IPv6 Confusion

Wed Feb 18 20:17:56 UTC 2009

On Wed, 18 Feb 2009 12:55:19 MST, Aria Stewart said:

> What operational reasons are there for working with RA turned off?

If the intent is to feed the just-booted box all its network config via
DHCPv6, including the network/netmask/default router, the *last* thing you
want is a second box blabbing a packet in the middle and potentially
confusing things in one of two ways:

1) Some chuckleheaded banana-eater made a typo and the RA bits don't match
the bits supplied by DHCP, resulting in a non-deterministic bug depending
which packet gets there first (at least with DHCPv4 or standalone RA, a
misconfigure busts *everything* on the subnet and makes debugging easier).

2) Some end-node box with a IPv6 stack from "Joe's Software Emporium and
Bait-n-Tackle" sees an RA packet, and concludes that since RA and DHCPv6
are mutually exclusive, to ignore any DHCPv6 packets it sees, and hilarity
ensues.

(Yes, both sorts of errors happen all the time, and people who have been
burnt once usually want to avoid a second one...)
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