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A cluster is a group of connected switches that are managed as a single entity. The switches can be in the same location, or they can be distributed across a network. All communication with cluster switches is through one IP address. You can have up to 16 switches in a cluster: 1 command switch and 15 member switches.
This chapter describes how to create and manage clusters of switches by using Cluster Management. Cluster Management has three components:
Cluster Management interface and navigation techniques are described in "Using the Management Interfaces."
The command switch is the single point of access used to configure and monitor the switches in a cluster. A member switch is managed through a command switch. Command switches must be running a version of IOS Release 11.2(8)SA6 software that supports the ability to be a command switch. See the "Supported Hardware" section for the complete list of command-capable switches.
When you first install your switches, you cable the switches together and assign an IP address to the command switch. In addition, you must enable the switch as the command switch. When the switches are turned on, the command switch uses information from Cisco Discovery Protocol (CDP) to identify candidate switches that you can add to a cluster. After the cluster is formed, you can access all switches in the cluster by entering the IP address of the command switch. The password you enter when you log in to the command switch also gives you access to cluster member switches. If the command switch fails, you can use its password to create a new command switch for the cluster.
After you have assigned an IP address to a switch and connected it to other switches running IOS Release 11.2(8)SA6, you can use Cluster Builder to create a cluster with one IP address. The switch assigned the IP address must be command-capable for it to be the command switch, and you must explicitly enable it to be the command switch on the CVSM home page. Command-capable switches that are not cluster members have two additional fields that appear on the switch home page: the Command Switch and the Cluster Name field. Use these fields to enable a switch as the command switch and enter the cluster name.
Cluster Builder displays by default when you click Cluster Management from a CVSM home page or the Cisco Access page. You can use Cluster Builder to access the following features:
How you create a cluster depends on your network. If the switches are arrayed in a star topology with the command switch at the center, you can add all the switches to the cluster at once. If the switches are connected in a daisy-chain topology, you add the candidate connected to the command switch and then continue adding each switch in the chain as it is discovered by CDP. If switches are daisy-chained off of a star topology, you can add all the switches directly connected to the command switch and then add the daisy-chained switches one at a time.
There can be a maximum of 16 switches in a cluster: 15 member switches and 1 command switch. If there are passwords defined for the candidate switches, you must know them before they can be added to the cluster. In addition, a candidate switch must satisfy the following requirements to join a cluster:
If a switch does not become part of the cluster, right-click it and select Disqualification Code to display the reason it did not join the cluster.
If the command switch fails, member switches continue forwarding but cannot be managed through the command switch. Member switches retain the ability to be managed through normal standalone means, such as the console-port CLI, and they can be managed through SNMP, HTML, and Telnet after they have been assigned an IP address.
You can recover from a failed command switch by replacing the failed unit with a cluster member or another switch. To have a cluster member ready to replace the command switch, assign an IP address to a cluster member, and know the command-switch enable password. To use Telnet, you also need to know the login password. The cluster member must be running software that allows it to become a command switch. See "Supported Hardware" section for the list of switches that can be command switches.
Redundant links from the backup command switch to the cluster make for a faster replacement in the event of failure but are dependent on your topology. For the actual recovery procedures, see the "Recovering from a Command Switch Failure" section.
Cluster Builder automatically prompts you to add cluster members when it first starts and when the topology changes. When Cluster Builder starts, a dialog box lists the candidate switches with their device types, MAC addresses, and the ports through which they are directly connected to the command switch. Only switches that are directly connected to the command switch can be added in this way.
You can set Cluster Builder to not automatically display suggested candidates. See the "Changing User Settings" section for instructions.
Figure 4-1 shows the dialog box for adding switches to a cluster. When the command switch presents the list of candidates, you can accept the suggested cluster or not. If you do not accept the suggested cluster, none of the switches are added, and members must be added one at a time. If you accept the cluster and there are more switches daisy-chained to a cluster member, they must be added one at a time.
You are prompted to enter a password at this point. Enter the enable password of the candidate switch if one has been defined. If no password has been defined for the candidate, click OK to add it to the cluster with no password.
If you enter a password that does not match the password defined for the candidate, or if you enter a password for a candidate that has not had a password defined for it, the switch is not added to the cluster. In all cases, once a candidate switch joins a cluster, it takes the enable password of the cluster command switch.
For more information on entering switch passwords, see the "Setting Passwords" section.
When a cluster is formed, the command switch automatically changes three parameters on the cluster member switches: the IOS host name, the enable password, and the SNMP community string.
If a switch has not been assigned an IOS host name, the command switch appends a number to the name of the command switch and assigns it sequentially to the member switches. For example, a command switch named eng-cluster could name a cluster member eng-cluster-5. If an IOS host name has already been assigned to a switch, it retains the name.
For the SNMP community strings, the command switch adds the following SNMP community strings to a member switch when it is added to a cluster:
For the enable password, the command switch configures the member switch with its password when the switch joins the cluster.
The same requirements for creating a cluster apply when you use the CLI to create it. Follow these steps to enable the cluster command switch and add member switches to a cluster:
Step 1 Enable the cluster commander:
switch> enable Password: <password> switch# switch# config terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# cluster enable An-Example-Cluster switch(config)# exit switch#
Step 2 Now discover the candidates:
switch# show cluster candidates 00E0.1E00.2222 Switch cisco WS-C2924-XL Fa0/16 1 0 Fa0/1 00E0.1E00.3333 Switch cisco WS-C2924-XL Fa0/1 1 0 Fa0/2
Step 3 Configure both candidates as cluster members:
switch# config terminal Enter configuration commands, one per line. End with CNTL/Z. switch(config)# cluster member 2 mac-address 00E0.1E00.2222 switch(config)# cluster member 4 mac-address 00E0.1E00.3333 switch(config)# exit
Step 4 Display status of the cluster:
switch# show cluster members
Link Upstream Upstream
MN Mac Address Interface Hops SN Interface State
--------------------------------------------------------------------------------
2 00E0.1E00.2222 Fa0/16 1 0 Fa0/1 Up
4 00E0.1E00.3333 Fa0/1 1 0 Fa0/2 Up
You can use the network map to add switches to the cluster (see Figure 4-2). Switches in the cluster are green, candidates are blue, and other connected devices that are running CDP are yellow. Follow these steps to add a switch to a cluster:
Step 1 Right-click a candidate (blue) switch to display the pop-up menu.
Step 2 From the pop-up menu, select Add to Cluster.
To remove a device, right-click a member switch, and select Remove from Cluster on the pop-up menu.
To hide or display candidate switches, click either Hide Candidates or Show Candidates.
Follow these steps to remove a member switch from a cluster:
Step 1 Display the status of the cluster and note the MAC address of the switch you want to remove:
switch# show cluster members
|---Upstream---| SN MAC Address Name PortIf FEC Hops SN PortIf FEC State 0 0050.5494.3c40 Tahiti-24 0 Cmdr 2 00e0.1e9f.8c00 Tahiti-24-2 Fa0/4 1 0 Fa0/7 Up
Step 2 Enter global configuration mode:
switch# config terminal
Step 3 Remove the switch from the cluster:
switch(config)# no cluster member 2 mac-address 00e0.1e9f.8c00
Step 4 Return to privileged EXEC mode:
switch# end
Step 5 Display the status of the new cluster:
switch# show cluster members
|---Upstream---| SN MAC Address Name PortIf FEC Hops SN PortIf FEC State 0 0050.5494.3c40 Tahiti-24 0 Cmdr
Click User Settings at the top of the page to change the parameters described in the following list. The user settings are saved in permanent storage on the command switch.
From Cluster Builder, click Toggle Views to display a map of the cluster and attached devices. In Cluster View, the cluster is condensed into an icon. You can save the view in Cluster View and toggle back and forth to Cluster Builder.
After you have created a cluster, you can use Cluster Manager to monitor and configure the switches in the cluster. Figure 4-4 shows a cluster displayed on the Cluster Manager page. The switch software updates the LEDs displayed on these images in real time, making the images displayed by Cluster Manager as informative as the switches themselves. From this page you can perform the following tasks:
The LEDs above the ports in Figure 4-4 can display the status, speed, or duplex setting of the port. Click the Mode button on the image to highlight in turn each of the settings. STAT displays the link status of the port, SPD displays the speed of the port, and FDUP displays whether the port is operating in half- or full-duplex mode. Click Legend to display the meanings of the colors.
You can operate on single and multiple ports by clicking them in the Cluster Manager window. The defaults of the different port types and port-configuration guidelines are described in the "Configuring Port Parameters" section.
When you select a port or ports, you can set the following parameters:
Status: | Enable or disable the port. |
Duplex: | Set a port to full-duplex (Full), half-duplex (Half), or autonegotiate (Auto). The default is Auto. For ATM ports, this field is read-only and displays Full. |
Speed: | Set a 10/100 port to 10 Mbps (10), 100 Mbps (100), or autonegotiate (Auto). The default is Auto. For Gigabit Ethernet ports, the field displays 1000 and is read-only. For ATM ports, the field displays 155 (155 Mbps) and is read-only. |
Port Fast | Set the port to come immediately into the STP forwarding state and bypass the normal transition from the listening and learning states to the forwarding state. |
Left-click a port to select it, and then right-click to display the pop-up menu. Select Port Configuration to display the dialog box shown in shown in Figure 4-5. Use this dialog box to enable or disable the port, change the speed and duplex settings, and enable or disable the STP Port Fast parameter.
When you configure a single port, the dialog box displays the current status and the current settings of the port, the VLAN mode of the port, and the VLANs that the port belongs to.
Left-click ports while holding down the Ctrl key to select more than one port at a time. After selecting the ports, right-click to display the pop-up menu, and select Port Configuration. The window shown in Figure 4-6 displays. You can use this window to change the ports settings for the selected ports, but the window does not display the actual port settings or VLAN information.
For more information on configuring ports, see the "Configuring Port Parameters" section or click Help.
The VLAN Membership page shown in Figure 4-7 displays the list of all the user-defined VLANs on the switch. By selecting a VLAN, you can display the ports that belong to the VLAN. In addition, the color coding indicates which VLAN mode a port is in.
To display the VLANs that are active on a switch, right-click the chassis of the switch in Cluster Manager. Select VLAN Membership from the pop-up menu.
To display the ports that belong to a given VLAN, select the VLAN ID on the VLAN Membership page, and click Display Members. Cluster Manager highlights all the ports in the window that belong to the selected VLAN. The Legend on the VLAN Management page shows the colors Cluster Builder uses to indicate the VLAN modes of the ports.
To display the VLAN membership for a single port, right-click the port, and select Port Configuration from the pop-up menu.
You can upgrade cluster switches by using the Software Upgrade window shown in Figure 4-8. New IOS software releases with new features are posted on Cisco Connection Online (CCO) and are available through authorized resellers. You can also download the Cisco TFTP server from CCO.
You can upgrade all or some of the switches in a cluster at once, but the switch performs a series of checks before the upgrade takes place. Organize your upgrades so that the following rules do not slow down the upgrade process:
New images are copied to Flash memory and do not affect the operation of the switch. The switch checks Flash memory to ensure there is sufficient space before the upgrade takes place. If there is not enough space in Flash memory for the new and old image, the new image replaces the old one. If there is enough space, the new image is copied to the switch without replacing the old image, and the old image is deleted after the download of the new image is complete. In this way, you can still restart the switch if the download of the new image fails.
You upgrade the cluster by using a tar file that contains the switch software image and the HTML files for the HTML interface. You can enter just the name of the file or a path. You do not need to enter a path if the image file is in the root directory of the TFTP server.
New features provided by the software are not available until you reload the software.
The Cisco TFTP server application can handle multiple requests and sessions, but you must first disable the Show File Transfer Progress and the Enable Logging options to avoid TFTP server failures. If you are performing multiple-switch upgrades with a different TFTP server, it must be capable of managing multiple requests and sessions at the same time.
As member switches might not be assigned an IP address, command-line software upgrades via TFTP are managed through the command switch. Follow these steps to upgrade the switch software on a member switch:
Step 1 Starting from the command switch in EXEC mode, log in to the member switch:
switch# rcommand 1
Step 2 Start the TFTP copy as if you were initiating it from the command switch. Press Enter when prompted by the switch:
switch1# tar /x tftp://server_ip_address//path/filename.tar flash: Source IP address or hostname [server_ip_address]?
Source filename [path/filename]?
Destination filename [flash:new_image]?
Loading /path/filename.bin from server_ip_address (via!)
[OK - 843975 bytes]
Step 3 Reload the new software with the following command:
switch# reload
System configuration has been modified. Save? [yes/no]:y
Proceed with reload? [confirm]
You lose contact with the switch while it reloads the software. See the "Understanding the CLI" section for more information on the rcommand.
The command switch manages SNMP communication for all switches in the cluster. The command switch forwards the set and get requests from SNMP applications to member switches, and it forwards the traps and other responses coming from the member switches to the appropriate management station. The description of SNMP configuration in the "Configuring SNMP" section also applies to the use of the page shown in Figure 4-9.
Use the SNMP Manager page (Figure 4-9) to enter read-write and read-only community strings for an entire cluster. Community strings provide authentication in the exchange of SNMP messages. The command switch appends numbers to the community strings of member switches so that these modified community strings can provide authentication for the member switches. When a new switch is added to the cluster, a community string is created for it from the community string for the cluster. Only the first read-only and read-write community strings are propagated to the cluster.
Traps are system alerts that the switch generates when certain events occur. The command switch forwards traps from member switches to the SNMP management station. From this page you can enable the switch to generate the following traps:
Config | Generate a trap when the switch configuration changes. |
TTY | Generate a trap when the switch starts a CLI session |
VTP | Generate a trap when the VLAN Trunk Protocol (VTP) changes (Enterprise Edition Software only). |
SNMP | Generate the switch SNMP traps. |
C2900/C3500 | Generate the Catalyst 2900 XL and Catalyst 3500 XL traps. See "Managing Your Switches" for the traps generated to support specific switch features. |
VLAN Membership | For Enterprise Edition Software, generate a trap when the VLAN Membership Policy Server (VMPS) changes. |
You can arrange the order in which switches are displayed by Cluster Manager. Select a device in the Device Arrangement page shown in Figure 4-10, and use the arrows to move it up or down in the list. Click OK when finished.
You can use Cluster Management to display real-time graphs that can help you analyze traffic patterns and identify problems with individual links. You can start a graph from Cluster Builder, Cluster Manager, or Cluster View. To display a link graph in Cluster Builder or Cluster View, click a link and then right-click to display the pop-up menu. Select Link Graph. To display a link graph in Cluster Manager, left-click a port and right-click to display the pop-up menu. Select Link Graph.
A graph runs as a separate browser session and can run in the background without interrupting the original session. The host name of the switch is displayed at the top of the browser window. The link port number is displayed above the graph itself.
When the graph window is displayed, use the drop-down menu in the upper right corner to select the data you want to present, as shown in Figure 4-11.
Select one of the following graphs from the drop-down menu:
This graph (Figure 4-11) displays the percentage of the maximum bandwidth in use by the port number displayed on the graph. The IP address of the switch is displayed at the very top of the window.
This graph (Figure 4-12) displays the number of bytes sent and received by the port number displayed on the graph.
The following colors represent three different graphs:
This graph displays the number of packets sent and received by the port number displayed on the graph. The following colors represent the two graphs:
This graph displays the total number of errors sent and received by the port number displayed on the graph. The following colors represent the two graphs:
Cluster Management can extract real-time information from cluster switches and present it in the form of device and link reports. This section describes the variety of reports that Cluster Management can generate.
Figure 4-13 shows the link report that you can create by selecting a link and right-clicking on the pop-up menu to select Link Report.
To display a device report, click the device, right-click to display the pop-up window, and select Device Report.
Each device report displays with a drop-down menu in the upper right corner. From the drop-down menu, you can display the following reports:
Posted: Wed May 26 10:48:17 PDT 1999
Copyright 1989-1999©Cisco Systems Inc.