Conference netcad::hub_mgnt

3559.0. "DEMPR and DS900EF configuration question ?" by GIDDAY::STANISLAUS () Mon May 27 1996 05:35

 

Posted in HUB and Ethernet notes conferences:
---------------------------------------------

	The following question pertains to our CSC's (Customer Support Centre's)
network reconfiguration using some old products and some new HUB products.

	We are in the process of moving to a 100 Mbs FDDI backbone, but all our
CSC systems and desktops will still be on Ethernet.

	We are trying to do this as cheap as possible and yet get the maximum 
benefit possible. Please give some tips and suggestions.

Current Configuration:
----------------------

	We have a rack of 12 DEMPRs in our comms room as follows:

	At the moment in our CSC we have the above 12 DEMPRs. 6 of them are 
connected to DELNI-1 ports 1 to 6 and the other 6 are connected to DELNI-2 
ports 1 to 6.

	DELNI-1's port 7 is connected to a LANbridge 200 port A. Port B of this
LANbridge 200 goes to our current 10 Mbs Ethernet backbone tap. DELNI-1's global
port has a loopback connector with the switch set to global.

	Similarly as above DELNI-2's port 7 is connected to a second LANbridge
200 port A. Port B of this LANbridge 200 goes to our current 10 Mbs backbone 
tap. DELNI-2's global port has a loopback connector with the switch set to 
global.

Proposed configuration:
-----------------------

	Need someone to do a sanity check and if necessary modify our proposal.

	No rewiring within the CSC floor and hence we will continue to use
the above 12 DEMPRs and thinwire cabling to all our systems. This is part of
our cost cutting exercise.

	A DEChub 900 with 2 x DS900EF will be installed in the CSC floor in
the comms room near the above DEMPRs.

	Only DEMPR-1 will be connected to DELNI-1 port 1. This DELNI-1's port 2
will be connected to DS900EF-1 port 2 (AUI port). DELNI-1 will still be in
global mode with a loopback plug on the global port. So DEMPR-1 users will
get 10 Mbs pipe.

	Only DEMPR-2 will be connected to DELNI-2 port 1. This DELNI-2's port 2
will be connected to DS900EF-1 port 7 (AUI port). Again DELNI-2 will still be in
global mode with a loopback plug on the global port. So DEMPR-2 users will get
10 Mbs pipe as well.

	What we have done with DEMPR-1 and DEMPR-2, we plan to do the same
with DEMPR-3 and DEMPR-4. We will ofcourse need 2 more DELNIs (DELNI-3 and 
DELNI-4) which someone is willing to donate us. So DEMPR-3 and DEMPR-4 users
will get 10 Mbs pipe each. So DEMPR-3 via DELNI-3 will connect to DS900EF-2
AUI port 2 and DEMPR-4 via DELNI-4 will connect to DS900EF-2 AUI port 7.


	Now the way we plan to connnect the remaining 8 x DEMPRS i.e.DEMPR-5, 
6, 7, etc. etc. upto DEMPR-12 is as follows, so that each of the users on these
DEMPRs get a 10 Mbs pipe per DEMPR :

	Connect a DETPM-AA (AUI to UTP MAU) on DEMPR-5. Connect BN24F crossover
UTP cable between this DETPM-AA UTP side and DS900EF-1 port 3.

	Do as above with DEMPR-6, 7, 8, etc. etc. upto DEMPR-12 using one
DETPM-AA (MAU)and one BN24F to go to DS900EF-1 ports 4,5,6 and then to DS900EF-2
(the 2nd DECswitch 900EF in the HUB) ports 3,4,5,6. So we need 8 x DETPM-AA
and 8 x BN24F cables.

	So basically we have the 12 DEMPRs connected to the DS900EF-1 and 
DS900EF-2.

Now FDDI:
---------

	Then DS900EF-1 will have port A to the front and B to the back and
DS900EF-2 will have port A to the back and B to the front and connect to an
FDDI Flex Channel. Then DS900EF-1's port A and DS900EF-2's port B will connect
to our MIS departments Gigaswitch FGL-2 card to form an FDDI ring. On this
Gigaswitch FGL-4 ports will sit all MIS's Systems. MIS stands for Management
and Information Department.

	Will the above all work ?

	I presume we cannot use BN26K or BN25G cable between the DETPM and
the DS900EF's UTP port because they I think are straight through UTP cables,
whereas BN24F is crossover UTP cable.

	Is there any other UTP cable that we can use ?We have a whole box of
different types.

	What is the longest length BN24F cable one get and what is the part 
number for these various lengths of BN24F ?

	Is there a wiring diagram for BN24F, so that I can get the cables 
made locally.

	Last question - Is there a better way of doing the above things, without
wiring our floor with UTP cables, but using the existing DEMPRs and existing
Thinwire cables.


Alphonse

    I'm not sure about cable lenghts....(I never could count anyway). 
    However things that I'd do in the config are:
    
     - Be sure to set the DIP switch on the DETPM properly.  I think that
       the rule is that when you connect to a repeater SQE is OFF (else it
       propagates the collision presence test (CPT) thru the repeater
       with gawd-awful performance consequences)
    
     - Do *NOT* ring the DECswitches in the hub.  Connect each to an
       individual Gigaswitch port.  This is because a point-to-point
       connection with Digital FDDI will enable Full Duplex operation
       (i.e. performance boost)  Connecting them in a ring would work,
       i.e. A in on one switch, to B across the backplane on that switch
       with A on the backplane of the other switch to B out of the 
       other swith...but no FDX in that case.  So if you have TWO
       Gigaswitch M ports, (or B or A) do it.
    
     - Could you eliminate the DELNI by doing additional two additional
       DETPMs and using a twisted pair segmenet on the 1st and 6th port
       of the DECswitch?  That removes an ACTIVE component (DELNI) hence
       less failure etc., no fans sucking dust, power etc.
    
    So, this is what it would look like:
    
                                  To GS Port   |
                                     |       To GS Port
                                     |         |
   1    2    3    4    5    6      7 |      8  |
 +----+----+----+----+----+----+-----+--+------+-+  Do *NOT* ring
 |    |    |    |    |    |    |FA---+  |FA----+ |  switches in hub for
 |    |    |    |    |    |    |FB      |FB      |  benefits of FDX FDDI
 |    |    |    |    |    |    |        |        |
 |    |    |    |    |    |    |EA-----+|EA-----+|
 |    |    |    |    |    |    |       ||       ||
 |    |    |    |    |    |    |ET----+||ET----+||
 |    |    |    |    |    |    |      |||      |||
 |    |    |    |    |    |    |ET---+|||ET---+|||
 |    |    |    |    |    |    |     ||||     ||||
 |    |    |    |    |    |    |ET--+||||ET--+||||
 |    |    |    |    |    |    |    |||||    |||||
 |    |    |    |    |    |    |ET-+|||||ET-+|||||
 |    |    |    |    |    |    |   ||||||   ||||||
 |    |    |    |    |    |    |EA+||||||EA+||||||
 +----+----+----+----+----+----+--||||||+--||||||+
                                  ||||||   |||||+-DETPM+DEMPR
                                  ||||||   ||||+--DETPM+DEMPR
                                  ||||||   |||+---DETPM+DEMPR
                                  ||||||   ||+----DETPM+DEMPR
                                  ||||||   |+-----DETPM+DEMPR
                                  ||||||   +------DETPM+DEMPR
                                  |||||+-DETPM+DEMPR
                                  ||||+--DETPM+DEMPR
                                  |||+---DETPM+DEMPR
                                  ||+----DETPM+DEMPR
                                  |+-----DETPM+DEMPR
                                  +------DETPM+DEMPR

    (note - the AUI ports of the DECswitch have DETPMs on 'em)
    
    Regards,
    j