Comments on ipSpace.net: IPv6 ND Managed-Config-Flag is just a hint

For me this entry in interface config ultimately s...

2012-02-14T09:57:20.625+01:00

For me this entry in interface config ultimately solved the DHCPv6 vs SLAAC problem.

interface FastEthernet0/0
ipv6 nd prefix default 2592000 604800 no-autoconfig no-rtr-address
ipv6 nd managed-config-flag
ipv6 nd other-config-flag

The key factor is no-rtr-address - without router all host are silent. :-P

Thanks for the feedback, will include some of (c) ...

2012-01-26T07:49:34.816+01:00

Thanks for the feedback, will include some of (c) in this blog post plus write another post on the same topic.

Sorry, AdvAutonomous isn't the canonical name,...

2012-01-20T21:05:51.167+01:00

Sorry, AdvAutonomous isn't the canonical name, that's just what radvd calls it. RFC4861 calls it the A flag, aka "autonomous address-configuration flag".

Don't forget about the AdvAutonomous flag in t...

2012-01-20T20:57:12.143+01:00

Don't forget about the AdvAutonomous flag in the prefix information option -- you can advertise a prefix in a router advertisement but say that it shouldn't be used for SLAAC. I believe the Linux kernel will not autoconfigure an address based on a prefix option missing the AdvAutonomous flag.

So, using SLAAC and DHCP address assignment are independent. You can set M+O and not AdvAutonomous for DHCP only, AdvAutonomous without M (O optional) for SLAAC only, or you can even set all three options and the host should get two addresses (three with privacy addresses), one with SLAAC and one with DHCPv6.

Haven't tried it on my Fedora box but will do ...

2012-01-20T10:01:35.346+01:00

Haven't tried it on my Fedora box but will do it for sure....(still using Fedora 8 64bit for Olive and Junos simulation via QEMU that unfortunately on all latest Linux distribution has not been working anymore...).

... if you're lucky enough to have the right L...

2012-01-20T09:56:08.246+01:00

... if you're lucky enough to have the right Linux distro. Maybe it's time to leave Fedora behind? :'(

Ivan, it's only one statement to install th...

2012-01-20T09:53:41.127+01:00

Ivan,
it's only one statement to install the packet:

-- apt-get install wide-dhcpv6-client

The default configuration in/etc/wide-dhcpv6/dhcp6c.conf can be used for stateless DHCPv6:

profile default
{
information-only;

request domain-name-servers;
request domain-name;

script "/etc/wide-dhcpv6/dhcp6c-script";
};

The rest needs some google search... :-)

That's nice to know, but in my totally persona...

2012-01-20T08:04:03.605+01:00

That's nice to know, but in my totally personal opinion a typical user of a Linux desktop distribution should not be forced to build something as simple as DHCPv6 client from source.

In /etc/wide-dhcpv6/dhcp6c.conf interface <na...

2012-01-19T22:13:32.897+01:00

In /etc/wide-dhcpv6/dhcp6c.conf

interface <name>
{
send ia-na 0; // For Statefull DHCPv6 IA_NA and comment the rest (and vice versa)
information-only; // For Stateless DHCPv6 (DNS and Domain name)
request domain-name-servers;
request domain-name;

script "/etc/wide-dhcpv6/dhcp6c-script";
};
id-assoc na { //For Stateful DHCPv6 IA_NA
};

For PPPoE with DHCPv6 PD i have used the following (used to work with my old good Kubuntu 804 64bit):

root@iordHp:/home/iord# cat /etc/wide-dhcpv6/dhcp6c.conf
# Default dhpc6c configuration: it assumes the address is autoconfigured using
# router advertisements.

#interface eth0
#{
# send ia-na 0;
# request domain-name-servers;
# request domain-name;

# script "/etc/wide-dhcpv6/dhcp6c-script";
#};

#id-assoc na {
#};

interface ppp0
{
send ia-na 1;
send ia-pd 0;
request domain-name-servers;
request domain-name;

script "/etc/wide-dhcpv6/dhcp6c-script";
};

id-assoc na 1 {
};

id-assoc pd {
prefix-interface eth0 {
sla-id 0;
sla-len 8;
};
};

root@iordHp:/home/iord# cat /etc/ppp/peers/dsl-provider
# Minimalistic default options file for DSL/PPPoE connections
+ipv6
noipdefault
defaultroute
replacedefaultroute
hide-password
#lcp-echo-interval 30
#lcp-echo-failure 4
noauth
persist
#mtu 1492
#persist
#maxfail 0
#holdoff 20
plugin rp-pppoe.so
#nic eth0
#nic eth0

usepeerdns
#nic eth0
nic-tap11
user "iord"
root@iordHp:/home/iord#

BR
Orestis Iordanidis</name>

Funny thing about 'M' bit and 3 clients te...

2012-01-19T21:42:19.745+01:00

Funny thing about 'M' bit and 3 clients tested (cisco with dhcp pd client in dialer interface, a cpe with dual/stack firmware , and a linux with pppoev6+wide-dhcp6c - [linux test is kind old in such scenario some months ago..but will do it soon again]) all served by a 7206 vxr with 15.1.3S2 as BRAS (using AAA and "Delegated-IPv6-Prefix" attribute). In case it ('M') is set in virtual-template on BRAS, according to RFC 6204 - IPv6 CE Router Requirements :
........
WAA-6: If the IPv6 CE router receives a Router Advertisement message
(described in [RFC4861]) with the M flag set to 1, the IPv6
CE router MUST do DHCPv6 address assignment (request an IA_NA
option).
.......

What i got was the following:
--- Cisco CE (a 2811 with 15.1M/12.4T)...never asks for IA_NA address and asks for IA_PD only
--- The dual stack CPE...asks for IA_NA and IA_PD, and in case you have configured in BRAS virtual-template...neighbor peer default ipv6 pool <name>...well..it is not enough..till get an IA_NA...reply.
--- Linux goes asking what you tell it to ask in configuration file (IA_NA/IA_PD) and only.

In case ('M' bit) it is not set on virtual-template:

--- Cisco CE it is not affected, still asks as before for IA_PD (explicitly)
--- CPE never asks for IA_PD or IA_NA (of course according to RFC)...
--- Linux..asks what you tell it to ask again...

Why this different approach ? Is this due to RFC 5887 and explicit configuration on the clients that results on this different behavior?
</name>

Linux works fine with wide-dhcp6c (checked and ve...

2012-01-19T21:09:16.897+01:00

Linux works fine with wide-dhcp6c (checked and verified for both Stateless/Statefull DHCPv6 --IA_NA/IA_PD as tested...with Kubuntu 8.04 64bit and (k)Ubuntu 11.10 x64bit)

Linux workstations seem to lack DHCPv6 client (at ...

2012-01-19T10:45:57.465+01:00

Linux workstations seem to lack DHCPv6 client (at least I couldn't find it at all in my Fedora distribution) and thus use SLAAC even when you want them to use DHCPv6.

Thanks! Turns out this is the only solution that w...

2012-01-19T10:44:46.644+01:00

Thanks! Turns out this is the only solution that works.

If you have configured an IPv6 address on a physic...

2012-01-18T19:00:20.722+01:00

If you have configured an IPv6 address on a physical Interface or SVI, you can remove the prefix information from the RA with the following command:

ipv6 nd prefix 2001:db8:dead:beef::/64 no-advertise

Cheers,
Christopher

Setting the Other Config flag is implied when sett...

2012-01-18T08:27:05.515+01:00

Setting the Other Config flag is implied when setting the Managed flag (RFC2462#5.2), but not all routers will do so automatically, and the clients I've tried it with will happily do stateful addressing without the options, if so instructed by the RA.