Network Interface Cards (NICs)

1. Network Interface Cards (NICs) ITEC 370 George Vaughan Franklin University

2. Sources for Slides • Material in these slides comes primarily from course text, Guide to Networking Essentials,Tomsho, Tittel, Johnson (2007). • Other sources are cited in line and listed in reference section.

3. TCP/IP and OSI Models

4. NIC • NIC – Network Interface Card • Hardware that connects computer to Network Media • NIC plugs into computer backplane (bus). • NIC is gate keeper for computer. • Uploading data: • NIC reads data (bits) from the system bus (parallel) • NIC packages data into frames along with error check codes and address. • NIC ships frames out onto the network medium (serial) • Downloading data: • NIC reads frames from network medium and checks address (serial) • NIC unpacks data and performs error checking • NIC places data (in bits) onto the system bus (parallel)

5. From Parallel to Serial and Vice Versa Tomsho, Tittel, Johnson (2007). Bus width

6. NIC and Backplane (Bus) • NIC plugs into computer backplane (bus). • The backplane (bus) on a computer: • Is a connection between CPU, memory, and certain devices such as the NIC. • Typically supports 32 bit or 64 bit parallel communication (for high speed) • Bus types described later. • NIC must match the number of bits in backplane (bus width). • Many computers have incorporated the functionality of NIC on motherboard.

7. Bus Types

8. NIC and Network Media • NIC also has an interface to the network. • Interface may be a wired or wireless serial connection. • Wire interface may support coax, twisted-pair or fiber or some combination of the three. • Wireless interface consists of a transceiver and antenna (which may be internal to card).

9. NIC With Multiple InterfacesTomsho, Tittel, Johnson (2007)

10. Wireless AdaptersTomsho, Tittel, Johnson (2007)

11. NIC Buffer • NIC also contains a buffer (memory) • Buffer is used to manage traffic bursts either from the CPU or from network. • Buffers allow CPU and network to operate more efficiently. • The bigger the buffer, the better the performance of both CPU and network. • A slow NIC can affect others on network.

12. NIC Address and OSI Model • NIC has link address burned in (MAC address) • MAC = Media Access Control – 48 bits. • MAC Example (Hex): 00:20:ED:73:B7:1D • First 3 numbers = Manufacturer (Red) • Last 3 numbers = Unique Address for the card (Turquoise) • MAC Address is burned on card • NIC manages layer 2 (link layer) for computer. • NIC also provides interface to network media (layer 1 or physical layer).

13. Available NIC Features • Direct Memory Access (DMA) – direct access to CPU memory. • Shared Adapter Memory – NIC buffer mapped into CPU memory • Shared System Memory – CPU memory mapped into NIC buffer • Bus Mastering – NIC can control Bus • NIC Buffer Size • On-board Co-processors – NIC can process network data w/o main CPU

14. Available NIC Features • Security – NIC on-board support for IPSec • Traffic Management – Quality of Service (QoS) • Automatic Link Aggregation – Multiple NICs to multiply bandwidth • Fault tolerance – Multiple NICs • Wake-on-Lan – Remote computer power-up by special signal received by NIC.

15. Choosing Network Adapters for Best PerformanceTomsho, Tittel, Johnson (2007) • Increased performance features have payoffs for servers that might not apply to workstations • The following is a checklist for purchasing NICs: • Bus width—Higher is better • Bus type—Use 64-bit PCI-X or PCIe for servers • Memory transfer—Shared memory outpaces I/O or DMA • Special features—Choose security, management, protocol-handling, and hot-plug capabilities • Bus mastering—Important for servers • Vendor factors—Look for quality, reliability, staying power, and reputation

16. References Tomsho, Tittel, Johnson (2007). Guide to Networking Essentials. Boston: Thompson Course Technology. Odom, Knott (2006). Networking Basics: CCNA 1 Companion Guide. Indianapolis: Cisco Press Wikipedia (n.d.). OSI Model. Retrieved 09/12/2006 from http://en.wikipedia.org/wiki/OSI_Model