From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [RFC NET 00/02]: Secondary unicast address support Date: Thu, 21 Jun 2007 22:30:57 -0600 Message-ID: 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=us-ascii Cc: Patrick McHardy , netdev@vger.kernel.org, shemminger@linux-foundation.org, davem@davemloft.net, jeff@garzik.org To: Ben Greear Return-path: Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:44807 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868AbXFVEb1 (ORCPT ); Fri, 22 Jun 2007 00:31:27 -0400 In-Reply-To: <467B423C.80504@candelatech.com> (Ben Greear's message of "Thu, 21 Jun 2007 20:30:04 -0700") Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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. > 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. Eric