Enhancing LAN Performance

Chapter 2: Ethernet, Token Ring, and ATM Frame and Cell Operations

Figure 2.1: Ethernet and IEEE 802.3 Frame Formats

Figure 2.2: Source and Destination Address Field Formats

Figure 2.3: Fast Ethernet Frame

Figure 2.4: Gigabit Ethernet Frame Format with Carrier Extension

Figure 2.5: Gigabit Ethernet Packet Bursting

Figure 2.6: Token, Abort, and Frame Formats

Figure 2.7: Differential Manchester Encoding

Figure 2.8: J and K Non-Data Symbol Composition

Figure 2.9: Priority and Reservation Field Utilization

Figure 2.10: Destination Address Subfields

Figure 2.11: Source Address Field

Figure 2.12: Routing Information Field

Figure 2.13: Frame Status Field

Figure 2.14: The ATM Cell

Figure 2.15: The ATM Protocol Stack

Figure 2.16: The ATM Protocol Stack within a Network

Figure 2.17: Using a LAN Switch

Figure 2.18: ATM Network Interfaces

Figure 2.19: The ATM Header

Figure 2.20: Relationship between Virtual Paths and Virtual Channels

Figure 2.21: ATM Cell Switching Example

Chapter 3: Estimating Network Traffic

Figure 3.1: The Method of Printing Can Double Network Traffic, Resulting from the Execution of a Print Job

Figure 3.2: Resulting Subdivided Network

Figure 3.3: The Effect on the Bandwidth of a Segmented Network Resulting from Inter-LAN Communications

Figure 3.4: Data Flow on a Tiered Switch-Based Network Topology

Figure 3.5: The Traffic Estimation Worksheet Excel Template for Ethernet LANs

Figure 3.6: An Example of a Completed Traffic Estimation Worksheet Excel Template

Chapter 4: Understanding and Applying Waiting Line Analysis

Figure 4.1: Basic Components of a Simple Waiting Line System

Figure 4.2: Other Types of Waiting Line Systems

Figure 4.3: Connecting Two Geographically Separated LANs via a Pair of Routers or Remote Bridges

Figure 4.4: Initial Computational Results

Figure 4.5: Temporary Frame Storage Relationship

Figure 4.6: Waiting Time Relationship

Figure 4.7: Queue Length and Waiting Time versus Utilization

Figure 4.8: Spreadsheet Model Screen Display

Figure 4.9: Comparing the Use of Single- and Dual-Port (Multi-port) Networking Devices

Figure 4.10: Transmission Gaps Commonly Occur on Multiple Circuits

Figure 4.11: The Excel QUEUE2 Model

Figure 4.12: Execution of the Excel Template UNITS

Figure 4.13: Execution of the Excel Remplate QVU

Chapter 5: Sizing Communications Equipment and Line Facilities

Figure 5.1: Telephone Traffic Sizing Problems

Figure 5.2: Using a Decision Model to Determine the Optimum Level of Service

Figure 5.3: Traffic Distribution Example

Figure 5.4: Access Controller Sizing

Chapter 6: Using the Availability Level as a Decision Criterion

Figure 6.1: Network Components in Series

Figure 6.2: Connecting Devices in Parallel

Figure 6.3: Computing the Availability of a Mixed Serial and Parallel Transmission System

Figure 6.4: Comparing Data Flow Using Conventional and Mirrored Disk Systems on a File Server

Figure 6.5: A Schematic Representation of a Fully Mirrored Disk Subsystem from the Perspective of Its Availability

Figure 6.6: Availability Levels: Base Template

Figure 6.7: Availability Levels: Entry of Values and Resulting Computations

Figure 6.8: Availability Levels: Reentering Computed Serial Availability Values Twice

Chapter 7: Estimating Ethernet Network Performance

Figure 7.1: Gigabit Ethernet Frame Format

Figure 7.2: Frame Length versus Information Transfer Rate

Figure 7.3: Using a Bridge to Improve Ethernet LAN Performance

Figure 7.4: Linking LANs with Different Operating Rates

Figure 7.5: Linking Remote Networks

Figure 7.6: LAN Throughput Predictor

Chapter 8: Estimating Token Ring Network Performance

Figure 8.1: Using a Local Token Ring Bridge

Chapter 9: ATM Performance

Figure 9.1: AAL-1 Cell Format

Figure 9.2: AAL-2 Cell Format

Figure 9.3: AAL-3/4 Data Flow and Cell Formation

Figure 9.4: AAL-5 Cell Formation

Figure 9.5: ATM versus Legacy LANs

Figure 9.6: Manually Configuring PVCs to Enable LAN-to-ATM Interoperatility

Figure 9.7: The LANE Process

Figure 9.8: The Excel LAN Emulation Initialization Model

Figure 9.9: When n layer 2 MAC stations become active and require an address resolution, queues develop in the switch which introduce delays

Figure 9.10: The Excel Model LANE2, which Computes the LANE Switch Delay Time

Chapter 10: Working with Images

Figure 10.1: An 8 10-Inch Photograph of the Author's Daughter Stored as a Noncompressed TIF File

Figure 10.2: Using the Collage Image Manager to Rotate the Retrieved TIF Image 90

Figure 10.3: The Resulting Rotated Image that Will Form the Basis for Performing Several Image Conversations and Image Manipulation Operations

Figure 10.4: Through the Collage Image Manager's "Save Image As" Option You Can Store a File in a Different Format

Figure 10.5: Display of the GIF Image Format of the Author's Daughter

Figure 10.6: A Printout of the Image AFTER Its Conversion to JPG Using the Collage Image Manager's Least Compression Specification

Figure 10.7: Printout of the File Stored Using Moderate JPG Compression

Figure 10.8: Printout of the File Stored Using the Highest JPG Compression Supported by the Collage Image Manager Program

Figure 10.9: Cropped TIF File Using LZW Compression (Requires 1,156,975 Bytes of Storage)

Figure 10.10: Cropped Moderately Compressed JPG File (Data Storage Reduced to 98,153 Bytes)

Figure 10.11: Collage Image Manager Change Image Type Window

Figure 10.12: LAN Segmentation

Figure 10.13: A Typical Web ServerInternet Connection

Chapter 11: Using Intelligent Switches

Figure 11.1: A Shared Media, Shared Bandwidth Ethernet LAN Segment

Figure 11.2: A Two-Hub 10BASE-T Ethernet Network

Figure 11.3: Conventional Hub Dataflow

Figure 11.4: The Connection of Token Ring MAUs Forms a Star-Ring Topology

Figure 11.5: Bridge Switching Operation

Figure 11.6: Basic Components of an Intelligent Layer 2 Switch

Figure 11.7: Shared Bus Switch

Figure 11.8: Shared Memory Switch Architecture

Figure 11.9: Cross-Point/Cut-Through Switching

Figure 11.10: Store-and-Forward Switching

Figure 11.11: Port-Based Switching

Figure 11.12: Segment-Based Switching

Figure 11.13: Support a Small Department or Workgroup

Figure 11.14: Generic Construction of a Two-Tiered Ethernet Switch-Based Network

Figure 11.15: Using a Gigabit Ethernet Switch as a Star-Based Backbone Switch

Figure 11.16: The Key to the Operation of a Switch Is a Matrix Module that Enables Each Port to be Cross-Connected to Other Ports

Figure 11.17: A Typical Ethernet Modular Switch Chassis Containing a Mixture of Port, CPU, Logic, Matrix, and Power Cards

Figure 11.18: The IEEE 802.3x Pause Frame

Figure 11.19: Switch Latency Includes a Built-In Delay Resulting from the Structure of the Ethernet Frame

Figure 11.20: The Need for Loop Control

Figure 11.21: Creating Port-Grouping vLANs Using a LAN Switch

Figure 11.22: Overcoming the Port-Based Constraint Where Stations Can Join Only a Single vLAN

Figure 11.23: Layer 2 vLAN

Figure 11.24: Moving Stations When Using a Layer 2 vLAN

Figure 11.25: Inter-vLAN Communications Require the Use of a Router

Figure 11.26: vLAN Creation Based on IP Subnets

Figure 11.27: vLAN Creation Based on Protocol

Figure 11.28: Using a Router to Interconnect Switches

Figure 11.29: Flow-Based Routing Using Packet Tagging Assuming Flow from Station 1 on LAN A to Station 5 on LAN 3 Is Identified by Tag Number 6

Figure 11.30: Using a Layer 4 Switch

Chapter 12: LAN Monitoring Tools

Figure 12.1: The EtherPeek Capture Screen Display

Figure 12.2: Use the Capture Buffer Options Dialog Box to Adjust the Size of Packets Captured and the Amount of Memory Used for Packet Capturing

Figure 12.3: Use the EtherPeek Filters Screen to Control the Type Captured

Figure 12.4: Use the Filter Settings Dialog Box to Set Values for up to Four Types of Filters

Figure 12.5: Captured Packets Meeting Your Filtering Criteria Are Listed by Time of Occurrence

Figure 12.6: Use the Packet Flags Tab in the Display Options Dialog Box to Control the Display Indicator Used to Denote Five Predefined Conditions

Figure 12.7: Use the Packet List Columns Tab to Control the Display of Packet Information on the Packet Capture Screen

Figure 12.8: Use EtherPeek's Statistics Menu to Display Summary Statistics Based on the IP Address of Packets Transmitted, Packet Destinations, or Both

Figure 12.9: EtherPeek Summary Statistics Display Provides a Summary of Packets by Packet Length Interval

Figure 12.10: Use the EtherVision Available Options Menu to Monitor the Traffic Based on Source or Destination Address

Figure 12.11: Monitoring Screen Display Indicates the Distribution of Frames by Network Address

Figure 12.12: The EtherVision Statistics Display Provides a Summary of Various Network Statistics

Chapter 13: Transmission Optimization Techniques

Figure 13.1: Effect of Local versus Remote Bridge Filtering

Figure 13.2: Token Ring to IEEE 802.3 Frame Conversion

Figure 13.3: First-In, First-Out Queuing

Figure 13.4: First-In, First-Out Queuing Delays

Figure 13.5: Precedence Queuing Based on Frame Length

Figure 13.6: Using Bandwidth-on-Demand Inverse Multiplexers

Figure 13.7: Examining the Effect of Service Advertising Protocol Broadcasts on WAN Circuits