DESCRIPTION
The vge driver provides support for various NICs and embedded Ethernet interfaces based on the VIA Networking Technologies VT6122 Gigabit Ethernet controller chips. The VT6122 is a 33/66Mhz 64-bit PCI device which combines a tri-speed MAC with an integrated 10/100/1000 copper PHY. (Some older cards use an external PHY.) The MAC supports TCP/IP hardware checksums (IPv4 only), TCP large send, VLAN tag insertion and stripping, as well as VLAN filtering, a 64-entry CAM filter and a 64-entry VLAN filter, 64-bit multicast hash filter, 4 separate transmit DMA queues, flow control and jumbo frames up to 16K in size. The VT6122 has a 16K receive FIFO and 48K transmit FIFO.
The vge driver takes advantage of the VT6122’s checksum offload and VLAN tagging features, as well as the jumbo frame and CAM filter support. The CAM filter is used for multicast address filtering to provide 64 perfect multicast address filter support. If it is necessary for the interface to join more than 64 multicast groups, the driver will switch over to using the hash filter.
The jumbo frame support can be enabled by setting the interface MTU to any value larger than the default of 1500 bytes, up to a maximum of 9000 bytes. The receive and transmit checksum offload support can be toggled on and off using the ifconfig(8) utility.
The vge driver supports the following media types:
