subnet prefix length > 64 breaks IPv6?

Glen Kent glen.kent at
Sun Dec 25 10:18:00 UTC 2011

Hi Ray,

> prefixes on the same link.  Choosing to make use of a 120-bit prefix
> (for example) will do nothing to protect against a rogue RA announcing
> its own 64-bit prefix with the A flag set.

I could not find any "A flag" in the RA. Am i missing something?


RA Option Bit  Description                              Reference
-------------  ---------------------------------------  ---------
0              M - Managed Address Configuration Flag   [RFC2461]
1              O - Other Configuration Flag             [RFC2461]
2              H - Mobile IPv6 Home Agent Flag          [RFC3775]
3              Prf - Router Selection Preferences       [RFC4191]
4              Prf - Router Selection Preferences       [RFC4191]
5              P - Neighbor Discovery Proxy Flag        [RFC4389]
6-53           R - Reserved; Available for assignment   [RFC5175]
54-55          Private Experimentation                  [RFC5175]


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