Many years ago the frame relay provider used a bunch of Cisco routers to build its Frame relay network. Service provider can use any kind of gear it wants to create the Frame Relay network. Today, as one of WAN connection technology, Asynchronous Transfer Mode (ATM) can be used in the core of the Frame Relay networks for most the service providers to build a well-established Frame Relay networks. ATM Wan works similarly to Frame Relay, but it has many features that make it much more robust than Frame Relay. For instance, ATM uses virtual connections (VCs), which provide the same function as Frame Relay VCs. However, ATM differs in that it segments all frames into 53-byte-long cells before transmitting them across the ATM network, and it reassembles them at the other side of the network.
ATM Wan also has significantly better quality of service (QoS) features, which lets the service provider better control the use of its core networks. Some very large scale network infrastructure use ATM wan as backbone WAN link inter-connecting the sites with high speed WAN connection over ATM. See also Network Quality of Services.
ATM Wan provides premium high speed connection oriented services with the ability to carry large amounts of network traffic, including; voice, video, and data. ATM Wan uses a cell-switching multiplexing technology that provides scalable bandwidth to OC-3 (155 Mbps) speeds and above. It also offers many inbuilt Quality of Service (QoS) functions that make it suitable for high bandwidth based network applications and services
ATM is a premium WAN technology that offers high speed performance and service levels in the WAN. It has many built-in QoS features making it an ideal transport vehicle for high bandwidth rich media services such as video conferencing, message collaboration and Voice over IP (VoIP).
ATM uses fixed 53-byte cells which are used to deliver data payloads with extremely low latency. It uses virtual circuits in a similar fashion to that of Frame Relay. ATM utilizes scalable Sonet/SDH signaling standards, with some carriers offering 155 Mbps (OC3) or 655 Mbps (OC-12) speed services
ATM Wan diagram
X.25 WAN network
X.25 is a WAN technology that was over-engineered to compensate for noise and line conditions across analogue circuitry. It is still in use today for robust low speed legacy connections and is available in most locations throughout the world.
X.25 has applications where low volume typically character-mode terminal traffic is required at remote sites. X.25 is a reliable connection orientated protocol which uses data acknowledgments to ensure network reliability
As a low speed WAN connection technology, if you should use it – follow the minimum requirement with regards to X.25 is:
- X.25 is a suitable WAN standard offering reliable connections using low bandwidth virtual circuits typically up to 56 Kbps (9.6 Kbps is common).
- X.25 is not recommended for use with high bandwidth services or where low latency is required.
- Frame Relay and ISDN are preferred WAN services over X.25.
X.25 is an OSI layer-3 legacy protocol designed for Public Data Networks (PDNs) and uses LAPB (Link Access Procedure Balanced) as its over-engineered reliable data-link. It uses connection orientated (virtual circuits) packet switched services (LAPB) to guarantee data delivery via data acknowledgements. X.25 does suffer from bandwidth and latency issues which makes it not suitable for the delivery of high-volume or real-time traffic.
However it is a service that is widely available in most parts of the world. X.25 is an ITU-T standards protocol.
Check also
- Layer 3 Switching and router redundancy for load balancing.
- networking home computers – a small network
- Some types of Internet security tools
- General computer networking hardware
- Computer networking diagram
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