The 2012 North American IPv6 Summit has come and gone but requests for my slides from the third day continue to roll in. So I’ve decided, as I often do, to post them up here. My talk “Carrier Grade NAT – Observations and Recommendations” was given as part of the “IPv6 Transition and IPv6 in the Home” Track on day 3 of the Summit. In it, I cover as much of our work here at CableLabs around CGN/LSN that I could squeeze into 45 minutes. I start with a brief overview of what NAT and CGN/LSN are and how they work. Then I report on the testing that CableLabs has conducted on CGN/LSN over the past two plus years, and on the challenges we’ve discovered. Next I cover many of the workarounds, mitigations and potential solutions to those challenges, including some novel ideas invented at CableLabs. I wrapped up my talk with some conclusions and parting recommendations. Enough of me yammering though – the slides should give you a decent understanding of what I presented:

A few things before I let you go:

First, slides 7 and 8 rely heavily on animation to describe the workings of a NAT444 and a DS-Lite deployment respectively. To make that a little clearer without the animations, here are the two graphics rebuilt for static viewing:

Second, if you’d like the rest of the story on CGN (all the details not in the slides), give me a shout – perhaps I can come give this talk at your event as well. This of course goes for any of the talks you may have seen me give and slides I may have posted.

Finally, as always, your comments, questions, suggestions, and other feedback is very welcome. Did I get something wrong? Miss something? Bore you? Blow your mind? Let me know!


  1. Alaa 27 April 2012 at 09:29 - Reply

    Great work Chris. Keep IPv6 rocks ! I wonder if it OK to download the slides ? How please?


  2. Christopher Cain 27 April 2012 at 13:15 - Reply

    Chris – great presentation. I you could send a copy of the slide deck my way as well, I would greatly appreciate it.


    • Chris Grundemann 27 April 2012 at 13:39 - Reply

      Since you made your request via IPv6, I’d have a hard time saying no. =)

  3. Arturo Servin 27 April 2012 at 14:48 - Reply

    Very nice presentation. I liked a lot because it shows the problem as it is, without any “religious” arguments.


  4. […] At the recent North American IPv6 Summit, Chris Grundemann of Cable Labs addressed exactly these points – and now has published a blog post with his CGN slides and some additional commentary: […]

  5. Matt Rowley 30 April 2012 at 13:39 - Reply

    Very good presentation, thanks for posting the slides.
    So, tongue-in-cheek summary:
    Last-mile ISPs don’t want to bother with IPv6 because it means replacing CPE stuff… cable modems, routers, etc.
    So enter CGN, which breaks stuff left and right.
    So fix that with PCP, which requires a new CPE router.
    GOTO 1 ? :)

  6. Raj Jayaraman 30 April 2012 at 23:23 - Reply

    Dear Chris,

    Great set of slides. Would appreciate if you could email me across the same.

    Best Wishes,
    Raj Jayaraman.

  7. Youssef 8 May 2012 at 05:47 - Reply

    Hi Chris,

    Can I have copy from the presentation?

  8. […] order to communicate directly with them; you need IPv6. Yes, various address sharing technologies (CGN) will very likely extend the useful lifetime of IPv4 but this is not without a cost. Address […]

  9. […] the potential to make IPv4 address based identification much more difficult: The emergence of CGN (Carrier Grade NAT) as an IPv4 life-extension technology and the emergence of IPv4 address transfers as a CGN […]

  10. Confluence: Get IPv6 Info 23 August 2013 at 13:26 - Reply

    IPv6 Presentations and Documents

    The following are links to documents/presentations

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