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

Conference 7.286::fddi

Title:FDDI - The Next Generation
Moderator:NETCAD::STEFANI
Created:Thu Apr 27 1989
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2259
Total number of notes:8590

1696.0. "VAX6520, XMI & Sparcstation Performance" by DPDMAI::DAVIES (Mark, SCA Area Network Consultant) Thu May 25 1995 01:12

    My customer was initally going to go with 100BaseTX for his "fat pipe"
    in his existing EThernet environment.  When we discussed using FDDI,
    they said that they ran some test some time back (a couple of years)
    and only say about 45Mbps thruput.   They didn't know what processors
    or whatever in use, so analysis isn't possible.
    
    They say if we can prove high bandwitch capability of FDDI (they have
    already read the HPN white paper), they would move to FDDI.
    
    They currently have a VAX 6520 with an XMI FDDI adapter and a
    SparcStation 10 with an FDDI adapter in their lab.  
    
    Questions:
    
    1. Can a VAX 6520  w/XMI FDDI drive an FDDI at 90Mbps+?
    
    2.  Got any clues on a Sparcstation 10?  # of MIPS, etc???
    
    Thanks,
    
    Mark
T.RTitleUserPersonal
Name		DateLines
1696.1FDDI speed or systems speed?JUMP4::JOYPerception is realityThu May 25 1995 13:4617
    Mark,
       I don't know about the system's abilities to drive FDDI to those
    speeds, but isn't that really a question of how fast do the
    systems/busses run, not how fast FDDI can run? In other words, if the
    systems can only drive data out the network at 40Mbps, then it won't
    matter if they use FDDI, 100BaseI or ATM, the bandwidth won't be
    utilized!
    
    If their concern is with FDDI, then set up a couple Alphas, which we
    KNOW can drive FDDI at over 100Mbps in FDX mode. THis should satisfy
    their concerns about FDDI performance. Then they just have to worry
    about their processor and bus speeds. 
    
    (where are they planning to get an XMI 100BaseT adapter anyway??)
    
    Deb
1696.2WHat can a 6520 do?DPDMAI::DAVIESMark, SCA Area Network ConsultantThu May 25 1995 19:2518
    Deb, the XMI can run much faster than 100Mbps.  So my question,
    remains, CAN a VAX6520 with a Digital FDDI XMI adapter drive the FDDI
    at full bandwidth?
    
    The XMI adapter is a full performance adapter so it is whether the 6520
    has to power to do it.
    
    Concerning a Fast Ethernet adapter for the XMI bus;  if Fast Ethernet
    wins, Digital and systems which can not connect lose, ie, no more
    buying those systems.  This customer uses mostly Sun and HP anyways.
    
    Let me restate the question:  How many MIPs does a 6520 have?  It takes
    about 1 MIP per Mbps on average.
    
    Regards,
    
    Mark
1696.3NETCAD::STEFANIWelcome to the Revolution!Thu May 25 1995 21:529
    >>Concerning a Fast Ethernet adapter for the XMI bus;  if Fast Ethernet
    >>wins, Digital and systems which can not connect lose, ie, no more
    >>buying those systems.  This customer uses mostly Sun and HP anyways.
    
    I'm not sure I would agree with this logic.  I would HOPE that
    customers are buying systems like the VAX6520 for more tangible reasons
    than the type of network connections offered.
    
    /l
1696.4What can a 6520 do...DPDMAI::DAVIESMark, SCA Area Network ConsultantFri May 26 1995 09:5016
    re:.-1
    
    This is not a "Digital" account.  They do not have a lot of VAXes.  The
    ones they have are old (like a 6520).  They have no Alphas.  This is
    not a VAXcluster, so that technology edge is gone.  If these folks go
    with Fast Ethernet, then only PCI bus DECsystems will be purchased
    here, since this is the card available or in the plans.
    
    All of this really has nothing to do with my original inquiry.  I still
    would like an opinion on whether a VAX 6520 can drive an FDDI at near
    saturation rates.
    
    Thanks,
    
    Mark