Can you always guarantee that WiFi will work at events?

Sadly not. And the last 2 events I have attended have been testament to that.

Planning Wireless Internet access for a technology conference is probably one of the hardest things that anyone will have to do. Anywhere between 200 and 600 tech-savvy people all looking to use the web and its your name/face they associate with it.

Advancements in social web 2.0 have made the Internet as essential to a conference as a chair. Facebook, Twitter, MySpace, Blogging as well as the urgency of email mean that you can pretty much guarantee, losing the Internet at a venue would be like losing an arm. Most attendees at a conference, will (like me) be a manager or business owner and the fact they are not in the office does not mean they are not working. Needless to say, Internet access is fundamental.

Having, in my previous lives, set up and managed two ISP’s in UK and Europe, I know that network capacity planning and infrastructure monitoring is key to the success of any provision. Sure, there are one or two provisos that can put a proverbial spanner in the works – however, if you plan for failure – you will implement a success.

So, this post is my attempt to try to impart some knowledge on successfully installing events wireless.

Step 1 : Capacity Planning

First thing to do is to figure out your attendance. If your conference has sold 300 tickets, assume that 75% of them (being hardcore techies) will also bring some kind of mobile device capable of wireless as well. In addition to this you should also provide access to your exhibitors if they are demonstrating. My recommendation would be to put your exhibitors on a separate network, even wire them up if you have the capability – after all, they did pay to be there!!

On the basis we’ve got an allowance of 100 for exhibitors, and 525 for your attendees, that’s a network of 625 devices in total. we should therefore assume that a £40 router isn’t going to cut the mustard!

Next thing we need to do is work out our bandwidth requirements. From history, I have worked on a magic figure of 200 users per xDSL connection. The key with bandwidth is to ‘overplan’. So 200 per connection, with 625 attendees – minimum 4 connections plus one for backup. 5 DSL Connections in total. The ‘spare’ connection is normally used as a backup, but also provides use for dedicated services (such as streaming cameras or maybe even exhibitors).

If you have the money of course, dedicated bandwidth (leased lines and/or satellite broadband) are the cream of the crop – but these generally cost *huge* amounts, unless you have a substantial budget – multiple DSL lines will suffice. The benefit of DSL lines is that there are plenty of ‘white-label’ providers on the market that will provide you a circuit for a one-month service – no long-term contracts.

So we now have our broadband and we have our network capacity planned.

Step 2 : Network Infrastructure

So, now we need to plan out how our network is going to be set up. Obviously, the easiest solution would be to slap 4 access points on the end of 4 routers connected to independent  xDSL connections – however, that’s a little  ‘amateurish’ in my opinion and when I see this, it doesn’t instill an awful lot of confidence that the network/IT company know what they are doing.

The most solid of network set ups I have found is to create a wireless mesh system across your entire venue to blanket with coverage. Wireless Distribution System (or WDS) is a system that enables interconnection of wireless access points. As well as allowing a wireless network to be expanded using multiple access points without the need for cabling, it also allows for ‘roaming’ of devices across access points since it preserves MAC addresses.

Unless you purchase routers which have dual bandwidth capabilities (5Ghz uplink with 2.4Ghz Downlink), one of the downsides of the WDS system however is that the connectivity throughput is halved for all wireless connected devices. For me it has always been an acceptable caveat.

The greatest benefit of working on a single WDS system is that you can use hardware to perform priority traffic routing (or traffic shaping) across the network to ensure a QoS (Quality of Service) for certain services – so you can give people better speeds to email/web and throttle speed to other services.

To finish our network planning, we need to look at routers. Since we have 200 connections per DSL in our imaginary conference, I would put in a Dual WAN connection per WDS Network. Looking at some of the high-end providers on the market that offer dual WAN routing such as Zyxel, Cisco or Draytek as examples.

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Sample Network Topology

Step 3 : Managing your IP Addresses

Setting your DHCP servers to cope with your user demand is fairly easy to manage. Based on our assumptions from above, we simply need to split our network in two. However, it’s not as straightforward as that. We need to take into account a few factors:

  • DHCP Scope : Number of IP addresses that your network can handle needs careful consideration
  • DHCP Lease Time : You need to ensure that devices dont keep hold of IP addresses for too long and therefore take up space on the network.

Ok – So, Scope first. 525 attendees across two networks would be 263 addresses per network – however, both networks need to cope with the strain of taking 100% of the connections in case of failure. Therefore, we need to plan for a network of 525 addresses per network. On this basis, I would set up a Class-B network range as follows:

IP Range : 172.16.0.1 – 172.16.7.255
Default Gateway : 172.16.0.1
DHCP Server : 172.16.0.2 (Scope: 172.16.0.101 – 172.16.7.254)
Static Range : 172.16.0.1 – 172.16.0.100
Subnet Mask : 255.255.248.0

This will give us more than enough IP addresses for our conference.

There is however, a small problem with this. Most DSL routers don’t handle networks of this size (I say ‘most’ because there are some which do allow you to change the complete scope), but it’s fairly easy to resolve by implementing a dedicated piece of hardware in to do the job. We combine our need for DHCP server with a DNS Server to give us a whole array of additional capabilities.

My recommendations for DHCP and DNS Servers is to use something like Ubuntu or even Knoppix for lightweight *Nix solutions. I also generally run them on solid state systems such as ITX Systems since the management is minimal, with no moving components.

The benefit of this is that you can run DNS Caching services on your hardware locally to your provision. Also, if you are running any webservices for the event, you can route them internally thus saving your bandwidth! Obviously, Ubuntu comes with a very healthy Web Service as well and can run as a commercial server with PHP/Apache/MySQL/Ruby etc etc.

One last thing is to adjust your DHCP lease times. Standard Lease time is 1 day (24 hours) or 86,400 seconds. With a conference/event you are rarely at the event for a whole 24 hours – so I usually set the lease to expire after 4 hours or 14,400 seconds. It means that devices get cycled a lot quicker and will ensure that you don’t get any problems running out of lease allocations.

I would also recommend giving your exhibitors ‘static addresses’ out of the pool – as part of the exhibitor application form, simply ask them how many devices they are bringing and ask for the network MAC addresses (i have a crib sheet to explain to users how to get this information from their computer),

Step 4 : Managing the network during the event

This is probably just as important as setting it up to begin with. When the event is on, you should always assume that something *will* go wrong rather than ‘if’. (Please See Murphys Law and Futher Finagle’s Law) . It doesn’t matter how much you invest on your network, something will inevitably not work as planned and whoever manages the network on the day needs to be able to think on their feet and be able to react quickly. Whether a cable doesn’t work and you need to be able to rustle up a length of CAT5 or a DSL link is down and you need to be able to reroute traffic – you need to be able to respond quickly and decisively – or face the wrath of hundreds of conference attendees who can’t get Internet!

As well as the reactive management, take stock in proactively managing your network with tools such as SNMP systems and MRTG statistics tools to monitor bandwidth usage. Too few businesses take advantage of software tools available on the market to proactively manage their network which, 99.9% of the time, will result in identifying and resolving a problem before it becomes an issue.

It will allow you to keep your network clean and clear for the event. For example, particularly pay attention to port usage or all of a sudden you’ll find your network swamped with Bit Torrent traffic or the like. Don’t be scared to block some ports to allow all your attendees the same level of access.

Acceptable Use / Port Allocation is :

80 (HTTP)
20/21 (FTP/sFTP)
22 (SSH)
23 (Telnet)
25/456/587 (SMTP)
110 (POP)
143/993 (IMAP)

Some Ports 30,000 and above are generally used for Bit Torrent Traffic, so watch out for this and simply shut them down – Alternatively if your router allows, simply throttle the network so that access on these ports is transmitted at 1kb/s.

Finally, I’m going to touch briefly on security. Having encryption (WEP/WPA) at an event is kind of a completely irrelevant point if you are simply going to broadcast the WEP / WPA Key throughout the event. Also the idea of a walled-garden is great, but don’t use then as ‘login’ pages which present unnecessary information.

Simply give your attendees solid, stable Internet and they will be immensely grateful.