Presentation on theme: "Introduction to WAN Technologies"— Presentation transcript:
1 Introduction to WAN Technologies Accessing WANIntroduction to WAN Technologies
2 Objectives Describe the key WAN technology concepts. Cisco Enterprise ArchitectureWAN Connections and DevicesKey WAN TechnologiesAnalog ModemLeased LineData RatesISDNFrame RelayATM
3 Why are WANs NecessaryWANs generally connect devices that are separated by a broader geographical area than can be served by a LAN.Why are WANs necessary?Business needsOrganizations often want to share information with other organizations across large distances.Distributed Organisational structuresPeople in the regional or branch offices of an organization need to be able to communicate and share data with the central site.Remote AccessEmployees who travel on company business frequently need to access information that resides on their corporate networkIndividual User needsHome computer users need to send and receive data across increasingly larger distances.to communicate with banks, stores etc
4 Common WAN Characteristics Three Major categories;WANs generally connect devices that are separated by a broader geographical area than can be served by a LAN.Use services of carriers,Telephone companies, cable companies, satellite systems, and network providers.Use serial connections of various types to provide access to bandwidth over large geographic areas.
5 Cisco Enterprise Architecture Networks often grow in a haphazard way as new components are added in response to immediate needs, leading to complex network - difficult to manage and administerCisco Enterprise Architecture is a modular network structure, consisting of:Enterprise Campus ArchitectureA campus network is a building or group of buildings connected into one enterprise network that consists of many LANsEnterprise Edge Architectureoffers connectivity to voice, video, and data services outside the enterpriseEnterprise Branch ArchitectureAllows to extend the applications and services found at the campus to remote locationsEnterprise Data Center ArchitectureEnterprise Teleworker Architecture
7 Physical layer WAN connections WAN operations focus primarily on Layer 1 and Layer 2.Commonly used physical WAN connections:Customer Premises Equipment (CPE)-The devices and inside wiring located at the premises of the subscriber.Customer either owns the CPE or leases the CPE from the service provider.Data Communications Equipment (DCE)-Also called data circuit-terminating equipment, the DCE consists of devices that put data on the local loop.Data Terminal Equipment (DTE)-The customer devices that pass the data from a customer network or hostDemarcation Point-A point established in a building or complex to separate customer equipment from service provider equipment.Local Loop-The copper or fiber telephone cable that connects the CPE at the subscriber site to the CO of the service provider
8 WAN DevicesModemCSU/DSU-Digital lines, such as T1 or T3 carrier lines, require a channel service unit (CSU) and a data service unit (DSU). The two are often combined into a single piece of equipment, called the CSU/DSU.WAN switch-A multiport internetworking device used in carrier networks.These devices typically switch traffic such as Frame Relay, ATM, or X.25, and operate at the Data Link layer of the OSI reference model.Router-Provides internetworking and WAN access interface ports that are used to connect to the service provider network.
9 Switching technologies in WANs Two switching technologies used for WANs in an Enterprise setting :Packet SwitchingCircuit SwitchingPacket Switched NetworksThe switches in a packet-switched network determine which link the packet must be sent on next from the addressing information in each packet.Two approachesConnectionless systems, such as the Internet, carry full addressing information in each packet.Connection-oriented systems predetermine the route for a packet, and each packet only has to carry an identifier. IIn the case of Frame Relay, these are called Data Link Connection Identifiers.The switch determines the onward route by looking up the identifier in tables held in memory
11 Key WAN Technologies The most common WAN data-link protocols are: HDLCPPPFrame RelayATMISDN and X.25 are older data-link protocols that are less frequently used today.Multiprotocol Label Switching (MPLS) protocol is increasingly being deployed by service providers to provide an economical solution to carry circuit-switched as well as packet-switched network traffic. It can operate over any existing infrastructure, such as IP, Frame Relay, ATM, or Ethernet.
12 Analog DialupWhen intermittent, low-volume data transfers are needed, modems and analog dialed telephone lines provide low capacity and dedicated switched connections.
13 ISDNIntegrated Services Digital Network (ISDN) turns the local loop into a TDM digital connection.Usually requires a new circuit.The connection uses 64 kbps bearer channels (B) for carrying voice or data and a signaling, delta channel (D) for call set-up and other purposes.Never really became popular in the U.S., known as It-Still-Does-Nothing or I-Still- Don’t Know
14 Leased LinesA point-to-point link provides a pre-established WAN communications path from the customer premises through the provider network to a remote destination.Point-to-point lines are usually leased from a carrier and are called leased lines.Leased lines are available in different capacities.Leased lines provide direct point-to-point connections between enterprise LANs and connect individual branches to a packet-switched network.
15 Link CapacitiesDescribe how Enterprises use leased line services to provide a WAN connection
16 PPPPPP is an Internet standard protocol to provide point-to- point, router-to-router, and host-to-host connections.It supports network layer protocolsIPNovell IPXApple TalkIt can be used over several different physical interfacesAsynchronous serialISDN synchronous serialHigh-speed Serial InterfaceWAN Networking Protocols
17 Establishing PPP Communication Communication process is established in three steps:Link EstablishmentAuthenticationPassword Authentication (PAP)Challenge Authentication Protocol (CHAP)Network Layer Protocol negotiationWAN Networking Protocols
18 Configuring PPP on Cisco Routers WAN Networking Protocols
19 Frame Relay Works at the data link layer. Frame Relay implements no error or flow control.The simplified handling of frames leads to reduced latency, and measures taken to avoid frame build-up at intermediate switches help reduce jitter.Most Frame Relay connections are PVCs (Permanent Virtual Connections)Frame Relay provides permanent shared medium bandwidth connectivity that carries both voice and data traffic.
20 Data Link Connection Identifiers (DLCI) WAN Networking ProtocolsData Link Connection Identifiers (DLCI)Frame Relay virtual circuits are identified by DLCIs.IP address need to be mapped DLCI
21 ATMCommunications providers saw a need for a permanent shared network technology that offered very low latency and jitter at much higher bandwidths.Their solution was Asynchronous Transfer Mode (ATM). ATM has data rates beyond 155 Mbps.
22 Summary A WAN is defined as A data communications network that operates beyond the geographic scope of a LANWAN primarily operate on layer 1 & 2 of the OSI modelWAN technologies includeLeased lineISDNFrame relayX.25ATM
23 Summary Cisco Enterprise Architecture This is an expansion of the hierarchical model that further divides the enterprise network intoPhysical areasLogical areasFunctional areasSelecting the appropriate WAN technology requires considering some of the following:WAN’s purposeGeographic scope of WANTraffic requirementsIf WAN uses a public or private infrastructure