IPv6 Test Case for LinkSys Routers - Based on Ubuntu + Radvd + DHCPv6 - E1200v2 isn't ready for IPv6

Question

Hello!
Here on this guide, you'll learn how to deploy your own Linux IPv6 Router, that can be used in ANY network, to give IPv6 connectivity to ANY ethernet device, including Windows, Mac, Ubuntu Server and Desktop, RedHat and, of course, LinkSys routers like E1200v2 and E2500 for its WAN interfaces.
I wrote this guide because I found a BUG on E1200v2, which doesn't work with IPv6 yet, already lost some money to figure this out.
That's it, when you see a E1200v2 box at the store, you can read: "* IPv6 Enabled", but that is not entirely true, since it does not work as expected.
Here on this post, it is a complete procedure to reproduce the problem.
NOTE: The model E2500 v1 does not suffer from this problem!
NOTE: This guide is very usefull if you have a LinkSys E2500 router and want to connect it directly into a Linux Router!
Who am I?
A.: I'm Thiago, I work in Brazil, for a company called iG (ig.com.br), I'm working here as a Network Engineer / SysAdmin and I have +10 years of experience with IPv4 networks + 5 years with IPv6.
* Brief
1- Install a Ubuntu 12.04.3, to act as your router, on a PC computer with two ethernet cards (eth0 will be Ubuntu's default route, eth1 will be used to connect LinkSys E1200v2);
2- Prepare your Ubuntu Router (very important step, read it carefully)
3- Connect E1200v2 directly into Ubuntu's eth1 ethernet card;
4- Connect a Windows PC at E1200v2 LAN port 1 (used to configure your E1200 with Cisco Connect everytime a reset is desired);
5- Reset (restore it from factory defaults) your E1200v2 router;
6- Install Cisco Connect in your Windows PC (LAN port 1);
7- Configure your E1200v2 as usual;
8- Browse the Internet (still IPv4);
9- Open Windows Command Prompt and type: ipconfig, ping, etc;
10- Open Google Chrome or Firefox and go to your E1200v2 Web Admin Interface at http://192.168.1.1/
11- Install a Ubuntu 12.04.3 Server connected at E1200v2 LAN port 2 to test IPv6 connectivity in deep, or;
12- Boot a Ubuntu Desktop 13.04 Live CD connected at E1200v2 LAN port 3 to test IPv6 connectivity in deep;
IMPORTANT NOTE:
* This tests will require IPv4 connectivity to the Internet, since the IPv6 blocks used on this example, are blocks used only for documentation (or small tests) porpuses, which means that those IPv6 tests we're about to do, will not reach the Internet (in IPv6), neighter be routed out from your E1200v2. But it is enough to prove that E1200v2 drops its clients IPv6 connectivity. Feel free to replace those IPv6 address with your current / valid IPv6 blocks (if you have a IPv6 /48 block from your ISP, you know what I'm talking about).
* Network Topology (Ubuntu Linux Router)
IPv6:
eth0
2001:db8:0:1::/64 = uplink allocation
2001:db8:0:1::1 = upstream router IP (Ubuntu's gateway IPv6)
2001:db8:0:1::2 = customer configured IP (your WAN uplink interface to provider - Ubuntu's eth0 IPv6 address)
eth1
2001:db8:1::/48 = statically routed subnet pointing at 2001:db8:0:1::2 that come from you IPv6-ISP
2001:db8:1::1 = your first IPv6 within your own infrastructure (Ubuntu's eth1 - E1200v2 directly connected here)
eth1:0
2001:db8:1:1::/64 = your first IPv6 /64 with Router Advertisement plus DHCPv6 running on Linux (radvd) (Ubuntu's eth1:0 - E1200v2 gets its WAN IPv6 address from this subnet)
2001:db8:1:1::1 = IP of your first /64 subnet, Radvd + DHCPv6 running here, Ubuntu as IPv6 router
IPv4:
eth0
192.168.10.0/24 = uplink allocation
192.168.10.1 = upstream router IP (Ubuntu's gateway IPv4)
192.168.10.2 = customer configured IP (your WAN uplink interface to provider - Ubuntu's eth0 IPv4 address)
eth1
192.168.20.1 = your E1200 will gets its WAN IPv4 address from this subnet - most common scenario for IPv4 wifi routers running inside enterprise environments today
* Complete procedure
1- Install a Ubuntu 12.04.3, to act as your router, on a PC computer with two ethernet cards
Install the following packages in your Ubuntu Router:
sudo apt-get install radvd isc-dhcp-server
2- Prepare your Ubuntu Router (very important step, read it carefully)
2.1- Ubuntu's file /etc/network/interfaces contents:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
# IPv6
iface eth0 inet6 static
   address 2001:db8:0:1::2
   netmask 64
   gateway 2001:db8:0:1::1
   # dns-* options are implemented by the resolvconf package, if installed
   dns-nameservers 2001:4860:4860::8888
   dns-search linksys.com
# IPv4
iface eth0 inet static
   address 192.168.10.2
   netmask 24
   gateway 192.168.10.1
   # dns-* options are implemented by the resolvconf package, if installed
   dns-nameservers 8.8.8.8 8.8.4.4
   dns-search linksys.com
# The secondary network interface, E1200 LinkSys wifi-router is connected here (WAN port)
auto eth1
# IPv6
iface eth1 inet6 static
   address 2001:db8:1::1
   netmask 48
auto eth1:0
iface eth1:0 inet6 manual
   up ip -6 address add 2001:db8:1:1::1/64 dev $IFACE
   down ip -6 address del 2001:db8:1:1::1/64 dev $IFACE
   # IPv6 /56 block routed to LinkSys E1200v2, it is delegated to it through Prefix Delegation using DHCPv6
   # Uncomment it later when your E1200v2 gets its own IPv6 Internet IP Address, keep reading this guide
   #up ip -6 route add 2001:db8:1:f00::/56 via 2001:db8:1:1::2000
# IPv4
iface eth1 inet static
   address 192.168.20.1
   netmask 24
2.2- Configure Ubuntu /etc/sysctl.conf file
Uncomment the following two lines on it:
net.ipv4.ip_forward=1
net.ipv6.conf.all.forwarding=1
After writting, run "sudo sysctl -p" to apply the changes.
2.3- Configuring Linux Router Advertisement daemon (radvd)
Your Linux Router Advertisement daemon running on Ubuntu, must have the following content:
# Ubuntu eth1
interface eth1
    # Enable RA
    AdvSendAdvert on;
    # Enable clients getting their IPs from DHCPv6
    AdvManagedFlag on;
    AdvOtherConfigFlag on;
    # Enable RA to the following subnet
    prefix 2001:db8:1:1::/64
       AdvOnLink on;
       # When not allowing clients to auto-generate their IPv6 address (SLAAC), DHCPv6 will be used instead
       AdvAutonomous off;
2.4- Configuring DHCPv6
Your isc-dhcp-server6 configuration file (/etc/dhcp/dhcpd6.conf) for IPv6 must have the following content:
ddns-update-style none;
default-lease-time 600;
max-lease-time 7200;
authoritative;
log-facility local7;
# Ubuntu eth1
# This is a very basic subnet declaration with Prefix Delegation enabled.
subnet6 2001:db8:1:1::/64 {
        # Range for clients
        range6 2001:db8:1:1::2 2001:db8:1:1::2000;
        # Extra DHCP options
        option dhcp6.name-servers 2001:4860:4860::8888, 2001:4860:4860::8844;
        option dhcp6.domain-search "linksys.com";
        # The following line will delegate a subnet to LinkSys E1200v2,
        # using Prefix Delagation standards.
        # You'll be able to see this "Prefix Address" under "Status -> Local Network" E1200v2 menu.
        prefix6 2001:db8:1:100:: 2001:db8:1:f00:: /56;
# No service will be given on this subnet, but declaring it helps the 
# DHCP server to understand the network topology.
# Ubuntu eth0 - no DHCPv6 running but doesn't hurt to declare it here
subnet6 2001:db8:0:1::/64 {
Reference: http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/hints-daemons-isc-dhcp.html
2.5- Configuring DHCPv4
Your isc-dhcp-server configuration file (/etc/dhcp/dhcpd.conf) for IPv4 must have the following content:
ddns-update-style none;
default-lease-time 600;
max-lease-time 7200;
authoritative;
log-facility local7;
# Ubuntu eth1
# This is a very basic subnet declaration.
subnet 192.168.20.0 netmask 255.255.255.0 {
   range 192.168.20.2 192.168.20.200;
   option routers 192.168.20.1;
   option domain-name "linksys.com";
   option domain-name-servers 8.8.8.8, 8.8.4.4;
# No service will be given on this subnet, but declaring it helps the 
# DHCP server to understand the network topology.
# Ubuntu eth0 - no DHCPv4 running but doesn't hurt to declare it here
subnet 192.168.10.0 netmask 255.255.255.0 {
* Reboot your Ubuntu Router to apply all the changes
After rebooting it, try to "ping 8.8.8.8" to make sure your Ubuntu Router have at least, IPv4 Internet connectivity.
NOTE: From this point, you'll be able to start testing IPv6 from behind your Ubuntu Router (i.e. from its eth1), if you connect a Ubuntu Desktop, a Mac or a Windows on Ubuntu's eth1, it will provide IPv4 and IPv6 address to that devices, including your E1200v2 WAN port...
3- Connect E1200v2 directly into Ubuntu's eth1 ethernet card;
Plug a RJ45 cable between Ubuntu eth1 ethernet card and E1200v2 WAN port.
4- Connect a Windows PC at E1200v2 LAN port 1
This Windows computer will be used to (re)configure your E1200v2 with Cisco Connect everytime a reset is desired.
5- Reset (restore it from factory defaults) your E1200v2 router;
Press and hold the reset button for about 10 seconds.
6- Install Cisco Connect in your Windows PC (LAN port 1);
Boot(reboot) Windows and install Cisco Connect on it.
7- Configure your E1200v2 as usual (by finishing Cisco Connect installation procedure);
After concluding this step, your Windows PC will have both IPv4 and IPv6 address, that come from E1200v2.
Windows gets its IPv4 from DHCP and IPv6 from SLAAC (main point of the problem), both provided by E1200v2.
NOTE: From this point, you'll be able to see the problem with E1200v2 internal RA daemon, you'll lose your IPv6 connectivity that come from E1200v2. But, lets keep testing it...
8- Browse the Internet (still IPv4);
That's it, try to browse google.com from your Windows PC, if Ubuntu Router can "ping google.com", Windows PC should be able to do it so.
9- Open Windows Command Prompt and type: ipconfig, ping, etc;
Run "ipconfig" to see your IPv4 and IPv6 address...
Run "ping 8.8.8.8" to see if you can reach the Internet...
10- Open Google Chrome or Firefox and open your E1200v2 Web Admin Interface at http://192.168.1.1/
Access your E1200v2 Web Admin and go to the "Status -> Router" menu.
Write down its Internet IPv6 address, it will be something like this:
IPv6 - Internet IP Address: 2001:db8:1:1::2000
NOTE: You can get this address at the Ubuntu Router itself, by reading the file /var/log/syslog (`grep pool' might help), for example:
# grep pool /var/log/syslog
Sep 24 00:47:13 ubuntu-router-1 dhcpd: Picking pool address 2001:db8:1:1::2000
Sep 24 00:47:13 ubuntu-router-1 dhcpd: Picking pool prefix 2001:db8:1:1::/56
You'll see the above message on your Ubuntu Router, right after turning on your E1200v2. Pool address is the IPv6 Internet IP Address of your E1200v2's WAN port, pool prefix is the delegated subnet to your E1200v2 router. After thatn, it will start to advertiser that block on its LAN ports and WiFi (which doesn't work as expected, there is a problem there, whithin E1200v2 itself.
11- Install a Ubuntu 12.04.3 Server connected at E1200v2 LAN port 2, to test IPv6 connectivity in deep;
Here is the most important test:
* Testing the IPv6 connectivity from E1200v2 LAN ports.
This test is very simple, we just need to try ping E1200v2's IPv6 Internet IP Address.
This Ubuntu Server will have the following content on its /etc/network/interfaces file:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
# IPv6 - SLAAC - No DHCPv6 client required - E1200v2 will kicks off this IPv6, and I don't know why...
iface eth0 inet6 auto
# IPv4 - Requires DHCPv4
iface eth0 inet dhcp
After this, your Ubuntu Server will be able to "ping 8.8.8.8" and "ping6 2001:db8:1:1::2000" (E1200v2 WAN IPv6 Address noted before).
To prove that E1200v2 have a problem with IPv6, try to ping it, just run:
mtr -n 2001:db8:1:1::2000
...And after a few minutes, Ubuntu Server will lose its IPv6 address, because E1200v2 is kicking it off.
You'll be able to see a lots of package loss going on "mtr -n 2001:db8:1:1::2000".
If you connect a Mac OSX on E1200v2 LAN por 3, for example, it will also lose its IPv6 from time to time.
Wireless clients connected at E1200v2, like Android, iPad, Windows, Mac and Ubuntu laptops, also loses its IPv6 (that come from E1200v2) from time to time.
You guys must note that the E1200v2 itself, ramdomly becomes unreacheable from its own LAN ports (via IPv6)!! Which is unnaceptable.
12- Boot a Ubuntu Desktop 13.04 Live CD connected at E1200v2 LAN port 3 to test IPv6 connectivity in deep;
Boot a Ubuntu Desktop connected at your LinkSys E1200v2 router, and open 2 Terminals, on each of it, you should run:
Terminal 1:
mtr -n 2001:db8:1:1::2000
Terminal 2:
sudo tail -f /var/log/syslog
You'll be able to see a lots of package loss going on "mtr -n 2001:db8:1:1::2000" after a few minutes AND at the syslog, you'll be able to see when you lose your IPv6, that come from E1200v2.
Conclusion
E1200v2 doesn't have a working IPv6 Router Advertisement service. Please Cisco, fix it!
The IPv4 from behind E1200v2 is fine, I'm using LinkSys products for about +10 years now... First time with problems like this but, IPv6 is more or like new and, problems are expected... Lets work on it?!
Best Regards,
Thiago

Answer 1

Try to use dhclient perhaps?  Might I also suggest letting systemd deal with the dhcp issue and not NM.  That may seem incongruous but it is possible NM is mis-handling the dhcp hand-off to the network card.  I'm no guru but I got thinking about this when I saw this in your output:
aug 26 19:15:39 arch_daboka NetworkManager[527]: <info> (enp1s0): device state change: ip-check -> secondaries (reason 'none') [80 90 0]
aug 26 19:15:39 arch_daboka NetworkManager[527]: <info> (enp1s0): device state change: secondaries -> activated (reason 'none') [90 100 0]
aug 26 19:15:40 arch_daboka NetworkManager[527]: <info> NetworkManager state is now CONNECTED_LOCAL
It is very possible that I'm mis-interpreting this information so please take it with a boulder of salt.