From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 0FD1F198005 for ; Fri, 22 Feb 2013 13:56:46 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 75BA921C03A; Fri, 22 Feb 2013 13:56:35 +0000 (UTC) Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id AE40421C00C for ; Fri, 22 Feb 2013 13:56:33 +0000 (UTC) Received: by mail-wi0-f182.google.com with SMTP id hi18so755387wib.15 for ; Fri, 22 Feb 2013 05:56:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:from:reply-to:to:subject:date:user-agent:references :in-reply-to:mime-version:content-type:content-transfer-encoding :message-id; bh=Jccbk26MT3galJ8gZwp8QwO/Hk0bt7ckdCoapbxDkoE=; b=oaDPiidaseQ8Rhsf3q7XC+cvjSDHgKffttQIxNA74dMQb1fnw3Q49slTOWSNnjYTr8 b5LSdfCCN2Or/2s/NnX92WY7+mnyQTrl7osoA7G0dMwC9JFI3OXPDK+e8qXrt7XM3+Lt ykWJa7vsdeELKV4Df3dgf07C7QaUHp6MbNnQ5b54MnAh6QAjgbKToa6Oegn6ANhTkwPs RCa2VTBbBmhnJew4sRPkkQk3jEVPOGrr0SCGMx63kRPOLAqwxK9inQ7vKatW0enB1vES ix6GJFtT3feacnpQ7uNXnSxS5+WvkzaqNbKjRUFDjRhF5Ba775sQJ8UITJkMQM7lHbwV M5Cw== X-Received: by 10.180.102.201 with SMTP id fq9mr49098464wib.2.1361541392366; Fri, 22 Feb 2013 05:56:32 -0800 (PST) Received: from dell_xps.localnet (230.3.169.217.in-addr.arpa. [217.169.3.230]) by mx.google.com with ESMTPS id q13sm2923379wie.0.2013.02.22.05.56.30 (version=TLSv1.2 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 22 Feb 2013 05:56:31 -0800 (PST) From: Mick To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] Slow local network - how to debug? Date: Fri, 22 Feb 2013 13:55:07 +0000 User-Agent: KMail/1.13.7 (Linux/3.6.11-gentoo; KDE/4.9.5; x86_64; ; ) References: <1361520278.18741.0@numa-i> In-Reply-To: <1361520278.18741.0@numa-i> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1531977.NgGL4p8U6s"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <201302221355.22320.michaelkintzios@gmail.com> X-Archives-Salt: e7c7aabc-29bf-4b06-95ae-04b5201e98e8 X-Archives-Hash: 28741cedde64e1c64b8234d2613db620 --nextPart1531977.NgGL4p8U6s Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Friday 22 Feb 2013 08:04:38 Helmut Jarausch wrote: > Hi, >=20 > I have no experiences in debugging a slow network. >=20 > At home, I have a router which is connected to my telephone line via > VDSL2. > I have 2 PCs one of which is connected by an ethernet cable (i.e. > wired) while the other > one uses a wireless connection which is specified as 56 Mbit/s. >=20 > When copying data from one machine to the other one I see varying > speeds from only 0.5 Mbits/s up to > more than 20 Mbits/s. I have no idea why it is so slow some times. > There are no other wireless devices nearby. Where do you see these transfer speeds? On the wired machine, or on the=20 wireless machine? What do you use to check the transfer speed? Do the speeds go up when you used a Cat5e cable at full duplex? Have you scanned for access points to be absolutely sure that there are no= =20 other wireless devices, or APs? Do you use encryption? What frequency and channel are you on and have you tried to change=20 channel/frequency? (some domestic devices like cordless phones, wireless=20 earphones, bluetooth, microwaves, perimeter sensors, etc. can cause co-chan= nel=20 and adjacent channel interference and/or force sharing of the bandwidth). Are both machines and the router's LAN on the same MTU? > What tools and techniques can I use to debug this situation? >=20 > Many thanks for a hint, =46irst use ifconfig to see how many dropped packets you get on both machin= es. =20 Then use iwconfig, or cat /proc/net/wireless on the PC running the wireless= to=20 see how many discarded packets you get, fragmentation, etc. as well as nwid= =20 packets from different networks on the same frequency. Then check with e.g. iptraf-ng what network connections are running, their= =20 rate(s) and if any of these should not be there. The router stats may also be revealing in this respect, as well as dropped= =20 packets on the WiFi. I hope the above will give something to work with, others may have better=20 ideas and more specialised tools for troubleshooting this. PS. I haven't mentioned spectrum analysers to keep this thread within the= =20 realm of quick fixes, but if you do have EM interference and the source of = it=20 is obscure, you may need more professional equipment to nail this problem. =2D-=20 Regards, Mick --nextPart1531977.NgGL4p8U6s Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iEYEABECAAYFAlEneMoACgkQVTDTR3kpaLbeoACg+vmm3PjW7W00Do1aRSLScCd9 Y7gAnjz1F0dDYuSuX2m6pu79V4XQybgZ =YalE -----END PGP SIGNATURE----- --nextPart1531977.NgGL4p8U6s--