Configuring Network Management

This chapter describes how you can manage the network management software for the Catalyst 5000 series switches. New network management software enables computer systems and other network devices to recognize problems on the network and send alerts to management entities who can execute operator notification, event logging, system shutdown, or automatic attempts at system repair.

Management entities can also poll end stations to check the values of certain variables and accept responses from agents that compile information about the managed devices. The agents provide information about the managed devices using Simple Network Management Protocol (SNMP).

The console port of the Catalyst 5000 series switch is an EIA/TIA-232 interface to which you can connect a console terminal or modem. You can directly access the command-line interface (CLI) or configure a Serial Line Internet Protocol (SLIP) interface to access network management functions, such as Telnet, ping, and SNMP.

CiscoWorks for Switched Internetworks

CiscoWorks for Switched Internetworks (CWSI) is a set of management applications (CiscoView, VLANDirector, and TrafficDirector) that allow you to detect, analyze, and manage traffic activity and to segment and build broadcast firewalls between logically dispersed users throughout a LAN. These tools improve network performance, allow you to monitor and detect networks problems, and enable you to configure and maintain workgroup communication across the network. A description of these tools is as follows:

CiscoView, a graphical device management application
VlanDirector, a drag-and-drop virtual LAN (VLAN) management application

: For more information on VlanDirector, refer to the VlanDirector User Guide.

TrafficDirector, an embedded remote monitoring (RMON)-based management application

Simple Network Management Protocol

This section details the procedure for configuring SNMP and describes how SNMP works.

Procedure

To configure the switch to be managed using an SNMP network management workstation, perform these steps:

Task	Command
Step 1 Configure the SNMP community strings.	set snmp community {read-only \| read-write \| read-write-all} community_string
Step 2 Assign a trap receiver address and community. If you enter incorrect information, enter the clear snmp trap command to delete the entry. Then reenter the set snmp trap command.	set snmp trap rcvr_address rcvr_community
Step 3 If desired, configure the switch so that it issues an authentication trap.	set snmp trap enable

After entering the set snmp community command, you see this display:

Console> (enable) set snmp community read-only public
SNMP read-only community string set.
Console> (enable) set snmp community read-write private
SNMP read-write community string set.
Console> (enable) set snmp community read-write-all secret
SNMP read-write-all community string set.
To enable RMON on the Catalyst please use the following command:
Console> (enable) set snmp rmon enable
SNMP RMON support enabled.
Console> (enable) set snmp 
Set snmp commands:
----------------------------------------------------------------------
set snmp community       Set SNMP community string
set snmp help            Show this message
set snmp rmon            Set SNMP RMON
set snmp trap            Set SNMP trap information
Console> (enable) set snmp trap
Usage:
set snmp trap <enable|disable> [all|module|chassis|bridge|repeater|auth|vtp]
set snmp trap <rcvr_address> <rcvr_community>
    (rcvr_address is ipalias or IP address, rcvr_community is string)
Console> (enable) set snmp trap enable all
All SNMP traps enabled.
Console> (enable)

To disable SNMP access, enter one of the following commands without specifying the community string:

set snmp community read-only
set snmp community read-write
set snmp community read-write-all

Verification

To verify SNMP settings, enter the show snmp command. After entering the command, you see this display:

Console> show snmp
RMON: Enabled
Traps Enabled: Chassis
Port Traps Enabled: None
Community-Access     Community-String    
----------------     --------------------
read-only            public
Trap-Rec-Address     Trap-Rec-Community
----------------     --------------------
192.122.173.42       public
Console>

How SNMP Works

SNMP is an application layer protocol designed to facilitate the exchange of management information between network devices. Using SNMP to access management information data, such as network error rates, you can easily manage network performance and resolve network problems. For more information, refer toWorkgroup MIB Reference.

Embedded Remote Monitoring

Embedded RMON is a standard monitoring specification that allows various network monitors and console systems to exchange network monitoring data. A Catalyst 5000 series switch provides support for the RMON of Ethernet and Fast Ethernet ports. Embedded RMON provides you with visibility into network activity. It enables you to access and remotely monitor the RMON specification RFC-1757 groupings of statistics, historical information, alarms, and events for any port, through SNMP or the TrafficDirector Management application.

Procedure

To configure the Catalyst 5000 series switch for RMON, perform this task:

Task	Command
Activate SNMP remote monitoring support.	set snmp rmon enable

After entering the set snmp rmon command, you see this display:

Console> (enable) set snmp rmon enable
SNMP RMON support enabled.

Verification

To verify the SNMP settings, enter the show snmp command. After entering the show snmp command, you see a display similar to the following:

Console> show snmp
RMON:enabled
Traps Enabled: Chassis
Port Traps Enabled: None
Comminity-Access 	Community String
----------------	----------------
read only	public
Trap-Rec-Address	Trap-Rec-Community
----------------	------------------
192.122.173.42	public
Console>

How RMON Works

RMON monitors network traffic at the link layer of the OSI model without requiring a dedicated monitoring probe or network analyzer. It allows a network manager to analyze network traffic patterns, set up proactive alarms to detect problems before they affect users, identify heavy network users as candidates to move to dedicated or higher speed ports, and perform trend analysis for long-term planning.

The RMON specification for Ethernet (RFC-1271) provides comprehensive network fault diagnosis, planning, and performance-tuning information to network administrators. RMON delivers this information in nine groups of monitoring elements, each providing specific sets of data to meet common network monitoring requirements.

The Catalyst 5000 series switch supports the following nine RMON groups; extended RMON capabilities are provided through a Cisco SwitchProbe connected to the switch Switched Port Analyzer (SPAN) port:

Segment statistics
Short- and long-term history
Host table
Host topN
Traffic matrix
Alarms
Filters
Packet capture
Events

The statistics group of the RMON specification maintains 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.

The history group takes periodic samples from the statistics section and stores them for later retrieval. This includes information such as utilization, error counts, and packet counts.

A system network administrator uses the alarm group to set a sampling interval and threshold for any RMON recorded item. Examples of alarm settings include absolute or relative values, rising or falling thresholds of utilization, packet counts, and CRC errors.

The events group allows events (generated traps) to be logged, printed, and provided to a network manager. The time and date are recorded with each logged event. Network managers use the events group to create customized reports that are based on alarm types.

With RMON enabled, the Catalyst 5000 series switch can collect and forward comprehensive network traffic information from multiple Ethernet segments simultaneously. This capability allows you to obtain information to help tune or troubleshoot a switched LAN. Because the Catalyst 5000 series switch can record traffic simultaneously from the server and client segments, you can troubleshoot client/server applications more easily.

Telnet Client Access

The Catalyst 5000 series switch allows you to use Telnet to transition from the CLI of the switch to other devices on the network. With Telnet, you can maintain a connection to a Catalyst 5000 series switch while connecting to another switch or router.

Cisco Discovery Protocol

Cisco Discovery Protocol (CDP) is a media- and protocol-independent protocol that runs on all Cisco-manufactured equipment including routers, bridges, access and communication servers, and switches. With CDP, network management applications can retrieve the device type and SNMP-agent address of neighboring devices. This enables applications to send SNMP queries to neighboring devices.

CDP meets a need created by the existence of lower-level, virtually transparent protocols. CDP allows network management applications to discover Cisco devices that are neighbors of already known devices, in particular, neighbors running lower-layer, transparent protocols. CDP runs on all media that support Subnetwork Access Protocol (SNAP), including LAN and Frame Relay. CDP runs over the data link layer only, not the network layer.

Cached CDP information is available to network management applications. Cisco devices never forward a CDP packet. When new information is received, old information is discarded.

Switched Port Analyzer

The Catalyst 5000 series switch SPAN enables you to monitor traffic on any port for analysis by a sniffer or RMON probe. Enhanced SPAN (E-SPAN) enables you to monitor traffic from a VLAN (multiple ports) to a port for analysis. The SPAN redirects traffic from an Ethernet, Fast Ethernet, or Fiber Distributed Data Interface (FDDI) port or VLAN to an Ethernet or Fast Ethernet monitor port for analysis and troubleshooting. You can monitor a single port or VLAN using a dedicated analyzer such as a Network General Sniffer, or an RMON probe, such as a Cisco SwitchProbe. Figure 13-1 is an example of the SPAN feature on the Catalyst 5000 series switch.

Figure 13-1: SPAN Configuration on the Catalyst 5000 Series Switch

In this configuration, all traffic seen on Ethernet port 5 is mirrored onto the configured SPAN port Ethernet 10. The network analyzer located on Ethernet 10 can gain visibility to network traffic on Ethernet 5 without being physically attached to it.

Serial Line Internet Protocol

You can access the Catalyst 5000 series switch administrative interface using SLIP. This protocol runs over serial links, allowing IP communications over the administrative interface.

System Message Logs

The Catalyst 5000 series switch system message log feature has the following enhancements:

Provides more logging information
Allows you to select the types of logging information captured
Allows you to select the destination of captured logging information

By default, the Catalyst 5000 series switch logs normal but significant system messages to its internal buffer and sends these messages to the system console. System message logs allow you to select the facility and severity level of messages that are captured and to redirect the log messages to specific destinations. Messages are time-stamped to enhance real-time debugging and management.

Table 13-1 lists and defines the facility types supported by the system message logs.

Table 13-1: Facility Definitions

Facility Name	Definition
cdp	Cisco Delivery Protocol
cgmp	Cisco Group Management Protocol
disl	Dynamic Inter-Switch Link
dvlan	Dynamic Virtual Local Area Network
earl	Encoded Address Recognition Logic
fddi	Fiber Distributed Data Interface
ip	Internet Protocol
snmp	Simple Network Management Protocol
spantree	Spanning-Tree Protocol
sys	System
tac	Terminal Access Controller
tcp	Transmission Control Protocol
telnet	Terminal Emulation Protocol
tftp	Trusted File Transfer Protocol
vmps	VLAN Membership Policy Server
vtp	Virtual Terminal Protocol

Table 13-2 lists and describes the severity levels supported by the system message logs.

Table 13-2: Level Definitions

Severity Level	Keyword	Description
0	emergencies	System unusable
1	alerts	Immediate action required
2	critical	Critical condition
3	errors	Error conditions
4	warnings	Warning conditions
5	notifications	Normal but significant condition
6	informational	Informational messages
7	debugging	Debugging messages

Procedures

The Catalyst 5000 series switch system message logs feature has several configurable options. The following sections provide instructions for configuring these options.

Default System Message Log Configuration

The Catalyst 5000 series switch is shipped with a default system message logs configuration. The default configuration is as follows:

Configuration Parameter	Default Setting
System message logging to the console	Enabled
Syslog servers	None configured
System message logging to Telnet sessions	Enabled
Facility/severity level for system messages	disl/5 sys/5 all other facilities/2

When first logging on to the Catalyst 5000 series switch console, you can enter the show logging command to display the default configuration. After entering the show logging command, you see this display:

Console <enable> show logging 
Logging console:            enabled
Logging server:             disabled
Facility	Server/Default Severity	Current Session Severity
--------	---------------------	------------------------
cdp	2	2
cgmp	2	2
disl	5	5
earl	2	2
fddi	2	2
ip	2	2
pruning	2	2
snmp	2	2
spantree	2	2
sys	5	5
tac	2	2
0(emergencies)	1(alerts)	2(critical)
3(errors)	4(warnings)	5(notifications)
6(information)	7(debugging)

Configuring the Console

You can change the default facility and severity levels by entering the set logging level command. To change the default facility and severity level for logging system messages to the console, perform these tasks:

Task	Command
Set the default facility and severity level for system messages.	set logging level facility severity
Disable system message logging to the console.	set logging console disable

Configuring the Syslog Daemon on a UNIX Syslog Server

Before system log messages can be sent to a UNIX syslog server, you must configure the syslog daemon on the UNIX server. To configure the syslog daemon on a 4.3 BSD UNIX system, log in as root, and perform these steps:

Step 1 Add a line such as the following to the file /etc/syslog.conf:

user.debug /var/log/myfile.log

Note In this example, there must be five tab characters between user.debug and /var/log/myfile.log. Refer to entries in the /etc/syslog.conf file for further examples.

The Catalyst 5000 series switch sends messages according to specified facility types and severity levels. The user keyword specifies the UNIX logging facility to be used. The messages from the Catalyst 5000 series switch are generated by user processes. The debug keyword specifies the severity level of the condition being logged. UNIX systems can be set to receive all messages from the Catalyst 5000 series switch.

Step 2 Create the log file by entering these commands at the UNIX shell prompt:

$ touch /var/log/myfile.log$ chmod 666 /var/log/myfile.log

Step 3 Make the syslog daemon read the new changes by entering this command:

$ kill -HUP `cat /etc/syslog.pid

Configuring Syslog Servers

Before system log messages can be sent to a UNIX syslog server, you must configure the syslog daemon on the UNIX server. To configure the syslog servers, perform these steps:

Task Command
Step 1 Add a syslog server to the configuration.¹ set logging server ip_addr
Step 2 Enable system message logging to configured syslog servers. set logging server enable
Step 3 Set the facility and severity level for syslog server messages. set logging level facility severity default

1. A maximum of three syslog servers can be configured at any time.

To delete a syslog server from the configuration, enter the clear logging server command as follows:

Console <enable> clear logging server ip_addr

To disable system message logging to configured syslog server, enter the set logging server command as follows:

Console <enable> set logging server disable

Configuring Telnet Login Sessions

By default, Telnet login sessions to the Catalyst 5000 series switch are enabled and receive system messages based on the default facility and severity values. To configure Telnet login sessions, enter these commands:

Task Command
Change the facility and severity values for Telnet login sessions. set logging level facility severity
Disable system message logging to the current Telnet login session. set logging session disable
or

set logging console disable

Reenable system message logging to the current Telnet login session. set logging session enable
or

set logging console enable

Displaying System Messages

To display the current configuration for system messages, perform this task:

Task Command
Display the current system message log configuration. show logging
To display the first N system messages in the internal buffer of the Catalyst 5000 series switch, perform this task:

Task Command
Display the first N messages in the buffer. show logging buffer N
To display the last N system messages in the internal buffer of the Catalyst 5000 series switch, perform this task:

Task Command
Display the last N messages in the buffer. show logging buffer -N

Verification

To verify the system message log configuration, enter the show logging command. If you are verifying the system message log configuration for the console and the syslog server is disabled, the first two lines of output look as follows:

Console <enable> show logging Logging console:            enabled Logging server:            disabled

If you are verifying the system message log configuration for a Telnet login session, an additional line showing the current logging session is displayed, as follows:

Console <enable> show loggingLogging console:            enabled Logging server:             disabled Current Logging Session:    enabled

Examples

This section provides examples for entering the system message log commands to perform the following tasks:

To enable system message logging to configured syslog servers, enter this command:

Console <enable> set logging server enableSystem logging messages will be sent to the configured syslog servers.

To add a new syslog server at IP address 171.69.192.205 to the system logging server table, enter this command:

Console <enable> set logging server 171.69.192.205171.69.192.205 added to the System logging server table.

To enable system logging messages to the current login session, enter this command:

Console <enable> set logging session enableSystem logging messages will be sent to the current login session.

To change the default facility to all and severity to 1, enter this command:

Console <enable> set logging level all 1 defaultSystem logging facility <all> set to severity 1(alerts).

To display the new system message log configuration, enter this command and note the new values in the Server/Default Severity and Current Session Severity columns:

Console <enable> show logging Logging console:            enabled Logging server:             disabled Facility Server/Default Severity Current Session Severity -------- --------------------- ------------------------ cdp 1 1 cgmp 1 1 disl 1 1 earl 1 1 fddi 1 1 ip 1 1 pruning 1 1 snmp 1 1 spantree 1 1 sys 1 1 tac 1 1 0(emergencies) 1(alerts) 2(critical) 3(errors) 4(warnings) 5(notifications) 6(information) 7(debugging)

To set the facility to snmp and the severity level to 3 for the current session, enter this command:

Console <enable> set logging level snmp 3System logging facility <snmp> set to severity 3(errors).

To display the new system message log configuration, enter the following command, and note the new value for snmp under the Current Session Severity column:

Console <enable> show logging Logging console:            enabled Logging server:             disabled Current Logging Session:    enabled Facility Server/Default Severity Current Session Severity -------- --------------------- ------------------------ cdp 2 2 cgmp 2 2 disl 5 5 earl 2 2 fddi 2 2 ip 2 2 pruning 2 2 snmp 2 3 spantree 2 2 sys 5 5 tac 2 2 0(emergencies) 1(alerts) 2(critical) 3(errors) 4(warnings) 5(notifications) 6(information) 7(debugging)

To display the first four messages in the internal buffer, enter this command:

Console <enable> show logging buffer 411/4/1996,13:52:46:SYS-5:Module 1 is online 11/4/1996,13:52:52:SYS-5:Module 5 is online 11/4/1996,13:52:54:SYS-5:Module 3 failed due to CBL0, CBL1, or CBL2 Error 11/4/1996,13:52:54:SYS-5:Module 3 failed configuration

To display the last four messages in the internal buffer, enter this command:

Console <enable> show logging buffer -411/4/1996,13:52:54:SYS-5:Module 3 failed configuration 11/4/1996,13:53:04:SYS-5:Module 4 is online 11/4/1996,13:53:31:SNMP-6:Subagent 2 connected 11/4/1996,13:54:45:SNMP-5:Cold Start Trap

How System Message Logging Works

Catalyst 5000 series switch software generates many different kinds of system messages. These messages can be saved in a log file or directed to other devices. You can specify which system messages should be saved based on two criteria: the type of facility being reported on, as shown in Table 13-1, and the severity level of the message, as shown in Table 13-2. These messages are saved in a 1-KB internal buffer in the Catalyst 5000 series switch. They can also be saved on UNIX servers that have been configured with an internal buffer. The syslog software then reads the messages from the buffer and sends them to the specified destination.

The system message log feature allows you to access system messages by logging in to the console using the Telnet protocol. In this way, you can monitor system messages remotely from any workstation that supports the Telnet protocol.

Default Configuration

Each Catalyst 5000 series switch ships with a default system message logging configuration. To view the default configuration, enter the show logging command. For an example of a display showing the default configuration, see the "Default System Message Log Configuration" section.

When initializing, the Catalyst 5000 series switch displays a severity level 5 (notifications) startup message showing the status of each module and port:

Login sessions:

9/24/1996,11:03:11:SYS-5:Module 1 is online. 8/22/1996,11:03:26:SYS-5:Port 1/1 has become trunk

After switch initialization, a severity level 6 (information) message shows SNMP socket status information:

Login sessions:

9/24/1996,13:59:26:SNMP-6:UDP socket [0] opened

UNIX syslog servers:

Sep 24 13:59:31 cat11-lnf.cisco.com :SNMP-6:UDP socket [0] opened

Note When the Catalyst 5000 series switch is first initialized, the network is not connected until the initialization completes. Therefore, the messages redirected to UNIX syslog servers are delayed up to 90 seconds.

Format of System Messages

System log messages begin with a percent sign (%) and contain up to 80 characters. The messages are displayed in the following format:

%TIMESTAMP: FACILITY-SEVERITY: Message-text;

The format elements are defined as follows:

Element Description
TIMESTAMP The current date and time in the following format: mm/dd/yy,hh:mm:ss
FACILITY Two or more uppercase letters that indicate the facility to which the message refers (for example, SNMP, SYS, etc.)
SEVERITY A single-digit code from 0 to 7 that indicates the severity of the message
Message-text A text string containing detailed information about the event being reported
These examples show typical Catalyst 5000 series switch system messages:

11/4/1996,13:52:46:SYS-5:Module 1 is online 11/4/1996,13:52:52:SYS-5:Module 5 is online 11/4/1996,13:52:54:SYS-5:Module 3 failed due to CBL0, CBL1, or CBL2 Error 11/4/1996,13:52:54:SYS-5:Module 3 failed configuration

Network Time Protocol

The Network Time Protocol (NTP) synchronizes timekeeping among a set of distributed time servers and clients. This synchronization allows events to be correlated when system logs are created and other time-specific events occur. NTP runs over User Datagram Protocol (UDP), which in turn runs over IP. NTP is documented in RFC 1305. All NTP communication uses Coordinated Universal Time (UTC), which is the same time as Greenwich Mean Time.

Prerequisite

An NTP server must be accessible by the Catalyst 5000 series client switch.

Procedures

Use the following procedures to configure NTP. For more information about NTP commands, refer to the Catalyst 5000 Series Command Reference publication.

Configuring NTP in Broadcast Client Mode

The broadcast client mode assumes that a broadcast server, such as a router, is regularly sending time-of-day information to the Catalyst 5000 series switch. To enable NTP in broadcast client mode, enter this command:

Task Command
Enable the NTP broadcast client mode. set ntp broadcastclient enable

After entering the set ntp broadcastclient enable command, you see this display:

Console> (enable) set ntp broadcastclient enable NTP Broadcast Client mode enabled.

To disallow the Catalyst 5000 series switch as a broadcast client, enter the
set ntp broadcastclient disable command.

Configuring NTP in Client Mode

The client mode assumes that the client, or Catalyst 5000 series switch, is regularly initiating time-of day requests to the NTP server. A maximum of 10 servers per client is allowed. To configure NTP in client mode, you must first configure the IP address of the NTP server. Perform these steps to enable NTP in client mode:

Task Command
Step 1 Configure the address of the NTP server to be queried. set ntp server ip-address
Step 2 Enable the NTP broadcast client mode. set ntp client enable

After entering the set ntp server command, you see this display:

Console> (enable) set ntp server 172.20.22.191 NTP server 172.20.22.191 added.

After entering the set ntp client enable command, you see this display:

Console> (enable) set ntp client enable NTP client mode enabled.

To remove an NTP server, enter the clear ntp server [ip-address | all] command. After entering this command, you see these displays:

Console> (enable) clear ntp server 172.20.22.193 NTP server 172.20.22.193 removed.

or

Console> (enable) clear ntp server all NTP server 172.20.22.192 removed. NTP server 172.20.22.193 removed.

To disallow the Catalyst 5000 series switch as a client, enter the set ntp client disable command. After entering this command, you see this display:

Console> (enable) set ntp client disable NTP client mode disabled.

Setting the Broadcast Delay

In broadcast client mode, the broadcast server regularly sends time-of-day information to the Catalyst 5000 series switch, which is unaware of the server-to-client packet latency. The NTP broadcast delay command configures a time adjustment factor for the receiving of broadcast packets by the switch. To set the estimated NTP broadcast packet delay, enter this command:

Task command
Set the NTP broadcast packet delay. set ntp broadcast delay microseconds
After entering the set ntp broadcast delay to 4000, you see this display:

Console> (enable) set ntp broadcast delay 4000 NTP broadcast delay set to 4000 microseconds.

Setting the Time Zone

You might want to set the time zone for display purposes. To set the time zone, enter this command:

Task Command
Set the time zone. set timezone zone hours [minutes]

The set timezone command is effective only when NTP is running. If you explicitly set the time and NTP is disengaged, this command has no effect. After entering the set timezone command when NTP is running, you see this display:

Console> (enable) set timezone PST -8 Timezone set to "PST", offset from UTC is -8 hours.

Note If you have enabled NTP and have not entered the set timezone command, the Catalyst 5000 series switch displays UTC by default.

To clear the time zone, enter the clear timezone command. To set the time zone for UTC, enter the clear timezone command.

To enable or disable setting the clock ahead one hour during daylight saving time, enter the set summertime [enable | disable] zone command. This command advances the clock one hour on the first Sunday in April at 2:00 a.m. and moves back the clock one hour on the last Sunday in October at 2:00 a.m. Summertime is configured to off by default. After entering the set summertime enable PDT command, you see this display:

Console> (enable) set summertime enable PDT Summertime is enabled and set to "PDT".

Verification

Enter the following commands to verify NTP:

To display the current NTP status, enter the show ntp command. After entering this command, you see this display:

Console> show ntp Broadcast client mode: disabled Broadcast delay: 4000 microseconds Client mode: enabled Server 172.20.22.191 172.20.22.192 172.20.22.193 Timezone: "PST", offset from UTC is -8 hours Summertime: "PDT", enabled

To check the current time zone offset, enter the show timezone command. After entering this command, you see this display:

Console> show timezone Timezone set to "PsT", offset from UTC is 8 hours.

To check the state of the summertime feature, enter the show summertime command. After entering this command, you see this display:

Console> show summertime Summertime is enabled and set to "PDT".

How Network Time Protocol Works

An NTP network usually gets its time from an authoritative time source, such as a radio clock or an atomic clock attached to a time server. NTP then distributes this time across the network. NTP is extremely efficient; no more than one packet per minute is necessary to synchronize two machines to within a millisecond of one another.

NTP uses a stratum to describe how many NTP hops away a machine is from an authoritative time source. A stratum 1 time server has a radio or atomic clock directly attached, a stratum 2 time server receives its time via NTP from a Stratum 1 time server, and so on. A machine running NTP automatically chooses as its time source the machine with the lowest stratum number that it is configured to communicate with via NTP. This strategy effectively builds a self-organizing tree of NTP speakers.

NTP has two ways to avoid synchronizing to a machine whose time might be ambiguous. First, NTP never synchronizes to a machine that is not synchronized itself. Secondly, NTP compares the time reported by several machines and does not synchronize to a machine whose time is significantly different from the others, even if its stratum is lower.

The communications between machines running NTP, known as associations, are usually statically configured; each machine is given the IP address of all machines with which it should form associations. Accurate timekeeping is possible by exchanging NTP messages between each pair of machines with an association. However, in a LAN environment, NTP can be configured to use IP broadcast messages instead. This alternative reduces configuration complexity because each machine can simply be configured to send or receive broadcast messages. However, the accuracy of timekeeping is marginally reduced because the information flow is one-way only.

Cisco's implementation of NTP does not support stratum 1 service; in other words, it is not possible to connect to a radio or atomic clock. Cisco recommends that the time service for your network be derived from the public NTP servers available in the IP Internet. If the network is isolated from the Internet, Cisco's NTP implementation allows a machine to be configured so that it acts as though it is synchronized via NTP, when in fact it has determined the time using other means. Other machines then synchronize to that machine via NTP.

A number of manufacturers include NTP software for their host systems, and a publicly available version for systems running UNIX and its various derivatives is also available. This software allows host systems to be time-synchronized as well.

Domain Name System

The Domain Name System (DNS) is a distributed database that allows you to map host names to IP addresses through the DNS protocol from a DNS server. When you configure DNS on the
Catalyst 5000 series switch, you can substitute the host name for the IP address with all IP commands, such as ping, upload, download, and outgoing telnet. DNS is disabled by default.

Prerequisite

To use DNS, you must have a DNS server configured on your network.

Procedures

You can configure up to three DNS name servers for backup and are provided with an option to configure any DNS server as primary. The primary server is the first one to query. If the primary server fails, the backup servers are queried.

If DNS is disabled, you must use the IP address with all commands that require explicit IP addresses. This feature is disabled by default.

To configure DNS, use this procedure:

Task Command
Step 1 Set the address of the DNS server. set ip dns server ip-addr [primary]
Step 2 Set the domain name. set ip dns domain name
Step 3 Enable DNS. set ip dns {enable | disable}

After entering the set ip dns server command, you see one of these displays:

Console> (enable) set ip dns server 171.69.2.132 primary DNS name server set to 198.92.30.35 as primary. Console> (enable) set ip dns server 198.92.30.32 DNS name server set to 198.92.30.32 as primary. Console> (enable) set ip dns server 161.44.128.70 Table is full. DNS name server 161.44.128.70 not added.

After entering the set ip dns domain command, you see this display:

Console> (enable) set ip dns domain hp.com Default DNS domain name set to hp.com.

After entering the set ip dns [enable | disable] command, you see one of these displays:

Console> (enable) set ip dns enable DNS enabled. Console> (enable) set ip dns disable DNS disabled.

To clear the address of the DNS server, enter the clear ip dns server ip-addr command. After entering this command, you see this display:

Console> (enable) clear ip dns server 198.92.30.32 DNS name server 198.92.30.32 cleared.

To clear the domain name, enter the clear ip dns domain command. After entering this command, you see one of these displays:

Console> (enable) clear ip dns domain Default DNS domain name hp.com cleared. Console> (enable) clear ip dns domain There is no default DNS domain name defined.

Verification

To show the DNS name server and the default domain name, enter the show ip dns command. After entering this command, you see this display:

Console> (enable) show ip dns DNS is currently enabled. The default DNS domain name is: hp.com DNS name server status --------------- ------- 198.92.30.32 171.69.2.132 primary 161.44.128.70

Login Banner

You can create a single or multiline message banner that appears on your screen before session login. To create the message, you must be in privileged mode.

Procedure

To configure a login banner, perform this task:

Task Command
Enter the message of the day. set banner motd
The first letter after the motd keyword is used as the delimiter to end the message. Characters following the ending delimiter are discarded. After the ending delimiter, you must press Return. The banner must be fewer than 255 characters.

Example

You see this display when you enter the set banner motd command:

Console> (enable) set banner motd Usage: set banner motd <C> [text] <C> (<C> is a delimiting character) Console> (enable) set banner motd " " MOTD banner cleared. Console> (enable) set banner motd # ** System upgrade at 6:00am Tuesday ** Please log out before leaving on Monday. # MOTD banner set.

Multiple Module Download

The Catalyst 5000 series switch can contain multiple modules, each of which has its own onboard Flash. Multiple module downloading allows you to perform a single Trivial File Transfer Protocol (TFTP) download that updates all modules of the same type. The download command is available only from the console enabled mode. To configure multiple module download, you must use FDDI software release 2.2 or greater.

Procedures

Use the appropriate procedure in this section to perform a serial and TFTP download on the supervisor, Asynchronous Transfer Mode (ATM), and FDDI modules.

Serial Download

Task Command
Perform a TFTP download. download serial [mod_num]
If you enter a mod_num (optional), a download to the module number specified occurs. If you omit the mod_num in this command, the download header determines the module type. The download then goes to all modules of that type. When specifying a mod_num, the target module must be the same type that is indicated by the download header. Otherwise, the download fails.

TFTP Download

Task Command
Perform a TFTP download. download host file [mod_num]

Verification

After the module receives the download header from the host, it determines the download type and gives a confirmation prompt similar to the following:

Download image atm_13.bin from 172.20.22.7 to ATM Module(s) 2 (y/n) [n]? Download image atm_13.bin from 172.20.22.7 to ATM Module(s) 6 (y/n) [n]? Download image atm_13.bin from 172.20.22.7 to ATM Module(s) 8 (y/n) [n]? Do you wish to continue to download (y/n) [n]?

Download Screen Examples

This section contains examples of the download command:

Download based on the download header type:

download 172.20.22.7 c5009_15.bin download 172.20.22.7 atm-13.bin download 172.20.22.7 fddi-13.bin

Download to module 5 only:

download 172.20.22.7 atm_13.bin 5

Make sure the module type matches.

Download to module 4:

download serial 4

Make sure the module type matches.

Download to all modules that match the download header type:

download serial

Download to ATM modules:

download 172.20.227 atm-13.bin

Download to FDDI modules:

download 172.20.227 fddi-13.bin

Download to the supervisor module:

download 172.20.227 C5009-15.bin

How Multiple Module Download Works

Downloading of multiple modules speeds up the download process significantly. A single download to multiple modules needs to be performed only once for each module type. With the multiple module download feature, the TFTP Flash image for the module is relayed packet by packet to the modules by using the Inter-Process Communications (IPC) protocol internal to the system, with communication taking place across the switching bus.

Each module has an IPC process and listens for the download packets, which are then stored in the download buffer. The TFTP packet is queued to the IPC process and is sent individually to each line module.

Task	Command
Step 1 Add a syslog server to the configuration.¹	set logging server ip_addr
Step 2 Enable system message logging to configured syslog servers.	set logging server enable
Step 3 Set the facility and severity level for syslog server messages.	set logging level facility severity default

Element	Description
TIMESTAMP	The current date and time in the following format: mm/dd/yy,hh:mm:ss
FACILITY	Two or more uppercase letters that indicate the facility to which the message refers (for example, SNMP, SYS, etc.)
SEVERITY	A single-digit code from 0 to 7 that indicates the severity of the message
Message-text	A text string containing detailed information about the event being reported

Task	Command
Step 1 Configure the address of the NTP server to be queried.	set ntp server ip-address
Step 2 Enable the NTP broadcast client mode.	set ntp client enable

Task	Command
Step 1 Set the address of the DNS server.	set ip dns server ip-addr [primary]
Step 2 Set the domain name.	set ip dns domain name
Step 3 Enable DNS.	set ip dns {enable \| disable}

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