Subject: Re: no can do

From: "Shannon Nix" <[email-masked]>
Date: Thu, 19 Aug 93 14:23:55 EST

On Thu, 12 Aug 1993 15:59:16 -0700, Choon Lee wrote:

Choon,

I must disagree with the following:-( explanation follows)

>
>it hit me suddenly that there are times that a "loop" should
>not be broken. An example is the triangular topology (full mesh)
>case:
>
>
>            LAN A
>           ========
>               |
>            -------
>            |     |
>            |     |
>            -------
>             |   |
>             |   |
>  -------    |   |     -------
>  |     |-----   ------|     |
>  |     |--------------|     |
>  -------              -------
>     |                    |
>  =======              ========
>  LAN B                   LAN C
>
>
>Spanning tree would detect a "loop" in the triangular topology, and
>will attempt to block one of the links. Since DLSw does not cascade,
>the network is broken!
>
>A case of spanning tree working too well! :-)

Let me redraw your picture:

            LAN A
           ========
               |
            -------
            |     |
            |     |
            -------
               |
  ============================ LAN D (DLSW CLOUD - it's virtual)
     |                    |                          
  -------              -------
  |     |              |     |
  |     |              |     |
  -------              -------
     |                    |
  =======              ========
  LAN B                  LAN C

No loops here! :-)

Rgds, Shannon

>Regards,
>Choon Lee
>3Com Corp
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