From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: [RFC NET 00/02]: Secondary unicast address support Date: Fri, 22 Jun 2007 05:08:14 -0700 Message-ID: <467BBBAE.40901@candelatech.com> References: <20070620180017.6685.70611.sendpatchset@localhost.localdomain> <467ACDE1.7070907@trash.net> <467B1311.6090001@trash.net> <467B423C.80504@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Patrick McHardy , netdev@vger.kernel.org, shemminger@linux-foundation.org, davem@davemloft.net, jeff@garzik.org To: "Eric W. Biederman" Return-path: Received: from ns2.lanforge.com ([66.165.47.211]:46851 "EHLO ns2.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752004AbXFVMN3 (ORCPT ); Fri, 22 Jun 2007 08:13:29 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Eric W. Biederman wrote: > Ben Greear writes: > >> Patrick McHardy wrote: >>> Eric W. Biederman wrote: >>>> 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. >> Assuming you mean you want to send between two mac-vlans on the same physical >> nic... >> >> This can work if your mac-vlans are on different subnets and you are >> routing between them (and if you have my send-to-self patch or have >> another way to let a system send packets to itself). > > Ok. I didn't know if you could trigger this case without without > having then endpoints in separate namespaces. I was suspecting > the routing code would realize what we were doing realize the > route is local and route through lo. The routing code will short-circuit by default. It takes quite a bit of effort to make them _not_ short circuit..that is what I was talking about. Mac-vlans will be just like any other ethernet nics as far as routing goes. > >> A normal ethernet switch will NOT turn a packet around on the same >> interface it was received, so that is why you must have them on different >> subnets and have a router in between. > > Yes. That is essentially the configuration I was wondering about. > >> For sending directly to yourself, something like the 'veth' driver >> is probably more useful. > > True. And I think it has a place. However the common case with > the tunnel devices is to just hook them all up to an ethernet > bridge as well as a real ethernet device. > > The far ends of the ethernet tunnels are dropped into different namespaces. > > Which gets a very similar effect to the mac vlan code. > > I'm just wondering if I can not setup an ethernet tunnel device > when my primary purpose is to talk to the outside world, but occasionally > want a little in the box traffic. mac-vlans should work on veth devices just fine, and the veths will also short-circuit route (at least if they are in the same namespace). I'm not sure I understand what you are trying to do..but in general both veth and mac-vlans should act like ethernet nics..so if you can find some way that does _not_ hold, please let us know. Thanks, Ben > > Eric > - > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Ben Greear Candela Technologies Inc http://www.candelatech.com