Conference 7.286::fddi

990.0. "DECbridge 620 not forwarding" by BELFST::R_MILLAR () Thu Jun 10 1993 12:42

    Hello there,
    
    I am a resident engineer for customer who uses a DECbridge 620 for
    their Root bridge on the network. We recently installed a FDDI ring to
    run a VAXcluster in an MDF configuration.
    
    Since the installation, at Christmas, three problems have occurred
    where LAT traffic suspends between the two main buildings. This can be
    resolved immediately by powering off and then on the DECbridge 620.
    While the bridge is in this non-forwarding states the LEDS indicate
    that all is working OK.
    
    A non-dec Bridge is sitting in backup mode and if the bridge 'fails',
    spanning tree works as it should do. We have tested this and the
    Sintrom bridge starts forwarding.
    
    The customer demanded a replacement DECbridge 620, yet in many ways
    hasn't co-operated with their part in the agreed action plan.
    The customer's network support team 'own' the network , and were asked
    for utilization details and advised on how best to monitor the bridge.
    
    We reluctantly replaced the bridge, but feel that the problem may occur
    again. The customer transfers large CAD files using NFS and has seen
    'Receive Packets too long' on all of the other Sintrom bridges on the
    network.
    
    QUESTIONS: 
    1. If a Enet loopback connector was not connected to one of the
    two spare ports on the 620 how often will the bridge hardware poll and
    test that port? Could this polling cause user data from forwarding on
    the live port, bearing in mind that the fault has only three times since 
    Christmas ? NB: I personally believe that the port was terminated but
    it possible that the customer may have removed it.
    
    
    2. The original bridge had v1.1 firmware, could v 1.1 cause this kind
    of failure?
    
     
    3. Anyone care to suggest pointers as to possible causes for this
    problem. I don't want the DECbridge 620 to be blamed for these three
    incidents. I can FAX the complete block diagram of the network to
    anyone who is interested.

    
   
    
    Regards and thanks,
    
    
    Ronnie Millar.
    Short Bros DECresident Engineer (Belfast N. Ireland)
    
                                                   

	Check note 944, it seems to be similar to the problem I have experienced
	at two customer sites.

	After lowering the snmp parameter I haven't seen the problem again yet.

	/Stefan