From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-x236.google.com (ie-in-x0236.1e100.net [IPv6:2607:f8b0:4001:c03::236]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 3B90D21F175 for ; Sun, 27 Jan 2013 23:52:42 -0800 (PST) Received: by mail-ie0-f182.google.com with SMTP id s9so834707iec.27 for ; Sun, 27 Jan 2013 23:52:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=YAkBG7w3QmILs9RKQUwcv2f5bMc8Fl1GKirdZkwF9ZY=; b=CCRlNkQ3qvLiiGkuo4vs9u8u88ITbIg/krb55/w0V2TVv+6lWWVJzBz5b/JcqLrDBw sBe4fXWPdwXTUBZPb+/dvuLXE2PhPGi3NSr0wDzFxzu8xoRjPdjquzwF27cVWG0Pxpeo Iy4ypvkp30cKO1lc3sIcVPH3PiCHnjjwUCanOjGT+BfqiWnaZowkiTCg2VK5il00MTrL d+ioZOMFE19xhnXAefcgRRuX8cBopJG2+g3iXlPY21QjfWp+rGHTluu16hvQqStditgM qAwlvpI7A2HCP3721ZudTsXRy8xkwc9mdPoZ6jlTJkJapK+vatnMQyfzd90gmIgEyIP1 +KhQ== MIME-Version: 1.0 X-Received: by 10.42.54.5 with SMTP id p5mr8368417icg.49.1359359561639; Sun, 27 Jan 2013 23:52:41 -0800 (PST) Received: by 10.64.135.39 with HTTP; Sun, 27 Jan 2013 23:52:41 -0800 (PST) In-Reply-To: References: Date: Sun, 27 Jan 2013 23:52:41 -0800 Message-ID: From: Dave Taht To: Robert Bradley , Felix Fietkau , cerowrt-devel@lists.bufferbloat.net Content-Type: multipart/alternative; boundary=90e6ba3fd72dcb254404d4548f8e Subject: Re: [Cerowrt-devel] deployed some cero this weekend, chasing checksums X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Jan 2013 07:52:42 -0000 --90e6ba3fd72dcb254404d4548f8e Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Put up a pic http://snapon.lab.bufferbloat.net/~d/yurt they aren't bad all the time, but when they go bad, bad things happen. On Sun, Jan 27, 2013 at 11:41 PM, Dave Taht wrote: > > I have been debugging some weirdness for a while. You might want to do > some captures on the latest cero and look at checksums. > > An unreasonably high number of checksum issues seem to be happening, but > there doesn't appear to be a whole lot of pattern to it, as yet. > > I will simplify. I pinged locally and 8.8.8.8 and surfed the web, and a > symptom is that some other routers can't ping sometimes nor access much o= f > the internet beyond the gateway. They can always reach the gateway. > > in the interim, the topology on this capture are > > 172.30.102.17 - laptop via ethernet to > 172.20.102.1 - cerowrt 3.7.4-4 via ethernet to > 172.20.6.1 - ubnt 3.3.8-26 via mesh to > 172.20.142.11 - ubnt 3.7.4-4 via ethernet to > * 192.168.100.1 - cerowrt 3.7.2 capture point (yes, updating that) > 10.0.10.1 - comcast box (yes, double nat, fixing that) > > I took a capture on the se00 interface > > tcpdump -i se00 -w/tmp/yurt.cap host 172.20.102.17 > > and stuck that capture there: > > http://snapon.lab.bufferbloat.net/~d/yurt/yurt.cap > > and then looked at it with wireshark with this filter > > ip.checksum_bad =3D=3D 1 > > and scratched my head at the error rate (about 1%) and the pattern (lack > thereof) > > I will simplify in the mroning > > -- > Dave T=E4ht > > Fixing bufferbloat with cerowrt: > http://www.teklibre.com/cerowrt/subscribe.html --=20 Dave T=E4ht Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html --90e6ba3fd72dcb254404d4548f8e Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Put up a pic http://s= napon.lab.bufferbloat.net/~d/yurt

they aren't bad all the ti= me, but when they go bad, bad things happen.

On Sun, Jan 27, 2013 at 11:41 PM, Dave Taht <dave.taht@gmail.com&g= t; wrote:

I have been debugging some weirdn= ess for a while. You might want to do some captures on the latest cero and = look at checksums.

An unreasonably high number of checksum issues s= eem to be happening, but there doesn't appear to be a whole lot of patt= ern to it, as yet.

I will simplify. I pinged locally and 8.8.8.8 and surfed the web, and a= symptom is that some other routers can't ping sometimes nor access muc= h of the internet beyond the gateway. They can always reach the gateway.=A0=

in the interim, the topology on this capture are

172.30.102.17 -= laptop via ethernet to
172.20.102.1 - cerowrt 3.7.4-4 via ethernet to172.20.6.1 - ubnt 3.3.8-26 via mesh to
172.20.142.11 - ubnt 3.7.4-4 vi= a ethernet to
* 192.168.100.1 - cerowrt 3.7.2 capture point (yes, updating that)
10.0.= 10.1 - comcast box (yes, double nat, fixing that)

I took a capture o= n the se00 interface

tcpdump -i se00 -w/tmp/yurt.cap host 172.20.102= .17

and stuck that capture there:

http://snapon.lab.bufferbloa= t.net/~d/yurt/yurt.cap

and then looked at it with wireshark with= this filter

ip.checksum_bad =3D=3D 1

and scratched my head at the error rate= (about 1%) and the pattern (lack thereof)

I will simplify in the mr= oning

--
Dave T= =E4ht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subs= cribe.html=20



--
Dave T=E4= ht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowr= t/subscribe.html=20 --90e6ba3fd72dcb254404d4548f8e--