Conference 7.286::fddi

>I thought that in FDDI, dual-fiber mode that one line was a send and one was
>a receive at 50 Mb/s each for 100 Mb/s?

    Let's back up.  In broadcast bus networks like Ethernet, you understand
    that the station can either send OR receive at 10 Mb/s.  This is called
    half-duplex communication.

    FDDI uses a token ring instead of a broadcast bus or token bus.  No
    matter how many fibers or copper cables you have in a given media
    variation, FDDI is still a token ring which basically implies half-
    duplex communication.  At any instance, you might either send OR
    receive a packet at 100 Mb/s.  (You never communicate at 50 Mb/s.)

    The "full-duplex FDDI" mode lets you send AND receive simultaneously
    at 100 Mb/s in each direction.  Again, this is basically independent
    of the media option on the station.  You could have a SAS station or
    a DAS station using two or four fibers, or using one (coax) or two
    or four copper links (twisted pairs).

> What happens when our FDDI devices is connected to someone elses and theirs
> only does Industry-standard FDDI.  Do we fall-back to ANSI-mode?

    Absolutely.  Every DEC port starts out with standard FDDI token passing.
    Only if the ring is limited to two stations and both ends of the link
    implement the full-duplex initiation protocol will the port switch modes.
    Then, if the link fails, it reverts automatically to token passing.
    --gw

thanks.  that clarifies everything.

	thanks	
 	 kam

    RE: .1
    
    Could you provide a brief description of how a Digital FDDI station
    would go about checking/interogating the other station for support of
    full-duplex mode.  I am curious as to how it would react to the other
    station being another DEC or one that doesn't support full-duplex mode.
    
    Thanks,
    
    Mark
    

    I'm also interested in the full-duplex FDDI, specifically which
    adapters and/or devices and which protocols support the use of this
    technology.
    
    Also, I have had customers ask if the specifications are available for
    other vendors to be able to take advantage of full duplex if they are
    using our chips from Motorola and/or AMD.
    
    Thanks,
    
    	Dennis

    re: .1
    
   > At any instance, you might either send OR
   > receive a packet at 100 Mb/s.  (You never communicate at 50 Mb/s.)
    
    Consider however: When a station is repeating a large frame, it is
    possible for code-bit reception & transmission of earlier code-bits to 
    be happening simultaneously. In fact, with a large frame and a small
    ring, it is possible to begin reception (and stripping) of your own
    frame before you complete its' transmission.

>                     -< don't forget the repeat function >-
>    Consider however: When a station is repeating a large frame, it is
>    possible for code-bit reception & transmission of earlier code-bits to 
>    be happening simultaneously. In fact, with a large frame and a small
>    ring, it is possible to begin reception (and stripping) of your own
>    frame before you complete its' transmission.

    Let's not confuse the issue by discussing low-level ring issues like
    repeating and stripping.  These are irrelevant to the communication
    throughput of the station.  In fact, I recall that the MAC state
    machines specifically prevent the station from receiving its own
    frames while stripping them.  No matter what address is in your
    transmitted frames, you do not receive them moments after transmitting.

>    I'm also interested in the full-duplex FDDI, specifically which
>    adapters and/or devices and which protocols support the use of this
>    technology.

    No adapter supports it yet.  Some will next year.  That's all I know.
    If you've read the GIGAswitch PID, you know more than me.

    Full-duplex operation is transparent to network protocols, so it
    supports them all.  It's not entirely transparent to the FDDI ring
    management software, of course.
    
>    Also, I have had customers ask if the specifications are available for
>    other vendors to be able to take advantage of full duplex if they are
>    using our chips from Motorola and/or AMD.
    
    The party line is:
    We hope to develop an open licensing program for the full-duplex
    autoconfiguration protocol.  Those interested in licensing the
    protocol (for a reasonable fee) may contact Jim Kuenzel, Email
    [email protected] (or kuenzel%[email protected])
    and he will keep them informed of the progress.  My free advice is:
    Don't worry about the configuration protocol yet.  Get to work in the
    lab to see if your products operate well at 200 Mb/s, using any means
    possible to switch the stations into full-duplex mode.

============================================================================
SUBJECT:  DIGITAL ANNOUNCES KEY AGREEMENTS FOR ITS PATENTED FDDI FULL DUPLEX
          NETWORK TECHNOLOGY
SOURCE:   Business Wire via First! by INDIVIDUAL, Inc.
DATE:     October 11, 1994
INDEX:    [7]
----------------------------------------------------------------------------

  MAYNARD, Mass.--(BUSINESS WIRE) via First! -- Digital  Equipment
Corporation, the leader in high-performance switched  networking, today
announced that its patented FDDI Full Duplex  Technology (FFDT) is available
to the industry as an open standard.   Two licensing agreements to
incorporate FFDT into other vendors' FDDI products have been signed.  Also
announced is a PCI FDDI adapter  family that incorporates the FFDT
technology.

  FDDI Full Duplex Technology and Licensing

  Digital has signed a license agreement with Distributed Systems
International, Inc.  (DSI, Inc.) to incorporate FFDT into its popular SMT
source code for Motorola FDDI chips.  CMD TECHNOLOGY Inc.  has  also agreed
to incorporate FFDT into its storage server products.   FFDT is a software-
based technique that enhances FDDI network  performance by permitting full-
duplex data transmission.  While  conventional FDDI technology offers
transmission speeds of 100 Mb/s,  FFDT enables pairs of network stations
connected point-to-point to  send and receive data at 100 Mb/s
simultaneously, providing 200 Mb/s  network capacity.

  FFDT is an enhancement to existing FDDI products that can be  implemented
in a high-performance FDDI switch such as Digital's  GIGAswitch/FDDI, as
well as high-performance workstations and servers with dedicated FDDI links.
Products running FFDT software  automatically sense when both nodes of a
point-to-point link support  FFDT, but will also automatically interoperate
on a standard FDDI LAN as necessary.

  "These announcements demonstrate that FFDT is an open standard  that will
enable customers to dramatically improve FDDI network  performance,"
according to William Maro, Digital's vice president of Network Product
Marketing and Engineering.  "We believe that  FFDT-based FDDI networks will
help organizations evolve to switched,  high-performance LAN backbones while
preserving their existing  investments in multivendor FDDI equipment."

  Many vendors already use software from DSI, Inc.  and the FDDI  chip set
from Motorola in their FDDI products.  Digital's  announcement means that
all of these vendors can, with minimal  effort, offer significantly improved
product performance to their  customers.  "FFDT enables dramatic
improvements in FDDI network  performance,"  according to Mark Wood, vice
president of Marketing at DSI, Inc.  "As we rapidly roll out this
breakthrough technology to  our customers around the world, FFDT will become
the de facto  standard for high-performance FDDI networking."  DSI, Inc.  is
based  in Wheaton, Illinois.

  According to Mike Shoemake, Data Communications Program Manager  in
Motorola's Microprocessor and Memory Technologies Group, "What  FFDT means
to vendors with products designed around the Motorola FDDI chip set is that
they can immediately offer their customers a  dramatic performance increase
with a simple software upgrade."

  CMD, based in Irvine, California, is a leading supplier of SCSI  and RAID
products for VAX, Alpha AXP, UNIX and PC systems.  By  drawing on FFDT for
storage server connectivity, CMD dramatically  enhances the performance of
its storage solutions.  According to Bob  Rudy, CMD's vice president of
Sales and Marketing, "CMD is committed  to working closely with Digital to
provide the highest performance  FDDI solutions to our customers.  We are
developing products that  will provide customers with expanded performance
and flexibility when implementing FDDI as part of their communications
strategy."

  FFDT is ideally incorporated into networks designed around FDDI  switches,
such as Digital's award-winning GIGAswitch/FDDI.  These  switches connect
high-performance workstations and servers that  incorporate FFDT on
dedicated FDDI links.  Digital's Maro adds,  "Customers who use Digital's
GIGAswitch/FDDI or FDDI system adapters  already have the advantage of FFDT.
We want to extend this  performance advantage to all FDDI environments."

  Vendors interested in implementing the FFDT standard may do so  through
Digital's FFDT licensing program.  Further information about  Digital's
program can be obtained from Digital's Corporate Licensing  Office at
(508)493-8254.

  Industry's First PCI FDDI Adapter Family

  Digital also announced the industry's first PCI FDDI adapters.   The 32-
bit high-speed DEC FDDIcontroller/PCI family of products  reduces the cost
of entry for FDDI connectivity and supports FFDT.   Additional product
features include a DMA engine which results in  very low CPU utilization.
The adapters are completely auto-  configurable and offer a full suite of
drivers for use on both Alpha  AXP and Intel based PCs, workstations, and
servers.

  Notes Digital's Maro, "Our full-duplex PCI FDDI adapters are by  far the
most robust, low-latency LAN adapters available today.  They  provide a
powerful solution for supporting multimedia and  video-on-demand
applications."


        The new adapters available in late November are:
    o    a single attachment station (SAS) adapter supporting
         unshielded twisted-pair copper cable, priced at $695;

    o    a single attachment station (SAS) adapter designed for
         multimode fiber, priced at $1,195 and;

    o    a dual attachment station (DAS) adapter supporting multimode
         fiber, priced at $1,695.


  Digital, the leader in high performance switched networking,  continues to
be a significant contributor to the development of many  popular networking
technologies including Ethernet, FDDI and ATM  LANs, network switches,
routers, bridges, network adapters, and  terminal servers.  Digital has
networked more than 10 million users  worldwide.

  Digital Equipment Corporation is the world's leader in open  client/server
solutions from personal computing to integrated  worldwide information
systems.  Digital's scalable Alpha AXP  platforms, storage, networking,
software and services, together with  industry-focused solutions from
business partners, help organizations compete and win in today's global
marketplace.

  Note to Editors:  Digital, the Digital logo, Alpha, AXP, VAX, and

  GIGAswitch are trademarks of Digital Equipment

  Corporation. Other trademarks are the property of

  their respective owners.

  CONTACT:  Susan Ursch | (508) 486-5198

[10-11-94 at 09:28 EDT, Business Wire, File: b1011092.700]