From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f171.google.com (mail-ie0-f171.google.com [209.85.223.171]) (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 B15B1208AC3; Tue, 11 Dec 2012 08:48:01 -0800 (PST) Received: by mail-ie0-f171.google.com with SMTP id 17so15864446iea.16 for ; Tue, 11 Dec 2012 08:48:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:date:message-id:subject:from:to:cc:content-type; bh=b2f7E3cjLsVfRlLE9f001S1vCpyyKmF1aDuWXFPoDqQ=; b=BL3/FKcfKg4LI+yr8SbxcZzCvdDQaDdWIthA73g3jChvsvlm0zahx6ZEiSxJd4euxw O4e3mMt3ENbjkX+btAEktl5VysSXO1UJQsahE245J9htroKlhvLlzmHp1/PjgvR8b1oi LVRioqNPA6uHDfFqcaPgU5UURDplWYKAoFQQM5SZ0SL6uVJns91Eu23+Dk6NylxXx9MV DdKx1cXByQyMdwX+QanOsNZ2e3VD3eZGwSWg480PxYUZGHfJApEuzrv+1/PTKggvEY2J InnCHGtfqft5lR1TEIZEbEJJDkvHPZxhIXF40RrzJTsOmcgaFYhtflfNm+QJqhNxVdmn PF1A== MIME-Version: 1.0 Received: by 10.43.70.7 with SMTP id ye7mr14944484icb.9.1355244480673; Tue, 11 Dec 2012 08:48:00 -0800 (PST) Received: by 10.64.53.105 with HTTP; Tue, 11 Dec 2012 08:48:00 -0800 (PST) Date: Tue, 11 Dec 2012 22:18:00 +0530 Message-ID: From: Ketan Kulkarni To: bloat , cerowrt-devel@lists.bufferbloat.net Content-Type: multipart/alternative; boundary=bcaec51f96c3dab6ba04d0967103 Subject: [Bloat] TCP TFO client behaviour X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 11 Dec 2012 16:48:02 -0000 --bcaec51f96c3dab6ba04d0967103 Content-Type: text/plain; charset=ISO-8859-1 Hi, I am testing tcp tfo behavior with httping client and polipo server. One observation from my TFO testing -If for a connection server sends a cookie to client, client always does TFO for subsequent connections. This is ok. If for some reason, server stops supporting TFO (either because server got restarted without TFO support (in my case) or because path changed and the nw node is dropping packet with unknown syn option or stripping the option), client does not clear up its cookie cache. It always sends data in syn and server never acks the syn-data and client retransmits. As per kernel code -if syn-data is not acked it is retransmitted immediately - with the assumption first syn was dropped (but the assumption server stopped supporting TFO might not have been considered) My opinion is to flush the cookie for this server and re-attempt the cookie "negotiation" on subsequent connection. Your thoughts? Thanks, Ketan --bcaec51f96c3dab6ba04d0967103 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi,
I am testing tcp tfo behavior with httping client and polipo server.=

One observation from my TFO testing =A0-If for a connection server = sends a cookie to client, client always does TFO for subsequent connections= . This is ok.

If for some reason, server stops supporting TFO (either because server = got restarted without TFO support (in my case) or because path changed and = the nw node is dropping packet with unknown syn option or stripping the opt= ion), client does not clear up its cookie cache. It always sends data in sy= n and server never acks the syn-data and client retransmits.

As per kernel code -if syn-data is not acked it is retransmitted immedi= ately - with the assumption first syn was dropped (but the assumption serve= r stopped supporting TFO might not have been considered)

My opinion = is to flush the cookie for this server and re-attempt the cookie "nego= tiation" on subsequent connection.

Your thoughts?

Thanks,
Ketan --bcaec51f96c3dab6ba04d0967103--