From owner-freebsd-virtualization@freebsd.org Thu Dec 22 11:25:24 2016 Return-Path: Delivered-To: freebsd-virtualization@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id F311AC8BEA9 for ; Thu, 22 Dec 2016 11:25:24 +0000 (UTC) (envelope-from freebsd@omnilan.de) Received: from mx0.gentlemail.de (mx0.gentlemail.de [IPv6:2a00:e10:2800::a130]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 7AFF71DD8 for ; Thu, 22 Dec 2016 11:25:24 +0000 (UTC) (envelope-from freebsd@omnilan.de) Received: from mh0.gentlemail.de (mh0.gentlemail.de [78.138.80.135]) by mx0.gentlemail.de (8.14.5/8.14.5) with ESMTP id uBMBPKW6056764; Thu, 22 Dec 2016 12:25:20 +0100 (CET) (envelope-from freebsd@omnilan.de) Received: from titan.inop.mo1.omnilan.net (titan.inop.mo1.omnilan.net [IPv6:2001:a60:f0bb:1::3:1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mh0.gentlemail.de (Postfix) with ESMTPSA id 42FC855C; Thu, 22 Dec 2016 12:25:20 +0100 (CET) Message-ID: <585BB81F.2020001@omnilan.de> Date: Thu, 22 Dec 2016 12:25:19 +0100 From: Harry Schmalzbauer Organization: OmniLAN User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; de-DE; rv:1.9.2.8) Gecko/20100906 Lightning/1.0b2 Thunderbird/3.1.2 MIME-Version: 1.0 To: "Andrey V. Elsukov" CC: freebsd-virtualization@freebsd.org Subject: Re: Jumbo frames truncated at 4084 bytes by virtio-net? (using if_bridge(4) and vtnet(4) with mtu 9000) References: <585AA902.50907@omnilan.de> <9b7951c0-9466-2b89-84de-c1026ee8f1c0@yandex.ru> In-Reply-To: <9b7951c0-9466-2b89-84de-c1026ee8f1c0@yandex.ru> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Greylist: ACL 119 matched, not delayed by milter-greylist-4.2.7 (mx0.gentlemail.de [78.138.80.130]); Thu, 22 Dec 2016 12:25:20 +0100 (CET) X-Milter: Spamilter (Reciever: mx0.gentlemail.de; Sender-ip: 78.138.80.135; Sender-helo: mh0.gentlemail.de; ) X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Dec 2016 11:25:25 -0000 Bezüglich Andrey V. Elsukov's Nachricht vom 22.12.2016 11:13 (localtime): > On 21.12.2016 19:08, Harry Schmalzbauer wrote: >> Hello, >> >> I'm having guest connectivity problems with jumbo frames. >> >> Since if_bridge(4) requires all interfaces to have the same MTU (and the >> uplink interface also handles iscsi traffic, which greatly benefits from >> jumbo frames), I >> 'ifconfig create vmnet0 mtu 9000' >> >> Now my problem is that I can't simply keep guest's mtu at 1500, since >> the host will send jumbo frames as answer wich never get through >> virtio-net. >> >> Does anybody have an idea how to fix/work arround? > > This looks like the problem with mbufs bigger than PAGE_SIZE. > Do you see some denied requests in the `netstat -m` output? Thanks for your attention! Nope, there are no denied mbuf requests after sending icmp echo-request through virtio-net with all participants' MTU set to 9000: 0/0/0 requests for mbufs denied (mbufs/clusters/mbuf+clusters) 0/0/0 requests for jumbo clusters denied (4k/9k/16k) 0 requests for sfbufs denied The icmp echo-reply just doesn't make it through virtio-net (the echo-request reaches the destination host, and the echo-reply reaches vmnet0!). Keeping everything untouched, just replacing '-s 5,virtio-net,vmnet0' with '-s 5,e1000,vmnet0', I get the reply into the guest: ping -D -s 8972 mirashare PING mirashare.egn.mo1.omnilan.net (172.21.34.11): 8972 data bytes 8980 bytes from 172.21.34.11: icmp_seq=0 ttl=64 time=1.590 ms Thanks, -harry