[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

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

453.0. "single point of failure?" by QCAV01::RANGARAJ () Wed Oct 27 1993 10:26

    Hi,
    
    	It may be the wrong place to ask this question, but does the DEChub
    900 have any single point of failure - the management module(?).
    Chipcom claims to provide bullet proof computing with redundancy at
    every stage. Does the DH900 have such a claim too? Am i missing
    something or does the DH900MS have a built in (redundant) management
    module?
    
    Regards,
    
    Raj
T.RTitleUserPersonal
Name		DateLines
453.1Single point of failureBACHUS::VANDENBERGHEFri Nov 26 1993 10:546
	What will happen if the Hub manager goes down or is reloaded (.. is 
	 this is possible).
	Can we consider it as a single point of failure

	Thanks,
	Robert
453.2only affects managementDELNI::GIUNTAMon Nov 29 1993 08:584
If the hub manager goes down, you lose the management it was performing,
but the hub doesn't go down, so the network is still up and running.
It's only a failure for the management, so it's not a single point of
failure.
453.3QUIVER::SLAWRENCEMon Nov 29 1993 09:0227
    This may be tempting fate a bit, but the question deserves an answer... 
    
    The hub manager plays no part in the normal movement of traffic
    through the hub; it just controls the way the modules configure
    themselves when they come up (those that are configurable).  For most
    purposes, the hub manager could crash any time and users would not see
    any effect.  When the hub manager comes back up it may reconfigure the
    backplane, which causes a very brief (less than a second) break in the
    Ethernet flexible channels as the modules are ordered to disconnect and
    reconnect.  The worst effect is in token ring; as part of its self test
    and initialization the hub manager has to wrap all the physical relays
    that connect the token ring modules to the backplane rings.  Once it is
    done with initialization it will reinsert the modules, but the break
    could be a few seconds (I havn't measured it).
    
    As noted elsewhere in this conference, when the hub manager is reloaded
    (yes, it is possible using DECNDU) it deletes all non-volatile
    configuration information.  We understand that this may cause some
    distress in the field, and plan to do something less drastic for the
    next release.
    
    Note also that the hub manager can be swapped easily in the field; if
    you have a customer who is concerned about such things and has enough
    hubs to justify keeping a spare around they can do it themselves.  the
    front cover comes off by pulling the tabs on the sides inward.  There
    are two ribbon cables to be reconnected, but they only fit one way. 
    You _cannot_ do this with power on, but it doesn't take long.
453.4passive backplane?ZUR01::SCHNEIDERRWed Dec 01 1993 02:0911
Hello,

If the HUBmanager is not nessesary for the backplane to run, are there any 
other active components in the backplane? Or is it compleatly passiv?

As I heard, for the future is planed to build the HUBmanager module 
"hot-swappable", too. Is that correct? If yes, when?



Roland