From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH V2 09/12] net/eipoib: Add main driver functionality Date: Sun, 12 Aug 2012 17:05:12 +0300 Message-ID: <20120812140511.GC6003@redhat.com> References: <501C3527.6060809@mellanox.com> <20120803.143315.151094375569109262.davem@davemloft.net> <501C5328.4060301@mellanox.com> <20120803.163627.1867181085116225405.davem@davemloft.net> <50205DE0.7080706@mellanox.com> <87obmnfs4p.fsf@xmission.com> <871ujjfkb1.fsf@xmission.com> <87hasd7pbz.fsf@xmission.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Eric W. Biederman" , Ali Ayoub , David Miller , ogerlitz@mellanox.com, roland@kernel.org, netdev@vger.kernel.org, sean.hefty@intel.com, erezsh@mellanox.co.il, dledford@redhat.com To: Or Gerlitz Return-path: Received: from mx1.redhat.com ([209.132.183.28]:51254 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751971Ab2HLOG1 (ORCPT ); Sun, 12 Aug 2012 10:06:27 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Aug 09, 2012 at 07:06:46AM +0300, Or Gerlitz wrote: > Eric W. Biederman wrote: > > Or Gerlitz writes: > > >> To put things in place, DHCPv4 is supported with eIPoIB, the DHCP > >> UDP/IP payload isn't touched, only need to set the BOOTP broadcast > >> flag in the dhcp server config file. > > > Wrong. DHCPv4 is broken over eIPoIB. Coming from ethernet > > htype == 1 not 32 as required by RFC4390 > > hlen == 6 not 0 as required by RFC4390 > > The chaddr field is has 6 bytes of the ethernet mac address not the > > required 16 bytes of 0. The client-identifier field is optional over ethernet. > > An ethernet DHCPv4 client simply does not generate a dhcp packet that > > conforms to RFC4390. > > > > Therefore DHCPv4 over eIPoIB is broken, and a dhcp server or relay > > may reasonably look at the DHCP packet and drop it because it is garbage. > > > > You might find a forgiving dhcp server that doesn't drop insane packets > > on the floor and tries to make things work. > > Under the eIPoIB design, the VM DHCP interaction follows > Ethernet DHCP, and not the IPoIB DHCP (RFC 4390). > > The DHCP server has no reason to drop such packets. > > DHCP is a L7 (L5 to be precise) construct, I don't see > why that the fact IPoIB DHCP RFC exists, means/mandates > the DHCP server to care on the link layer type. > > Or. For example DHCP server could be configured with HW address/IP address table. -- MST