 54Mbps shared between the first Unit with 2 PCs, 2 Mitel VOIP handsets, 1 high-speed scanner and internet/email access be sufficient to support another 3 PCs  with 2 VoIP phones which email and SQL access?

Otherwise I will setup another pair to ensure dedicated bandwidth.

[Nicolas Darchis]

Hi Nathan,

1) The fact that hiding the SSID improves security is mostly a myth. Your ssid can still be seen with the right tools But yes indeed the 1300 can hide it.

2) Yes Mac filtering is ok. If you're setting up a bridge, more than mac filtering you can simply define the mac address with which your bridge can associate to. It won't associate with anything else.

3) You need to order the power method you like : power supply or power injector.

I don't think 54Mbps is enough for 5 PCs, 4 phones and scanner/internet/sql access. It could only be ok if the phones are never calling at the same time and bandwitdh usage is low on all PCs. But I wouldn't expect the speed to be too satisfying if you start a heavy usage.

For your information 54Mbps data rate means around 19Mbps of real throughput. This is how the standard works, it's not ap specific or brand specific.

Hope this helps,

Nicolas

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[nathan.boisse]

Thanks again for your advice Nicolas,

I'll bundle the power supplies into the proposal.

I had my reservations about the total load - as such I will provision another 2 1300's in the same configuration (different name/ different channel).

I take it there are no 802.11n standard units that are designed for outdoor use? I have located some other brands that offer such things, but would prefer to use Cisco kit.

[Nicolas Darchis]

Correct. The only way to .11n outdoor with Cisco is a 1250 or 1260 in the appropriate enclosure (or inside the building with antennas being outside for example). That is supported.

Nicolas

[nathan.boisse]

I completely ignored this fact. Why on earth did I do that. I was fretting about the 1250 because it wasnt external and never considered just having the antenna outside. That's great news. Will probably cost a bit more like this, but a much better throughput,

Looking at the site: http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008022b11b.html  would the AIR-ANT5170P-R be a suitable outdoor antenna? 5Ghz band at 7dBi?

I think its worth spending the money to reduce future costs, and efficiency

[Nicolas Darchis]

I'm not an antenna freak so I will refrain from giving advices.

However, everything that shows "diversity" and only has 2 connectors will not give you full MIMO performance (required for 11n speed). So you might look for an antenna certified MIMO and having 3 connectors.

Hope this helps.

Nicolas

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[nathan.boisse]

Cheers again Nicolas, really helpful advice

From the looks of things, the Cisco Aironet 5-GHz MIMO (3 element) 6-dBi Patch Antenna should do the trick and all in all, only boosts the total cost of the project to £1900.

Is there any benefit in connecting up 2 of these to the 1252? I see it has 6 antenna connectors.

[Nicolas Darchis · Accepted solution]

The 1250 has 6 connectors because 3 are for the 5ghz radio (802.11a/n) and 3 are for the 2.4Ghz radio (802.11b/g/n).

So if you buy 2 antennas, you need the second one to be for the 2ghz band.

You can make 2 bridge links out of 1 AP with this. However if the 2 bridge links are between the same 2 APs (to double the bandwitdh then) you'll have a problem of load balancing, I'm not really sure how it would balance the packets ... It will not I think. If you split some vlans on 1 radio and other vlan on the other radio it should be fine then.

The only setups I've ever witnessed using the 2 radios was to bridge to different locations (central building to 2 remote buildings).

Nicolas

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[nathan.boisse]

Thanks for all your help