IPv6 support for IPVS

Introduction

This page has some information on the current state of LVS/IPVS IPv6 support which we worked on at Google and which is now in Linux mainline. The kernel patches were mainly written by Julius Volz, the new ipvsadm version by Vince Busam. Please note that these patches are experimental and have only had limited testing.

Software

Kernel support:

The IPVS IPv6 patches went into Linux mainline in October 2008. The first stable release expected to contain the IPv6 support is Linux 2.6.28.

Note: To activate IPv6 support for IPVS, CONFIG_IP_VS_IPV6 (Networking support -> Networking options -> Netfilter -> IP virtual server support -> IPv6 support for IPVS) needs to be set to Y!

New ipvsadm:

To use the new kernel features, a new version of ipvsadm is required. You may get the latest version from subversion:

svn co http://svn.linuxvirtualserver.org/repos/ipvsadm/trunk/ ipvsadm

or download it from here:

http://sixpak.org/vince/google/ipvsadm/

To compile the new ipvsadm, you will need at least version 1.1 of libnl-dev.

Some ipvsadm IPv6 examples:


	# Add IPv6 TCP service with one real server:

	ipvsadm -A -t [fc00::1]:80

	ipvsadm -a -t [fc00::1]:80 -r [fc00::2]:80 -g

	

	# Add an IPv6 fwmark service

	ipvsadm -A -f 1 -6

Current State

What works with IPv6:

forwarding mechanisms: NAT, DR, maybe Tunnel (not fully tested yet)
protocols: TCP, UDP, ESP, AH (last two not tested)
manipulation and inspection of both IPv4 and IPv6 entries with ipvsadm
6 out of 10 schedulers (10/10 in latest net-next dev tree)

What is not supported with IPv6:

handling fragmentation or other extension headers
FTP application helper (can be loaded, but only operates on v4)
sync daemon (can be started, but only operates on v4)
probably some incorrect handling of ICMPv6 or other corner cases

Since fragmentation and extension headers should not occur very often, things should "mostly" work. I tested HTTP and DNS over NAT and DR with various supported schedulers without encountering any problems. But we didn't test any exotic situations. Also, there are some TODOs in the code for things that haven't been tested or implemented yet.