Building Dreamhack, part two

The next generation network or IPv6

Why change to IPv6
Every device connected to the internet need to have a IP address to be able to communicate.
Today on internet the main OSI layer 3 (network layer) protocol used is IPv4. The IPv4 addresses is 32-bit, in total that makes 4294967296 addresses. The main problem with IPv4 is that it is running out of addresses. By using NAT (Network Address Translation) the problem has been managed.

But the more internet grows, the more you need a long term solution. The long term solution is IPv6. The length of an IPv6 address is 128 bits, in total that makes 4,8 × 10^28 addresses, which is a gigantic amount. One other advantage over IPv4 is that IPv6 has the multicast specification. Multicast is the transmission of a packet to multiple destinations in a single send operation.

Configuring IPv6 address
There are three ways to set a IPv6 address:
-SLAAC(Stateless address autoconfiguration)
I will describe those three options in detail below:

You configure the IPv6 address, netmask, gateway and DNS servers manual. This method is preferable on servers and routers where the address needs to be consistent over time.

The client ask for a IPv6 address, the DHCPv6 server gives the client its IPv6 address, netmask and options like gateway, DNS servers, NTP servers etc. The DHCPv6 server know about which MAC address has what IP and for how long, which means DHCPv6 is statefull.

SLAAC(Stateless address autoconfiguration)
Every IPv6 enabled device has a link-local IPv6 address, this address is used to communicate on the local network. This link-local address is set if the client has IPv6 enabled. The link-local address always begin with FE80:: and is calculated on the client. When the client connects to a network physically, the client will use its link-local address as a source and send a router solicitation message to a specific multicast group on the local network. Every router on the local network will listen to this specific multicast group and answer the clients with a RA (Router Advertisement) message. In the RA there is a prefix specified, the client will use this prefix to calculate its own IPv6 address. The client will use the routers link-local address as the default gateway.

In the initial IPv6 specification there where no way of setting the DNS server using the SLAAC method. Instead there are a M-FLAG in the RA package specifying a DHCPv6 server that the client can connect to get options like DNS, NTP etc. Lately support for setting DNS server using the SLAAC method has been developed, but it is not supported by all operating systems.

IPv6 implementation at Dreamhack
At Dreamhack the client set its IPv6 address, prefix and gateway using the SLAAC method. In the RA there are a DHCPv6 server specified that the client use to set the DNS server.

1: Client connect to network.
2: Client calculate its own link-local address.
3: Client send out a router solicitation package on the specific multicast group using the link-local address as source.
4: Router listen on the specific multicast group and answer the client with a RA(Router Advertisement) containing the network prefix using its own link-local address as source.
5: The client calculates its own IPv6 address using the prefix in the RA.
6: The client sets the gateway to the routers link-local address.
7: Client ask the DHCPv6 server for the DNS server.
8: DHCPv6 server response with a list of DNS IPv6 servers.
8: Client is IPv6 ready 🙂

Problems with IPv6
Even if your computer, your ISP and you destination is fully IPv6 functional you can have problems with IPv6 because all ISP/routers etc where the IPv6 package travel from, source to destination needs to be IPv6 functional.

1: Client gets a IPv6 address.
2: Client now has dualstack IPv4 and IPv6 addresses.
3: Client asks the DNS server for the ip of
4: DNS server answer with the IPv6 address for
5: Client tries to communicate with the IPv6 address of
6: If IPv6 is not configured correctly form source to destination the request will timeout when it reaches the none IPv6 ready router/network.
7: Client fallbacks to IPv4.
8: Client is unhappy because request took a long time.

Building Dreamhack, part one

Dreamhack is the world’s largest digital festival and holds the official world record as the world’s largest LAN party in the Guinness Book of World Records. Last event (november 2011) the network had 13 292 uniqe devices connected.

The Dreamhack network team is responsible for planning, building, development, operations and teardown of the network. The team consists of 30 people with a great passion for technology from different companies and universities. The team is divided into four subgroups: core, services, access and logistics. I’m a member of the services group which is responsible for the services required in the network.

Part one: building anycast DNS system supporting IPV4 and IPV6
Anycast is a technology where an (anycast) IP is announced on more than one location using a routing protocol. By doing this the routing protocol thinks that it has multiple routes to the (anycast) IP when in fact there are two different endpoints with the same (anycast) IP. The routing protocol will send the client packages to the endpoint with the shortest path from the client. To achieve high availability you need to be able to remove an endpoint service when errors occur. You can do this by removing the specific route to the broken endpoint from the routing table.


In the example image above, the client computer’s request to the anycast IP will be routed to the adns server with the IP because that is the shortest path to the anycast IP If the route saying is reachable via is removed the client’s request will be routed to the server adns with IP instead.

To build our anycast DNS infrastructure at Dreamhack we use Debian GNU/Linux, Bind, iptables, ip6tables and quagga with the routing protocol BGP. We have two anycast DNS servers connected to two different Cisco ASR 9000 routers. On the servers we have loopback interfaces that have the anycast IPV4 and IPV6 address configured. We are then using iptables to forward DNS requests from the interface connected to the routers to the loopback interface. On the servers, bind is handling the DNS requests. To achieve high availability we have built a service which checks if a DNS server is unable to answer 5 different DNS request in a row. If it is, the route to that specific DNS server will be removed from the routing table making all the clients’ DNS request go to the other working DNS server.

Dreamhack anycast DNS design.

During Dreamhack winter 2011, me and my colleague Karl Andersson held a lecture where i discuss the Dreamhack anycast DNS implementation. You can find this presentation on Youtube: Dreamarena Orange – Dreamhack Behind the Scenes.


Breakfast cloud seminar with Basefarm in Stockholm!

We claim that the cloud uncertainly is a myth. Since the cloud became a household word, studies have indicated that the main concern of the IT department is how the information you store in the cloud is handled in a secure manner. How do you know that the cloud provider doesn’t abuse your information? Welcome to a morning with speakers in security and how to use cloud services in practice with concrete examples.

On May 8, 7.30-9.45 AM, we at Basefarm arrange this breakfast seminar at Grand Hotel in Stockholm. The theme is security in the cloud and with us this morning we have speakers from Truesec, TV4 and Marval. If you think this sounds interesting, you can register via Linkedin or send an e-mail to me at

The seminar is free but the number of places is limited. There are already many registered and it’s first come, first served! More information about the seminar and agenda can be found on Linkedin

Kista Arbetsmarknadsdag – Basefarm Competition winner

For those of you who came to our stand at KTH earlier in the week you may have noticed (and entered) our competition to win some very cool wireless headphone by guessing the Basefarm bandwidth we serve from our Stockholm data center.

As with all such calculations there are slightly different ways to calculate it depending on how often your sample size is and what period you average over and things like that, but the network team tell me that the correct answer is 546 Gbps (averaged on a daily basis over the year).

The lucky winner was Jennie Johansson (who guessed closest with 500), so watch out for her wearing her nice new headphones in coming days. The prize is in the post Jennie.

Compete with Basefarm on KAM 2012: Win headphones from Beats by dr. dre!

This Wednesday representatives from Basefarm will attend the career day Kista arbetsmarknadsdag (KAM) in Stockholm. We will arrange a competition in our booth where you studentens can compete to win awesome beatspro headphones from Beats by dr. dre. Come by our booth to find out how to win them! Wonder how you can find us? Just listen to the music and you will see us in our Basefarm t-shirts. We have created a playlist on Spotify that will be played in the booth. If you want to listen to the playlist already today, the playlist is called Musik@Basefarm.

My colleague Graham has previously written that he will hold a lecture on KAM about career opportunities in the IT-industry. The lecture starts at 2.30 PM, so be sure to attend the lecture if you want tips and advice in your career.

See you on Wednesday!

Basefarm will be at Kista Arbetsmarknadsdag next week – come and meet us

A selection of Basefarm employees will be at Kista Arbetsmarknadsdag next week on 28th March. Details are here:

We’ll be on the conference floor all day available to chat, but also myself and another colleague will be doing a talk about IT career development at 1430.

We regularly try to take on graduates for both internships and full time employment (in fact we have an intern working in the windows group currently who joined as a result of the talk that myself and Andreas did last year at KYH in Stockholm), so if you’re interested in seeing what we’ve got to say, please do pop along and say hello.

En konferens i molnet…

I torsdags den 1 december var (ännu) en dag i molnets tecken då 2011 års Cloud Conference gick av stapeln i Kista Entré. Personligen uppskattade jag detta format mycket. Spännande keynotes varvas med pauser där deltagare och utställare byter erfarenheter och skapar relationer.

Ser vi till de föredrag som hölls så är det primärt 2 st som lämnat intryck så här några dagar efter.

1. Jan-Erik Gustavsson (CTO) på Ericsson Global Service Center i Indien delgav sin syn på molnet. Förutom att de har en process med att byta merparten av sin IT från traditionell Windows/Office till Ubuntu/OpenOffice med en takt av c:a 500 – 1000 användare i månaden så är de enligt egen utsago världens största NOC. Med 5000+ anställda så blir det ibland så att man har 100+ personer på “bänken” mellan olika projekt. För att lösa detta sjösätter man olika projekt för crowd computing.

2. Carl-Magnus Hallberg (SVP Global IT Services) Nasdaq OMX berättade om alla fördelar med molnet, men att det för deras del varit besparingar som driver. Virtualisering och automatisering är det som gör att de kan lägga mer tid på innovationer/utveckling och mindre tid på förvaltningen (ett argument som även Per Åström på TV4 delger). Med drift av flera börser så omfattas man av kravet att samtliga transaktioner (många) ska lagras 10 år tillbaka i tiden. Det skapar svindlande volymer av data som måste kunna plockas fram.

Annars verkar de flesta ganska eniga om att begreppet “digital natives digital immigrants” börjar slå igenom på allvar. Dagens utvecklare har en hög mognadsgrad och väldigt sofistikerad IT-miljö “hemma” för sin utveckling. Närmast obegränsade dataresurser via t. ex. Amazon, bygger in funktioner från t. ex. Disqus och versionshanterar från Github etc. Nätet fullständigt exploderar just nu med SaaS-tjänster och den interna IT-avdelningen och CIO/CTO upplevs av en del användare som “bromskloss”.

Reflections from Internetdagarna 2011

As we previously have mentioned on, we have been an exhibitor at the swedish digital event Internetdagarna 2011 in Stockholm. It was our first visit to Internetdagarna, but probably not the last! We had many nice discussions in our booth and met several interesting contacts. Moreover, our sales team could be seen in some pictures at Binero’s blog on their photo tour, and they where also seen on the pictures from IT24.

Our sales team would like to share 2 stories from Internetdagarna:

1. Internet is becoming an increasingly important part of the community

Today, everything from banking, insurance, social interaction and media (newspapers, television, news) as well as archives of personal creations on the Internet. But who really watches the Internet? Under the theme “United Nations and The Governance of the Internet” was that the topic of one of Monday’s themes. Should there be a UN for the Internet? Should NATO guard internet also and not only countries? To illustrate this, a history was told that NATO is threated by “hacker groups” because they were investigating and were asked to stop doing so. Read more about this.

2. Amazon is not only a bookstore or a rainforest

Amazon Web Services had sent their technology evangelist Matt Wood (@mza on Twitter) who spoked about the development of “pay-as-you-go” for infrastructure. We really liked this part especially when we (even though we are big in application management) sees a player like AWS as a natural part of the delivery. Can you rent out 30 472 cores for a few hours, there is demonstrably capacity that impress on tech geeks like us.

As a visitor, it was a lot of exiting events. As an exhibitor, we had however liked a bit more and longer pauses between the various speakers. It had given more time to talk to many of the exciting visitors who were there. Now it was a little speed-dating over the breaks.

Employees at Basefarm are building the network for DreamHack

This weekend it is once again time for DreamHack – the world’s largest LAN-party. The event runs from 18th to 21st of June and for 72 hours gamers, coders and hackers from all over the world will gather in Jönköping, Sweden to compete in e-sports, creative competitions or just to hang out with likeminded people. Last winter the network hosted 12 757 unique MAC-addresses which once again meant a new Guiness world record. The network which is designed, implemented, operated and disassembled by the Dreamhack Network Crew, consists of 30 people: two of these are consultants at Basefarm.

The crew is represented by top IT-companies in Sweden and students from IT-universities and our skills and backgrounds are varying from operations, development, engineering to electricians. The core network is built using Cisco enterprise routers and switches and is connected to Internet by 2×10 Gbit connections from Telia. The access-layer consists of over 400 access-switches where the visitors connect their computers. The entire area is also covered with wi-fi and more than 20 internet streams cover the event live, including Swedish Public Service. The design process starts four months before the event and the reoccurring thing we discuss in our meetings is how to improve the network since last time.

This is in my mind the best equipment and foundation to build an enterprise network on. And by happy accident this is the exact same equipment we use in our datacenters at Basefarm. Building the network at Dreamhack is therefore like disassembling, analyzing and rebuilding our entire datacenter-core at Basefarm twice per year. After every event we sit down and analyze what we want to do better and what we want to learn for our next event.

For more information about the event, go to