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Conference netcad::hub_mgnt

Title:DEChub/HUBwatch/PROBEwatch CONFERENCE
Notice:Firmware -2, Doc -3, Power -4, HW kits -5, firm load -6&7
Moderator:NETCAD::COLELLADT
Created:Wed Nov 13 1991
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:4455
Total number of notes:16761

3062.0. "New Twist on Cascaded DELNIs" by SVCVAX::GAMBARDELLA (Gamby Gumba) Tue Dec 12 1995 09:03

One of my customers has installed the configuration below as recommended by
a VAR.  It looks like the Delni's are cascaded and I told the VAR that.  
They are telling me that because we are not going to a physical backbone the 
guidelines are different and the configuration is ok.  

What do you think - is the following configuration supported?

Thanks,

Mike Gambardella

  
Delni             Delni            DECswitch 900 EF       
+------------+    +------------+   +--------------------------+
|12345678  G |    |12345678  G |   |  1A  1B  2  3  4  5  6  7|
+------------+    +------------+   +--------------------------+  
           ^       ^         ^                   ^
           |       |         |                   |
           +-------+         + DETPM-------------+        
T.RTitleUserPersonal
Name
DateLines
3062.1If it remains a local config as shown, it's fine...NETCAD::BATTERSBYTue Dec 12 1995 10:5114
    It will work ok, especially if it's not going to a physical
    backbone. Where you run into trouble with cascaded DELNI's is
    when there may multiple repeater hops, and a very large backbone
    infrastructure, meaning more opportunities to eat up preamble
    budget. Try contacting someone like Dick Kirk NPSS::KIRK for a
    more definitive answer as to what is "officially" support and
    what isn't. If Dick can't give you a definitive answer, he should
    be able to send you in the right direction.
    You may also want to browse in the Ethernet notes conference for 
    information on DELNI configs. However, I personally don't think you 
    are going to experience problems in your small network config that 
    isn't going to a large backbone.
    
    Bob
3062.2A More Complete Picture of the NetworkLAVC1B::GAMBARDELLAGamby GumbaWed Dec 13 1995 14:0541
I realize now that I should have given a more complete explanation of this 
customers network.  My original diagram only showed the area that I was 
concerned  with.  This is part of a large network and the scenario of
DELNI to DELNI to DECSwitch happens on other ports on the same DECSwitch and
happens on 3 other nodes on the FDDI ring.  There are also DEMPRs hung off of 
the DELNIs. The ring is also connected to a large ethernet backbone.  

This changes the picture quite a bit. So is this configuration supported?

Thanks,

Mike Gambardella   
                                                                            
                                          The 1st 3 switches       This last   
                                          are configured           one connects
                                          similarly with           to an ENET  
                                          DELNIs and DEMPRs        backbone    
Delni            Delni                    +--+     +--+     +--+     +--+     
+------------+   +------------+           |1A|-----|1B|-----|1A|-----|1B|     
|12345678  G |   |12345678  G |           |  |     |  |     |  |     |  |     
+------------+   +------------+           |1B|-----|1A|-----|1B|-----|1A|     
 |         |      |         |             |  |     |  |     |  |     |  |     
 |         +------+         + DETPM------>|2 |     |2 |     |2 |     |2 |     
 +--------+                               |  |     |  |     |  |     |  |     
          |                               |3 |     |3 |     |3 |     |3 |     
+----------+                              |  |     |  |     |  |     |  |     
|  Dempr   |                              |4 |     |4 |     |4 |     |4 |     
+----------+                              |  |     |  |     |  |     |  |     
                                          |5 |     |5 |     |5 |     |5 |     
                                          |  |     |  |     |  |     |  |     
Delni            Delni               +--->|6 |     |6 |     |6 |     |6 |     
+------------+   +------------+      |    |  |     |  |     |  |     |  |     
|12345678  G |   |12345678  G |      |    |7 |     |7 |     |7 |     |7 |-+   
+------------    +------------+      |    +--+     +--+     +--+     +--+ |   
 |         |      |         |        |                                    |  
 |         +------+         + DETPM--+                                 to ENET
 +--------+                                                            backbone
          |                                
+----------+                               
|  Dempr   |                               
+----------+                               
3062.3NO, plain and simple, NOT supported....NETCAD::BATTERSBYWed Dec 13 1995 14:3316
    Yes you should have been more clear of course. It usually
    helps if we have the most concise & complete depiction of
    your configuration if you wish us to provide you an answer.
    No, you lose, do not go past GO. Find a way of eliminating the
    cascaded DELNI's. Let's put this another way, many customers
    cascade a pair of DELNI's (in several places on their LANs mind you).
    They don't have problems per-se, but they are inviting problems
    with preamble budgets being eaten up, and then eventually they
    end up with problems.
    There are many and numerous horror stories with sites with cascaded
    DELNI's that went un-detected, with numerous hours spent on site
    troubleshooting problems only to find out it was something like a
    single pair of cascaded DELNI's causing wierd network problems.
    So, beware of proceeding further down this well-trodden path.
    
    Bob
3062.4Thanks - that's what I thought. Sorry for the confusion.LAVC1B::GAMBARDELLAGamby GumbaWed Dec 13 1995 16:310
3062.5Delnis & demprs & Desprs oh myPTOJJD::DANZAKPittsburgher �Sun Dec 17 1995 20:0728
    Of course, if you did the AUI port on the DECswitch you could do AUI
    from DECswitch to any OTHER (non-global) DELNI port and it would work
    fine. 
    
    
    
      DELNI 1        DELNI 2
    12345678G      12345678G
    |       +------+      |
    |                      --------->AUI port on DECswitch
    DEMPR etc...
    
    I believe the rule is that cascaded DELNIs can cascade from ONE DELNI
    in which the global port is NOT used.  In this case, DELNI #2's global
    port is NOT used, others may cascade FROM it, but it acts like the lan
    backbone.
    
    Delnis and demprs and desprs oh my.....delnis and demprs and desprs oh
    my.... 
    
    (sing the above to the Wiz of Oz tune of Lions and Tigers and Bears oh
    my....)
    
    ttfn,
    j
    ^--who lost it