full-duplex

Discussion in 'Cisco' started by oraclepz@gmail.com, Mar 4, 2005.

  1. Guest

    Which of the following statements about full-duplex Ethernet operation
    are true? (Choose two.)

    1. Full duplex is supported on shared media.
    2. In full duplex, only one station may transmit at a time.
    3.Full duplex is preferred over half duplex in link establishment
    negotiation.
    4. All implementations of Ethernet can support both half duplex and
    full duplex.
    5. Two methods of achieving a full duplex are auto-negotiation and
    administrative configuration.

    5 it is one answer, do you know second answer?
     
    , Mar 4, 2005
    #1
    1. Advertising

  2. <> wrote:
    > 3.Full duplex is preferred over half duplex in link establishment
    > negotiation.


    This sounds correct too. If both devices are configured to auto-
    negotiate connection parameters, they will try full-duplex first,
    and if it won't work, will fail down to half-duplex.

    --
    andrei
     
    Andrei Ivanov, Mar 4, 2005
    #2
    1. Advertising

  3. Toby Guest

    <> wrote in message
    news:...
    > Which of the following statements about full-duplex Ethernet operation
    > are true? (Choose two.)
    >
    > 1. Full duplex is supported on shared media.
    > 2. In full duplex, only one station may transmit at a time.
    > 3.Full duplex is preferred over half duplex in link establishment
    > negotiation.
    > 4. All implementations of Ethernet can support both half duplex and
    > full duplex.
    > 5. Two methods of achieving a full duplex are auto-negotiation and
    > administrative configuration.
    >
    > 5 it is one answer, do you know second answer?
    >

    The answer is 3 & 5

    1 - Full duplex is only available when only 2 devices can talk on a network
    segment at the same time and each device has a seperate transmit/recieve
    path so FALSE..

    2 - Transmit and recieve are on a seperate pair of wires so both can transit
    simultaneously. so FALSE

    3 - Full duplex increases bandwidth see 2 above so TRUE

    4 - See 1 above so FALSE, i.e. hubs and older types of Ethernet, thinnet,
    thicknet and certain other devices.

    5 - If full duplex available to both, devices can negotiate by default or be
    set in config so TRUE

    This question though would better be suited to

    alt.certification.cisco and not in this newsgroup.

    Toby
     
    Toby, Mar 4, 2005
    #3
  4. Hansang Bae Guest

    wrote:
    > Which of the following statements about full-duplex Ethernet operation
    > are true? (Choose two.)


    Better suited to alt.certification.cisco

    > 3.Full duplex is preferred over half duplex in link establishment
    > negotiation.


    This is true for copper based Ethernet. The rule says to use the
    *highest* common denominator.


    > 4. All implementations of Ethernet can support both half duplex and
    > full duplex.


    not really. Older 10Mbps only NICs cannot handle FD. Some can but
    it's not universal.

    > 5. Two methods of achieving a full duplex are auto-negotiation and
    > administrative configuration.


    Ture.


    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not not be able to
    reply to emails sent to my account. Please post a followup instead.
    ********************************************************************
     
    Hansang Bae, Mar 5, 2005
    #4
  5. Guest

    Hi,

    Andrei is pretty close however maybe this is closer.

    There is a pre link-up announcement phase
    during which a device configured for Auto will
    announce it's capabilities.

    Before bringing the link up each end listens
    for anouncements for a while.

    A device that has sent announcements
    of its capabilities and has received announcements
    of its neighbours capabilities chooses the
    'best' common capability in order of

    100-FD -> 100-HD -> 10-FD -> 10-HD

    If there are NO received announcements
    then the device does HD. (And I guess detects
    speed - see later)

    Hard coded devices DO NOT SEND announcements.

    The announcements are sent out of band using
    something apparently called Fast Link Pulses.
    I would assume that these are not propagated through repeaters. [or,
    clearly, switches or routers)

    Speed detection is done seperately if required. For
    some reason you **NEVER** get a speed mis-match.

    If you want to know more search
    comp.dcom.lans.ethernet for the required
    keywords and Rich Seifert. I have not read his book
    but it seems a safe assumption that it
    will discuss all of this correctly and in sufficent
    detail for any network admin purpose.
     
    , Mar 6, 2005
    #5
  6. In article <>,
    <> wrote:
    :Speed detection is done seperately if required. For
    :some reason you **NEVER** get a speed mis-match.

    Well, sometimes you do. I've seen it happen on a Bay LattisSwitch
    28xxx -- a device we retired a number of years ago but still have
    hanging around. More modernly, it happens with our all our
    100 Mb SX <-> copper media convertors (which are mostly MiLan.)
    --
    "This was a Golden Age, a time of high adventure, rich living and
    hard dying... but nobody thought so." -- Alfred Bester, TSMD
     
    Walter Roberson, Mar 6, 2005
    #6
  7. Hansang Bae Guest

    wrote:
    [snip]
    > Speed detection is done seperately if required. For
    > some reason you NEVER get a speed mis-match.


    Because it uses parallel detection. 10Base-T's signalling is
    sufficiently different from 100Base-T signalling. So if FLP is not
    heard, it listens for the signalling (e.g. NLP for 10Base-T) and uses
    the info to determine the speed.


    > If you want to know more search
    > comp.dcom.lans.ethernet for the required
    > keywords and Rich Seifert. I have not read his book
    > but it seems a safe assumption that it
    > will discuss all of this correctly and in sufficent
    > detail for any network admin purpose.


    More than sufficient! :)

    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not not be able to
    reply to emails sent to my account. Please post a followup instead.
    ********************************************************************
     
    Hansang Bae, Mar 6, 2005
    #7
  8. Guest

    Thanks, yes I was too strong on that.
    I was thinking of correctly functioning standards
    compliant kit. I do very little hands on at the
    moment and have not seen a speed mis-match
    for years.

    Are Media convertors catered for in the standards or
    are they a hack?

    I have nothing against hacks by the way, however is
    is just as well to know when you are dealing with them.
     
    , Mar 8, 2005
    #8
  9. Hansang Bae Guest

    wrote:

    > Thanks, yes I was too strong on that.
    > I was thinking of correctly functioning standards
    > compliant kit. I do very little hands on at the
    > moment and have not seen a speed mis-match
    > for years.
    >
    > Are Media convertors catered for in the standards or
    > are they a hack?
    >
    > I have nothing against hacks by the way, however is
    > is just as well to know when you are dealing with them.



    Not a hack at all but a limitation of auto-negotiation. AN signals
    work over copper but not fiber. So there is no way to make a device
    that's supposed to connect fiber to copper work with AN.

    --

    hsb


    "Somehow I imagined this experience would be more rewarding" Calvin
    **************************ROT13 MY ADDRESS*************************
    Due to the volume of email that I receive, I may not not be able to
    reply to emails sent to my account. Please post a followup instead.
    ********************************************************************
     
    Hansang Bae, Mar 10, 2005
    #9
  10. Guest

    It is many moons since I saw a 10 or 100 fiber link.

    OH yes! 10 and 100 fiber are completely incompatible.
    Different wavelengths IIRC.

    Thanks.
     
    , Mar 10, 2005
    #10
    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. Jay B

    Cisco 2900 Full-duplex

    Jay B, Dec 2, 2003, in forum: Cisco
    Replies:
    1
    Views:
    685
  2. Jim
    Replies:
    9
    Views:
    8,811
    mikester
    Jan 5, 2004
  3. Sam
    Replies:
    2
    Views:
    7,080
    Dan Lanciani
    Jan 5, 2004
  4. chuck

    full-duplex on a 804

    chuck, Apr 5, 2004, in forum: Cisco
    Replies:
    4
    Views:
    506
    AnyBody43
    Apr 6, 2004
  5. DigitalSierra

    ECP Half-duplex or Full-Duplex?

    DigitalSierra, Oct 18, 2004, in forum: A+ Certification
    Replies:
    0
    Views:
    671
    DigitalSierra
    Oct 18, 2004
Loading...

Share This Page