© synergon informatika rt., 1999 chapter 13 wan connectivity overview
TRANSCRIPT
2
Objectives
Upon completion of this chapter, you will be able to perform the following tasks:
List at least four common issue to be considered when evaluating a WAN service
Describe Cisco”s implementation of the following WAN connection type, including the key features of each type:
Dialin line via modem
Leased lines
Dial-up connections services
Packet-switched services
Identify encapsulation and compression methods for each WAN service type
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Network Growth
TokenRing
TokenRing
TokenRing
• As networks expand, remote connection methods must be closely evaluated
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Connection Considerations
• Availability
• Bandwidth
• Cost
• Easy of management
• Application traffic
• Routing protocol characteristics
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Types of Connections
Async dialin using modems
Dedicated (leased) lines
Dial-up connections using a router
Packet-switched services
Async dialin using modems
Dedicated (leased) lines
Dial-up connections using a router
Packet-switched services
Access servers
Point-to-point over serial lines
Dial-on-demand routing and circuit-switched services
X.25, Frame Relay, SMDS/ATM
Access servers
Point-to-point over serial lines
Dial-on-demand routing and circuit-switched services
X.25, Frame Relay, SMDS/ATM
Services Description Cisco Offerings
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Access Servers
Async Ports
Dialin Client
PSTN Network
File Server
E-Mail Server
Cisco 2511
• Asynchronous dial-up connections allow users access to shared data
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Point-to-Point Serial Lines
DSU/CSU DSU/CSU
DSU/CSU DSU/CSU
• Dedicated links continuously available
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Dial-on-Demand Routing
TokenRing
• Connections are made only when traffic dictates a need
PSTN or ISDN
A
B
C
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Packet-Switched Service
Frame RelayX.25
SMDSATM
• Packet-switched networks are multiaccess, and data is carried within frames, packets, or cells
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Frame Relay Networks
• Use a frame-based digital technology
• Have error checking but no error notification or retransmissions
• Are widely available in the United States and Europe
• Now support PVCs and SVCs (Cisco IOS Release 11.2)
• Support connection-oriented service
• Operate at speeds of 56/64 kbps up to 45 Mbps (T3)
• Have well-defined specifications
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X.25 Networks
• Use a packet-based analog technology
• Have extensive error checking and retransmissions
• Are widely available in the Europe; some usage in the United States
• Now support PVCs and SVCs
• Support connection-oriented service
• Typically operate at speeds of 56/64 kbps up to T1/T3
• Have well-defined specifications
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SMDS Networks
• Use a fast packet-based technology
• Have no end-to-end error checking or retransmissions
• Available in part of the United States and Europe
• Support connectionless service (SMDS)
• Operate at Ds-1 and DS-3 speeds
• Have well-defined specifications
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ATM Networks
• Use a cell-switching technology
• Have no end-to-end error checking or retransmissions
• Available in the United States and growing rapidly in Europe
• Support both PVCs/SVCs and connectionless service
• Operate at speeds up to 155 Mbps
• Have still-evolving implementation standards
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WAN Encapsulation Protocol
X.25/LAPB Frame Relay
ISDN/LAPD
Dial-up
Point-to-Point
Switched
PPP
PSTN
HDLC, PPP, LAPB
Packets Switched
Circuit Switched
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Encapsulation Command
Router (config-if) #
Encapsulation encapsulation-typeEncapsulation encapsulation-type
Defines the encapsulation (framing) type
Encapsulation are protocol-specific
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LAPB Encapsulation Commands
Router (config-if) #
Encapsulation lapb [ dte | dce | multi | protocol-name ]Encapsulation lapb [ dte | dce | multi | protocol-name ]
Selects LAPB as the encapsulation type
Uses the multi option allows multiple protocols to be carried within the LAPB frame
Using the protocol-name option allows a single protocol to be carried within the LAPB frame
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Configuring LAPB
Parameter Range Default
Lapb n1 bits 1088-32832 largest available lapb t1 milliseconds 1-64000 3200 lapb n2 retries 1-255 20 lapb k window-size 1-7 7 lapb modulo modulos 8 or 128 8
Lapb n1 bits 1088-32832 largest available lapb t1 milliseconds 1-64000 3200 lapb n2 retries 1-255 20 lapb k window-size 1-7 7 lapb modulo modulos 8 or 128 8
These parameters alter the retransmission characteristics of
LAPB
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Encapsulation Example
Interface serial 0
encapsulation ppp
ip address 144.200.18.1 255.255.255.0
ipx network 10
Interface serial 0
encapsulation ppp
ip address 144.200.18.1 255.255.255.0
ipx network 10
PSTN
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Serial Compression Techniques
Uncompressed (default )
Header compression
Payload compression
Link compression
header Payload
• More efficient use of bandwidth
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Compression CommandsRouter (config-if) #
Ip tcp header-compression [ passive ]Ip tcp header-compression [ passive ]
Specifies that headers for TCP traffic will be compressedRouter (config-if) #
Frame-relay payload-compressFrame-relay payload-compress
Enables payload compression on a specified poitn-to-point
interface or subinterface
Router (config-if) #
Compress [ predictor | stac ]Compress [ predictor | stac ]
Configure software compression for LAPB, PPP, and HDLC for a
link