Subject: Flow Control Issues

From: [email-masked] (Anand Subramaniam)
Date: Tue, 10 Aug 93 11:06:07 PDT

Hi,

If the proposed pacing scheme were to work well, we need to figure out a way
by which the the IPM could be delivered to the peer without the possibility
of a closed TCP send window. One way to do that is to ensure that the
receiving TCP always has receive window open. The other way is to have a
"control channel" which is used to send only control messages.

Consider the connection,

		--------------						 --------------
		|		      |	    1				 |			   |
		|			   ======================>			   |
		|			  |			2			 |			   |
		|	A		  |<---------------------|    B		   |
		|             |					     |			   |
		|		      |					     |			   |
		|			  |			3	 		 |			   |
		|			   <=====================|			   |
		|			  |			4			 |			   |
		|			  |---------------------->			   |
		|-------------						 ---------------

1 and 2 form a full duplex  TCP connection while 3 and 4 form another. 
Whenever A wants to send data to B it sends on 1 and B sends data to A on 3.
We could use 2 and 4 for control messages. Whenever a circuit in A is
beginning to get congested, A can send an IPM to B on 4 and B can respond on
2. This way we have a larger bandwidth for control messages and we don't have
to really depend upon the transport flow control. This also ensures that the
control messages which are important and are the basis for Dlsw flow control
reach the peer faster. Thus we could use the existing transport connection
scheme in the RFC and get around the "urgent data" problem.

If this suggestion is agreeable, we can explore other issues further with
this approach and nail them.

I had sent a mail sometime back regarding TCP connection management on July
30th. So far I have received only one response. If the existing implementors can come out and explain how this has been done or how it ought to be done, it 
would be of great help to all of us so that we could avoid inconsistencies in
implementation.

Thanks,

andy

-- 
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| UUCP:  {ames,apple,sun,mtxinu}!excelan!andy         (Anand Subramaniam) |
| INTERNET:  [email-masked]                          Ph : (408)-473-8413 |
| " Now and then I go off in to my own little world; But they know me     |
|   there"                                                                |
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---

From: [email-masked] (Anand Subramaniam)
Date: Tue, 10 Aug 93 11:18:44 PDT

My previous mail had the diagram screwed up because I used tabs instead of
spaces. Please ignore that.
>         |    A        |<--------------------- |    B          |
>         |             |                       |               |
>         |             |                       |               |
>         |             |        3              |               |
>         |              <===================== |               |
>         |             |            4          |               |