From mboxrd@z Thu Jan 1 00:00:00 1970 From: Toshiaki Makita Subject: Re: 802.1AD packets - Kernel changes ether type from 88A8 to 8100 on all packets. Date: Sun, 13 Apr 2014 01:20:36 +0900 Message-ID: <1397319636.1789.11.camel@localhost.localdomain> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" To: Dennis Punjabi Return-path: Received: from mail-pd0-f169.google.com ([209.85.192.169]:52093 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751448AbaDLQUm (ORCPT ); Sat, 12 Apr 2014 12:20:42 -0400 Received: by mail-pd0-f169.google.com with SMTP id fp1so6513529pdb.28 for ; Sat, 12 Apr 2014 09:20:42 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: 1. On Fri, 2014-04-11 at 11:01 +0000, Dennis Punjabi wrote: > Background: > 1) I need to setup a Linux software bridge and ensure that packets coming in on one bridge port exit unchanged on another bridge port, like a normal HW bridge. > 2) I need to use the new vlan filtering capability of the bridge. Good news of this feature is made in the kernel announcement of release 3.9 @ http://kernelnewbies.org/Linux_3.9 > 3) I need to test what presently happens to 802.1AD tagged packets when bridge vlan filtering is enabled because I also need support for Q-in-Q. > > I am using a packet generator (Ostinato) and creating 802.1AD packets as follows: > > (MAC_HDR) (8021AD_HDR) (8021Q HDR) (PAYLOAD) > > (DA | SA | TYPE) (TCI | TPID) (TCI | TPID) (TEST PAYLOAD - ARP BCAST PACKET) > > (DA | SA | 88A8) (TCI | 8100) (TCI | 0806) (TEST PAYLOAD - ARP BCAST PACKET) > > (hopefully the alignment is ok above, if not I apologize and hope its clear enough) > > Even before setting up the the bridge, I want to ensure that packets are being received properly to my system. > I do a tcpdump output for the port receiving the generated packets. > > What I notice is that the 88A8 TPIC/ether type get changed to 8100. > Ie, all packets with ether type 802.1AD get changed to 802.1Q type, ie 8100. > I initially tested this on a 3.14 vanilla kernel. Hi. Though I'm not an expert with libpcap, I feel tcpdump sometimes shows a wrong vlan protocol (if vlan_tci is used). Maybe this topic has relevance? packet: deliver VLAN TPID to userspace http://marc.info/?l=linux-netdev&m=138728859001934&w=2 http://marc.info/?l=linux-netdev&m=138728859601935&w=2 http://marc.info/?l=linux-netdev&m=138728860101937&w=2 http://marc.info/?l=linux-netdev&m=138728860601939&w=2 Thanks, Toshiaki Makita > > I recompiled my 8139too.c driver and printed printk the packets in the driver before they are handed over to netif_receive_skb. > Before being passed to the kernel networking stack the packet is as it is supposed to be, ie it has the correct 88A8 ether type. > > I went ahead and tested this on kernel 3.12, 3.11, 3.10. I Saw the same result. > > I also tested it on 3.9, 3.8 and 2.6 and these kernels did not change the 88A8 to 8100. > > Is this intentional or a bug? Does this have something to do with the addition of the new feature (vlan: Add 802.1ad support) announced in kernel 3.10? http://kernelnewbies.org/Linux_3.10 > > I have been following the net-dev mailing lists and want to test the bridge 802.1AD filtering feature discussed here http://www.spinics.net/lists/linux-ethernet-bridging/msg05207.html but cannot do so if the bridge does not even get the 802.1AD tagged packets to begin with. > > Assuming I don't want to use filtering and just want a simple bridge. The expected behaviour is that the bridge must not change my packet and should simply pass it along. Is my thinking correct? > > Thanks for any help provided. > > Dennis > -- > 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