Three options for connecting over a telephone service:
• Dial-up connections.
• Integrated Services Digital Network(ISDN) - A method of sending voice and data information on a digital phone line.
o Basic ISDN - Two 64Kbps B-channels with one 16Kbps D channel is provided. The D-channel is used for call control and setup. Basic ISDN can provide 128Kbps speed capability.
o Primary ISDN - 23 B-channels and one D channel is provided.
• Leased Lines - This involves the leasing of a permanent telephone line between two locations.
Remote Communication Protocols
• Serial Line Internet Protocol (SLIP) - Allows computers to connect to the internet with a modem. No error checking or data compression is supported. Only the TCP/IP protocols are supported.
• Point to Point Protocol (PPP) - Provides error checking and data compression. Also supports multiple network protocols such IPX/SPX and NetBEUI in addition to TCP/IP. Supports dynamic allocation of IP addresses.
Remote Access Service
Remote Access Service (RAS) with Windows NT allows users connecting to the network using a modem to use network resources. RAS may be called dial up networking (DUN) depending on the version of Windows you are using. The NT RAS server can handle 256 connections. Windows NT RAS servers provide the following security features:
1. User account security
2. Encryption between the DUN (dial up networking) client and the server
3. Callback capability
The client software is called Dial up networking (DUN) in windows NT4 and Windows95. For NT 3.51 and Windows 3.1 it is called a RAS client. These clients may be used to connect to the internet through an internet service provider (ISP).
Tuesday, October 7, 2008
Saturday, October 4, 2008
FFDI
Fiber Distributed Data Interface (FDDI)
The Fiber Distributed Data Interface (FDDI) standard is ANSI X3T9.5 . The Fiber Distributed Data Interface (FDDI) topology is ring with two counter rotating rings for reliability with no hubs. Cable type is fiber-optic. Connectors are specialized. The media access method is token passing. The maximum length is 100 kilometers. The maximum number of nodes on the network is 500. Speed is 100 Mbps. FDDI is normally used as a backbone to link other networks. A typical FDDI network can include servers, concentrators, and links to other networks.
Devices called concentrators provide functions similar to hubs. Most concentrators use dual attachment station network cards but single attachment concentrators may be used to attach more workstations to the network.
FDDI token passing allows multiple frames to circulate around the ring at the same time. Priority levels of a data frame and token can be set to allow servers to send more data frames. Time sensitive data may also be given higher priority. The second ring in a FDDI network is a method of adjusting when there are breaks in the cable. The primary ring is normally used, but if the nearest downstream neighbor stops responding the data is sent on the secondary ring in attempt to reach the computer. Therefore a break in the cable will result in the secondary ring being used. There are two network cards which are:
1. Dual attachment stations (DAS) used for servers and concentrators are attached to both rings.
2. Single Attachment stations (SAS) attached to one ring and used to attach workstations to concentrators.
A router or switch can link an FDDI network to a local area network (LAN). Normally FDDI is used to link LANs together since it covers long distances.
The Fiber Distributed Data Interface (FDDI) standard is ANSI X3T9.5 . The Fiber Distributed Data Interface (FDDI) topology is ring with two counter rotating rings for reliability with no hubs. Cable type is fiber-optic. Connectors are specialized. The media access method is token passing. The maximum length is 100 kilometers. The maximum number of nodes on the network is 500. Speed is 100 Mbps. FDDI is normally used as a backbone to link other networks. A typical FDDI network can include servers, concentrators, and links to other networks.
Devices called concentrators provide functions similar to hubs. Most concentrators use dual attachment station network cards but single attachment concentrators may be used to attach more workstations to the network.
FDDI token passing allows multiple frames to circulate around the ring at the same time. Priority levels of a data frame and token can be set to allow servers to send more data frames. Time sensitive data may also be given higher priority. The second ring in a FDDI network is a method of adjusting when there are breaks in the cable. The primary ring is normally used, but if the nearest downstream neighbor stops responding the data is sent on the secondary ring in attempt to reach the computer. Therefore a break in the cable will result in the secondary ring being used. There are two network cards which are:
1. Dual attachment stations (DAS) used for servers and concentrators are attached to both rings.
2. Single Attachment stations (SAS) attached to one ring and used to attach workstations to concentrators.
A router or switch can link an FDDI network to a local area network (LAN). Normally FDDI is used to link LANs together since it covers long distances.
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