Re: Summary of responses so far and proposal moving forward[WasRe: [tcpm] Is this a problem?]
David Borman <david.borman@windriver.com> Wed, 28 November 2007 16:40 UTC
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From: David Borman <david.borman@windriver.com>
To: MURALI BASHYAM <murali_bashyam@yahoo.com>
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Subject: Re: Summary of responses so far and proposal moving forward[WasRe: [tcpm] Is this a problem?]
Date: Wed, 28 Nov 2007 10:40:12 -0600
References: <362265.35986.qm@web31708.mail.mud.yahoo.com>
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Cc: TCP Maintenance and Minor Extensions WG <tcpm@ietf.org>, Joe Touch <touch@isi.edu>, Mark Allman <mallman@icir.org>
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On Nov 27, 2007, at 5:51 PM, MURALI BASHYAM wrote: >> Now, it might be that connections that have been in persist state for >> a long period of time are good candidates for the OS to abort to free >> up resources. But doing that has to be a decision of the OS or the >> application, not of TCP. TCP can keep track of how long connections >> are in persist state, so that if the OS or application asks, it can >> judiciously choose which ones are the best to abort. > > Since you going down this path, what's wrong with TCP doing it by > itself having > received go-ahead from the application and/or the administrator of > the system? > Seems as if we are going to extreme lengths and playing with system > boundary > definitions here to avoid making a change where it hurts most (TCP). Ok. Don't confuse the protocol design with the implementation. To paraphrase David Clark from many years ago: Strict protocol layering is a great way to design a protocol, but a terrible way to implement it. In the RFCs, we are dealing with the protocol design, not the implementation, so we need crisp boundaries, and clarity on which side of the boundary things are on. The implementation is free to do as much blurring between the boundaries as it wants, as long as what goes on the wire is still correct. RFC 793 and 1122 talk about how to process a *single* TCP stream. They do not discuss interaction between TCP multiple streams (because from a protocol design standpoint, there shouldn't be any). When we get into the area of resource starvation, we are now talking about how multiple TCP streams interact between each other through the use of common resources. Dealing with that is not part of the design of TCP. If the user timeout on the SEND call is not sufficient for the application when dealing with a connection, then we would need a proposal to add a new timer to TCP, with a clear description of how the application sets the timer, when TCP should clear/restart the timer, and what to do when the timer goes off. That has nothing to do resource starvation. If the timeout on the SEND call would be sufficient for the application, but the TCP implementation does not provide the ability to set a timer on the SEND call, then that is an implementation issue. If you want to have a higher-level view that goes through and aborts connections in persist state when resources are low, perhaps based on how long they've been in persist state, that is not part of the TCP design. It might be *implemented* right in the middle of the TCP code, but it is not part of the TCP protocol design. -David Borman _______________________________________________ tcpm mailing list tcpm@ietf.org https://www1.ietf.org/mailman/listinfo/tcpm
- Re: Summary of responses so far and proposal movi… MURALI BASHYAM
- Re: Summary of responses so far and proposal movi… David Borman
- Re: Summary of responses so far and proposal movi… MURALI BASHYAM
- Re: Summary of responses so far and proposal movi… David Borman
- Re: Summary of responses so far and proposal movi… Ted Faber
- Re: Summary of responses so far and proposal movi… Joe Touch
- RE: Summary of responses so far and proposal movi… Anantha Ramaiah (ananth)
- Re: Summary of responses so far and proposal movi… David Borman
- RE: Summary of responses so far and proposal movi… Caitlin Bestler
- Re: Summary of responses so far and proposal movi… MURALI BASHYAM
- Re: Summary of responses so far and proposal movi… Joe Touch