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Southampton Open Wireless Network

The Topology Talk

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Southampton Open Wireless Network

Outline• The SOWN VLAN

• The Topology Schematic

• Community Area Network (CAN)

• Parts of SOWN– Core Network– Campus Nodes– sown[at]home

• IPv4 addressing on SOWN

• IPv6 addressing on SOWN

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Southampton Open Wireless Network

VLANs

• A VLAN is a Virtual LAN– Think of a set of computers connected to a single switch– A VLAN switch emulates many dumb switches and you

spread a LAN across many VLAN switches transparently

• SOWN uses a campus wide VLAN– Servers in 3 different buildings– VLAN connected nodes on 1 of those + 1 other (SUSU)

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Southampton Open Wireless Network

The Topology (1)

Where’s the SOWN VLAN?

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Southampton Open Wireless Network

SOWN CAN• SOWN is a Community Area Network (CAN)

• A CAN is a wide area LAN where all users are connected to the SOWN LAN no matter on their location.

• Users of the network can connect to each other directly

• Has the advantage that you don’t need NAT internally and can offer services such as VOIP and LAN gaming

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Southampton Open Wireless Network

SOWN Nodes

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Southampton Open Wireless Network

Campus Nodes• A wireless hotspot providing connectivity to the SOWN CAN

• High power nodes with large coverage areas

• Have direct connection to the sown servers for internet connection and authentication

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Southampton Open Wireless Network

sown[at]home Nodes• Plug’n’Play wireless access points to allow SOWN access to be

broadcast from users house with the minimum of fuss• Just plug it in to a free network port on your router and switch on!

• Makes use of home ADSL line for internet access

• Tunnels are set up to sown-vpn so SOWN network access is granted.

• User authentication is passed down the tunnel to sown-auth

• Nodes are made by Meraki, but run with our own firmware based on OpenWRT (linux distribution for home routers) which is configured to work with SOWN.

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Southampton Open Wireless Network

Core Servers

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Southampton Open Wireless Network

nat.sown.org.uk

• Gateway between sown and internet.

• Acts as a Network Address Translator (IPv4) and Firewall for IPv4 traffic.

• NAT is required due to the lack of free availability of global IPv4 addresses.

• (also runs the sown-bot on our irc channel)

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Southampton Open Wireless Network

auth.sown.org.uk

• The Authentication Server and SOWN Control Server

• When users join a SOWN node this server hosts the captive portal pages which enable login

• Server is peered with ECS and Eduroam authentication servers

• Auth is the main server on the network and can also control firmware updates being sent to the nodes

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Southampton Open Wireless Network

vpn.sown.org.uk

• Hosts connections between the SOWN VLAN and the sown[at]home nodes

• Home nodes establish a tunnel to this server when they are bought online

• Runs Nagios to monitor the status of the SOWN network as it is at the most central point of the network

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Southampton Open Wireless Network

dev.sown.org.uk

• The SOWN development server

• Allows testing of new services

• A place from which new users can experiment with the SOWN network

• Acts as the fallover VPN server.

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Southampton Open Wireless Network

The Topology (2)

When someone joins a node what happens and how do they get on the internet?