Essay on Unit 6 Research Project JM

Submitted By joesoto79
Words: 1177
Pages: 5

Unit 6 Research Project - Report
When comparing frame relay with ATM, (asynchronous transfer mode), as a layer 2 protocol you are comparing packets with cells and two technologies that will both be obsolete soon. In regards to frame relay, it is a slower, more careful, error-correcting X.25 packet based technology. Frame Relay differs from X.25 in several ways though. It is a much simpler protocol that works at the data link layer rather than the network layer. It implements no error or flow control and its simplified handling of frames leads to reduced latency. It is a packet switching technology for connecting network points in Wide Area Networks or WAN’s. It’s a connection oriented data service and establishes a virtual circuit between two end points. Data transfer is done in packets of data known as frames. These frames are variable in packet size and more efficient due to flexible transfers. Frame Relay was originally introduced for ISDN interfaces though it is currently used over a variety of other network interfaces as well. It was designed to carry variable-length frames over high-quality connections such as fiber optics. ATM was designed earlier than frame relay and had to deliver five distinct levels of QoS. Users could send traffic with greater or less delay. ATM is a network switching technology that uses a cell-based methodology to quantize data. ATM data communication consists of fixed size cells of 53 bytes. ATM was designed to be extremely scalable. An ATM cell contains a 5-byte header and 48 bytes of ATM payload. This smaller size, fixed-length cells are good for transmitting voice, image, and video data as the delay is minimized. If the payload used was longer than 48 bytes, it would have to be split-up and used in other cells. Frame relay did not have to do this because it could accommodate frames of varying length. One reason Related Content
ATM was liked was that it could emulate direct circuits and guarantee bandwidth, something frame relay could not. ATM didn’t do well initially because it was only offered as a service on T-3 connections, whose capacity was more than what most businesses needed or wanted to pay for. Frame relay, on the other hand, was less expensive than the common alternative, dedicated circuits, and was cost-effective. Frame relay eventually won out in the competition. Ultimately, both frame relay and ATM will be totally replaced by MPLS or some other new technology.
Some important features of layer 2 WAN protocols are PPP, which is Point-to-Point Protocol, it is a data link protocol used to establish a direct connection between two nodes. It can provide connection authentication, transmission encryption, and compression. PPP is used over many types of physical networks including serial cable, phone line, trunk line, cellular telephone, specialized radio links, and fiber optics. PPP is also used over Internet access connections. Internet service providers (ISPs) have used PPP for customer dial-up access to the Internet, since IP packets cannot be transmitted over a modem line on their own, without some data link protocol. Two derivatives of PPP, Point-to-Point Protocol over Ethernet (PPPoE) and Point-to-Point Protocol over ATM (PPPoA), are used most commonly by Internet Service Providers (ISPs) to establish a Digital Subscriber Line (DSL) Internet service connection with customers. PPP is commonly used as a data link layer protocol for connection over synchronous and asynchronous circuits, where it has largely superseded the older Serial Line Internet Protocol (SLIP) and telephone company mandated standards (such as Link Access Protocol, Balanced (LAPB) in the X.25 protocol suite). The only requirement for PPP is that the circuit provided be full duplex. PPP was designed to work with numerous network layer protocols, including Internet Protocol (IP), TRILL, Novell's Internetwork Packet Exchange (IPX), NBF, DECnet and AppleTalk. SLIP is an encapsulation of the Internet Protocol…