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Re: prefixlen of IPv6 over PPP
On Nov 6, 2009, at 12:46 PM, Nagae Hidetake wrote:
From: "Brian A. Seklecki" <seklecki%noc.cfi.pgh.pa.us@localhost>
Subject: Re: prefixlen of IPv6 over PPP
Date: Fri, 06 Nov 2009 11:43:41 -0500
Very curious. check some RFCs, or check an XP box. What is RTADV
giving them and what are they accepting?
Assigning a /128 to an v6 PPP interface is like assiging a /32 to an
IPv4 (/31 is...maybe known to work in some exotic platforms, but..)
In Section 4.1 (Interface Identifier) of RFC 5072 (IP Version 6 over
This Configuration Option provides a way to negotiate a unique, 64-
bit interface identifier to be used for the address autoconfiguration
 at the local end of the link (see Section 5).
In Section 5.3 (Creation of Link-Local Addresses) of RFC 4862 (IPv6
Stateless Address Autoconfiguration):
If the sum of the link-local prefix length and N is larger than 128,
autoconfiguration fails and manual configuration is required.
So I think prefixlen should be 64, but I'm not sure...
I wonder if the problem is that it's a ppp interface. Stateless
autoconfig is defined for Ethernet-like devices with 6-byte MAC
addresses that are expanded to 8 bytes per an algorithm. Maybe the
NetBSD code doesn't handle the ppp interface type properly with a 64-
--Steve Bellovin, http://www.cs.columbia.edu/~smb
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