Network Adapter

How can you identify a network card manufacturer from its MAC address?

The first 6 characters in a MAC address represent the manufacturer and the last 6 represent the device number itself.

At which OSI layer does a network adapter card operate? At which layer does the media converter work?

The network card operates at the Layer 1 and Layer 2 of the OSI model. The media converter only operates at the Layer 1 of the OSI model.

Network Adapter Facts: A network adapter (also called a network interface card, or NIC) connects a host to the network medium. It is responsible for converting binary data into a format that can be sent on the network medium.

+ The network adapter is responsible for converting binary data into a format that can be sent on the network medium. * A transceiver is responsible for converting digital data into digital signals to be sent on the medium. The type of signal the transceiver sends depends on the type of network. A fiber optic NIC sends light signals, a wired NIC sends electronic signals on a wire, and a wireless NIC sends radio signals. To recieve signals, the transceiver converts digital signals from the network to digital data for the PC. * A modem coverts binary data to analog waves on the sending end (modulation) and then converts the analog waves back to binary data on the receiving end (demodulation). + Some computers, like laptops, come with built-in network adapters. Other computers use NICs that plug in to the system's expansion slots or are external to the computer and connect through an existing computer port. + Network adapter are Layer 1 devices because they send and receive signals on the network medium. They are alos Layer 2 devices because they must follow the rules for media access and because they read the physical address in a frame. + The type of network adapter you choose must match the network architecture you are connecting to. + Older network adapters used an external transceiver to connect to the network media. However, all modern network adapters use a built-in transceiver.

A transceiver module is used to change the media type of a port on a network divice, such as a switch or a router. The following are the most common types of transceiver modules: GBIC (Gigabit Interface Converter)

A GBIC (Gigabit Interface Converter) is a large transceiver that fits in a port slot and is used for Gigabit media, including copper, and optical fiber.

MAC Address

A Media Access Control (MAC) address is unique identifier burned into the ROM of every Ethernet NIC. + The MAC address is a 12-digit (48-bit) hexadecimal number (each number ranges from 0-9 or A-F). + The address is often written as 00-B0-D0-06-BC-AC or 00B0.D006.BCAC (dashes, periods, and colons can be used to divide the MAC address parts). + The Mac address is globally unique by design. The first half of the MAC address, the first six digits, is assigned to each manufacturer. The manufacturer determines the rest of the address, assigning a unique value that identifies the host address. A manufacturer that uses all the address in the original assignment can apply for a new MAC address assignment. + Devices use the MAC address to send frames to other devices on the same subnet. * (Some network cards allow you to change the MAC addreess through jumpers, switches, or software, but there are few legitimate reasons for doing so).

Transceiver Module XFP

A XFP transceiver is similar to an SFP in size, but is used for 10-Gigabit networking.

Media Converter

A media converter is used to connect network adapters that are using different media types. For example, a media converter could be used to connect a server with a fiber optic Ethernet NIC to a copper Ethernet cable. + Media Converters work at the Physical layer (Layer 1). Media converters do not read or modify the MAC address in any way. + Media converters only convert from one media type to another within the same architecture ( such as Ethernet). A media converter cannot translate between two different architectures. This must be done using a bridge or a router. Converting from one architecture to another would require modifying the frame contents to modify the Data Link Layer address.

What are two major differences a modem and an Ethernet NIC?

A modem uses old telephone wire connections, and also the modem coverts digital signals into analog sound signals.

NIC (Network Interface Card)

A network interface card (NIC), also called a network adapter, connects a host to the network medium. It is responsible for converting binary data into a format that can b sent on the network medium.

Transceiver Module (Small Form Factor Pluggable)

An SFP (Small Form-Factor Pluggable) is similar to a GBIC, but is a smaller size . An SFP is sometimes called a mini-GBIC. + SFP + is a newer version of the SFP. SFP + supports data rates as high as 10 Gbit/s, 8 Gbit/s Fibre Channel, 10-gigabit Ethernet, and the Optical Transport Network standard OTU2.

Address Resolution Protocol (ARP)

Hosts use ARP to discover the MAC address of a device from its IP address. Before two devices can communicate, they must know the MAC address of the receiving device. If the MAC address isn't known, ARP does the following to find it: 1. The sending device sends out a broadcast frame. + The destination MAC address is all Fs (FFFF;FFFF;FFFF). + The sending MAC address is its own MAC address. + The destination IP address is the known IP address of the destination host. + The sending IP address is its own address. 2. All hosts on the subnet process the broadcast frame, looking at the destination IP address. 3. If the destination IP address matches its own address, the host responds with a frame that includes its own MAC address as the sending MAC address. 4. The original sender reads the MAC address from the frame and associates the IP address with the MAC address, saving it in its cache. Once the sender knows the MAC address of the receiver, it sends data in frames addressed to the destination device. These frames include a cyclic redundancy check (CRC0, which is used to detect frames that have been corrupted during transmission. * (Hosts use the reverse address resolution protocol (RARP) to find the IP address of a host with a known MAC address).

Reverse Address Resolution Protocol (RARP)

Hosts use the reverse address resolution protocol (RARP) to find the IP address of a host with a known MAC address.

What is the function of a transceiver?

It accepts the digital data represented by zeroes and ones and converts it into an electrical signal by converting the ones and zeroes into negative and positive on the cable.

What does the MAC address FF-FF-FF-FF-FF-FF indicate?

It indicates another computer is trying to find the MAC address of a computer its trying to communicate with. By setting all values to F its using the ARP to broadcast the F address to all connected host.

How does a computer find the MAC address of another device on the same subnet?

It uses the ARP, Address Resolution Protocol. By creating a special frame with its own source address and the broadcast MAC address, which is a MAC address with all values set to F.

Transceiver Module (Quad, Or 4-Channel, Small Form-Factor Pluggable)

QSFP (Quad, Or 4-Channel, Small Form-Factor Pluggable) is a compact hot-pluggable transceiver that is also used for data communications applications.

Can you use a media converter to connect network segments that are using different architecture types? Why or why not?

Yes, using a media converter allows two different architecture types, but only allowed to convert one type of transmission media into another.