IPv6 in XCP 1.6

by Jeff Loughridge

The intent of this post is to document how to enable IPv6 in XCP 1.6 and manage the host using IPv6 transport. I hope Google leads many people to this page, as I wasn’t able to find anything else on the web on the subject. I’d like to see more people experimenting with IPv6 on XCP hosts.

XCP 1.6 is built on an optimized Centos 6 dom0 kernel. Enabling IPv6 is not as simply a matter of editing files in /etc/sysconfig/ as you would for a typical Centos server. XCP takes over network configuration during system start-up. Fortunately, the process is very straightforward. To manage IPv6 networking on an XCP host, you must be comfortable with the ‘xe’ command line tools, as this cannot be performed using XenCenter.

Here are the steps for enabling IPv6 and configuring an IPv6 address.

  1. Log in to the XCP host as root and execute ‘/opt/xensource/bin/xe-enable-ipv6 enable’.
  2. Reboot.
  3. Verify that an IPv6 link-local address appears on xenbr0 using ‘ip -6 addr show dev xenbr0’. You should see a /64 address that begins with fe80 (e.g., fe80::20c:29ff:fe48:5bc9/64).
  4. Configure an IPv6 address on the host using ‘xe pif-reconfigure-ipv6’.

I’ll  provide some sample ‘xe pif-reconfigure-ipv6’ configuration commands.

Static IPv6 address – ‘xe pif-reconfigure-ipv6 mode=static uuid=<PIF_UUID> ipv6=<IPV6_ADDRESS>. The address is specified using the standard IPv6 notation with a slash followed by the prefix length (e.g., 2001:DB8::2/64). Fill in the UUID parameter with the Physical Interface (PIF) UUID of your management domain as provided by ‘xe pif-list’.

Stateless Autoconfiguration  (SLAAC) – ‘xe pif-reconfigure-ipv6 mode=autoconf uuid=<PIF_UUID> ipv6=<IPV6_ADDRESS>’. After executing this command the XCP host will create an IPv6 address using IPv6 Route Advertisements (RA). If there are no routers sending RAs on your network, the XCP host will not assign an address to xenbr0.

DHCPv6 – ‘xe pif-reconfigure-ipv6 mode=dhcp uuid=<PIF_UUID>’. XCP starts dhcp6c after the command is executed; however, the address assignment does not take place. If anyone wants DHCP on the hypervisor, feel free to fire up wireshark and track down the problem. I’ll update the post.

I’ve verified that the ‘xe’ commands can be run remotely using IPv6 transport. XenCenter also connects over IPv6. If you use an IPv6 literal, you must enclose it in brackets as you would in a web browser (e.g., [2001:DB8::2]). As I mentioned earlier in the post, XenCenter cannot configure IPv6 networking.

I want to thank Grant McWilliams for his tips that led me to figuring out IPv6 in XCP 1.6.

UPDATE 9/4/13 – This process also works in Xenserver 6.2.


2 Comments to “IPv6 in XCP 1.6”

  1. Thanks for the article!

    PS! On XenServer 6.5 it is also needed to comment out the following lines in /etc/sysctl.conf:
    # disable ipv6 on interfaces
    #net.ipv6.conf.all.disable_ipv6 = 1
    #net.ipv6.conf.default.disable_ipv6 = 1

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