[lvs-users] thoughts on making IPVS sync multicast address adjustable

Simon Horman horms at verge.net.au
Wed Jul 1 02:09:58 BST 2015

Hi Phillip,

On Tue, Jun 30, 2015 at 03:59:12PM -0500, Phillip Moore wrote:
> Has any thought been giving to making the multicast address IPVS sync
> daemons use to sync state be configurable?
> is in the link local multicast subnet. Our hope is to have
> the IPVS directors be distributed in multiple L3 networks so the
> multicast traffic would have to  be routed between them. This wouldn't
> be a problem except for the choice of this link-local subnet is
> treated specially by network vendors. Routing devices do not want to
> route this and according to my network folks it would cause it to hit
> the control plane and cause excessive usage on the routers where an
> alternate multicast subnet would not.
> Looking at the code it would appear some what trivial to change this
> to a proc setting but I do not know the context or history of the
> choice behind as the address to be hard coded.
> Interestingly the IANA assignments document shows the .81 address as
> being in a reserved range.
> Our configuration idea is to have a small pool of directors all acting
> as master and backup (running both daemons). We will anycast with
> BGP/exabgp the VIP addresses to live on all of the directors which
> would live on several subnets.
> I appreciate any thoughts or feedback on this idea or experiences with
> using the existing address at scale.

I would be happy to review patches from you (or anyone else) to add the
feature you describe above. I would guess that it should be configured via
the netlink mechanism IPVS uses for other portions of its configuration.

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