Return-path: Received: from mail-yw0-f170.google.com ([209.85.161.170]:34635 "EHLO mail-yw0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1425276AbcBRNgl (ORCPT ); Thu, 18 Feb 2016 08:36:41 -0500 Received: by mail-yw0-f170.google.com with SMTP id h129so39890717ywb.1 for ; Thu, 18 Feb 2016 05:36:40 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <56C4A5ED.4060802@openwrt.org> References: <1455710131-9967-1-git-send-email-grzegorz.bajorski@tieto.com> <56C4A5ED.4060802@openwrt.org> Date: Thu, 18 Feb 2016 14:36:40 +0100 Message-ID: (sfid-20160218_143645_710635_70A08F14) Subject: Re: [RFC] mac80211: add extap functionality From: Grzegorz Bajorski To: Felix Fietkau Cc: linux-wireless@vger.kernel.org, Johannes Berg Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: 2016-02-17 17:55 GMT+01:00 Felix Fietkau : > On 2016-02-17 12:55, Grzegorz Bajorski wrote: >> Client interface briding was only possible when 4addr frames were used with >> a 4addr/WDS aware AP. It was not possible to do it otherwise due to 3addr >> frame limitation. >> >> The extap logic introduces a smart MAC address masking/translation >> (including modyfing packets beyond SA/DA, e.g. DHCP broadcast flag is set). >> >> There are still some unsolved problems and bugs: >> - due to bridge port routing and sk_buff payload sharing skb_copy() is >> performed; this ideally should be reworked >> - ipv6 support is still not finished >> - extap is enabled by default currently; it should be configurable via >> nl80211 the same way 4addr is >> >> There's also an idea to move this as a generic link driver (just like >> macvlan, et al) which would allow unmodified cfg80211 drivers to enjoy the >> extap functionality. Thoughts? >> >> Note: This changes cfg80211 file in this single patch only for reviewing >> convienence. >> >> This is an early draft to solicit comments on the design. >> >> Signed-off-by: Grzegorz Bajorski > You can get a lot of the same effect (sharing the same subnet between > hosts behind multiple interfaces and having forwarding between them) > without any changes to mac80211. > > OpenWrt uses a daemon called 'relayd' which I wrote some years ago. It > does ARP translation, DHCP packet mangling and sets up policy routing to > forward packets between multiple interfaces. > > You can find it here: > http://git.openwrt.org/?p=project/relayd.git;a=summary > git://git.openwrt.org/project/relayd.git > > Since you can cover the same use cases with user space code, I don't > think it's a good idea to put bridge emulation hacks in the kernel's > wireless stack. What about performance? Quick test show that is slow ~ 100-120 mbps (UDP tests) and procesor is overloaded. Am I missing something? I would expect it to be greater. (4 x 4 antena setup VHT80) /Grzegorz