Conference netcad::hub_mgnt

2663.0. "repeater90c PCs hang/slowdown" by VNABRW::SCHATZMANN_H () Tue Aug 22 1995 15:00

    Dear collegues,
    
    We are not familiar with pc's in Lan-Networks, so we try to
    describe the effects. Maybe someone can help us.
    
    1.) we tryed to find out our problem also about  www:
        http://kuiper.alf.dec.com:8032/
        search string "hub 90 decrepeater packet hang"
        But we are not sure, which are the reasons; which are
        the solutions  to our problem.
    
    2.) Our costumer has until jul-95:
        2 DECserver5240(ultrix) about DEMPR and DESPR
        connected with 120 PC's  
        - d5240  ultrix 4.3.a ; pathworks 4.2
        - 119 PCs  DELL/IBM/Targa-ACtebis   386-486-p5 processor
              LANcard: only: 3com 503
                       and : Acton 1666,1657,1650 
        - and "1" DEC-PC  !!!!
    
     3. Until end of july-95 all works fine.
    	-Now he have a dechub900 with decrepeater 90c 
    	    		  	      decswitch 900ef 
    	   			      concentrator900mx 
                                      (hubwatch 4.011)
         (decrepeater 900 pm is currently not deliefered
          ....does anybody know the Logistik partnumber??)
     
     4.)Since this time 10% random pc's hang's or slow down,
        when the Costumer try to send or receive files from
        the FILE-Servers.
    
     5.)The Costumer isolated the effects as following.
        -all cables tested and ok.
        -no errors on the network 
        -no problems with hub900 products.
        -no problems with dempr, despr products 
        -only a problem when using repeater90c
                (same effect standalone also as used  in 900hub)
        -He takes 6 different standalone decrepeater90c to verify
         the problem. Some PC's (from the first 10%) will work
         fine, some other will slow done or hang (files >=30KB)
        -Problems are the same;  1 PC on Segment, or max 10 PC on 
         the Segment.
    
      6.)If he use DECNET, the problem get bigger, more PCs slow down
         or hanging
         If he use IP;  no PC hangs, but they also slow down. 
    
      7.)The Costumer took a MS-Help-Library  for Testing.
         Usual, read or write from the server takes between
         3-5 seconds (depend on System).
         With a "bad" repeater90c it takes 10-15 seconds for
         reading, 
         and 15 to 30 second for writing down to the File-Server.
         Some PCs are hanging continous with some Repeater90c
         
       8.)Here the Matrix, the full serialnumber I have not yet here.
       
         decmr-ma:    REV;      serial#         DECNET        IP
                      j03       1r??         works fine    ok
                      j03	1r??         hang >=30kb   slow down
                      j03	1r??         slow down     slow down
    		      j03	as??         hang >=30kb   slow down
                      j03       as??         slow down     slow down
    		      h02	as20204558   slow down     slow down
    
    
      Any ideas??  
      thanks for interesting, helmut;
       

	1)Make sure DNP.EXE ECO is all done for Pathworks ver 5 clients.

	2)Make sure the problem is not due to 3rd party Ethernet cards not
obeying IEEE 802.3 specs of clock frequency 10Mhz+/-0.01%. DR90C and DR90T have
smaller FIFO size than DEMPR and DECrepeater 900TM. So problem will not be
seen with DEMPR and DR900TM, but with DR90T and DR90C.

Alphonse

    
    Do we know if the 90T-16 have the same limitation with smaller FIFO
    size as the 90T & 90T+? Does the DR90TS have the same smaller FIFO size
    as the 90T & 90T+?

    90T16 and 90TS do not use the same chips as the 90T and 90T+.
    It's not FIFO size, but elastisity buffer size.