Subject: [Simple] Questions regarding MSRP Relay drafts

From: Smile Wang <[email-masked]>
Date: Fri, 19 Aug 2005 11:24:08 +0800

Hi,all

I have a doubt about the draft-ietf-simple-msrp-relays-05.txt.

In section 3 the second example about a message being re-chunked

through two relays.

Alice           a.example.org(relay1)  b.example.net(relay2)         Bob

     |                     |                    |                     |

     |--- SEND 1-3 ------->|                    |                     |

     |<-- 200 OK ----------|                    |  (slow link)        |

     |--- SEND 4-7 ------->|--- SEND 1-5 ------>|                     |

     |<-- 200 OK ----------|<-- 200 OK ---------|--- SEND 1-3 ------->|

     |--- SEND 8-10 ------>|--- SEND 6-10 ----->|                ....>|

     |<-- 200 OK ----------|<-- 200 OK ---------|                  ..>|

     |                     |                    |<-- 200 OK ----------|

     |                     |                    |<-- REPORT 1-3 ------|

     |                     |<-- REPORT 1-3 -----|--- SEND 4-7 ------->|

     |<-- REPORT 1-3 ------|                    |                 ...>|

     |                     |                    |<-- REPORT 4-7 ----->|

     |                     |<-- REPORT 4-7 -----|--- SEND 8-10 ------>|

     |<-- REPORT 4-7 ------|                    |                  ..>|

     |                     |                    |<-- 200 OK ----------|

     |                     |<-- REPORT done-----|<-- REPORT done -----|

     |<-- REPORT done -----|                    |                     |

     |                     |                    |                     |

Why relay1 receive the part of message(1-3,4-7,8-10) not direct send to
relay2,but

re-chunked 1-5,6-10? I consider that MSRP is app layer protocol which don't
take 

into account the things that transfer layer to do.And MSRP use TCP or TSL
which

send the stream data,unlike UDP which data length exceed MTU must be split.

Smile  

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---

From: Paul Kyzivat <[email-masked]>
Date: Fri, 19 Aug 2005 09:03:37 -0400

Smile Wang wrote:
> relay2,but re-chunked 1-5,6-10?

There is no requirement that this rechunking be done. Relay1 could, if 
it wished, do as you suggest.

I suppose if the outbound link is congested, so that the relay receives 
multiple chunks that it has not been able to send, it might as well 
combine them.

> I consider that MSRP is app layer protocol which 
> don’t take
> 
> into account the things that transfer layer to do.And MSRP use TCP or 
> TSL which
> 

Its a little more complicated than that. Several MSRP sessions may be 
multiplexed over the same link. In that case, it may become necessary to 
break a large message into chunks so that other messages (or parts of 
them) may be interleaved.

	Paul

---

From: Smile Wang <[email-masked]>
Date: Mon, 22 Aug 2005 10:30:32 +0800

Thank Paul.inline

Smile

> -----Original Message-----
> From: Paul Kyzivat [mailto:[email-masked]]
> Sent: Friday, August 19, 2005 9:04 PM
> To: Smile Wang
> Cc: 'SIMPLE'
> Subject: Re: [Simple] Questions regarding MSRP Relay drafts
> 
> 
> 
> Smile Wang wrote:
> > Hi,all
> >
> > don't take

The mechanism of being re-chunked for MSRP is to avoid queue long time for
many users, when one user send a very large message cross a relay, the relay
can 
fragment the large message to many litte one, send some of it and deal with 
other users message. To one user is the same that can send many message at 
one time, not to wait one large message completely send out.

I thought of above.