From owner-freebsd-net@FreeBSD.ORG Thu Dec 7 12:53:51 2006 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 3CC4916A50D for ; Thu, 7 Dec 2006 12:53:51 +0000 (UTC) (envelope-from maillist.ifiaas@gmail.com) Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.184]) by mx1.FreeBSD.org (Postfix) with ESMTP id AC4B543D83 for ; Thu, 7 Dec 2006 12:51:05 +0000 (GMT) (envelope-from maillist.ifiaas@gmail.com) Received: by nf-out-0910.google.com with SMTP id x37so837602nfc for ; Thu, 07 Dec 2006 04:51:55 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=ITPqjVUrRVHVEULiOtpKCluhcaS19eSop25mGQJmmPqDQ1dReClnPQHfaja5nkc0UjgKV7/SZfWiM5Maa3FeJcJbS/utXnbOQZAmoUy7Hu4qOWeKNm0yZ88GoE6xT0eIB2FXWBFsisQg954uh+cE4PHPr2B+QUDK4gFGi123iLY= Received: by 10.49.10.17 with SMTP id n17mr3887573nfi.1165495914842; Thu, 07 Dec 2006 04:51:54 -0800 (PST) Received: by 10.48.242.15 with HTTP; Thu, 7 Dec 2006 04:51:54 -0800 (PST) Message-ID: <161d69110612070451o6945c7c0y9cf7a7e8b6b7225d@mail.gmail.com> Date: Thu, 7 Dec 2006 20:51:54 +0800 From: "maillist ifiaas" To: "Randall Stewart" In-Reply-To: <4578057B.9080002@cisco.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <161d69110612060709n3bf99bd4y47d94b021b8f1d02@mail.gmail.com> <4577D858.4010300@freebsd.org> <2786D1DE-E8FA-490C-AFF7-E458E262AEF7@lurchi.franken.de> <161d69110612070242p612e2318ya8d285a15a54e9fc@mail.gmail.com> <4578057B.9080002@cisco.com> Cc: freebsd-net@freebsd.org Subject: Re: Urel, a TCP option for Unreliable Streaming. Need your help. X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 Dec 2006 12:53:51 -0000 Thanks Randall. Am I right to say that, in SCTP, the loss information is reported to the sender, instead of the receiver? Btw, TCP Urel is a option. To use it, you have to add something like, int rc = setsockopt( inSettings->mSock, IPPROTO_TCP,TCP_URE, (char*) &val, len ); to enable Urel option in TCP. I still think that partial reliability should be performed in the application layer. Although transport layer knows more about the channel condition, but they can either be reported to the application (like we did on segment loss in TCP Urel), or be infered by application (e.g. estimating the current bitrate by looking at the buffersize). As QoS is only meaningful to application, allowing flexibilty of implementing QoS (such as partial relaibility) mechenism in application layer rather than transport layer, looks much natrual to me. -gavin On 12/7/06, Randall Stewart wrote: > maillist ifiaas wrote: > > Michael, > > > > In PR-SCTP where retranmission is set off, does it allows the > > applications to know which part of data is lost in the stream? > > Thanks > > Yep.. you subscribe for a notification event and SCTP will > return you the data that was not sent. > > So not only does it let you know you can actually let > SCTP hold and return the data that did not get > acknowledged.. The API also has a context so you > can attach a user defined 32 bit value to the > data.. to say bind a pointer to an object to > the actual data... for lookup or other stuff :-) > > R > > > > > > -- > Randall Stewart > NSSTG - Cisco Systems Inc. > 803-345-0369 803-317-4952 (cell) >