15. Gigabit Ethernet. Network technology

Gigabit Ethernet is an escalation of the Fast Ethernet standard using the same IEEE 802.3 Ethernet frame format. Gigabit Ethernet builds on the Ethernet protocol but increases speed tenfold over Fast Ethernet, to 1000 Mbps, or 1 Gbps.. Like Fast Ethernet, Gigabit Ethernet is compatible with earlier Ethernet standards. However, the physical layer has been modified to increase data transmission speeds: The IEEE 802.3 Ethernet standard and the American National Standards Institute (ANSI) X3T11 FibreChannel. IEEE 802.3 provided the foundation of frame format, CSMA/CD, full duplex, and other characteristics of Ethernet. FibreChannel provided a base of high-speed ASICs, optical components, and encoding/decoding and serialization mechanisms. The resulting protocol is termed IEEE

802.3z Gigabit Ethernet.

Gigabit Ethernet supports several cabling types, referred to as 1000BaseX. IEEE 802.3z specifies operations over fiber optics, and IEEE 802.3ab specifies operations over twisted-pair copper cable. It has become a dominant player in high-speed LAN backbones and server connectivity. Gigabit Ethernet uses Ethernet as its basis, and network managers have been able to take advantage of their existing knowledge to manage and maintain gigabit networks.

Gigabit Ethernet is often used for connecting buildings on the campus to a central multi-layer gigabit switch located at the campus data center. Servers located at the campus data center would also be connected to the same gigabit multilayer switch that provides connectivity to the entire campus.

topology	star
transfer rate	1000 Мбит/с
access method	CSMA/CD
Transmission medium	Twisted pair and fiber optic
collision	Yes

16. Apple Talk network technology and Arc net

AppleTalk is the Apple network architecture and is included in the Macinstosh operating system software.

AppleTalk networks are commonly referred to as LocalTalk networks. It is not widely used. A LocalTalk network supports a maximum of 32 devices.

The features: AppleShare(file server on an AppleTalk network), EtherTalk (To useon an Ethernet with coaxial cable), and TokenTalk(to connect to a Token Ring). When a device attached to an AppleTalk network comes online, three things happen in the following order:

1. The device checks to see if it has stored an address from a previous networking session. If not, the device assigns itself an address chosen at random from a range of allowable addresses.

2. The device broadcasts the address to determine if any other device is using it.

3. If no other device is using the address, the device stores the address to use the next time the device comes online.Attached Resource Computer Network was developed (ArcNet) in 1977. It is a simple, inexpensive, flexible network architecture designed for workgroup-size networks. Because ArcNet is a token-passing architecture, a computer in an ArcNet network must have the token in order to transmit data. The token moves from one computer to the next according to the order in which they are connected to the hub, regardless of how they are physically located in the network environment The standard ArcNet packet contains:A destination address,a source address, up to 508 bytes of data Each computer is connected by cable to a hub. A maximum cable distance of 610 meters from a workstation to the hub.. The maximum distance on a linear-bus segment is only 305 meters (1000 feet)

	AppleTalk	ARC
topology	Bus or tree	Bus, Star
transfer rate	230 Кбит/с	2,5 Мбит/с
access method	CSMA/CA	token-passing
Transmission medium	Twisted pair, fiber optic	Coaxil, twisted pair.
collision	yes	no