Subject: multicast proposal question

From: Harry Silverstone <[email-masked]>
Date: Tue, 9 Jul 1996 14:03:30 -0400 (EDT)

Hi,

	In reviewing the proposal and preparing myself for the AIW next week
I have come across somthing that I would like to verify.

	As I understand the proposal, if no sessions exist, when Remote 1 
wants to communicate with the host a CANUREACH_ex is sent via a UDP 
datagram. The host is found and a TCP connection gets established. 
(Let's say from C to A.)

	Now if Remote 2 wants to talk to the Host, as a TCP pipe exist, 
it will use the path from C to A. What if instead, it was desired to go 
from C to B? This does not seem to be covered by the proposal and in fact 
seems to be in violation.

	The reason for wanting to do this is to be able to provide 
redundancy that many customers want. Although the proposal is meant to 
address only scalability I believe that we must allow for this. 
"Redundancy" as a functionality is not described very well but unfortunately
it is a very important issue for IBM environments.
 
                  ____
               __| A  |       ------    -----  
        ---   /  |____|------/      \   |C   |       __ Remote 1    
HOST --( TR )<    _____     < IP net >--|    |--(TR)<
        ---   \__| B   |-----\______/   |____|       --- Remote 2
                 |_____|            

~harry

---

From: Harry Silverstone <[email-masked]>
Date: Wed, 10 Jul 1996 13:14:44 -0400 (EDT)

Hi Dave,

	Thanks for the response and yes it does make sense. I think that 
the key is is 'that a DLSw should use the TCP/IP pipe' when it is available.
The way that I read the proposal I felt that was inferred was that is it 
'must' use TCP for all other connections if the pipe existed.

Thanks,

~harry

On 9 Jul 1996, David Bryant/HQ/3Com wrote:

>  Harry - 
> 
> The intent of the multicast proposal is not to prevent what you discuss.  
> Neither RFC 1795 or this proposal address the details of DLSw caching 
> mechanisms or searching specifics.   This is typically left to the 
> implementer.  
> 
> The intent of the Multicast proposal is that a DLSw should use the TCP/IP pipe 
> in preference to UDP when sending a frame directly to a specific DLSw peer. 
> 
> In the case you describe, it is possible to establish connections over C to B 
> by either: sending a CANUREACH via UDP multicast and choosing the C to B path 
> or using previously cached information to send the CANUREACH from C to B.
> 
> Does this make sense and address your issue?
> 
> -Dave Bryant
> 3Com Corp
> 
>  ----- Previous Message ---------------------------------------------------- 
> 
> 
> 
> To: aiw-siglets-dlsw-redist  @ 3mail.3com.com @ UGATE
> cc:  
> From: hsilvers @ baynetworks.com (Harry Silverstone) @ UGATE    
> Date: Tuesday  July 9, 1996 02:07 PM
> Subject: multicast proposal question
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> 
> Hi,
> 
>