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  1. #1

    3c509b NIC in full duplex mode!?!?!?

    hi all!

    i have two old 3com 3c509b NICs and its not possible for me to enable the full-duplex option.

    there are some docs in the RH9.0 (/usr/src/linux-2.4.20-8/Documentation/networking/3c509.txt)

    i always saw the following message in /var/log/messages:

    Jan 10 10:16:33 router kernel: eth1: Setting 3c5x9/3c5x9B half-duplex mode if_port: 0, sw_info: 9321
    Jan 10 10:16:33 router kernel: eth1: Setting Rx mode to 1 addresses.
    Jan 10 10:16:33 router kernel: eth2: Setting 3c5x9/3c5x9B half-duplex mode if_port: 0, sw_info: 9321

    all modules are compiled into the kernel (2.4.20)

    i tried to setup the NICs in these configuration (/etc/lilo.conf):




    i also enabled the full-duplex option with the 3com config tool on the NICs.

    this was my original config in /etc/lilo.conf and it works fine, but only in half-duplex mode!

    append="ether=15,0x300,eth1 ether=5,0x310,eth2"

    maybe someone know something about my problem and can give some tips.



  2. #2
    Linux Guru
    Join Date
    Oct 2001
    Täby, Sweden
    Are you sure that your network allows full duplex mode? Some switches and hubs and other cards don't support that, so it depends on what you have connect it to on the other end. Also, if the cable is long, then the signal quality might not be good enough to allow for full duplex.

  3. #3

    the switch is a surecom EP-808SX. the spec. shows me for transfer rate:

    ethernet: 10Mbps (half-duplex); 20Mbps (full-duplex)
    fast ethernet: 100Mbps (half-duplex); 200 Mbps (full-duplex)

    the NIC is a 3com 3c509b:

    original text from "EtherLink®III Parallel Tasking®16-Bit ISA
    Network Interface Card User Guide"

    The 3C509B NIC has the following features:

    Full-duplex support, which allows data to be sent and
    received at the same time in a switched-Ethernet

    the cables between the switch and the NIC are: 2-Pair, CAT5 and not longer than 5m!!!! (no crossover cable)

    i think my components match all criteria for a full duplex support in my network.

    maybe i'm wrong! than give me an update.



  4. $spacer_open
  5. #4
    Linux Guru
    Join Date
    Oct 2001
    Täby, Sweden
    Is this an ISA card? In that case, I seriously doubt that it is actually capable of full-duplex operation, despite what the manual says. I have yet to see a single ISA NIC that does more than 10 mbps half-duplex.

  6. #5
    yes! it's a ISA ethernet card.
    but i think it's possible to configure the card in full-duplex mode.

    in the 3com config tool is a tuple to change between full and half duplex mode.
    also it's described in the 3com spec.

    take a look into :



  7. #6
    Linux Guru
    Join Date
    Oct 2001
    Täby, Sweden
    I see. I can't deny that it seems to be possible, then. However, that document revealed something else, that I suspect that you did not read:
    /////Extremely important caution concerning full-duplex mode/////
    Understand that the 3c509B's hardware's full-duplex support is much more
    limited than that provide by more modern network interface cards. Although
    at the physical layer of the network it fully supports full-duplex operation,
    the card was designed before the current Ethernet auto-negotiation (N-way)
    spec was written. This means that the 3c509B family ***cannot and will not
    auto-negotiate a full-duplex connection with its link partner under any
    circumstances, no matter how it is initialized***. If the full-duplex mode
    of the 3c509B is enabled, its link partner will very likely need to be
    independently _forced_ into full-duplex mode as well; otherwise various nasty
    failures will occur - at the very least, you'll see massive numbers of packet
    collisions. This is one of very rare circumstances where disabling auto-
    negotiation and forcing the duplex mode of a network interface card or switch
    would ever be necessary or desirable.
    I believe that the switch will only use auto-negotiation, and thus I don't think that it's possible to force the switch into full-duplex mode, unless it actually has some kind of switch for it.

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