Thursday, August 30, 2012

Wireless Network Routers

A wireless router integrates a wireless access point with an Ethernet switch and an Ethernet router. The integrated switch connects the integrated access point and the integrated Ethernet router internally, and allows for external wired Ethernet LAN devices to be connected as well as a (usually) single WAN device such as a cable modem or DSL modem. A wireless router advantageously allows all three devices (mainly the access point and router) to be configured through one central configuration utility, usually through an integrated web server. However one disadvantage is that one may not decouple the access point so that it may be used elsewhere.

Wednesday, August 29, 2012

Token passing


In Token Ring another access method is used, called Token Passing.

With Token Passing, a small message, called a token, constantly circulates around the ring. If the token is marked as free, the host that receives the ”free” token can transmit its data and mark the token as busy. All the hosts along the ring receive the data and the busy token, until the host that sent the original message sets the token free again.

Right now the token is with host B, and it is marked free. Let’s say that host B wants to send data to host D. B sets the token to busy and adds its data. The host C has now received the token and the data, but since C is not the receiver it just passes on the token and the data into the ring.

The host D receives the data and sets the token to copied. The token and the data are then
passed on into the ring.

The host A just passes on the token and the data. The host B sees that the data has been received in a proper way by D. B therefore deletes the data and sets the token free again.

Saturday, August 25, 2012

Fiber To Home


Fiber-To-The-Home (FTTH)

"How Fiber to the Home Works"

FTTH In an FTTH (Fiber-to-the-Home)system, glass fiber cables go directly from the Internet backbone to the user’s premises, using high-speed pulses of light to transport information. Fiber-optic cables have large bandwidth (speeds greater than 2.5 gigabits per second).

More and more, both traditional phone companies and start-up companies are installing FTTH to deliver broadband services, particularly in areas with new residential and commercial construction. Companies with older copper networks are, in some cases, overlaying copper-wired networks with new FTTH systems, then removing the old networks. Two types of FTTH architectures are currently used: Pointto- point and passive optical network (PON).

Point-to-point providers install an optical transceiver in the provider’s central office for each customer. Fiber-optic cable then connects the central offi ce to the customer’s premises, much like a telephone line. PON is a fiber optic network without active electronics, such as repeaters. A PON uses passive splitters to deliver signals to multiple terminal devices using a tree structure transmission network. PON systems use transceivers with splitters that may be located as far as 30,000 feet from the provider’s central offi ce. An optical electrical converter (OEC) installed on or near the customer’s property converts the optical signal to an electrical signal, allowing it to connect to the end user.

Tag

Assignment Lanka Tag Cloud
Computer Networks The History of Local Area Networks, LAN, The Topologies of a Networks, LANs describe different types of transmission Medias, Local Area Networks Access Methods, Carrier Sense Multiple Access with Collision Detect, Development of LAN Technologies. LAN -Token Ring, LAN Ethernet Digital, LAN - Ethernet Sun microsystems, LAN - Ethernet Mixed Environment, LAN - Token Ring was introduced by IBM LAN - IBM implementation of Token Ring, Token Ring Novell, LAN Token Ring - in a mixed environment, LAN - Fiber Distributed Data Interface, LAN - ATM, LAN Components, LAN Switching Methods, Virtual Local Area Network, Port based VLAN, Mac based VLAN, Protocol based VLAN, User Base VLAN, PC networks Components, PC networks Shared resources, PC Network operating systems, PC networks Novell Netware, PC networks Windows NT, PC networks IBM LAN Server Computer Programming Languages HTML Language, The Generations of Programming Languages, Different types of High Level Languages, Different types of High Level Languages Disadvantages
Computer Networks - IBM LAN Server, Windows NT Networks, Novell Netware, Network operating systems, Networks Shared, Networks Components, User Base, Protocol based, Mac based, Port based, VLAN, LAN Switching, LAN Components, ATM, Fiber Data, Token Ring, Token Ring Novell, IBM implementation, Ethernet, Sun microsystems, Ethernet Digital, Token passing, LAN Technologies, CSMA/CD, Access Methods, Transmission, Networks, The History of Local Area Networks, LAN