Implementing Enterprise WAN Links Introducing Routing and Switching in the Enterprise Chapter 7 Version 4.0 1
Objectives Describe the features and benefits of common WAN connectivity options. Compare and configure common WAN encapsulations. Describe Frame Relay 2
Describe the Features and Benefits of Common WAN Connectivity Options Serial transmissions Match WAN technology to type of devices required 3
Describe the Features and Benefits of Common WAN Connectivity Options Translation device: modem Preparing the data: CSU/DSU Central Office (CO) and Customer Premises Equipment (CPE) Demarc 4
Describe the Features and Benefits of Common WAN Connectivity Options Physical Layer standards: HSSI, V.35 Link speed: North America:T1, T3 Europe: E1, E3 5
Describe the Features and Benefits of Common WAN Connectivity Options Data link Layer standards: LAPF HDLC PPP 6
Describe the Features and Benefits of Common WAN Connectivity Options Modems enable POTS to be used for WAN connections Analog signals modulate a carrier wave in the speech band The modulated carrier wave carries information to destination across the telephone network Destination demodulates the carrier and extracts information Modems are also used for DSL and cable connections to ISP 7
Describe the Features and Benefits of Common WAN Connectivity Options DSO channel = time slice Fractional connections Time Division Multiplexing (TDM) Statistical Time Division Multiplexing (STDM) 8
Describe the Features and Benefits of Common WAN Connectivity Options Circuit switching: Dedicated bandwidth Higher cost Higher level of security 9
Describe the Features and Benefits of Common WAN Connectivity Options Packet switching: Bandwidth efficiency Identifier on each packet Preconfigured, but non-exclusive, link Cell switching: high-speed packet switching 10
Describe the Features and Benefits of Common WAN Connectivity Options Virtual circuits Switched virtual circuits Permanent virtual circuits 11
Describe the Features and Benefits of Common WAN Connectivity Options Last mile and long range WAN technologies 12
Compare and Configure Common WAN Encapsulations Elements of Layer 2 encapsulations Flag Address Control Protocol Data FCS 13
Compare and Configure Common WAN Encapsulations Standard bit-oriented Layer 2 encapsulation: HDLC Cisco HDLC: additional Type field Default WAN encapsulation on Cisco devices Allows multiple Network Layer protocols to share a link 14
Compare and Configure Common WAN Encapsulations Point-to-Point Protocol) PPP: Multi-protocol datagrams Sub-protocols: LCP, NCP 15
Compare and Configure Common WAN Encapsulations Link Control Protocol options: authentication compression error detection multilink PPP callback 16
Compare and Configure Common WAN Encapsulations Phases of PPP sessions: Link-establishment Authentication (optional) NCP negotiation 17
Compare and Configure Common WAN Encapsulations Change encapsulation from HDLC to PPP on both ends of link Configure desired optional features 18
Compare and Configure Common WAN Encapsulations Verification and troubleshooting commands: show interfaces serial show controllers debug serial interface debug ppp 19
Compare and Configure Common WAN Encapsulations Password Authentication Protocol (PAP) Challenge Handshake Authentication Protocol (CHAP) 20
Describe Frame Relay Nonbroadcast multiaccess network Packet switching with variable length packets STDM Virtual circuit between two DTE devices 21
Describe Frame Relay Data link connection identifier (DLCI) Inverse ARP LMI 22
Describe Frame Relay Service parameters: Committed information rate (CIR) Excess information rate (EIR) Discard eligible (DE) frames 23
Describe Frame Relay Traffic management: Forward explicit congestion notification (FECN) Backward explicit congestion notification (BECN) 24
Summary Circuit switching WAN technologies create a physical circuit between end devices before sending data Packet and cell switching WAN technologies use virtual circuits to send data across the network Layer 2 encapsulation changes as frames move across a WAN PPP permits many advanced features including authentication, compression, and load balancing Frame Relay is a packet switched technology using switched or permanent virtual circuits Frame Relay uses parameters such as CIR to establish the bandwidth used on each VC 25
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