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Date: Fri, 22 Jun 2007 02:08:49 +0200 From: Patrick McHardy <kaber@...sh.net> To: "Eric W. Biederman" <ebiederm@...ssion.com> CC: netdev@...r.kernel.org, shemminger@...ux-foundation.org, davem@...emloft.net, jeff@...zik.org Subject: Re: [RFC NET 00/02]: Secondary unicast address support Eric W. Biederman wrote: > Patrick McHardy <kaber@...sh.net> writes: > > >> Eric W. Biederman wrote: >> >>> I'm trying to understand what the point of this patch is. >>> >>> In once sense I find the concept of filtering and listening for multiple >>> mac addresses very interesting, especially if we could break out different >>> streams of traffic by destination mac address into separate network devices. >>> This would remove the need to any kind of ethernet tunnel and makes multiple >>> network namespaces much more pleasant. >>> >>> However this just seems to allow a card to decode multiple mac addresses >>> which in some oddball load balancing configurations may actually be >>> useful, but it seems fairly limited. >>> >>> Do you have a specific use case you envision for this multiple mac >>> functionality? >>> >>> >> Yes, please see the MACVLAN patch I posted one or two days earlier. >> > > Thanks. That is what I was envisioning. I keep suspecting one of > the cool multi-rx queue nics my start doing some of the demux in hardware. > But whatever if it works and is relatively fast it is good enough for me. > When NICs support that I guess they the macvlan driver could be adapted to take advantage of that. > >> 8021q can also make use of it and Dave mentioned some virtualization >> devices want this as well. >> > > Right makes sense. And ethernet bridging (which is the general case > of the virtualization Dave mentioned should also be able to take > advantage of multiple unicast addresses). So this definitely make > sense. > It needs promiscous mode to learn, so I'm not sure how much this will help bridging. > Have you done any performance testing with the macvlan code? With > the ethernet tunnel device we keep getting copied unicast packets on > some path or other which slowed things down. Simply not doing the > firewalling until the packets have made it through the macvlan device > should help here. > Performance should be at least as good as on a bridge device since the macvlan driver does basically nothing and uses the same functions for receiving and sending packets. > For the macvlan code do we need to do anything special if we transmit > to a mac we would normally receive? Another unicast mac of the same > nic for example. That doesn't happen under normal circumstances. I don't believe it would work. > For the macvlan hash you just use an upper byte. Is that just a > simple starting place, or do we not need a more complex hash. > It comes from the original code, I think it should be good enough. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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