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.
Prerequisites for
Switch Stacks
All the switches in
the switch stack need to be running the same license level as the active
switch. For information about license levels, see the
System Management Configuration Guide (Catalyst 3850 Switches).
All switches in the
switch stack need to be running compatible software versions.
Restrictions for
Switch Stacks
The following are
restrictions for your switch stack configuration:
Switch stacks
running the LAN Base license level do not support Layer 3 features.
A switch stack
can have up to nine stacking-capable switches connected through their
StackWise-480 ports.
You cannot have
a switch stack containing a mix of
Catalyst 3850 and
Catalyst 3650 switches.
A switch stack can have up to nine stacking-capable switches connected through their StackWise-480 ports. The stack members work together as a unified system. Layer 2 and Layer 3 protocols present the entire switch stack as a single entity to the network.
A switch stack always has one active switch and one standby switch. If the active switch becomes unavailable, the standby switch assumes the role of the active switch, and continues to the keep the stack operational.
The active switch controls the operation of the switch stack, and is the single point of stack-wide management. From the active switch, you configure:
System-level (global) features that apply to all stack members
Interface-level features for each stack member
The active switch contains the saved and running configuration files for the switch stack. The configuration files include the system-level settings for the switch stack and the interface-level settings for each stack member. Each stack member has a current copy of these files for back-up purposes.
If the active switch is running the cryptographic universal software image (supports encryption), the encryption features are available on the switch stack.
StackWise-480
The stack members
use the StackWise-480 technology to work together as a unified system. Layer 2
and Layer 3 protocols support the entire switch stack as a single entity in the
network.
Note
Switch stacks running the
LAN Base image do not support Layer 3 features.
StackWise-480 has a
stack bandwidth of 480 Gbps, and uses stateful switchover (SSO) to provide
resiliency within the stack. The stack behaves as a single switching unit that
is managed by an active switch elected by the member switches. The active
switch automatically elects a standby switch within the stack. The active
switch creates and updates all the switching, routing and wireless information
and constantly synchronizes that information with the standby switch. If the
active switch fails, the standby switch assumes the role of the active switch
and continues to the keep the stack operational. Access points continue to
remain connected during an active-to-standby switchover unless the access point
is directly connected to the active switch. In this case the access point will
lose power and reboot. A working stack can accept new members or delete old
ones without service interruption.
Fast Stack Convergence
When a single link in a full ring stack becomes inoperable, there is a disruption in the forwarding of packets, and the stack moves to a half ring. With Catalyst 3850 switches this disruption of traffic (or stack convergence time)
takes milliseconds.
StackPower
StackPower allows the power supplies in a stack to be shared as a common resource among all the switches in the stack. StackPower unifies the individual power supplies installed in the switches and creates a pool of power, directing that power where it is needed. Up to four switches can be configured in a StackPower stack using the StackPower cable.
For more information about StackPower, see the Interface and Hardware Component Configuration Guide (Catalyst 3850 Switches) .
Switch Stack Membership
A standalone switch is a switch stack with one stack member that also operates as the active switch. You can connect one standalone switch to another to create a switch stack containing two stack members, with one of them as the active switch. You can connect standalone switches to an existing switch stack to increase the stack membership.
If you replace a stack
member with an identical model, the new switch functions with exactly the same
configuration as the replaced switch, assuming that the new switch (referred to
as the provisioned switch) is using the same member number as the replaced
switch.
The operation of the
switch stack continues uninterrupted during membership changes unless you
remove the
active switch or you add powered-on standalone
switches or switch stacks.
Adding powered-on switches (merging) causes all switches to
reload and elect a new active switch from among themselves. The newly elected
active switch retains its role and configuration. All other switches retain
their stack member numbers and use the stack configuration of the newly elected
active switch.
Removing
powered-on stack members causes the switch stack to divide (partition) into two
or more switch stacks, each with the same configuration. This can cause:
An IP address
conflict in your network. If you want the switch stacks to remain separate,
change the IP address or addresses of the newly created switch stacks.
A MAC address
conflict between two members in the stack. You can use the
stack-mac update
force command to resolve the conflict.
If a newly created switch stack does not have an active switch
or standby switch, the switch stack will reload and elect a new active switch.
Note
Make sure that you
power off the switches that you add to or remove from the switch stack.
After adding or
removing stack members, make sure that the switch stack is operating at full
bandwidth
(480 Gbps). Press the Mode button on a stack member until
the Stack mode LED is on. The last two right port LEDs on all switches in the
stack should be green. Depending on the switch model, the last two right ports
are 10-Gigabit Ethernet ports or small form-factor pluggable (SFP) module ports
(10/100/1000 ports). If one or both of these LEDs are not green on any of the
switches, the stack is not operating at full bandwidth.
If you remove
powered-on members but do not want to partition the stack:
Power off the
switches in the newly created switch stacks.
Reconnect them to
the original switch stack through their stack ports.
Power on the
switches.
For cabling and power considerations that affect switch stacks,
see the
Catalyst 3850 Switch Hardware Installation Guide .
The stack member number (1 to 9) identifies each member in the switch stack. The member number also determines the interface-level configuration that a stack member uses. You can display the stack member number by using the show switch EXEC command.
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.
If you manually change the stack member number by using the switchcurrent-stack-member-numberrenumbernew-stack-member-numberEXEC command, the new number goes into effect after that stack member resets (or after you use the reload slotstack-member-number
privileged EXEC command) and only if that number is not already assigned to any other members in the stack. Another way to change the stack member number is by changing the SWITCH_NUMBER environment variable.
If the number is being used by another member in the stack, the switch selects the lowest available number in the stack.
If you manually change the number of a stack member and no interface-level configuration is associated with that new member number, that stack member resets to its default configuration.
You cannot use the switchcurrent-stack-member-numberrenumbernew-stack-member-numberEXEC command on a provisioned switch. If you do, the command is rejected.
If you move a stack member to a different switch stack, the stack member retains its number only if the number is not being used by another member in the stack. If it is being used, the switch selects the lowest available number in the stack.
If you merge switch stacks, the switches that join the switch stack of a new active switch select the lowest available numbers 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
active switch 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
active switch. This ensures that the switch is
reelected as the
active switch if a reelection occurs.
To change the priority
value for a stack member, use the
switchstack-member-numberprioritynew
priority-value
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 the switch stack resets.
A switch stack is identified in the network by
its bridge ID and, if it is operating as a Layer 3
device, its router MAC address. The bridge ID and router MAC address
are determined by the MAC address of the
active switch.
If the active switch changes, the MAC address
of the new active switch determines the new bridge ID and router
MAC address.
If the entire switch stack reloads, the switch
stack uses the MAC address of the active switch.
You can use the persistent
MAC address feature to set a time delay before the stack MAC address changes.
During this time period, if the previous active switch rejoins the stack, the
stack continues to use its MAC address as the stack MAC address, even if the
switch is now a stack member and not an active switch. If the previous active
switch does not rejoin the stack during this period, the switch stack takes the
MAC address of the new active switch as the stack MAC address. By default, the
stack MAC address will be the MAC address of the first active switch, even if a
new active switch takes over.
You can also
configure stack MAC persistency so that the stack MAC address never changes to
the new
active switch
MAC address.
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 switch
stack is reset.
The active
switch is removed from the switch stack.
The active
switch is reset or powered off.
The active
switch fails.
The switch
stack membership is increased by adding powered-on standalone switches or
switch stacks.
The
active switch is elected or reelected based on one
of these factors and in the order listed:
The switch that
is currently the
active switch.
The switch with
the highest stack member priority value.
Note
We recommend
assigning the highest priority value to the switch that you prefer to be the
active switch. This ensures that the switch is
reelected as
active switch if a reelection occurs.
The switch
with the shortest start-up time.
The switch
with the lowest MAC address.
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.
Switch Stack
Configuration Files
The active switch has the
saved and running configuration file for the switch stack. The standby switch
automatically receives the synchronized running configuration file. Stack
members receive synchronized copies when the running configuration file is
saved into the startup configuration file. If the active switch becomes
unavailable, the standby switch takes over with the current running
configuration.
The configuration
files record these settings:
System-level
(global) configuration settings such as IP, STP, VLAN, and SNMP settings that
apply to all stack members
Stack member
interface-specific configuration settings that are specific for each stack
member
Note
The
interface-specific settings of the
active switch are saved if the
active switch is replaced without saving the running
configuration to the startup configuration.
A new, out-of-box
switch joining a switch stack uses the system-level settings of that switch
stack. If a switch is moved to a different switch stack before it is powered
on, that switch loses its saved configuration file and uses the system-level
configuration of the new switch stack. If the switch is powered on as a
standalone switch before it joins the new switch stack, the stack will reload.
When the stack reloads, the new switch may become the active switch, retain its
configuration and overwrite the configuration files of the other stack members.
The interface-specific
configuration of each stack member is associated with the stack member number.
Stack members retain their numbers unless they are manually changed or they are
already used by another member in the same switch stack. If the stack member
number changes, the new number goes into effect after that stack member resets.
If an
interface-specific configuration does not exist for that member number, the
stack member uses its default interface-specific configuration.
If an
interface-specific configuration exists for that member number, the stack
member uses the interface-specific configuration associated with that member
number.
If you replace a
failed member with an identical model, the replacement member automatically
uses the same interface-specific configuration as the failed switch. You do not
need to reconfigure the interface settings. The replacement switch (referred to
as the provisioned switch) must have the same stack member number as the failed
switch.
You back up and
restore the stack configuration in the same way as you would for a standalone
switch configuration.
You can use the
offline configuration feature to
provision (to
supply a configuration to) a new switch before it joins the switch stack. You
can configure the stack member number, the switch type, and the interfaces
associated with a switch that is not currently part of the stack. The
configuration that you create on the switch stack is called the
provisioned
configuration. The switch that is added to the switch stack and that
receives this configuration is called the
provisioned
switch.
You manually create the provisioned configuration through
the
switchstack-member-numberprovisiontype global configuration command. You must change
the
stack-member-number on the provisioned switch
before you add it to the stack, and it must match the stack member number that
you created for the new switch on the switch stack. The switch type in the
provisioned configuration must match the switch type of the newly added switch.
The provisioned configuration is automatically created when a switch is added
to a switch stack and when no provisioned configuration exists.
When you configure the interfaces associated with a
provisioned switch, the switch stack accepts the configuration, and the
information appears in the running configuration. However, as the switch is not
active, any configuration on the interface is not operational and the interface
associated with the provisioned switch does not appear in the display of the
specific feature. For example, VLAN configuration information associated with a
provisioned switch does not appear in the
show vlan user
EXEC command output on the switch stack.
The switch stack
retains the provisioned configuration in the running configuration whether or
not the provisioned switch is part of the stack. You can save the provisioned
configuration to the startup configuration file by entering the
copy running-config
startup-config privileged EXEC command. The startup configuration
file ensures that the switch stack can reload and can use the saved information
whether or not the provisioned switch is part of the switch stack.
Effects of Adding a Provisioned Switch to a Switch Stack
When you add a provisioned switch to the switch stack, the stack applies either the provisioned configuration or the default configuration. This table lists the events that occur when the switch stack compares the provisioned configuration with the provisioned switch.
Table 1 Results of Comparing the Provisioned Configuration with the Provisioned Switch
Scenario
Result
The stack member numbers and the switch types match.
If the stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, and
If the switch type of the provisioned switch matches the switch type in the provisioned configuration on the stack.
The switch stack applies the provisioned configuration to the provisioned switch and adds it to the stack.
The stack member numbers match but the switch types do not match.
If the stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, but
The switch type of the provisioned switch does not match the switch type in the provisioned configuration on the stack.
The switch stack applies the default configuration to the provisioned switch and adds it to the stack.
The provisioned configuration is changed to reflect the new information.
The stack member number is not found in the provisioned configuration.
The switch stack applies the default configuration to the provisioned switch and adds it to the stack.
The provisioned configuration is changed to reflect the new information.
The stack member number of the provisioned switch is not found in the provisioned configuration.
The switch stack applies the default configuration to the provisioned switch and adds it to the stack.
If you add a provisioned switch that is a different type than specified in the provisioned configuration to a powered-down switch stack and then apply power, the switch stack rejects the (now incorrect) switchstack-member-numberprovisiontype
global configuration command in the startup configuration file. However, during stack initialization, the nondefault interface configuration information in the startup configuration file for the provisioned interfaces (potentially of the wrong type) is executed. Depending on the differences between the actual switch type and the previously provisioned switch type, some commands are rejected, and some commands are accepted.
Note
If the switch stack does not contain a provisioned configuration for a new switch, the switch joins the stack with the default interface configuration. The switch stack then adds to its running configuration with a switchstack-member-numberprovisiontype
global configuration command that matches the new switch.
Effects of Replacing a Provisioned Switch in a Switch Stack
When a provisioned switch in a switch stack fails, it is removed from the stack, and is replaced with another switch, the stack applies either the provisioned configuration or the default configuration to it. The events that occur when the switch stack compares the provisioned configuration with the provisioned switch are the same as those when you add a provisioned switch to a stack.
Effects of Removing a Provisioned Switch from a Switch Stack
If you remove a provisioned switch from the switch stack, the configuration associated with the removed stack member remains in the running configuration as provisioned information. To completely remove the configuration, use the no switchstack-member-numberprovision
global configuration command.
Upgrading a Switch
Running Incompatible Software
The auto-upgrade and auto-advise
features enable a switch with software packages that are incompatible with the
switch stack to be upgraded to a compatible software version so that it can
join the switch stack.
The purpose of the
auto-upgrade feature is to allow a switch to be upgraded to a compatible
software image, so that the switch can join the switch stack.
When a new switch
attempts to join a switch stack, each stack member performs compatibility
checks with itself and the new switch. Each stack member sends the results of
the compatibility checks to the
active switch, which uses the results to determine
whether the switch can join the switch stack. If the software on the new switch
is incompatible with the switch stack, the new switch enters version-mismatch
(VM) mode.
If the auto-upgrade
feature is enabled on the new switch, the
active switch automatically upgrades the new
switch with the same software image running on a compatible stack member.
Auto-upgrade starts a few minutes after the mismatched software is detected
before starting.
Auto-upgrade is disabled by
default.
Auto-upgrade includes
an auto-copy process and an auto-extract process.
Auto-copy
automatically copies the software image running on any stack member to the new
switch to automatically upgrade it. Auto-copy occurs if auto-upgrade is
enabled, if there is enough flash memory in the new switch, and if the software
image running on the switch stack is suitable for the new switch.
Note
A switch in
VM mode might not run all released software. For example, new switch hardware
is not recognized in earlier versions of software.
Automatic extraction (auto-extract) occurs when the auto-upgrade
process cannot find the appropriate software in the stack to copy to the new
switch. In that case, the auto-extract process searches all switches in the
stack for the bin file needed to upgrade the switch stack or the new switch.
The bin file can be in any flash file system in the switch stack or in the new
switch. If a bin file suitable for the new switch is found on a stack member,
the process extracts the file and automatically upgrades the new switch.
The auto-upgrade feature is
not available in bundle mode. The switch stack must be running in installed
mode. If the switch stack is in bundle mode, use the
software expand
privileged EXEC command to change to installed mode.
You can enable auto-upgrade
by using the
software
auto-upgrade enable global configuration command on the new switch. You can
check the status of auto-upgrade by using the
show
running-config privileged EXEC command and by checking the
Auto upgrade
line in the display.
You can configure
auto-upgrade to upgrade the new switch with a specific software bundle by using
the
software
auto-upgrade source url global configuration command. If the software
bundle is invalid, the new switch is upgraded with the same software image
running on a compatible stack member.
When the auto-upgrade
process is complete, the new switch reloads and joins the stack as a fully
functioning member. If you have both stack cables connected during the reload,
network downtime does not occur because the switch stack operates on two rings.
For more information about upgrading a switch running
incompatible software see the
Cisco IOS File
System, Configuration Files, and Bundle Files Appendix, Cisco IOS XE Release
3SE (Catalyst 3850 Switches).
Auto-Advise
The auto-advise
feature is triggered when:
The
auto-upgrade feature is disabled.
The new switch
is in bundle mode and the stack is in installed mode. Auto-advise displays
syslog messages about using the
software
auto-upgrade privileged EXEC command to change the new switch to
installed mode.
The stack is in
bundle mode. Auto-advise displays syslog messages about booting the new switch
in bundle mode so that it can join the stack.
An auto-upgrade
attempt fails because the new switch is running incompatible software. After
the switch stack performs compatibility checks with the new switch, auto-advise
displays syslog messages about whether the new switch can be auto-upgraded.
Auto-advise cannot
be disabled. It does
not give
suggestions when the switch stack software and the software of the switch in
version-mismatch (VM) mode do not contain the same license level.
Auto-Upgrade Is
Disabled and Incompatible Switch Attempting to Join: Example
This sample
auto-advise output shows the system messages displayed when the auto-upgrade
feature is disabled and an incompatible switch 1 tries to join the switch
stack:
*Oct 18 08:36:19.379: %INSTALLER-6-AUTO_ADVISE_SW_INITIATED: 2 installer: Auto advise initiated for switch 1
*Oct 18 08:36:19.380: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: Searching stack for software to upgrade switch 1
*Oct 18 08:36:19.382: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: Switch 1 with incompatible software has been
*Oct 18 08:36:19.382: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: added to the stack. The software running on
*Oct 18 08:36:19.382: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: all stack members was scanned and it has been
*Oct 18 08:36:19.382: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: determined that the 'software auto-upgrade'
*Oct 18 08:36:19.382: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: command can be used to install compatible
*Oct 18 08:36:19.382: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: software on switch 1.
Auto-Upgrade is
Disabled and New Switch is in Bundle Mode: Example
This sample
auto-advise output shows the system messages displayed when auto-upgrade is
disabled and a switch running in bundle mode tries to join the stack that is
running in installed mode:
*Oct 18 11:09:47.005: %INSTALLER-6-AUTO_ADVISE_SW_INITIATED: 2 installer: Auto advise initiated for switch 1
*Oct 18 11:09:47.005: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: Switch 1 running bundled software has been added
*Oct 18 11:09:47.005: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: to the stack that is running installed software.
*Oct 18 11:09:47.005: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: The 'software auto-upgrade' command can be used to
*Oct 18 11:09:47.005: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: convert switch 1 to the installed running mode by
*Oct 18 11:09:47.005: %INSTALLER-6-AUTO_ADVISE_SW: 2 installer: installing its running software.
SDM Template Mismatch in Switch Stacks
All stack members use the Switch Database Management (SDM) template configured on the active switch. When a new switch is added to a stack, the SDM configuration that is stored on the active switch overrides the template configured on an individual switch.
You can use the show switch privileged EXEC command to see if any stack members are in SDM-mismatch mode.
Version-mismatch (VM) mode has priority over SDM-mismatch mode. If a VM-mode condition and an SDM-mismatch mode exist, the switch stack first attempts to resolve the VM-mode condition.
Switch Stack Management Connectivity
You manage the switch stack and the stack member interfaces through the active switch. You can use the CLI, SNMP, and supported network management applications such as CiscoWorks. You cannot manage stack members on an individual switch basis.
Note
Use SNMP to manage network features across the stack that are defined by supported MIBs. The switch does not support MIBs to manage stacking-specific features such as stack membership and election.
If you want to
configure a specific stack member port, you must include the stack member
number in the CLI command interface notation.
To debug the standby switch,
you can access it from the active switch using the
session standby
ios privileged EXEC command. To debug a specific stack member,
use the
session switchstack-member-number privileged EXEC command from
the active switch to access the diagnostic shell of the stack member. Only the
show and
debug commands
are available in a CLI session to a specific stack member.
Connectivity to the Switch Stack Through an IP Address
The switch stack is managed through a single IP address. The IP address is a system-level setting and is not specific to the active switch or to any other stack member. You can still manage the stack through the same IP address even if you remove the active switch or any other stack member from the stack, provided there is IP connectivity.
Note
Stack members retain their IP addresses when you remove them from a switch stack. To avoid a conflict by having two devices with the same IP address in your network, change the IP addresses of any switches that you remove from the switch stack.
Connectivity to the Switch Stack Through Console Ports or Ethernet Management Ports
You can connect to the active switch by using one of these methods:
You can connect a terminal or a PC to the active switch through the console port of one or more stack members.
You can connect a PC to the active switch through the Ethernet management ports of one or more stack members.
Be careful when using multiple CLI sessions to the active switch. Commands that you enter in one session are not displayed in the other sessions. Therefore, it is possible that you might not be able to identify the session from which you entered a command.
We recommend using only one CLI session when managing the switch stack.
The following table shows the default switch stack configuration settings:
Table 2 Default Switch Stack Configuration
Feature
Default Setting
Stack MAC address timer
Disabled.
Stack member number
1
Stack member priority value
1
Offline configuration
The switch stack is not provisioned.
Persistent MAC address
Disabled.
Enabling the
Persistent MAC Address Feature
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
active switch MAC address elsewhere in the same
domain could result in lost traffic.
SUMMARY STEPS
1.configure terminal
2.stack-mac persistent
timer [0 |
time-value]
3.end
4.copy running-config startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
configure terminal
Example:
Switch# configure terminal
Enters global
configuration mode.
Step 2
stack-mac persistent
timer [0 |
time-value]
Example:
Switch(config)# stack-mac persistent timer 7
Enables a time
delay after an active-switch change before the stack MAC address changes to
that of the new active switch. If the previous active switch rejoins the stack
during this period, the stack uses that MAC address as the stack MAC address.
Enter the
command with no value or with a value of
0 to continue
using the MAC address of the current active switch indefinitely.
Enter a
time-value
from 1 to 60 minutes to configure the time
period before the stack MAC address changes to the new active switch.
The stack
MAC address of the previous active switch is used until the configured time
period expires.
Step 3
end
Example:
Switch(config)# end
Returns to
privileged EXEC mode.
Step 4
copy running-config startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves
your entries in the configuration file.
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.
Step 2
reload slotstack-member-number
Example:
Switch# 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.
This optional task is available only from the active switch.
SUMMARY STEPS
1.show switch
2.configure terminal
3.switchstack-member-numberprovisiontype
4.end
5.copy running-config startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
show switch
Example:
Switch# show switch
Displays summary information about the switch stack.
Step 2
configure terminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 3
switchstack-member-numberprovisiontype
Example:
Switch(config)# switch 3 provision WS-xxxx
Specifies the stack member number for the preconfigured switch. By default, no switches are provisioned.
For stack-member-number, the range is 1 to 9. Specify a stack member number that is not already used in the switch stack. See Step 1.
For type, enter the model number of a supported switch that is listed in the command-line help strings.
Step 4
end
Example:
Switch(config)# end
Returns to privileged EXEC mode.
Step 5
copy running-config startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
Removing Provisioned Switch Information
Before you begin, you must remove the provisioned switch from the stack. This optional task is available only from the active switch.
SUMMARY STEPS
1.configure terminal
2.no switchstack-member-numberprovision
3.end
4.copy running-config startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
configure terminal
Example:
Switch# configure terminal
Enters global configuration mode.
Step 2
no switchstack-member-numberprovision
Example:
Switch(config)# no switch 3 provision
Removes the provisioning information for the specified member.
Step 3
end
Example:
Switch(config)# end
Returns to privileged EXEC mode.
Step 4
copy running-config startup-config
Example:
Switch# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
If you are removing a provisioned switch in a stack with this configuration:
The stack has four members
Stack member 1 is the active switch
Stack member 3 is a provisioned switch
and want to remove the provisioned information and to avoid receiving an error message, you can remove power from stack member 3, disconnect the StackWise-480 cables between the stack member 3 and switches to which it is connected, reconnect the cables between the remaining stack members, and enter the no switchstack-member-numberprovision
global configuration command.
Displaying Incompatible Switches in the Switch Stack
SUMMARY STEPS
1.show switch
DETAILED STEPS
Command or Action
Purpose
Step 1
show switch
Example:
Switch# 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 active switch.
For information about managing license levels, see the System Management Configuration Guide (Catalyst 3850 Switches).
Upgrading an Incompatible Switch in the Switch Stack
SUMMARY STEPS
1.software auto-upgrade
2.copy running-config startup-config
DETAILED STEPS
Command or Action
Purpose
Step 1
software auto-upgrade
Example:
Switch# 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:
Switch# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
Troubleshooting the Switch Stack
Accessing the Diagnostic Console of a Stack Member
Before You Begin
This optional task is available only from the active switch.
SUMMARY STEPS
1.session switchstack-member-number
2.exit
DETAILED STEPS
Command or Action
Purpose
Step 1
session switchstack-member-number
Example:
Switch# session switch 2
Accesses the diagnostic shell of the stack member from the active switch.
If a stack port is flapping and causing instability in the stack ring, to disable the port, enter the switchstack-member-numberstack portport-numberdisable
privileged EXEC command. To reenable the port, enter the switchstack-member-numberstack portport-numberenable command.
Note
Be careful when using the switchstack-member-numberstack portport-numberdisable command. When you disable the stack port, the stack operates at half bandwidth.
A stack is in the full-ring state when all members are connected through the stack ports and are in the ready state.
The stack is in the partial-ring state when the following occurs:
All members are connected through their stack ports but some are not in the ready state.
Some members are not connected through the stack ports.
switchstack-member-numberstack port port-numberenable
Example:
Switch# switch 2 stack port 1 enable
Reenables the stack port.
When you disable a stack port and the stack is in the full-ring state, you can disable only one stack port. This message appears:
Enabling/disabling a stack port may cause undesired stack changes. Continue?[confirm]
When you disable a stack port and the stack is in the partial-ring state, you cannot disable the port. This message appears:
Disabling stack port not allowed with current stack configuration.
Reenabling a Stack Port While Another Member Starts
Stack Port 1 on Switch 1 is connected to Port 2 on Switch 4. If Port 1 is flapping, you can disable Port 1 with the switch 1 stack port 1 disable
privileged EXEC command. While Port 1 on Switch 1 is disabled and Switch 1 is still powered on, follow these steps to reenable a stack port:
Step 1
Disconnect the stack cable between Port 1 on Switch 1 and Port 2 on Switch 4.
Step 2
Remove Switch 4 from the stack.
Step 3
Add a switch to replace Switch 4 and assign it switch-number 4.
Step 4
Reconnect the cable between Port 1 on Switch 1 and Port 2 on Switch 4 (the replacement switch).
Step 5
Reenable the link between the switches. Enter the switch 1 stack port 1 enable privileged EXEC command to enable Port 1 on Switch 1.
Step 6
Power on Switch 4.
Caution
Powering on Switch 4 before enabling the Port 1 on Switch 1 might cause one of the switches to reload.
If Switch 4 is powered on first, you might need to enter the switch 1 stack port 1 enable and the switch 4 stack port 2 enable privileged EXEC commands to bring up the link.
Monitoring the
Switch Stack
Table 3 Commands for
Displaying Stack Information
Command
Description
show switch
Displays
summary information about the stack, including the status of provisioned
switches and switches in version-mismatch mode.
show switchstack-member-number
Displays
information about a specific member.
show switch detail
Displays
detailed information about the stack.
show switch neighbors
Displays the
stack neighbors.
show switch
stack-ports [summary]
Displays
port information for the stack.
Use the
summary keyword
to display the stack cable length, the stack link status, and the loopback
status.
show
redundancy
Displays
the redundant system and the current processor information. The redundant
system information includes the system uptime, standby failures, switchover
reason, hardware, configured and operating redundancy mode. The current
processor information displayed includes the active location, the software
state, the uptime in the current state and so on.
show redundancy
state
Displays
all the redundancy states of the active and standby
switches.
Most of these
switch stack configuration scenarios assume that at least two switches are
connected through their
StackWise-480 ports.
Table 4 Configuration
Scenarios
Scenario
Result
Active switch election
specifically determined by existing
active switches
Connect two
powered-on switch stacks through the
StackWise-480 ports.
Only one of
the two
active switches becomes the new
active switch.
Active switch election
specifically determined by the stack member priority value
Connect
two switches through their
StackWise-480 ports.
Use the
switchstack-member-numberpriority
new-priority-number
EXEC command to set
one stack member with a higher member priority value.
Restart
both stack members at the same time.
The stack
member with the higher priority value is elected
active switch.
Active switch election
specifically determined by the configuration file
Assuming
that both stack members have the same priority value:
Make
sure that one stack member has a default configuration and that the other stack
member has a saved (nondefault) configuration file.
Restart
both stack members at the same time.
The stack
member with the saved configuration file is elected
active switch.
Active switch election
specifically determined by the MAC address
Assuming
that both stack members have the same priority value, configuration file, and
license level, restart
both stack members at the same time.
The stack
member with the lower MAC address is elected
active switch.
Stack member
number conflict
Assuming
that one stack member has a higher priority value than the other stack member:
Ensure
that both stack members have the same stack member number. If necessary, use
the
switchcurrent-stack-member-numberrenumbernew-stack-member-numberEXEC command.
Restart
both stack members at the same time.
The stack
member with the higher priority value retains its stack member number. The
other stack member has a new stack member number.
Add a stack
member
Power
off the new switch.
Through
their
StackWise-480 ports, connect
the new switch to a powered-on switch stack.
Power on
the new switch.
The
active switch is retained. The new switch is added
to the switch stack.
Active switch failure
Remove (or
power off) the
active switch.
The standby switch becomes
the new active switch. All other stack members in the stack remain as stack
members and do not reboot.
Add more than nine stack
members
Through their
StackWise-480 ports, connect
ten
switches.
Power
on all switches.
Two
switches become
active switches. One
active switch has
nine stack members.
The other
active switch remains as a standalone switch.
Use the
Mode button and port LEDs on the switches to identify which switches are
active switches and which switches belong to each
active switch.
Enabling the
Persistent MAC Address Feature: Example
This example shows
how to configure the persistent MAC address feature for a 7-minute time delay
and to verify the configuration:
Switch(config)# stack-mac persistent timer 7
WARNING: The stack continues to use the base MAC of the old Master
WARNING: as the stack MAC after a master switchover until the MAC
WARNING: persistency timer expires. During this time the Network
WARNING: Administrators must make sure that the old stack-mac does
WARNING: not appear elsewhere in this network domain. If it does,
WARNING: user traffic may be blackholed.
Switch(config)# endSwitch# show switch
Switch/Stack Mac Address : 0016.4727.a900
Mac persistency wait time: 7 mins
H/W Current
Switch# Role Mac Address Priority Version State
----------------------------------------------------------
*1 Active 0016.4727.a900 1 P2B Ready
Provisioning a New
Member for a Switch Stack: Example
This example shows
how to provision a switch with a stack member number of 2 for the switch stack.
The
show
running-config command output shows the interfaces associated
with the provisioned switch:
show switch
stack-ports summary Command Output: Example
Only Port 1 on stack
member 2 is disabled.
Switch# show switch stack-ports summarySwitch#/ Stack Neighbor Cable Link Link Sync # In
Port# Port Length OK Active OK Changes Loopback
Status To LinkOK
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 OK 3 50 cm Yes Yes Yes 1 No
1/2 Down None 3 m Yes No Yes 1 No
2/1 Down None 3 m Yes No Yes 1 No
2/2 OK 3 50 cm Yes Yes Yes 1 No
3/1 OK 2 50 cm Yes Yes Yes 1 No
3/2 OK 1 50 cm Yes Yes Yes 1 No
Table 5 show switch
stack-ports summary Command Output
Field
Description
Switch#/Port#
Member
number and its stack port number.
Stack Port
Status
Status of
the stack port.
Absent—No cable is detected on the stack port.
Down—A
cable is detected, but either no connected neighbor is up, or the stack port is
disabled.
OK—A
cable is detected, and the connected neighbor is up.
Neighbor
Switch
number of the active member at the other end of the stack cable.
Cable Length
Valid
lengths are 50 cm, 1 m, or 3 m.
If the
switch cannot detect the cable length, the value is
no
cable. The cable might not be connected, or the link might be unreliable.
Link OK
Whether the
stack cable is connected and functional. There may or may not be a neighbor
connected on the other end.
The
link
partner
is a stack port on a neighbor switch.
No—There
is no stack cable connected to this port or the stack cable is not functional.
Yes—There is a functional stack cable connected to this port.
Link Active
Whether a
neighbor is connected on the other end of the stack cable.
No—No
neighbor is detected on the other end. The port cannot send traffic over this
link.
Yes—A
neighbor is detected on the other end. The port can send traffic over this
link.
Sync OK
Whether the
link partner sends valid protocol messages to the stack port.
No—The
link partner does not send valid protocol messages to the stack port.
Yes—The
link partner sends valid protocol messages to the port.
# Changes to
LinkOK
The relative
stability of the link.
If a large
number of changes occur in a short period of time, link flapping can occur.
In Loopback
Whether a
stack cable is attached to a stack port on the member.
No—At
least one stack port on the member has an attached stack cable.
Yes—None
of the stack ports on the member has an attached stack cable.
Software Loopback:
Examples
In a stack with
three members, stack cables connect all the members:
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 OK 3 50 cm Yes Yes Yes 1 No
1/2 OK 2 3 m Yes Yes Yes 1 No
2/1 OK 1 3 m Yes Yes Yes 1 No
2/2 OK 3 50 cm Yes Yes Yes 1 No
3/1 OK 2 50 cm Yes Yes Yes 1 No
3/2 OK 1 50 cm Yes Yes Yes 1 No
If you disconnect
the stack cable from Port 1 on Switch 1, these messages appear:
01:09:55: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 3 has changed to state DOWN
01:09:56: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has changed to state DOWN
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 Absent None No cable No No No 1 No
1/2 OK 2 3 m Yes Yes Yes 1 No
2/1 OK 1 3 m Yes Yes Yes 1 No
2/2 OK 3 50 cm Yes Yes Yes 1 No
3/1 OK 2 50 cm Yes Yes Yes 1 No
3/2 Down None 50 cm No No No 1 No
If you disconnect
the stack cable from Port 2 on Switch 1, the stack splits.
Switch 2 and Switch
3 are now in a two-member stack connected through stack cables:
Switch# show sw stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
2/1 Down None 3 m No No No 1 No
2/2 OK 3 50 cm Yes Yes Yes 1 No
3/1 OK 2 50 cm Yes Yes Yes 1 No
3/2 Down None 50 cm No No No 1 No
Switch 1 is a
standalone switch:
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 Absent None No cable No No No 1 Yes
1/2 Absent None No cable No No No 1 Yes
Software Loopback
with Connected Stack Cables: Examples
On Port 1 on
Switch 1, the port status is
Down, and
a cable is connected.
On Port 2 on
Switch 1, the port status is
Absent,
and no cable is connected.
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 Down None 50 Cm No No No 1 No
1/2 Absent None No cable No No No 1 No
In a
physical
loopback, a cable connects both stack ports on a switch. You can use this
configuration to test
Cables on a
switch that is running properly
Stack ports
with a cable that works properly
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
2/1 OK 2 50 cm Yes Yes Yes 1 No
2/2 OK 2 50 cm Yes Yes Yes 1 No
The port status
shows that
Switch 2 is
a standalone switch.
The ports
can send and receive traffic.
Software Loopback
with no Connected Stack Cable: Example
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 Absent None No cable No No No 1 Yes
1/2 Absent None No cable No No No 1 Yes
Finding a
Disconnected Stack Cable: Example
Stack cables connect
all stack members. Port 2 on Switch 1 connects to Port 1 on Switch 2.
This is the port
status for the members:
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 OK 2 50 cm Yes Yes Yes 0 No
1/2 OK 2 50 cm Yes Yes Yes 0 No
2/1 OK 1 50 cm Yes Yes Yes 0 No
2/2 OK 1 50 cm Yes Yes Yes 0 No
If you disconnect
the cable from Port 2 on Switch 1, these messages appear:
%STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 2 has changed to state DOWN
%STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN
This is now the port
status:
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 OK 2 50 cm Yes Yes Yes 1 No
1/2 Absent None No cable No No No 2 No
2/1 Down None 50 cm No No No 2 No
2/2 OK 1 50 cm Yes Yes Yes 1 No
Only one end of the
cable connects to a stack port, Port 1 on Switch 2.
The
Stack Port
Status value for Port 2 on Switch 1 is
Absent,
and the value for Port 1 on Switch 2 is
Down.
The
Cable
Length value is
No cable.
Diagnosing the
problem:
Verify the cable
connection for Port 2 on Switch 1.
Port 2 on Switch 1 has a port
or cable problem if
The
In
Loopback value is
Yes.
or
The
Link
OK,
Link
Active, or
Sync
OK value is
No.
Fixing a Bad
Connection Between Stack Ports: Example
Stack cables connect
all members. Port 2 on Switch 1 connects to Port 1 on Switch 2.
This is the port
status:
Switch# show switch stack-ports summarySwitch#
Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In
Status Length OK Active OK To LinkOK Loopback
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 OK 2 50 cm Yes Yes Yes 1 No
1/2 Down None 50 cm No No No 2 No
2/1 Down None 50 cm No No No 2 No
2/2 OK 1 50 cm Yes Yes Yes 1 No
Diagnosing the
problem:
The Stack Port
Status value is
Down.
Link OK, Link
Active, and Sync OK values are
No.
The Cable Length
value is
50 cm. The switch detects and correctly identifies the
cable.
The connection
between Port 2 on Switch 1 and Port 1 on Switch 2 is unreliable on at least one
of the connector pins.
Additional References for Switch Stacks
Related Documents
Related Topic
Document Title
Cabling and powering on a switch stack.
Catalyst 3850 Switch Hardware Installation Guide
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