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

17. Network fddi, main characteristics

FDDI(Fiber Distributed Data Interface ) was developed in the 1980s. Standards for fiber distributed data interface networks were defined by the American National Standards Institute (ANSI), to provide for a high-speed networking architecture that could be used for LANs and MANs

FDDI was designed to be a reliable architecture that could handle high-traffic mission-critical networking implementations.  FDDI runs on fiber optic cable, using pulses of light to transmit data form one station to another. A related architecture, called CDDI for Copper Distributed Data Interface, can use copper cable in the same configuration as a FDDI network.

FDDI's topology is a dual ring. It can be implemented as a physical ring, or it can be a star-wired ring. In the star configuration, the computers connect to a FDDI concentrator, which is a special type of hub.

How it works: FDDI uses two rings, one of which is designated as the primary and the other as the secondary ring. The second ring provides fault tolerance, so that if the primary ring fails, data has an alternate path to take. This makes FDDI a highly reliable architecture. Traffic flows in opposite directions on the two rings.

Computers (referred to as "stations") on the FDDI network are classed as type A or B. Class A stations are physically connected to both rings; class B stations are connected to only one ring.

FDDI uses a token passing access control method. All the computers on the network monitor the token-passing activity.

topology	ring
transfer rate	100Мбит/с
access method	Token-passing
Transmission medium	Twisted pair and fiber optic
collision	no