Welcome to IPv6

Joni Julian

SouthEast Linux Fest

June 22, 2014

About Me

I Want You To Use IPv6

Vint Cerf wants YOU to use IPv6


IPv4 address report

just to be fair: IPv6 address report

Why Do You Want It?

Why Do I Want It?


from Phil Benchoff

IPv6 Infographic

IPv6 infographic

IPv6 Basics

It's So Different!

not really, you just need to translate some of it

arpndp, part of ICMPv6
hosthost -6

see also University of Wisconsin-Madison's list of network troubleshooting tools with translations


You can't turn it off!


"there's a multicast group for that"

Wikipedia is your friend

No Broadcast

What's My Address?

hope@moose$ ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:14:4F:01:A6:DA  
          inet addr:  Bcast:  Mask:
          inet6 addr: 2001:db8:1000:2001::13/64 Scope:Global
          inet6 addr: fe80::214:4fff:fe01:a6da/64 Scope:Link
          RX packets:7033253 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3272993 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:776277559 (740.3 MiB)  TX bytes:718801387 (685.5 MiB)

Many Other IPv6 Addresses

IPv6 can have random addresses that change often thanks to RFC 4941 - Privacy Extensions for Stateless Address Autoconfiguration in IPv6 (the update to RFC 3041)

IPv6 Addresses

A wise co-worker once told me that if you have a handle on IPv6 addresses, you're most of the way to understanding IPv6.

IPv6 Scopes

IPv6 Scopes for Multicast

IPv6 Addresses

IPv6 Performance

native IPv6 performance is best

IPv6 Performance

Since "prefer v6" goes 6 then 4, there may be a timeout. Web pages may be partly or entirely blank, and IE has it the worst since it doesn't render as pieces arrive.


ndp and friends

ndp hostname

      -a (all)
      -d (delete)
      -n (numeric, skip name resolution)

If ndp isn't present, use ip -f inet6 neighbor or ip -6 neighbor show (may use neigh instead)

hope@moose$ sudo ndisc6 bacon6 eth0
Soliciting bacon6 (2001:db8:1000:2001::5) on eth0...
Target link-layer address: 00:14:4F:01:29:8C
 from 2001:db8:1000:2001::5

prefer v6

When we added IPv6 to moose's DNS registration, only non-Windows users could ssh in. So I would describe Microsoft's version of "prefer v6" to be "fail badly if IPv6 isn't working" when Linux and Mac failed over to IPv4 silently and quickly under the same circumstances. (My guess is that Mac and Linux listened to the NUD message, and Windows is just a nudnik.)

IPv6 Packet Header

from Wikipedia

IPv6 Packet Header


Most higher-level protocols, like TCP and UDP, are unchanged by IPv6, but some, like FTP and NTP, need specific updates. (ref) The checksum calculation does change for TCP and UDP, though.



All of your network troubleshooting instincts are still valid for IPv6, but some of the commands are updated.

Don't fear the

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