The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
You must ensure the following before stacking controllers:
You must ensure that the controllers in the stack are configured with the same Cisco IOS Software Release version and licenses.
A controller stack can have one stacking-capable controller connected through their StackWise-480 ports; which implies that the stack has two members- an active and a standby controller. The stack member work together as a unified system using the use the StackWise-480 technology. If the active controller becomes unavailable, the standby controller assumes the role of the active switch, and continues to the keep the stack operational.
The active controller contains the saved and running configuration files for the controller stack. The configuration files include the system-level settings for the controller stack and the interface-level settings the stack member. The stack member has a current copy of all these files for back-up purposes. The controllers in the stack use Cisco StackWise-480 technology which provides a robust distributed forwarding architecture through each stack member switch and a unified, fully centralized control and management plane to simplify operation in a large-scale network design.
In the stack, all configuration in the active unit is synced to the standby unit once standby unit changes its state from member to the hot standby state. Thus, all the start-up configuration available in the unit prior to synchronization is lost. If you would need the start-up configuration of the standby unit again, you must save the startup configuration of the unit in secondary memory- Flash memory to reuse the configurations later.
You must use the following Cisco StackWise-480 and Cisco StackPower cables to connect the units in the stack.
Stack Cable | Description |
---|---|
STACK-T1-50CM | Cisco StackWise-480 50cm stacking cable spare |
STACK-T1-1M | Cisco StackWise-480 1m stacking cable spare |
STACK-T1-3M | Cisco StackWise-480 3m stacking cable spare |
CAB-SPWR-30CM | Cisco Catalyst 3850 StackPower cable 30cm spare |
CAB-SPWR-150CM | Cisco Catalyst 3850 StackPower cable 150cm spare |
In the stack, all configuration in the active unit is synced to the standby unit once standby unit changes its state from member to the hot standby state. Thus, all the start-up configuration available in the unit prior to synchronization is lost. If you would need the start-up configuration of the standby unit again, you must save the startup configuration of the unit in secondary memory- Flash memory to reuse the configurations later.
When you use the controller stack, all the six controller ports of both the controllers are combined hence providing an availability of 12 ports for usage. The bandwidth of a controller port is a 10 gig ethernet port; however on combination of 12 ports the controller, a throughput of 60 Gbps is only available for use. These ports can be combined to form an Etherchannel, a flex link, or a Link Aggregation Group (LAG).
1. Connect two controllers that are up and running using the stack cable.
2. Power up and perform a boot on both controllers simultaneously or power and boot one controller.
3. Configure Etherchannel or LAG on the units. The deployment type of Etherchannel, LAG, and LACP is based on your network design.
4. Execute the command show etherchannel summary to view status of the configured Etherchannel.
5. Configure LACP .
6. Execute the commands defined for displaying stack information on the console of the active controller to verify that the redundancy high availability pair exists.
A standalone switch is a switch stack with one stack member that also operates as the . You can connect one standalone switch to another to create a switch stack containing two stack members, with one of them as the . You can connect standalone switches to an existing switch stack to increase the stack membership.
A new, out-of-the-box switch (one that has not joined a switch stack or has not been manually assigned a stack member number) ships with a default stack member number of 1. When it joins a switch stack, its default stack member number changes to the lowest available member number in the stack.
Stack members in the same switch stack cannot have the same stack member number. Every stack member, including a standalone switch, retains its member number until you manually change the number or unless the number is already being used by another member in the stack.
As described in the hardware installation guide, you can use the switch port LEDs in Stack mode to visually determine the stack member number of each stack member.
A higher priority value for a stack member increases the probability of it being elected and retaining its stack member number. The priority value can be 1 to 15. The default priority value is 1. You can display the stack member priority value by using the show switch EXEC command.
Note |
We recommend assigning the highest priority value to the switch that you prefer to be the . This ensures that the switch is reelected as the if a reelection occurs. |
To change the priority value for a stack member, use the switch stack-member-number priority new priority-value EXEC command.
The new priority value takes effect immediately but does not affect the current . The new priority value helps determine which stack member is elected as the new when the current or the switch stack resets.
All stack members are eligible to be the active switch or the standby switch. If the active switch becomes unavailable, the standby switch becomes the active switch.
An active switch retains its role unless one of these events occurs:
The is elected or reelected based on one of these factors and in the order listed:
Note |
We recommend assigning the highest priority value to the switch that you prefer to be the . This ensures that the switch is reelected as if a reelection occurs. |
Note |
The factors for electing or reelecting a new standby switch are same as those for the active switch election or reelection, and are applied to all participating switches except the active switch. |
After election, the new active switch becomes available after a few seconds. In the meantime, the switch stack uses the forwarding tables in memory to minimize network disruption. The physical interfaces on the other available stack members are not affected during a new active switch election and reset.
When the previous active switch becomes available, it does not resume its role as the active switch.
If you power on or reset an entire switch stack, some stack members might not participate in the active switch election. Stack members that are powered on within the same 2-minute timeframe participate in the active switch election and have a chance to become the active switch. Stack members that are powered on after the 120-second timeframe do not participate in this initial election and become stack members. For powering considerations that affect active-switch elections, see the switch hardware installation guide.
As described in the hardware installation guide, you can use the ACTV LED on the switch to see if the switch is the active switch.
This procedure is optional.
Note |
When you enter the command to configure this feature, a warning message appears with the consequences of your configuration. You should use this feature cautiously. Using the old MAC address elsewhere in the same domain could result in lost traffic. |
1. configure terminal
2. stack-mac persistent timer [0 | time-value]
3. end
4. copy running-config startup-config
This optional task is available only from the .
1. switch current-stack-member-number renumber new-stack-member-number
2. reload slot stack-member-number
Command or Action | Purpose | |
---|---|---|
Step 1 | switch current-stack-member-number renumber new-stack-member-number Example: Controller# switch 3 renumber 4
|
Specifies the current stack member number and the new member number for the stack member. The range is 1 to 2. You can display the current stack member number by using the show switch user EXEC command. |
Step 2 | reload slot stack-member-number Example: Controller# reload slot 4
|
Resets the stack member. |
This optional task is available only from the .
1. switch stack-member-number priority new-priority-number
2. reload slot stack-member-number
Command or Action | Purpose | |
---|---|---|
Step 1 | switch stack-member-number priority new-priority-number Example: Controller# switch 3 priority 2
|
You can display the current priority value by using the show switch user EXEC command. The new priority value takes effect immediately but does not affect the current . The new priority value helps determine which stack member is elected as the new when the current or switch stack resets. |
Step 2 | reload slot stack-member-number Example: Controller# reload slot 3
|
Specifies the stack member number and the new priority for the stack member. The stack member number range is 1 to 9. The priority value range is 1 to 15. You can display the current priority value by using the show switch user EXEC command. The new priority value takes effect immediately but does not affect the current active switch. The new priority value helps determine which stack member is elected as the new active switch when the current active switch or switch stack resets. |
1. show switch
Command or Action | Purpose | |
---|---|---|
Step 1 | show switch Example: Controller# show switch
|
Displays any incompatible switches in the switch stack (indicated by a 'Current State' of 'V-Mismatch'). The V-Mismatch state identifies the switches with incompatible software. The output displays Lic-Mismatch for switches that are not running the same license level as the . For information about managing license levels, see the System Management Configuration Guide (Catalyst 3850 Switches)System Management Configuration Guide (Cisco WLC 5700 Series) . |
1. software auto-upgrade
2. copy running-config startup-config
Command or Action | Purpose | |
---|---|---|
Step 1 | software auto-upgrade Example: Controller# software auto-upgrade
|
Upgrades incompatible switches in the switch stack, or changes switches in bundle mode to installed mode. |
Step 2 | copy running-config startup-config Example: Controller# copy running-config startup-config
|
(Optional) Saves your entries in the configuration file. |