Saturday, October 29, 2016

Getting DHCPv6 delegation working

...or "How I learned to make friends with duct tape"

Last week I wrote about not being able to route delegated prefixes as none of the servers seemed to have functionality to update the routing table. Shortly after tweeting this, a colleague replied with a way forward. In case Twitter's memory goes a bit hazy, I'll recap here:

Wes: Most CMTSs solve this with logic that snoops DHCP and installs routes as it sees allocations go by. DHCP server is standalone
Me: Hmm... it feels kinda kludgy, but it does keep it vendor neutral. Does the CMTS track the PD lease time to revoke the route too?
Wes: not exactly, because the leases normally get renewed indefinitely. We've asked for a feature to expire it like that to ease moves
I let this conversation percolate while I was attending All Things Open. Between the energy of a conference full of people trying to change the world and a few other inspiring conversations with friends, I decided to take a whack at this.

I'll spare you the details of how many rabbit holes I went down before I had my "Ah ha!" moment of getting Wireshark to do most of the heavy lifting. Many hours later, I have a working prototype!

You can get the code at:

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