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Conference 7.286::fddi

Title:FDDI - The Next Generation
Moderator:NETCAD::STEFANI
Created:Thu Apr 27 1989
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2259
Total number of notes:8590

1630.0. "Dual Homing question" by TKOV51::KATSUBE (Taiji Katsube) Mon Mar 20 1995 01:07

I found a dual homing configuration as below in the video 'FDDI primer'.
When a trouble occurs between CON2 and CON3, does the standby line of DAS1
work ?

I think :
Even if the line between CON2 and CON3 is cut, M-B path between CON3 and DAS1
is active. So, CON3, DAS1 and SAS2 will make up another ring.
Am I wrong ?

   A +------+ B     A +------+ B  Dual Ring
=====| CON1 |=========| CON2 |===========
     +------+         +------+
     M|    |M            M|
      |    |              |  <-- If the problem occurs at this point...
     S|    |             B|
   +----+  |          +--------+
   |SAS1|  |          | CON3   |
   +----+  |          +--------+
           |          M|      |M
           |           |      |
           |          B|      |S
           |       A+----+  +----+
           +--------|DAS1|  |SAS2|
                    +----+  +----+

	Regards,

	Katsube
T.RTitleUserPersonal
Name		DateLines
1630.1NETCAD::STEFANIWelcome to the Revolution!Mon Mar 20 1995 07:4015
>>I found a dual homing configuration as below in the video 'FDDI primer'.
>>When a trouble occurs between CON2 and CON3, does the standby line of DAS1
>>work ?

    No.
    
>>Even if the line between CON2 and CON3 is cut, M-B path between CON3 and DAS1
>>is active. So, CON3, DAS1 and SAS2 will make up another ring.
>>Am I wrong ?
    
    I believe you're correct.  Dual-homing cut-over is based on the current
    device B and A ports and does not look "down the road" to see what
    connections were cut.
    
    /l