This chapter describes two upgrade paths for 4.3 BSD network drivers. One path simply ports the 4.3 BSD network driver to the BSD 4.4 model. The other path upgrades the 4.3 BSD network driver to an NPT driver (described in the Network Protocol Toolkit User's Guide).

Porting a network driver to the 4.4 BSD model should require only minimal changes to the code. In fact, porting some drivers has taken less than a day's work. However, an older driver that does not already use a transmission startup routine can take longer to port.

Porting a network driver to an NPT driver requires more extensive changes. However, it is worth the effort if the driver must handle the following: