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Chapter 7To find out the capabilities of an interface, you may either read related manual pages(for example, man fxp) or use ifconfig with -m flag:# ifconfig -m xl0xl0: flags=8843 metric0 mtu 1500options=9capabilities=49ether 00:01:02:ae:13:57inet 192.168.14.1 netmask 0xffffff00 broadcast 192.168.14.255media: Ethernet autoselect (100baseTX )status: activesupported media:media autoselectmedia 100baseTX mediaopt full-duplexmedia 100baseTXmedia 10baseT/UTP mediaopt full-duplexmedia 10baseT/UTPmedia 100baseTX mediaopt hw-loopbackIn the above example, the hardware capabilities of xl0 interface are shown. Theinterface is able to offload RX checksums, support VLAN MTUs, and interfacepolling. It is also capable of supporting 10baseT and 100baseT in both half-duplexand full-duplex modes. Configuring certain interface capabilities and options isexplained later in this chapter.By default, if no media type is specified, system sets media type for networkinterfaces to autoselect. This setting would be fine for interface speed, but there arecertain cases where the media duplex is not correctly negotiated. Generally, it is notadvisable to configure ports to auto-negotiate in production environment. Port speedand duplex should be explicitly configured on both host and switch sides.To configure xl0 interface for 100baseT full-duplex, the following command shouldbe used:# ifconfig xl0 media 100baseTX mediaopt full-duplexChanging interface media options when you are connected through anetwork connection, for example ssh, may lock you out of the host. It isrecommended that you use physical console or any other non-networkmethod to change these network settings.[ 111 ]