Conference netcad::hub_mgnt

306.0. "Configuration Clarification" by MORO::MAUTZ_RI (Networks >= to DECnet) Tue Jul 20 1993 04:14

Have I evaluated this configuration correctly or not?  I read the DECrepeater
90FL and FA Owner's Manuals.  The manual seems to indicate that the below
configuraiton is a valid one, however, I think the total segment length is
in violation of the 2500 meter limitation that the manuals speicfy.  Am I
missing something?  

This drawing excerpted from DECrepeater 90 FA Owners Manual page 2-4.

		-------------------------
		| r | r |	   p/s	|
		| p | p |	        |
		| t | t |  Hub #1	|
		| 9 | 9 |		|
		| 0 | 0 |		|
		|fl |fl |		|
		-------------------------
		 |    |
		 |    |		1000M fiber
	1000M	 |    `--------------------------------------------+
	fiber--> |						   |
		 |						   |
+----------------------+			+-------------------------+
|r|r|		|r| p/s|			|		  |D| p/s |
|p|p|		|p|    |			|		  |E|	  |
|t|t|		|t|    |			|		  |W|     |
|9|9|		|9|    |			|		  |G|	  |
|0|0|	Hub #2	|0|    |			|  Hub #3	  |F|	  |
|t|f|		|f|    |			|		  | |	  |
| |l|		|a|    |			|		  | |	  |
+----------------------+			+-------------------------+
 | |
 | | 500M fiber     
 | `-------------MAU---DTE#1
 |100M 10baseT
 `------------DTE#2

			Trying to apply the 5-4-3 rule and total segment
			length rule for path from DTE#1 to DEWGF in Hub 
			#3 seems to me to result in the following:

			1.  # segments - 3 fiber segments, 2 "mixing"
			segments (Hub 1 & 2)
			2.  4 repeater sets - Hub 2 rpt90fl, Hub 2 rpt90fa,
			Hub 1 rpt90fl(2 of them).
			3.  There are only 2 mixing segments (the 3 of 5-4-3
			says max of 3 mixing segements).
			4.  Total segment length =>

				 500m	fiber link segment
				  65m	Hub 2 backplane mixing segment
				1000m	repeater to repeater link segment
				  65m	Hub 1 backplane mixing segment
				1000m	repeater to DECbridge 90 link segment
				-----
				2630m	total segment length, violates
					2500m segment length rule!


Thanks,

Richard

    I forgot to say that I'll cross-post this in the Ethernet notes
    file!
    
    Richard