From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vadim Kochan Subject: [PATCH] man ip-link: Add more explanation about vlan reordering Date: Mon, 17 Aug 2015 22:22:24 +0300 Message-ID: <1439839344-12772-1-git-send-email-vadim4j@gmail.com> Cc: Vadim Kochan To: netdev@vger.kernel.org Return-path: Received: from mail-wi0-f170.google.com ([209.85.212.170]:35050 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750921AbbHQTZH (ORCPT ); Mon, 17 Aug 2015 15:25:07 -0400 Received: by wicne3 with SMTP id ne3so78309259wic.0 for ; Mon, 17 Aug 2015 12:25:06 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: From: Vadim Kochan Add more explanation about VLAN reordering and what it affects. Signed-off-by: Vadim Kochan --- man/man8/ip-link.8.in | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in index df2fcce..b9137fb 100644 --- a/man/man8/ip-link.8.in +++ b/man/man8/ip-link.8.in @@ -313,7 +313,31 @@ the following additional arguments are supported: - specifies the VLAN Identifer to use. Note that numbers with a leading " 0 " or " 0x " are interpreted as octal or hexadeimal, respectively. .BR reorder_hdr " { " on " | " off " } " -- specifies whether ethernet headers are reordered or not. +- specifies whether ethernet headers are reordered or not (default is +.BR on ")." + +.in +4 +If +.BR reorder_hdr " is " on +then VLAN header will be not inserted immediately but only before passing to the +physical device (if this device does not support VLAN offloading), the similar +on the RX direction - by default the packet will be untagged before being +received by VLAN device. Reordering allows to accelerate tagging on egress and +to hide VLAN header on ingress so the packet looks like regular Ethernet packet, +at the same time it might be confusing while the packet sniffing as the VLAN header +does not exist within the packet. + +VLAN offloading can be checked by +.BR ethtool "(8):" +.in +4 +.sp +.B ethtool -k + | +.RB grep " tx-vlan-offload" +.sp +.in -4 +where is the physical device to which VLAN device is bound. +.in -4 .BR gvrp " { " on " | " off " } " - specifies whether this VLAN should be registered using GARP VLAN Registration Protocol. @@ -1065,7 +1089,8 @@ IEEE 802.15.4 device wpan0. .SH SEE ALSO .br .BR ip (8), -.BR ip-netns (8) +.BR ip-netns (8), +.BR ethtool (8) .SH AUTHOR Original Manpage by Michail Litvak -- 2.4.2