On 17/12/12 11:38, Gert Doering wrote:
Hi,
On Mon, Dec 17, 2012 at 10:58:12AM +0000, Robert Williams wrote:
(PS. For the NLB fans, you'll be pleased to know the cluster is now going for
good I'm told)
I know I'm going to get stoned for that, but hey, it's Monday anyway...
I actually *like* NLB. It's a brilliant way to twist IP/ARP into
"create resiliency and load distribution across a few servers, without
having to buy and set up extra boxes to do resilient load balancing".
NLB has two modes of course - unicast and multicast. The unicast is
completely uncontroversial - float an IP between two hosts and use
grat-arp to move it, or float an IP & virtual MAC. Nothing to see, really.
The multicast is, I agree, a creative use of the various protocols.
Sadly it's one of those things that probably looked good on paper and in
the lab with hubs, but ended up only working on a subset of switches -
it's not just Cisco gear it breaks.
I have a suspicion that re-using the IPv4/IPv6 multicast MAC OUI was
part of the problem - that is special-cased in a lot of kit,
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