Building network automation solutions

9 module online course

Start now!

MUST READ: IPv4, IPv6, and a Sudden Change in Attitude

Avery Pennarun continued his if only IPv6 would be less academic saga with a must-read IPv4, IPv6, and a sudden change in attitude article in which he (among other things) correctly identified IPv6 as a typical example of second-system effect:

If we were feeling snarky, we could perhaps describe IPv6 as “the String Theory of networking”: a decades-long boondoggle that attracts True Believers, gets you flamed intensely if you question the doctrine, and which is notable mainly for how much progress it has held back.

In the end, his conclusion matches what I said a decade ago: if only the designers of the original Internet wouldn’t be too stubborn to admit a networking stack needs a session layer. For more details, watch The Importance of Network Layers part of Networks Really Work webinar


  1. It strikes me that maybe multipoint-TCP goes some way towards adding this to TCP/IP, kind of shoving it into layer-4?

    1. s/multipoint/multipath

      i.e. RFC 8684.

    2. Multipath TCP provides some of the functionality of the missing session layer, but not all of it.

      For example, you still need either an always-on server IP address to connect to, or application logic capable of iterating across all addresses returned by a DNS response... but yeah, once the TCP session is established life becomes easier.

Add comment