Re: [grobj] Referral definition and its purpose?
bo zhou <zhouboyj@gmail.com> Thu, 27 May 2010 07:40 UTC
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Date: Thu, 27 May 2010 15:39:59 +0800
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From: bo zhou <zhouboyj@gmail.com>
To: Dan Wing <dwing@cisco.com>
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Cc: grobj@ietf.org
Subject: Re: [grobj] Referral definition and its purpose?
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Hi Dan, Some comments inline. On Thu, May 27, 2010 at 8:21 AM, Dan Wing <dwing@cisco.com> wrote: > > > > -----Original Message----- > > From: grobj-bounces@ietf.org [mailto:grobj-bounces@ietf.org] > > On Behalf Of Sheng Jiang > > Sent: Tuesday, May 18, 2010 2:01 AM > > To: grobj@ietf.org > > Subject: [grobj] Referral definition and its purpose? > > > > Hi, all, > > > > We are now working on an referral PS draft, targeting to > > submit end of May > > or the beginning of June. We'd like to discuss the relevant > > contents/topic > > publicly in the mail list during our writing. Comments or > > contributions are > > more than welcome. > > > > The first target is to understand what is referral and its > > purpose. There > > may be different understanding, our goal here is to find a > > common definition > > for our PS draft. The following is my understanding and > > what's in the draft > > now. > > > > In abstract: The purpose of a referral is to enable a given > > entity in a > > multiparty Internet application to pass information to > > another party. It > > enables a communication initiator to aware relevant information of its > > destination entity before launching the communication. > > > > In the introduction: A frequently occurring situation is that > > one entity A > > connected to the Internet (or to some private network using > > the Internet > > protocol suite) needs to inform another entity B how to reach either A > > itself or some third-party entity C. This is known as a referral. > > > > Does everyone can agree on this Referral definition and its > > purpose? Only if > > consensus can reach here, our next discussion for referral > > scenarios can make sense. > > The definition of referral should be tightened up slightly > that the parties are exchanging the information via one > channel (e.g., SIP signaling) but want to communicate (as) > directly (as possible) with each other *not* using that > channel. I often get asked "if they can communicate referral > information with each other, why don't they just use that > communication channel for everything else?". > [bo]The path which they communicate referral information maybe not the "best" path for the information they really want to communicate. Many today's peer-to-peer applications are working like this way, one reason could be avoiding monitor from operator or others and protect privacy. > > In SIP, this is often called the "SIP trapezoid". > We can generalize this a bit resulting in the following > figure: > > +-----------+ +-----------+ > |application| |application| > | server(s) +.......+ server(s )| > +---+-------+ +-------+---+ > / \ > | | > | referral information | > | | > | | > +-+-+ +-+-+ > | A +-----------------------+ B | > +---+ direct communication +---+ > > The application server(s) might be one single server, a distributed hash > table, two servers, or any sort of combination. The referral data is > carried > on bewtween A and B on the top, through those servers. A and B are trying > to > communicate directly with one another, using the communication line at the > bottom. > > A simplier model which is good to think about is a simple protocol which > collapses the model above, such as FTP. FTP follows the same model as > above, > except the 'application server' is the FTP server and FTP control channel > (TCP/21) is what carries the referral (PASV, EPSV, PORT, EPRT). TFTP is > another example of a collapsed model. > > +-+-+ +-+-+ > | | FTP control connection | | > | | (referral information) | | > | +............................+ | > | | | | > | A | | B | > | | FTP data connection | | > | +----------------------------+ | > | | | | > +---+ +---+ > > -d > > > > Best regards, > > > > Sheng > > > > _______________________________________________ > > grobj mailing list > > grobj@ietf.org > > https://www.ietf.org/mailman/listinfo/grobj > > _______________________________________________ > grobj mailing list > grobj@ietf.org > https://www.ietf.org/mailman/listinfo/grobj > -- Regards, Bo Zhou China Mobile
- [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Keith Moore
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Dong Zhang
- Re: [grobj] Referral definition and its purpose? Keith Moore
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Brian E Carpenter
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Dan Wing
- Re: [grobj] Referral definition and its purpose? Keith Moore
- Re: [grobj] Referral definition and its purpose? Dan Wing
- Re: [grobj] Referral definition and its purpose? Keith Moore
- Re: [grobj] Referral definition and its purpose? bo zhou
- Re: [grobj] Referral definition and its purpose? bo zhou
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Keith Moore
- Re: [grobj] Referral definition and its purpose? Scott Brim
- Re: [grobj] Referral definition and its purpose? Scott Brim
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Sheng Jiang
- Re: [grobj] Referral definition and its purpose? Brian E Carpenter