1. Client Communication NIC is Really The physical hardware plus
Software: device driver
Upper-layer software talks to device driver
Together, implement subnet layer protocols
NIC and
Device driver
Together handle
PHY, MAC, LLC
Device Driver
NIC

2. Client Communication
Client PC has Multiple Transport-Internet Layer Protocol Stacks for Different Protocols
NDIS in Windows Governs their Communication with the Single NIC
TCP
SPX IP
IPX
NDIS

3. Client Communication
NDIS routes incoming packets to correct stack (IPX to SPX/IPX, etc.)
TCP
SPX IP
IPX
NDIS

4. Client Communication
NDIS feeds outgoing packets one at a time to the NIC
TCP
SPX IP
IPX
NDIS