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Configuring Ethernet Speed

Symptom

Some switches and routers may fail to correctly auto-negotiate speed settings that will give the best performance over the MAS Ethernet connections, which can result in very poor Ethernet throughput. This document describes how to manually configure the MAS Ethernet ports rather than rely on the default auto-negotiation.

Resolution

  • Open a superuser terminal session on the MAS.  howto

  • Enter the following commands to back up, then edit, the file '/etc/modules.conf':
    cd /etc
    cp modules.conf modules.old
    vi modules.conf
  • You will see one or more lines that look like this:
    alias eth0 e1000
    alias eth1 e1000
    Add a new line immediately after the last "alias ethn" line:  howto
    options e1000 Duplex=2,2 Speed=1000,1000
    Be sure to enter upper and lower case exactly as shown.

    The example above will set both boards to Full Duplex, Gigabit Ethernet.

    For the Duplex parameter, you can set 2 for full-duplex, 1 for half-duplex, or 0 for auto-negotiate (the default).

    For the Speed parameter, you can set 1000 for Gigabit, 100 for 100 Mbps, 10 for 10 Mbps, or 0 for auto-negotiate (the default).

    If you need to change only one of the ports, the first value is the setting for port eth0, and the second is for eth1; they can have different values for each of the ports if necessary.

  • Save the changes and exit the vi editor:
    :wq
  • Reboot the MAS to use the new configuration.
    •

    Note 1: How to open a superuser terminal session:
    Note 2: How to insert a line in vi:


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