This issue was discussed in some detail.
I've done the following:
- Clarified the prefix length field in 4.6.2
- Added clarifications to the second last paragraph in
6.3.4.
Text in 4.6.2:
Prefix Length 8-bit unsigned integer. The number of leading bits
in the Prefix that are valid. The value ranges
from 0 to 128. The prefix length field provides
necessary information for on-link determination
(when combined with other flags in the prefix
option). It also assists with address
autoconfiguration as specified in [ADDRCONF], for
which there may be more restrictions on the prefix
length.
Text in 6.3.4:
Stateless address autoconfiguration [ADDRCONF] may in some
circumstances increase the Valid Lifetime of a prefix or ignore it
completely in order to prevent a particular denial of service attack.
However, since the effect of the same denial of service targeted at
the on-link prefix list is not catastrophic (hosts would send packets
to a default router and receive a redirect rather than sending
packets directly to a neighbor) the Neighbor Discovery protocol does
not impose such a check on the prefix lifetime values. Similarly,
[ADDRCONF] may impose certain restrictions on the prefix length for
address configuration purposes. Therefore, the prefix might be
rejected by [ADDRCONF] implementation in the host. However, the
prefix length is still valid for on-link determination when combined
with other flags in the prefix option.
Currently there is no text that limits the prefix length
to 64 if the A flag is set (as recommended by the IAB).
I'd like to hear from the WG if this should be added.
Hesham
--------------------------------------------------------------------
IETF IPv6 working group mailing list
[EMAIL PROTECTED]
Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6
--------------------------------------------------------------------
