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I will be hosting a Ruby on Rails workshop at a small hotel in the near future, and while they have 'Wifi' everywhere on the property, and the property normally hosts 150 - 300 people, I am not 100% confident that they have hosted 150 tech people that tend to have heavy web surfing habits/needs.

Their tech department is also 1 or 2 guys.

Are there any automated tests I can download and run from my laptop, on the network, that would simulate 100 'heavy users' on the network at the same time?

Their broadband pipe is a 15mbps cable connection. Would that suffice for the general surfing needs of 100 - 150 techies? I know all it takes is 1 or 2 bit torrenters to kill the entire network, but assuming we can at the very least block those ports or encourage the attendees not to file share on the network, would that speed suffice for general surfing needs?

What are good resources online that would allow me to quickly get up to speed on the IT related issues, so that I can ask their sysadmins the right questions?

Edit: Note that I am fairly technical, so assume I can get up to speed quickly even with technical manuals, etc.

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4 Answers

Have you seen this question? A couple of the answers provide some excellent information.

http://serverfault.com/questions/72767/why-is-internet-access-and-wi-fi-always-so-terrible-at-large-tech-conferences

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Mostly what you already know but...

I have a mate that has a habit of ending up at events like you speak of, and it seems like pretty much standard practice for hotels etc to assume that 20% of geusts will bring a laptop and check thier email once per day with it.

In actual fact you have not only laptops, but smart phones and a host of other devices, the question is not whether the system can handle 600 devices.

The answer to that will be -- if they are using the 192.168... address range, almost certainly not, they will only be able to dhcp 250ish addresses. Though there is a chance they are doing somthing useful.

And note that you only need 3 sods running bit torrent on the "free internet" to kill the everything connection.

Another important question -- this workshop, is it hands on? or will it mostly be lecturing? because that makes a huge diference to load levels.

I'd say (please correct me if i've missed anything) there are 3 pinch points: dhcp addresses; raw bandwidth; open connections. All 3 could be a problem.

Speak to the tech people, see what other events they have had, and how things performed.

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Simulating users is very hard. There are various sorts of load generators, but in the end you have to make assumptions about how your users use the network, and what service level you want to give them. Without this you are pretty lost. There is a huge difference between 150 users checking mail, and 150 users on netflix. This is one of those things that are so much work to simulate that it's not worth it.

With that said...

Typical over-subscription rates for an ISP here are in the range 3-20x. That means that if you have an uplink of 15 mbit you would subscribe 45-300 mbit, or in your case each user would get 0.3-2 mbit each. Enough for basic surfing and e-mail, but don't expect it to go fast by any measurement. Considering that your users are probably in the high load category you are likely to end up at the lower number.

I would worry a lot more about the basic infrastructure. Can the DHCP even hand out 150 addresses (many hotels only hand out 64 or 128), will their authorization/accounting server barf and what do you do when it happens?

You can try to block bittorrent, but it's mostly a pointless exercise unless you do DPI. The users will find a way around the block, or in a worst case run VPN. It's much better to do some basic traffic shaping and give each user a fair share of the bandwidth. It's also easier to implement.

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