network half/full duplex - Hewlett Packard

This is a discussion on network half/full duplex - Hewlett Packard ; i seem to remember a few years back that there was an issue with full vs. half duplex on some servers and network equipment. i have my link configured as 100 mb half duplex but the switch is configured as ...

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  1. network half/full duplex

    i seem to remember a few years back that there was an issue with full vs.
    half duplex on some servers and network equipment.

    i have my link configured as 100 mb half duplex but the switch is
    configured as full duplex. we are having some random sessions drop.

    this is a 'e3000/A400-100-11' system. what is the suggested settings?
    -------------------------------------------------
    Larry Simonsen
    System Analyst
    Flowserve Corporation 1350 North Mountain Springs Parkway Springville,
    UT 84883 Phone: 801-489-2450 Fax: 801-491-1750
    -------------------------------------------------
    All opinions expressed herein are my own and reflect, in no way, those of
    my employer.
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  2. Re: network half/full duplex

    Larry,

    Do a

    LINKCONTROL @,a

    and post the output.

    -Craig


    --- On Mon, 7/14/08, Larry Simonsen wrote:

    > From: Larry Simonsen
    > Subject: network half/full duplex
    > To: HP3000-L@RAVEN.UTC.EDU
    > Date: Monday, July 14, 2008, 2:31 PM
    > i seem to remember a few years back that there was an issue
    > with full vs.
    > half duplex on some servers and network equipment.
    >
    > i have my link configured as 100 mb half duplex but the
    > switch is
    > configured as full duplex. we are having some random
    > sessions drop.
    >
    > this is a 'e3000/A400-100-11' system. what is the
    > suggested settings?
    > -------------------------------------------------
    > Larry Simonsen
    > System Analyst
    > Flowserve Corporation 1350 North Mountain Springs Parkway
    > Springville,
    > UT 84883 Phone: 801-489-2450 Fax: 801-491-1750
    > -------------------------------------------------
    > All opinions expressed herein are my own and reflect, in no
    > way, those of
    > my employer.
    > -------------------------------
    > NOTICE: The information contained in this e-mail, and
    > attachment(s)
    > thereto, is confidential and may contain attorney - client
    > privileged
    > communications. If you are not the intended recipient, you
    > are hereby
    > notified that any dissemination, distribution, or copying
    > of this
    > communication is strictly prohibited. If you have received
    > this
    > communication in error, please notify the sender
    > immediately and delete
    > the e-mail from your computer system without retaining any
    > copies. Thank
    > you.
    >
    > * To join/leave the list, search archives, change list
    > settings, *
    > * etc., please visit
    > http://raven.utc.edu/archives/hp3000-l.html *


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  3. Re: network half/full duplex

    Woooo(I like this word the spell checker struggles with it) does this
    bring back memories. You do not want any speed sensing anywhere on you
    internal network. Even one cheap hub doing speed sensing will slow
    everything down. The way to prevent this is to have everything at 100
    mb, the switch, the hub, the HP3000 everything.

    I cannot remember what the half or full duplex setting was set at, but
    make sure it does not sense the speed. 10 or 100 mb.

    We had some contractors (They were MS experts) install a cheap HUB on
    our system. This made the system very slow.

    Woe Woe Woe
    Kent Wallace

    On another note I have seen 1 gigabyte cards out, I am not sure how to
    implement one of these and what effect they will have on speed sensing.


    -----Original Message-----
    From: HP-3000 Systems Discussion [mailto:HP3000-L@RAVEN.UTC.EDU] On
    Behalf Of Larry Simonsen
    Sent: Monday, July 14, 2008 12:31 PM
    To: HP3000-L@RAVEN.UTC.EDU
    Subject: [HP3000-L] network half/full duplex

    i seem to remember a few years back that there was an issue with full
    vs.
    half duplex on some servers and network equipment.

    i have my link configured as 100 mb half duplex but the switch is
    configured as full duplex. we are having some random sessions drop.

    this is a 'e3000/A400-100-11' system. what is the suggested settings?
    -------------------------------------------------
    Larry Simonsen
    System Analyst
    Flowserve Corporation 1350 North Mountain Springs Parkway Springville,

    UT 84883 Phone: 801-489-2450 Fax: 801-491-1750
    -------------------------------------------------
    All opinions expressed herein are my own and reflect, in no way, those
    of
    my employer.
    -------------------------------
    NOTICE: The information contained in this e-mail, and attachment(s)
    thereto, is confidential and may contain attorney - client privileged
    communications. If you are not the intended recipient, you are hereby
    notified that any dissemination, distribution, or copying of this
    communication is strictly prohibited. If you have received this
    communication in error, please notify the sender immediately and delete
    the e-mail from your computer system without retaining any copies. Thank

    you.

    * To join/leave the list, search archives, change list settings, *
    * etc., please visit http://raven.utc.edu/archives/hp3000-l.html *


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  4. Re: network half/full duplex

    Larry Simonsen wrote:
    > i seem to remember a few years back that there was an issue with full vs.
    > half duplex on some servers and network equipment.
    >
    > i have my link configured as 100 mb half duplex but the switch is
    > configured as full duplex. we are having some random sessions drop.


    For almost anything produced in the last decade or more, full-duplex is
    the status quo. As long as you have a true switch (not a hub), and it's
    a point-to-point media, you want it to be full-duplex.

    Port speed, duplex, throttling, and other parameters are usually
    negotiated automatically as well, and the "common sense" default these
    days is to let it auto-negotiate and troubleshoot the exceptions.

    With that said, the venerable old 3000 has a less than stellar track
    record with auto-negotiation, and you should set BOTH sides of the
    connection to a specific speed and duplex.

    With any auto-negotiated connection, if both sides don't agree (or
    participate), the connection will fall back to the least common
    denominator, typically 10/half, but that is somewhat vendor specific.
    The point being, if you hard code ONE side, you must hard code the OTHER
    side as well.

    For the 3000, you can hard-code speed/duplex in NMMGR at the
    LINK.linkname path.

    NS Configuration -> Unguided -> NS -> Link -> Modify:

    > Path: LINK.DTSLINK
    >
    > Physical path of device adapter [0/0/0/0 ]
    >
    > Use factory-configured local station address? [Y] (Y/N)
    > Local station address [FF-FF-FF-FF-FF-FF] (Hex)
    >
    > When auto-negotiation is enabled, the system can only
    > properly configure the link if the hub also auto-negotiates.
    > Use auto-negotiation to determine link settings? [N] (Y/N)
    > If 'N': Link speed [100 ] (100 or 10 MBits/sec)
    > Full Duplex mode [Y] (Y/N; N=Half)


    If your duplex is mismatched, the "half-duplex" side will see lots of
    collisions, while the "full-duplex" side will see received CRC errors
    (among other things).

    Jeff

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  5. Re: network half/full duplex

    Hello All,

    I ran some test on this when 100BT first came out on 3000e MPE systems
    against HP Procure switches that I could get my hands on: 4000, 2708 and
    2224 as well as a HP 100BT hub (I do not have a number for this hub and I am
    pretty sure is no longer sold).

    Results:

    Hub: 100/duplex=half/auto-negotiate=no (works)

    Procure:

    4000: 100/duplex=full/auto-negotiate=yes (works)
    4000: 100/duplex=full/auto-negotiate=no (works)

    2708: 100/duplex=full/auto-negotiate=yes (works)
    2708: 100/duplex=full/auto-negotiate=no (RECV CRC Err, RECV Dropped)

    2224: 100/duplex=full/auto-negotiate=yes (works)
    2224: 100/duplex=full/auto-negotiate=no (RECV CRC Err, RECV Dropped)

    These tests were run with matching configuration in the switch and the host.

    I found the details of this operation in the ProCurve reference for 2708
    10/100/1000 that switch that "auto-negotiate=yes" was as per compliance with
    the IEEE 802.3 standard:

    See: ftp://ftp.hp.com/pub/networking/software/59903055.pdf page 3-1

    ---------------------------------------------------------------------------
    Basic Troubleshooting Tips
    Most problems are caused by the following situations. Check for these items
    first when starting your troubleshooting:
    Connecting the RJ-45 ports to devices that have a fixed full-duplex
    configuration. The Series 2700 Switch RJ-45 ports are configured as
    "Auto". That is, when connecting to attached devices, the switch will
    operate in one of two ways to determine the link speed and the communication
    mode (half duplex or full duplex):
     if the connected device is also configured to Auto, the switch will
    automatically negotiate both link speed and communication mode
     if the connected device has a fixed configuration, for example 100
    Mbps, at half or full duplex, the switch will automatically sense the
    link speed, but will default to a communication of half duplex
    Because the Series 2700 Switches behave in this way (compliance with
    the IEEE 802.3 standard), if a device connected to the switch RJ-45 ports
    has a fixed configuration at full duplex, the device will not connect
    correctly to the switch. The result will be high error rates and very
    inefficient communications between the switch and the device.
    Make sure that all devices connected to the Series 2700 Switches' RJ-45
    ports are configured to auto negotiate, or are configured to connect at half
    duplex (all hubs are configured this way, for example).
    ---------------------------------------------------------------------------

    As always your mileage will vary. What ever configuration you go with for
    your 3000e MPE 100BT, check your results with ":linkcontrol @;status=all"!!!


    I hope this helps:

    Regards,
    James Hofmeister

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