Table of Contents

Features
Front-Panel Description

Switched 10-Mbps Ports
Switched 100-Mbps Ports
LEDs and Modes

System Status LED
Redundant Power Supply LED
Port LEDs and Modes

Rear-Panel Description

Power Connectors
Console Port
Switched AUI Port

Management Options

Hardware and Software Requirements

Hardware Requirements for the Management Station
Software Requirements for Using the Management Console
Software Requirements for Using the Switch Manager

Cluster Management and Membership
Catalyst 1900 Switch Manager
Management Console
Command-Line Interface
Simple Network Management Protocol

Remote Monitoring

Network Configuration Examples

Client/Server Workgroup with a Single Switch
Distributed 100BaseT Backbone with Multiple Switches
100BaseT Collapsed Backbone with Multiple Switches
100BaseT Redundant Backbone with Multiple Switches
Extended Network with Multiple Switches

Overview

The following topics in this chapter describe the benefits and features of the Catalyst 1900 series Ethernet switches, also referred to as the Catalyst 1900 switches:

• Features

• Front and rear panels

• Management options

• Network configuration examples

Features

The Catalyst 1900 switches (shown in Figure 1-1) can improve network performance to the desktop, server, and backbone, especially in networks that use high-performance workstations and servers, use bandwidth-intensive applications, transfer large graphic, audio, and video files, and require access to the same network resources and the Internet.

These switches have up to 25 10BaseT switched Ethernet ports (including the AUI switch port on the back panel), each port providing users or groups of users dedicated 10-Mbps bandwidth to resources within the network. These ports connect to other 10BaseT-compatible devices, such as single workstations and 10BaseT hubs. The switches also have two 100BaseT switched ports for delivering maximum performance to high-speed servers and to backbone switches and routers.

Each Catalyst 1900 switch is designed for plug-and-play operation, requiring only that you assign basic IP information to the switch and connect it to the other devices in your network. If you have specific network needs, you can also configure the switch through its various management interfaces. The switch can be configured and monitored individually or as part of a switch cluster that is managed by a Catalyst 2900 series XL or Catalyst 3500 series XL command switch.

Figure 1-1: Catalyst 1900 Switches

In Figure 1-1, switches shipped with the standard software features (listed in Table 1-1) are indicated by "-A" in the part number. Switches shipped with the Cisco Catalyst 1900/2820 Enterprise Edition Software are indicated by "-EN." For information about the enterprise edition software features (such as support for up to 1005 virtual LANs (VLANs); VLAN, Inter-Switch Link (ISL), and Asynchronous Transfer Mode (ATM) LAN emulation (LANE) trunk connections; ATM permanent virtual connections (PVCs); Fast EtherChannel connections; and TACACS+ authentication), refer to the Catalyst 1900 Series and Catalyst 2820 Series Enterprise Edition Software Configuration Guide.

Front-Panel Description

The front panel of a Catalyst 1900 switch provides 12 or 24 10-Mbps and two 100-Mbps switched ports (Figure 1-2) to connect to other network devices and a set of LEDs and a Mode button for monitoring the switch and its ports (Figure 1-3).

Figure 1-2: Front-Panel Ports

Switched 10-Mbps Ports

The 10BaseT network ports on the switch (1x through 12x or 1x through 24x) use standard RJ-45 connectors. These ports can connect to 10BaseT-compatible devices, such as individual workstations and hubs, with Category 3, 4, or 5 cabling. Using this type of cabling, the distance between the switch and the attached device can be up to 100 meters. For connection information, see the "Connecting to the Switched 10BaseT Ports" section.

Switched 100-Mbps Ports

Depending on the model, the switch can have the following high-speed network ports:

• Two switched 100BaseTX ports

• One switched 100BaseTX port and one switched 100BaseFX port

• Two switched 100-Mbps fiber-optic ports

The model with the 100BaseTX ports (Ax and Bx) use standard RJ-45 connectors. These ports can connect to 100BaseTX-compatible servers, hubs, switches, and routers, with Category 5 cabling. Using this type of cabling, the distance between the switch and the attached device can be up to 100 meters. For connection information, see the "Connecting to the Switched 100BaseTX Ports" section.

The model with one 100BaseFX port (A) uses a duplex square connector (SC). This port can connect to other 100BaseFX-compatible devices with 50/125- or 62.5/125-micron multimode fiber-optic cabling. For connection information, see the "Connecting to the Switched 100BaseFX Port" section.

The fiber-optic connections between the switch and the attached device can be as follows:

• If the switch port and the port on the attached device are configured for half-duplex operation, the connection can be over distances of up to 412 meters.

• If the switch port and the port on the attached device are configured for full-duplex operation, the connection can be over distances of up to 2 kilometers.

The model with two fiber-optic ports (A and B) use MT-RJ connectors and have a fiber-optic wavelength of 1300 nanometers. To connect each fiber-optic port on the switch to an SC or ST port on a 100BaseFX-compatible device on your network, you must use the appropriate MT-RJ fiber-optic patch cable. You can order MT-RJ patch cables from your cable vendor, or you can order these cables from Cisco:

• CAB-MTRJ-SC-MM-1M (1-meter, MT-RJ-to-SC multimode cable)

• CAB-MTRJ-SC-MM-3M (3-meter, MT-RJ-to-SC multimode cable)

• CAB-MTRJ-SC-MM-5M (5-meter, MT-RJ-to-SC multimode cable)

• CAB-MTRJ-ST-MM-1M (1-meter, MT-RJ-to-ST multimode cable)

• CAB-MTRJ-ST-MM-3M (3-meter, MT-RJ-to-ST multimode cable)

• CAB-MTRJ-ST-MM-5M (5-meter, MT-RJ-to-ST multimode cable)

For connection information, see the "Connecting to the Switched 100-Mbps Fiber-Optic Ports" section.

LEDs and Modes

You can use the LEDs to monitor switch activity and performance by using the Mode button to select the modes in which the port LEDs operate (Figure 1-3).

Figure 1-3: LEDs and Mode Button

System Status LED

The colors of the system status (SYSTEM) LED show that the switch is receiving power and functioning properly (Table 1-2).

Table 1-2: SYSTEM LED Description

Color	System Status
Off	Switch is not powered up.
Solid green	Switch is operating normally.
Solid amber	Switch is receiving power, but might not be functioning properly. One or more power-on self-test (POST) errors occurred. The Management Console Logon Screen message identifies which nonfatal test(s) failed. Note If a fatal error occurs, the switch is not operational, and no message is displayed. (See the "Powering Up and Using POST to Test the Switch" section and the "Understanding POST Failures" section.)

Redundant Power Supply LED

The colors of the redundant power system (RPS) LED show the status (Table 1-3) of a connected Cisco RPS (model PWR600-AC-RPS). For more information about the RPS, see the "Power Connectors" section.

Table 1-3: RPS LED Description

Color	RPS Status
Off	RPS is off or is not installed.
Solid green	RPS is operational.
Blinking green	RPS and the switch AC power supply are both powered up. Note This is not a recommended configuration. For more information, see the "Power Connectors" section.
Solid amber	RPS is connected, but is not functioning properly. One of the power supplies in the RPS could be powered down, or a fan in the RPS could have failed.

Port LEDs and Modes

Each port has an LED above it. These LEDs, as a group or individually, display information about the switch and about individual ports (Table 1-4).

Table 1-4: Port LED Modes Summary

Mode	LED	Determines...
Port status (default)	STAT	Status of individual ports
Bandwidth utilization	UTL	Percentage of the switch total bandwidth being used at any one time
Full-duplex operation	FDUP	Which ports are operating in half- or full-duplex mode

Pressing the Mode button on the front panel changes the mode of the port LEDs. The STAT, UTL, and FDUP LEDs show which mode is active (Table 1-5). The selected mode remains on approximately for 30 seconds before returning to the default mode (port status). You can change the default mode from the Console Settings Menu.

Table 1-5: Changing Between Modes

For this Mode...	Push the Mode Button Until...
Port status	Only the STAT LED is on.
Bandwidth utilization	Only the UTL LED is on.
Full-duplex operation	Only the FDUP LED is on.

This is the factory default mode. The colors of the LEDs above the ports show the status of the corresponding ports (Table 1-6).

Table 1-6: Port Status Mode LED Description

Color	Port Status
Off	No link.
Solid green	Link operational (with no link activity).
Flashing green	Link operational (with activity).
Alternating green and amber	Link fault. Error frames can affect connectivity. Excessive collisions and cyclic redundancy check (CRC), alignment, and jabber errors are monitored for a link-fault indication.
Solid amber	Port is not forwarding. This could be because the port was disabled by management, suspended because of an address violation, or suspended by Spanning-Tree Protocol (STP) because of network loops.

Bandwidth Utilization Mode

In the UTL mode, the port LEDs as a group show the switch bandwidth being used at any one time (see Figure 1-4 and Figure 1-5). The more LEDs that are lit, the higher the bandwidth being used. The peak utilization is recorded in the bandwidth-capture interval, described in the "Bandwidth Usage Report" section.

Figure 1-4: Bandwidth Utilization Mode on a 12-Port Switch

Bandwidth Utilization Mode on a 24-Port Switch

The colors of the LEDs in FDUP mode show which 10BaseT and 100BaseT ports are operating in full-duplex mode (Table 1-7).

Table 1-7: FDUP LED Description

Color	Full-Duplex
Off	Half-duplex mode is operational.
Solid green	Full-duplex mode is operational.

Rear-Panel Description

The rear panel of a Catalyst 1900 switch has an AC power connector, a console port, a redundant power system (RPS) connector, and a switched AUI port (see Figure 1-6).

Figure 1-6: Rear-Panel Ports and Connectors

Power Connectors

Warning Attach only the Cisco RPS (model PWR600-AC-RPS) to the RPS connector.

You can provide power to the switch either by using the switch internal AC power supply or by connecting the optional Cisco 600W AC Redundant Power System (RPS) to the RPS connector on the switch.

The RPS can provide a quasi-redundant power source for four external devices that use up to 150W DC each. You can use a one-to-one cable (one connector at each cable end) to connect four external devices to the four DC output power modules. The power source is quasi-redundant because there are two AC input power modules for the RPS and one DC output power module for each external device. The AC input to the RPS is fully redundant, but the DC output to the external devices is not.

For information about the RPS LED, see the "Redundant Power Supply LED" section. For complete information about the RPS, refer to the Cisco RPS documentation.

Console Port

To configure and manage the switch through the menu-based management and diagnostic consoles and the command-line interface (CLI), you can connect the console port to a management station or modem with the supplied RJ-45-to-RJ-45 rollover console cable and an appropriate adapter. For additional information, see the "Connecting to the Console Port" section.

Switched AUI Port

You can connect the switched AUI port to an Ethernet transceiver, which is then connected to a 10-Mbps Ethernet device through the following cable types:

• 10Base5---Thick coaxial cable connects the switch to another device up to a distance of 500 meters. This cable type uses F connectors.

• 10Base2---Thin coaxial cable connects the switch to another device up to a distance of 185 meters. This cable type uses T-type BNC connectors.

• 10BaseFL---Single- or multimode fiber-optic cable connects the switch to another device up to a distance of 2 kilometers. This cable type uses S T or Bayonet connectors.

• 10BaseT---Unshielded twisted-pair cable connects the switch to another device over a distance of 100 meters. This cable type uses standard RJ-45 connectors.

For connection information, see the "Connecting to the Switched AUI Port" section.

Management Options

You can use the default settings shipped with the Catalyst 1900 switch, or you can customize the switch configuration through the management options described in this section. The Catalyst 1900 Switch Manager is the easiest interface to use for basic configuration and monitoring tasks. To perform all the configuration and monitoring tasks, use the management console, the SNMP, or the command-line interface (CLI).

Access to the management console or CLI requires a direct connection to the switch console port or a Telnet session. Access to the Catalyst 1900 Switch Manager, Cluster Management applications, or SNMP requires a connection to one of the switch network ports. For more information about accessing the management interfaces, see the "Accessing the Management Interfaces" section.

This section describes the hardware and software requirements and provides the following overviews:

• Configuring the switch as an individual switch or as a cluster member

• Catalyst 1900 Switch Manager, including the default settings

• Management console, including the default settings

• CLI

• SNMP

Hardware and Software Requirements

This section describes the requirements and recommended configurations for using the Catalyst 1900 Switch Manager and the management console.

Hardware Requirements for the Management Station

The minimum hardware requirement for a PC is a Pentium processor running at 166 MHz with 64 MB of DRAM. The minimum requirement for a UNIX workstation is a Sun Ultra 1 running at 143 MHz.

Table 1-8 lists the configurations that yield the best results for web-based management:

Software Requirements for Using the Management Console

To use the management console, you must have terminal emulation software (such as ProComm, HyperTerminal, tip, or minicom) installed on your management station.

Software Requirements for Using the Switch Manager

To use the Catalyst 1900 Switch Manager, you must have one of these web browsers installed on your management station:

For information about how to configure your browser for web-based management, see the "Accessing the Switch Manager" section.

Cluster Management and Membership

As with previous Catalyst 1900 releases, you can configure and monitor the switch as an individual device in your network. To do this, you must assign it an IP address and password and then use the options available from the Catalyst 1900 Switch Manager, management console, SNMP, or the CLI. (See "Configuring and Monitoring from the Switch Manager," and "Configuring and Monitoring from the Management Console.")

The switch can also be a member of a switch cluster. A cluster is a group of connected switches that are managed as a single entity. A cluster has a command switch and member switches. The Catalyst 1900 switches can only be member switches. Certain models of the Catalyst 2900 XL switches can be command switches, and all models of the Catalyst 3500 XL switches can be command switches.

The command switch is the central management point used to configure and monitor the switch cluster. All communication with member switches is through the command switch IP address. Clustering can simplify your network management tasks. For example, from a command switch, you can manage and monitor member switches regardless of their geographic location, and you can perform cluster-wide firmware upgrades.

Not all Catalyst 1900 configuration and monitoring options are available from the Cluster Management applications of the command switch; however, you can access the Catalyst 1900 management interfaces (switch manager, management console, and CLI) from the command switch at any time.

Each switch in a cluster can belong to only one cluster at a time. The switches in a cluster can be in the same location, or they can be distributed across a network. The Catalyst 1900 switches can be connected to a cluster in a star or daisy-chain topology through copper or fiber-optic cables.

To configure and monitor a Catalyst 1900 switch as a cluster member, the following requirements must be met:

When the Catalyst 1900 switch joins a cluster, the following configuration settings change:

• The highest privileged-level password (encrypted or unencrypted) of the command switch becomes the password to the Catalyst 1900 Switch Manager, management console, and CLI. If the command switch does not have a password, then no password is required when accessing the Catalyst 1900 switch from the command switch. (See the "Changing the Switch Password" section or the "Console Settings Menu" section.)

• The host name you assign to the Catalyst 1900 switch is kept even when the switch joins or leaves a cluster. If the Catalyst 1900 switch does not have a name when it joins a cluster, the command switch assigns it a name. (See the "Switch Host Name" section and the "System Configuration Menu" section.)

• The command switch propagates its first SNMP Read and Write community strings as the last Read and Write community strings for the member switch. If the joining Catalyst 1900 switch already has four Read and four Write community strings, the command switch overrides the fourth community strings with its own first community strings. When the switch leaves the cluster, the command-switch community strings are deleted.

Each string from the command switch contains up to 27 characters and a suffix "@esNN" where NN is the member switch number. (See the "Changing the SNMP Settings" section or the "Network Management (SNMP) Configuration Menu" section.)

Caution Do not use "@es" in the community strings you define for the switch. When the switch joins a cluster, any community string containing "@es" is deleted.

For complete information about cluster management and membership, refer to the Cisco IOS Desktop Switch Software Configuration Guide, Catalyst 2900 Series XL and Catalyst 3500 Series XL Cisco IOS Release 12.0(5)XP.

Catalyst 1900 Switch Manager

The Catalyst 1900 Switch Manager (hereafter referred to as the switch manager) is a web-based, graphical user interface for basic switch configuration and monitoring. Using the switch manager, you can configure and monitor the switch from anywhere on your intranet.

• Provides fields, check boxes, and lists for individual configuration settings.

• Displays current information about the switch.

• Provides online help for each page:

  • Detailed information about the fields, lists, check boxes, and buttons.

  • Specific procedures for performing management tasks.

For information about using the switch manager, see "Configuring and Monitoring from the Switch Manager."

Table 1-10 lists the configuration settings, including default values, available from the switch manager.

Table 1-10: Features, Default Settings, and Switch Manager Pages

Feature		Default Setting	Switch Manager Page
Management
	IP address, subnet mask, and default gateway of the switch	0.0.0.0	System Management Page
	Cisco Discovery Protocol (CDP)	Enabled	CDP Management Page
Performance Tuning
	Switching mode	FragmentFree (cut-through)	System Management Page
	Enhanced congestion control on 10BaseT ports	Disabled	System Management Page
	Enhanced congestion control on 100BaseT ports	Disabled	Port Management Page
	Duplex mode on 10BaseT ports	Half duplex	Port Management Page
	Half-duplex back pressure on 10BaseT ports	Disabled	System Management Page
	Duplex mode on switched 100BaseFX ports	Half duplex	Port Management Page
	Duplex mode on switched 100BaseTX port	Autonegotiate	Port Management Page
Flooding/Traffic Control
	Broadcast storm control	Disabled	System Management Page
	Store-and-forward on multicast	Disabled	System Management Page
	Network port	None	System Management Page
	Cisco Group Management Protocol (CGMP)	Enabled	CGMP Management Page
	Flooding unknown unicast packets	Enabled	Port Management Page
	Flooding unregistered multicast packets	Enabled	Port Management Page
Network Redundancy/Fault Tolerance
	Spanning-Tree Protocol (STP)	Enabled	Spanning-Tree Management Page
	Port Fast mode on 10BaseT ports	Enabled	Spanning-Tree Management Page
	Port Fast mode on 100BaseT ports	Disabled	Spanning-Tree Management Page
Diagnostics
	Port monitoring (SPAN)	Disabled	SPAN Configuration Page
	Remote monitoring (RMON)	Enabled	---
	Usage reports	---	Detailed Port Statistics Page Statistics Reports Page
Security
	Password	None	Home Page
	Action on address violation	Suspend	System Management Page
	Address security	Disabled	Address Table Management Page Port Security Table Page
	Trap managers	None	SNMP Management Page
	Write (read/write) managers	None	SNMP Management Page
	Community strings	Public/Private	SNMP Management Page
Upgrades
	Firmware	---	Console and Upgrade Configuration Page

For procedures on how to reset all switch settings to the factory defaults, see the "System Configuration Menu" section or the "Resetting the Switch to the Factory Defaults" section.

Management Console

The management console is a menu-driven interface for configuring and monitoring the switch. If your management station is directly connected to the switch console port, you can use the management console even when the network is down because your direct connection to the console bypasses the network and communicates directly with the switch.

For information about using the management console, see "Configuring and Monitoring from the Management Console."

Table 1-11 lists the configuration settings, including default values, available from the management console.

Table 1-11: Features, Default Settings, and Management Console Menus

Feature		Default Setting	Console Menu
Management
	IP address, subnet mask, and default gateway of the switch	0.0.0.0	IP Configuration Menu
	Cisco Discovery Protocol (CDP)	Enabled	CDP Configuration/Status Menu
Performance Tuning
	Switching mode	FragmentFree (cut-through)	System Configuration Menu
	Enhanced congestion control on 10BaseT ports	Disabled	System Configuration Menu
	Enhanced congestion control on 100BaseT ports	Disabled	Port Configuration Menu (100BaseT Ports)
	Duplex mode on 10BaseT ports	Half duplex	Port Configuration Menu (10BaseT Ports)
	Half-duplex back pressure on 10BaseT ports	Disabled	System Configuration Menu
	Duplex mode on 100BaseFX port	Half duplex	Port Configuration Menu (100BaseT Ports)
	Duplex mode on 100BaseTX ports	Autonegotiate	Port Configuration Menu (100BaseT Ports)
Flooding/Traffic Control
	Broadcast storm control	Disabled	System Configuration Menu
	Network port	None	System Configuration Menu
	Cisco Group Management Protocol (CGMP)	Enabled	Cisco Group Management Protocol (CGMP) Configuration Menu
	Overlapping bridge groups	Disabled	Bridge Group Configuration Menu
	Store-and-forward on multicast	Disabled	System Configuration Menu
	Flooding unknown unicast packets	Enabled	Port Addressing Menu
	Flooding unregistered multicast packets	Enabled	Port Addressing Menu
Network Redundancy/Fault Tolerance
	Spanning-Tree Protocol (STP)	Enabled	Spanning Tree Configuration Menu
	Port Fast mode on 10BaseT ports	Enabled	Port Configuration Menu (10BaseT Ports)
	Port Fast mode on 100BaseT ports	Disabled	Port Configuration Menu (100BaseT Ports)
Diagnostics
	Port monitoring (SPAN)	Disabled	Monitoring Configuration Menu
	Remote monitoring (RMON)	Enabled	---
	Usage reports	---	Port Status Report Port Addressing Report Exception Statistics Report Utilization Statistics Report Bandwidth Usage Report
Security
	Password	None	Console Settings Menu
	Action on address violation	Suspend	System Configuration Menu
	Address security	Disabled	Port Addressing Menu
	Trap managers	None	Network Management (SNMP) TRAP Configuration Menu
	Write (read/write) managers	None	Network Management (SNMP) WRITE Configuration Menu
	Community strings	Public/Private	Network Management (SNMP) READ Configuration Menu Network Management (SNMP) WRITE Configuration Menu
Upgrading
	Firmware	---	Firmware Configuration Menu

For procedures on how to reset all switch settings to the factory defaults, see the "System Configuration Menu" section or the "Resetting the Switch to the Factory Defaults" section.

Command-Line Interface

For switches shipped or upgraded with the Cisco Catalyst 1900/2820 Enterprise Edition Software, you can use the command-line interface (CLI) to access the configuration options and perform the same configuration and monitoring tasks available through the Catalyst 1900 Switch Manager and management console. You can also perform privileged configuration and monitoring tasks available only through the CLI and SNMP.

Simple Network Management Protocol

You can configure and monitor the switch by accessing the Management Information Base (MIB) variables through Simple Network Management Protocol (SNMP), an application-layer protocol designed to facilitate the exchange of management information between network devices. The switch supports a comprehensive set of MIB objects, including four Remote Monitoring (RMON) groups.

Figure 1-7 shows how the SNMP agent gathers data from the MIB file, which holds information about device parameters and network data. The agent can send traps, or notification of certain events, to the manager.

Figure 1-7: SNMP Network

The SNMP manager uses information in the MIB files to perform the operations described in Table 1-12.

Table 1-12: SNMP Manager Operations

Operation	Description
get-request	Retrieves a value from a specific variable.
get-next-request	Retrieves a value from a variable within a table.1
get-response	Reply to a get-request, get-next-request, and set-request sent by an NMS.
set-request	Store a value in a specific variable.
trap	Send an unsolicited message from an SNMP agent to an SNMP manager indicating that some event has occurred.

1An SNMP manager does not need the exact variable name. It sequentially searches to find the needed variable from within a table.

Remote Monitoring

The Remote Monitoring (RMON) MIB is used by network managers to monitor remote devices. An RMON implementation consists of a software probe that continually collects statistics about a LAN and a management station that communicates with the probe. The probe transfers information to the management station on request or when a predefined threshold is crossed. You can use the statistics to help tune or troubleshoot your switched LAN.

RMON is enabled by default on the switches and is not displayed on the Catalyst 1900 Switch Manager or management console. The switch supports four RMON groups (Table 1-13) as defined in RFC 1757. You can obtain information about the four supported groups by using any SNMP management application.

Table 1-13: RMON Groups and Their Functions

Group Name	Description
Statistics	This group collects utilization and error statistics for the monitored switch. Statistics include information about collisions, cyclic redundancy checks (CRCs) and alignment; undersized or oversized packets, jabber, fragments, broadcast, multicast, and unicast messages; and bandwidth utilization. For example, you could use this group to determine how many error packets have been seen on a given port. Statistics from this group can be used by the history group to record historical views of network performance. A statistics row is established by default for each switch port.
History	This group takes periodic samples from the statistics section and stores them for later retrieval. This sampling includes information such as utilization, error counts, and packet counts. This information can be used to establish baseline information regarding network activity. You can define the intervals you want to record information for, and you can define how many of the samples are to be stored. Note RMON statistics gathering has a maximum limit of 540 history tables that can be allocated among all switch ports.
Alarm	This group generates alarms according to user-defined thresholds. You could, for example, configure RMON to generate an alarm when alignment errors on a port exceeded a predefined limit. Rising and falling thresholds can be defined, and the events group can generate traps and automated responses based on the alarms.
Event	This group sends traps (events) to the management station based on information (alarms) received from the alarm group. The time and date are recorded with each logged event. You can use the events group to create customized reports that are based on alarm types.

Network Configuration Examples

As your network users compete for network bandwidth, it takes longer to send and receive data. Network performance can degrade for reasons such as:

Client/Server Workgroup with a Single Switch

Figure 1-8 illustrates a standard configuration in which bandwidth is shared by all attached devices. The nodes (workstations, hubs, and servers) in the workgroup are divided into smaller groups to increase the bandwidth available to each of them and to improve server response time. Grouping servers in a centralized location can provide benefits such as security and easier maintenance.

Network resources (such as web and mail servers) are connected to the 100BaseT ports on the Catalyst 1900 switch, allowing 100-Mbps throughput to users when needed. When the switch and server ports are configured for full-duplex operation, the links provide 200 Mbps of bandwidth.

Bandwidth-intensive workstations, such as computer-aided design (CAD) users or other power users, are connected to the switch 10BaseT ports for their own 10-Mbps bandwidth access to servers. Single workstations, configured for full-duplex operation, receive 20 Mbps of dedicated bandwidth from each switched port.

Other workstations are connected to 10BaseT hubs, which provide 10-Mbps shared bandwidth to users with multiple workstations or to workgroups that require minimal network bandwidth. These workstations share the available 10-Mbps of bandwidth available from the switched link. Because hubs run only in half-duplex, each connected port provides 10 Mbps of bandwidth.

Connecting a router to a 100BaseT switch port provides multiple, simultaneous links to the Internet through one line.

Figure 1-8: High-Performance Client/Server Workgroup with a Switch

Distributed 100BaseT Backbone with Multiple Switches

Figure 1-9 illustrates a network configuration that uses the 100BaseT ports on multiple Catalyst 1900 switches to interconnect workgroups and network resources. All workgroups have full access to the network resources (such as a Dynamic Host Configuration Protocol (DHCP)/Bootstrap Protocol (BOOTP) server or an IPTV multicast server).

You optimize your network performance by placing workstations on the same logical segment as the servers they access most often. This configuration reduces the amount of traffic that travels over a network backbone, which is a high-bandwidth (such as Fast Ethernet) connection between the segments. A backbone is required if numerous users access the servers.

When the 100BaseT ports are configured for full-duplex operation, they provide a total of 200 Mbps of bandwidth on each switch port. Switched 10BaseT ports configured for full-duplex operation provide 20 Mbps of bandwidth to workstations.

For increased performance to the workstations, replace the hubs shown in Figure 1-9 with Catalyst 1900 switches. In place of the Catalyst 1900 switches, you can add Catalyst 2900 XL or Catalyst 3500 XL switches and form a switch cluster of Catalyst 1900, Catalyst 2900 XL, and Catalyst 3500 XL switches. A Catalyst 3500 XL switch can be the command switch, the central point of network management. As your network grows, you can add more switch clusters.

Figure 1-9: Distributed 100BaseT Backbone with Multiple Switches

100BaseT Collapsed Backbone with Multiple Switches

Figure 1-10 illustrates a Fast Ethernet collapsed-backbone configuration in which all segments and subnetworks are connected to a single device, such as a hub, switch, or router, to form the enterprise internetwork. A collapsed backbone network is easy to manage and troubleshoot, as it provides a single point for monitoring and controlling the network.

Two different workgroups, perhaps located in different buildings, are connected by Catalyst 1900 switches connected to a 100BaseT backbone switch or router (such as a Catalyst 5000 switch or Cisco 7000 router). In full-duplex mode, 200 Mbps of bandwidth is available to both Catalyst 1900 switches.

The distance between each Catalyst 1900 switch and the backbone switch or router can be increased to 2 kilometers by using fiber-optic ports in full-duplex mode. The Catalyst 1900 models---WS-C1924C, WS-C1912C, and WS-C1924F---provide one duplex SC port or two fiber-optic MT-RJ ports. Connections through the 100BaseTX switch ports with Category 5 cabling can be up to a distance of 100 meters.

Figure 1-10: 100BaseT Collapsed Backbone with Multiple Switches

100BaseT Redundant Backbone with Multiple Switches

Figure 1-11 illustrates how network redundancy provides two advantages:

• A backup path, in the event of a failure in the network

• Load-balancing, when two or more paths to a destination exist and both can be used, depending on the network load

A 100-Mbps (200 Mbps in full-duplex) redundant backbone is created by connecting Catalyst 1900 switches to 100BaseT backbone switches or routers, such as Catalyst 5000 switches or Cisco 7000 routers. Each Catalyst 1900 switch connects to the two backbone devices, shown in the top-left and top-right corners, in a redundant configuration. If connectivity is lost to one of the backbone routers or switches, the network uses the redundant connection.

Spanning-Tree Protocol, available only on switches, ensures that only one of the two connections from each switch is active (the primary link), ensuring that there are no loops in the network paths. If the primary link fails, the secondary link becomes active.

Figure 1-11: 100BaseT Redundant Backbone with Multiple Switches

Extended Network with Multiple Switches

A system of routers, switches, and hubs can be combined to create a high-performance network that extends beyond the main office LAN to connect to branch offices, remote sites, mobile users, and the Internet. Figure 1-12 is an example of an extended network.

Figure 1-12: Extended Network with Multiple Switches

Posted: Thu Oct 28 19:57:36 PDT 1999
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