[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

3091.0. "900CP port led status wrong" by HLFS00::BROUWERS_A () Wed Dec 20 1995 10:35

    DECswitch 900CP  SW V2.1.0.
    
    Port LED status ON means: Port connected to a propper terminated cable.
    
    If a port is put via the switch matrix on a group or virtual lan which 
    has no traffic. The LED is put ON even with an open connector. 
    It is a problem for Troubleshooting, thinking Thin-wire is connected 
    and there is no cable on it !
    
    resuming: LED indication of proper termination works only, if there is
    traffic on the group connected to.
    
    It would be better in software to initialise the LED status off after
    switching a port.
    
    
    Happy N.Y.  Ad

T.R Title User Personal
Name Date Lines

3091.1 10BASE-2 ports can't accurately detect status on a quiet network NETCAD::PAGLIARO Rich Pagliaro, Networks BU, HPN Thu Dec 21 1995 11:20 45

T.R	Title	User	Personal Name	Date	Lines
3091.1	10BASE-2 ports can't accurately detect status on a quiet network	NETCAD::PAGLIARO	Rich Pagliaro, Networks BU, HPN	`Thu Dec 21 1995 11:20`	45
	Port status LED ON means: 1. Port is operational (that is, not management disabled or disabled due to security vialation) (rptrPortOperStatus) AND 2. Port is not auto-partitioned (rptrPortAutoPartitionState) AND 3. Port's media is available (erptrMauMediaAvailable) Port status LED OFF means: 1. Port is auto-partitioned. (rptrPortAutoPartitionState) OR 2. Port's media is unavailable. (erptrMauMediaAvailable) The goal of the erptrMauMediaAvailable MIB object is to indicate if there is a media fault. In the case of link type MAUs (e.g. 10Base-T, 10Base-FL), this is equivalent to the status of the link test function. For an AUI or coax interface, this is equivalent to a loopback error (that is, whether or not the transmit data is looped back to the receive data path). Note that this case requires that data be transmitted out a repeater port in order to detect if there is a media fault. If such a repeater port is placed in a group or virtual LAN that has no traffic, then the repeater can never really know if there is a media fault or not on that port. The rptrPortAutoPartitionState MIB object reports whether or not a port is auto-partitioned. A non-terminated 10Base-2 repeater port will auto-partition due to excessive number of consecutive transmit collisions. This requires that data be tranmitted out such a port in order to detect the fault and auto-partition the port. Again, such a repeater port connected to a completely quiet group/virtual lan will never transmit a packet and never auto-partition. This auto-partition algorithm is defined by IEEE 802.3, and the media available status indication is consistent with the IETF MAU MIB (RFC 1515) It appears we have a dilemma here. A 10Base-2 repeater port that has never transmitted data cannot know if a media fault (such as improper termination) exists...until of course it does transmit. We can always come up with a scenario for incorrect LED status whether we initialize a port status LED to ON or OFF. If we initialize the LED to OFF, then a properly terminated 10Base-2 repeater port's status LED will falsly report a fault when it is moved to a quiet group/vlan.

             
    Port status LED ON means: 
    
       1. Port is operational (that is, not management disabled or disabled 
          due to security vialation) (rptrPortOperStatus) *AND*
       2. Port is not auto-partitioned (rptrPortAutoPartitionState) *AND*
       3. Port's media is available (erptrMauMediaAvailable)
     
    Port status LED OFF means:
    
       1. Port is auto-partitioned. (rptrPortAutoPartitionState) *OR*
       2. Port's media is unavailable. (erptrMauMediaAvailable)
    
    The goal of the erptrMauMediaAvailable MIB object is to indicate if
    there is a media fault. In the case of link type MAUs (e.g. 10Base-T, 
    10Base-FL), this is equivalent to the status of the link test function. 
    For an AUI or coax interface, this is equivalent to a loopback error 
    (that is, whether or not the transmit data is looped back to the receive 
    data path). Note that this case requires that data be transmitted out a
    repeater port in order to detect if there is a media fault.  If such a 
    repeater port is placed in a group or virtual LAN that has no traffic, 
    then the repeater can never really know if there is a media fault or
    not on that port.
    
    The rptrPortAutoPartitionState MIB object reports whether or not a port
    is auto-partitioned.  A non-terminated 10Base-2 repeater port will
    auto-partition due to excessive number of consecutive transmit
    collisions. This requires that data be tranmitted out such a port  in
    order to detect the fault and auto-partition the port. Again, such a
    repeater port connected to a completely quiet group/virtual lan will
    never transmit a packet and never auto-partition.  This auto-partition
    algorithm is defined by IEEE 802.3, and the media available status
    indication is consistent with the IETF MAU MIB (RFC 1515)
       
    It appears we have a dilemma here. A 10Base-2 repeater port that has
    never transmitted data cannot know if a media fault (such as improper 
    termination) exists...until of course it does transmit.  We can always
    come up with a scenario for incorrect LED status whether we initialize
    a port status LED to ON or OFF.  If we initialize the LED to OFF, then
    a properly terminated 10Base-2 repeater port's status LED will falsly 
    report a fault when it is moved to a quiet group/vlan.