fast ethenet vs fddi module

Discussion in 'Cisco' started by JOHN, Nov 24, 2003.

  1. JOHN

    JOHN Guest

    hi

    just like to which module is faster in cisco 4700 router

    fddi vs fast ethernet
     
    JOHN, Nov 24, 2003
    #1
    1. Advertising

  2. JOHN

    CCIE8122 Guest

    > hi
    >
    > just like to which module is faster in cisco 4700 router
    >
    > fddi vs fast ethernet


    FDDI is by its architecture more efficient than FastEthernet, as you can
    truly achieve 100Mb throughput with FDDI, but not with FastE (collisions
    and the whole CSMA/CD process caps FastE to an effective rate of 70-80Mb
    IIRC).

    Unless you are running FastE FD, then FastE has better throughput than
    FDDI, since FDDI is a 100Mb Unidirectional ring (sort of a
    half-duplex-type architecture).

    But why would you ever consider FDDI?

    kr
     
    CCIE8122, Nov 27, 2003
    #2
    1. Advertising

  3. JOHN

    Andre Beck Guest

    CCIE8122 <> writes:
    > > hi
    > > just like to which module is faster in cisco 4700 router
    > > fddi vs fast ethernet

    >
    > FDDI is by its architecture more efficient than FastEthernet, as you
    > can truly achieve 100Mb throughput with FDDI, but not with FastE
    > (collisions and the whole CSMA/CD process caps FastE to an effective
    > rate of 70-80Mb IIRC).


    As long as you actually use CSMA/CD, yes.

    > Unless you are running FastE FD,


    That's the point. Switch off CSMA/CD and what remains is almost exactly
    the same technology. 100Base has copied FDDI/CDDI at the PHY instead of
    reinventing the wheel.

    > then FastE has better throughput than
    > FDDI, since FDDI is a 100Mb Unidirectional ring (sort of a
    > half-duplex-type architecture).


    About the same time that Ethernet lost its CSMA/CD heritage, ANSI folks
    or at least FDDI vendors stroke back with Full Duplex FDDI. It just uses
    the backup path of a double ring to run FD. Not as widespread as
    Ethernet today, but it did exist (as did switched FDDI).

    Then again, that's all pure theory. The question is actually, which
    of the interfaces performs better in a 4700 - and to which fraction
    of the theoretical bandwidth until the CPU melts down? I don't expect
    any 4000 series model to be able to saturate 100Mbps, let alone the
    same thing full duplex.

    > But why would you ever consider FDDI?


    For instance because you have a production network that ran rock solid
    on FDDI for more than 8 years and you would like for it to stay that way?
    Or you have to connect legacy FDDI to new Ethernet infrastructure and
    long for one possible solution to the problem - routing?

    --
    The _S_anta _C_laus _O_peration
    or "how to turn a complete illusion into a neverending money source"

    -> Andre "ABPSoft" Beck +++ ABP-RIPE +++ Dresden, Germany, Spacetime <-
     
    Andre Beck, Dec 7, 2003
    #3
  4. JOHN

    CCIE8122 Guest

    >>But why would you ever consider FDDI?
    >
    > For instance because you have a production network that ran rock solid
    > on FDDI for more than 8 years and you would like for it to stay that way?
    > Or you have to connect legacy FDDI to new Ethernet infrastructure and
    > long for one possible solution to the problem - routing?


    Yeah those networks are all being migrated to 802.3 topologies.

    I ran a network that you described. Had a zillion DEC Alphas running on
    FDDI.

    We yanked the FDDI NICs, and switches and ran FastEthernet, then Gigabit.

    My point is that FDDI is just a dead transport that has reached the end
    of its life cycle. As you noted, with FD FastEthernet and now with Gig,
    couple with the fact that FDDI is an architecture foreign to most
    network admins, every org that I know of that went down the FDDI road
    has replaced it with ethernet. TCO is just all-around too high
    (comparatively) for FDDI.

    And with the ubiquity of Ethernet, the cost to migrate away from FDDI is
    so cheap, there really is no reason why an ROI-conscious company would
    have incentive to remain on the platform. Let's face it--LAN is now
    commodity--it is not the esoteric mysticism that it was ten or to some
    degree even 5 years ago. You can go down to Best Buy and for under a
    hundred dollars, buy an end-to-end better network than those for which
    companies shelled out thousands then. Point being, in the post dot-com
    bust, why pay a relatively specialized (therefore pricey) admin to
    manage a legacy FDDI network, when any out-of-work admin off the street
    can come manage a simple 802.3 network at a migration cost of $100 per
    box, if that.

    Now if this question had been asked 7 or 8 years ago, when vendors were
    actively marketing FDDI, the answer would be a little different.

    My .02

    kr
     
    CCIE8122, Dec 8, 2003
    #4
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Ryan Goolevitch
    Replies:
    1
    Views:
    510
    shope
    Oct 17, 2003
  2. Replies:
    0
    Views:
    593
  3. JOHN
    Replies:
    0
    Views:
    568
  4. Paul Jawlinski
    Replies:
    1
    Views:
    733
    AnyBody43
    Jul 19, 2004
  5. Replies:
    3
    Views:
    491
    Sam Wilson
    Nov 30, 2005
Loading...

Share This Page