Friday, January 12, 2007

University Accommodation Network Design

I have been in the process of designing the network topology and enacting it within a Mikrotik RouterOS 2.9.38 configuration. It has been an interesting exercise since its not everyday you get to design a new Internet access system around a quality physical infrastructure.

The Universityhas a Cisco switched network throughout the on-campus student accommodation campuses. This entails Catalyst 29xx and 3550 switches running VLANs and trunked into a route/switched core network.

Particulars about the environment:
  • 100Mbit to each room, 1Gbit between campuses
  • Each campus has approximately 300 units - a total of 950 units
  • There are two VLANs per campus
What I have planned is to trunk the VLANs into two 1Gbit/s ports on a Eber230, three VLANs per port. Then create three bridge interfaces corresponding to each campus and add the appropriate VLAN pair to each bridge. I will deny forwarding on all bridges to force routing. Then I can apply services to each bridge as per normal - in this case a Hotspot and a PPPoE Server.

This will give the guests an option of using the Hotspot or the PPPoE service to connect. I would expect most will use the Hotspot given its simplicity however there will be the power user who will want to run a 24x7 connection using a broadband router, possibly wishing to have a public IP to run other services.

I have modified the plan and I will now use three servers - one per campus. The main reason for this is to simplify the configuration on each of the servers and provide better resources to each campus. The VLANs will still be in place however I will still need to use a bridge on each to combine the two to offer both a hotspot and a PPPoE service too. Running both a Hotspot and a PPPoE service on the one interface is generally frowned upon - I will investigate the inclusion of a single PPPoE server that services all three campuses.

Network Topology including services Revision 5:

Network Topology including services Revision 2:

Network Topology including services Revision 1:

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