Date: Fri, 18 Mar 2011 19:56:36 +0100 (CET) From: sthaug@nethelp.no To: eugene@zhegan.in Cc: freebsd-net@freebsd.org Subject: Re: ipv6, stateful config and non-default prefixlen Message-ID: <20110318.195636.74687196.sthaug@nethelp.no> In-Reply-To: <4D8370AB.1070000@zhegan.in> References: <4D8370AB.1070000@zhegan.in>
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> I'm trying to get a working freebsd workstation with an ipv6 network > where addresses are received from DHCP. Are you using IA_PD or IA_NA on your DHCPv6 server? > ATM my IPv6 setup copies the IPv4 layout with vlans and /24 masks, so > I'm using /120 prefixes. > Is that even possible ? > As the Handbook lacks any information about such setup, I decided to ask > for help here. > > Currently I'm having problems with prefixes. > I'm using the net/isc-dhcp41-client port (as the dhclient from the base > system is unable to work with DHCPv6). > I have a working rtadvd on a router, and a working DHCPv6 setup. > But my client FreeBSD still gets 64 prefix length, with or without > running rtsold. rtadvd can give you the default router. DHCPv6 IA_NA gives you a single /128 address and no netmask. DHCPv6 IA_PD gives you a prefix (with the netmask of your choice), but I don't know whether FreeBSD can (easily) use this. > Since DHCPv6 doesn't advertise any routing information at all (including > the prefix information), As mentioned, DHCPv6 IA_PD gives you a prefix. And ISC dhclient can ask for it, see the the -P option. > and its only function is to provide the client > with an address, I assume that the prefix information has to be received > from the router advertisements. A router advertisement (RA) gives you a default router, and 0 or more prefixes - except that rtadvd seems unable to send RAs with 0 prefixes. > I am currently looking at the wireshark > dump, and it appears that my workstation is receiving such > advertisements. However it doesn't affect the 64 prefix displayed in > ifconfig, and all operation involving the nodes outside the actual link > are simply not working. If you use DHCPv6 IA_NA, you receive a single /128 address (it is /128 by definition, the DHCP answer doesn't include a netmask). You should *not* expect to reach other computers on the link through such a /128 address. Steinar Haug, Nethelp consulting, sthaug@nethelp.no
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