Getting started with DN42

A week or two ago I became aware of DN42, a private network run to teach people how to use BGP. DN42 users connect to each other using site-site VPNs and then use BGP to exchange routing information. As someone who learns best from hands-on activity I simply couldn’t resist.

This blog post will discuss getting connected to the DN42 network using a Cisco router, be it physical or in a virtualisation solution such as GNS3/VIRL. At a high level there are three main steps:

  1. Create a number of “objects” in order to allocate a network address that you advertise in BGP;
  2. Configure your router so it can access the internet;
  3. Locate a suitable network to establish a VPN with and then form a BGP adjacency;

I’ll try and cover off the various DN42 specifics, but do not plan on covering basic router configuration tasks.
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Broken network connectivity on a Windows 2003 system

I spent a few hours today troubleshooting broken network connectivity on a broken Windows 2003 virtual machine. The issue was puzzling as the system showed entries in its ARP cache (arp -a) after a reboot, and yet it could not communicate with other network devices. The system had also managed to pick up a DHCP lease before networking ceased.
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