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The high availability feature is enabled by default when the controllers are connected using the stack cable and the technology is enabled. You cannot disable it; however, you can initiate a manual graceful-switchover using the command line interface to use the high availability feature enabled in the controller.
In Cisco Wireless LAN Controllers, high availability is achieved with redundancy.
In Cisco Wireless LAN Controllers, redundancy is achieved in two ways— n+1 and AP SSO redundancy.
In case of n+1 redundancy, access points are configured with primary, secondary, and tertiary controllers. When the primary controller fails, depending upon the number of access points managed by a controller, the access point fails over to the secondary controller. In case of AP SSO redundancy, once the primary controller is unavailable, the access points re-discovers the controller and reestablishes the CAPWAP tunnel with the secondary controller. However, all clients must disconnect and a re-authentication is performed to rejoin the controller.
You can configure primary, secondary, and tertiary controllers for a selected access point and a selected controller.
In an ideal high availability deployment, you can have access points connected to primary and secondary controllers and one controller can remain with out connection to any access points. This way the controller that does not have any access points can take over when a failure occurs and resume services of active controller.
You must use the commands explained in this section to configure primary, secondary, or tertiary controllers for a selected access point.
1. conf t
2. ap capwap backup primary
3.
ap capwap backup secondary
4. ap capwap backup tertiary
Once you complete configuration of the primary, secondary, and tertiary controllers for a selected access point, you must verify the configuration using the show ap name AP-NAME command. For more details on, show ap name AP-NAME command, see the Lightweight Access Point Configuration Guide for Cisco Wireless LAN Controller.
Hearbeat messages enable you to reduce the controller failure detection time. When a failure occurs, a switchover from active to hot standby happens after the controller waits for the heartbeat timer. If the controller does not function within the heartbeat time, then the standby takes over as then active controller. Ideally the access point generates three heartbeat messages within the time out value specified, and when the controller does not respond within the timeout value, the standby controller takes over as active. You can specify the timeout value depending on your network. Ideally the timer value is not a higher value as some chaos will occur while performing a switchover. This section explains on how to configure heartbeat interval between the controller and the access points using a timeout value to reduce the controller failure detection time.
1. conf t
2. ap capwap timers heartbeat-timeout
Command or Action | Purpose |
---|
An Access Point Stateful Switch Over (AP SSO) implies that all the access point sessions are switched over state-fully and the user session information is maintained during a switchover, and access points continue to operate in network with no loss of sessions, providing improved network availability. The active controller in the stack is equipped to perform all network functions, including IP functions and routing information exchange. The controller supports 1000 access points and 12000 clients.
However, all the clients are de-authenticated and need to be re-associated with the new active controller except for the locally switched clients in FlexConnect mode when a switchover occurs.
Once a redundancy pair is formed while in a stack, high availability is enabled, which includes that access points continue to remain connected during an active-to-standby switchover.
Note | You can not disable AP SSO while in a controller stack once the controllers form a redundant pair. |
To perform a manual switchover and to use the high availability feature enabled in the controller, execute the redundancy force-switchover command. This command initiates a graceful switchover from the active to the standby controller.
Controller# redundancy force-switchover
System configuration has been modified. Save ? [yes/no] : yes
Building configuration …
Preparing for switchover …
Compressed configuration from 14977 bytes to 6592 bytes[OK]This will reload the active unit and force switchover to standby[confirm] : y
The LAG, or an EtherChannel, bundles all the existing ports in both the standby and active units into a single logical port to provide an aggregate bandwidth of 60 Gbps. The creation of an EtherChannel enables protection against failures. The EtherChannels or LAGs created are used for link redundancy to ensure high availability of access points.
1.
configure terminal
2.
interface port-channel
number
3.
lacp max-bundle
number
4.
lacp port-priority
number
5.
switchport backup interface
po2
6.
end
7.
show etherchannel summary
8.
show interfaces switchport backup
You can only access the console of the active controller in a stack. To access the standby controller, use the following commands.
Use this functionality only under supervision of Cisco Support.
1.
configure terminal
2.
service internal
3.
redundancy
4.
main-cpu
5.
standby console enable
6.
exit
A switchover happens when the active controller fails; however, while performing a manual switchover, you can execute these commands to initiate a successful switchover:
1.
show redundancy states
2.
show
switch detail
3.
show
platform ses states
4.
show
ap summary
5.
show
capwap detail
6.
show
dtls database-brief
7.
show
power inline
This section defines the steps that you must perform to ensure that successful switchover from the active to standby controller is performed. On successful switchover of the standby controller as active, all access points connected to the active need to re-join the standby (then active) controller.
1.
show ap uptime
2.
show wireless summary
3.
show wcdb database all
4.
show power inline
Command or Action | Purpose | |
---|---|---|
Step 1 | show ap uptime
Example: Controller# show ap uptime
|
Verify if the uptime of the access point after the switchover is large enough. |
Step 2 | show wireless summary
Example: Controller# show wireless summary
|
Display the clients connected in the active controller. |
Step 3 | show wcdb database all
Example: Controller# show wcdb database all
|
Display if the client has reached the uptime. |
Step 4 | show power inline
Example: Controller# show power inline
|
Display the power over Ethernet power state. |
Command |
Description |
---|---|
show switch |
Displays summary information about the stack, including the status of provisioned switches and switches in version-mismatch mode. |
show switch stack-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 |
Displays port information for the stack. |
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 controllers. |
This example shows how to configure LACP and to verify creation of the LACP bundle and the status:
Controller(config)# ! interface TenGigabitEthernet1/0/1 switchport mode trunk channel-group 1 mode active lacp port-priority 10 ip dhcp snooping trust ! interface TenGigabitEthernet1/0/2 switchport mode trunk channel-group 1 mode active lacp port-priority 10 ip dhcp snooping trust ! interface TenGigabitEthernet1/0/3 switchport mode trunk channel-group 1 mode active lacp port-priority 10 ip dhcp snooping trust ! interface TenGigabitEthernet1/0/4 switchport mode trunk channel-group 1 mode active ip dhcp snooping trust ! interface TenGigabitEthernet1/0/5 switchport mode trunk channel-group 1 mode active ip dhcp snooping trust ! interface TenGigabitEthernet1/0/6 switchport mode trunk channel-group 1 mode active ip dhcp snooping trust ! interface TenGigabitEthernet2/0/1 switchport mode trunk channel-group 1 mode active lacp port-priority 10 ip dhcp snooping trust ! interface TenGigabitEthernet2/0/2 switchport mode trunk channel-group 1 mode active lacp port-priority 10 ip dhcp snooping trust ! interface TenGigabitEthernet2/0/3 switchport mode trunk channel-group 1 mode active lacp port-priority 10 ip dhcp snooping trust ! interface TenGigabitEthernet2/0/4 switchport mode trunk channel-group 1 mode active ip dhcp snooping trust ! interface TenGigabitEthernet2/0/5 switchport mode trunk channel-group 1 mode active ip dhcp snooping trust ! interface TenGigabitEthernet2/0/6 switchport mode trunk channel-group 1 mode active ip dhcp snooping trust ! interface Vlan1 no ip address ip igmp version 1 shutdown ! Controller# show etherchannel summary Flags: D - down P - bundled in port-channel I - stand-alone s - suspended H - Hot-standby (LACP only) R - Layer3 S - Layer2 U - in use f - failed to allocate aggregator M - not in use, minimum links not met u - unsuitable for bundling w - waiting to be aggregated d - default port Number of channel-groups in use: 1 Number of aggregators: 1 Group Port-channel Protocol Ports ------+-------------+-----------+----------------------------------------------- 1 Po1(SU) LACP Te1/0/1(P) Te1/0/2(P) Te1/0/3(P) Te1/0/4(H) Te1/0/5(H) Te1/0/6(H) Te2/0/1(P) Te2/0/2(P) Te2/0/3(P) Te2/0/4(H) Te2/0/5(H) Te2/0/6(H)
This example shows the switch backup interface pairs:
Controller# show interfaces switchport backup
Switch Backup Interface Pairs:
Active Interface Backup Interface State
------------------------------------------------------------------------
Port-channel1 Port-channel2 Active Standby/Backup Up
This example shows the summary of the EtherChannel configured in the controller:
Controller# show ethernet summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 2
Number of aggregators: 2
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) LACP Te1/0/1(P) Te1/0/2(P) Te1/0/3(P)
Te1/0/4(P) Te1/0/5(P) Te1/0/6(P)
2 Po2(SU) LACP Te2/0/1(P) Te2/0/2(P) Te2/0/3(P)
Te2/0/4(P) Te2/0/5(P) Te2/0/6(P)
This example shows how to configure flex link and to verify creation and the status of the created link:
Controller(config)# ! interface Port-channel1 description Ports 1-6 connected to NW-55-SW switchport mode trunk switchport backup interface Po2 switchport backup interface Po2 preemption mode forced switchport backup interface Po2 preemption delay 1 ip dhcp snooping trust ! interface Port-channel2 description Ports 7-12connected to NW-55-SW switchport mode trunk ip dhcp snooping trust ! interface GigabitEthernet0/0 vrf forwarding Mgmt-vrf no ip address negotiation auto ! interface TenGigabitEthernet1/0/1 switchport mode trunk channel-group 1 mode on ip dhcp snooping trust ! interface TenGigabitEthernet1/0/2 switchport mode trunk channel-group 1 mode on ip dhcp snooping trust ! interface TenGigabitEthernet1/0/3 switchport mode trunk channel-group 1 mode on ip dhcp snooping trust ! interface TenGigabitEthernet1/0/4 switchport mode trunk channel-group 1 mode on ip dhcp snooping trust ! interface TenGigabitEthernet1/0/5 switchport mode trunk channel-group 1 mode on ip dhcp snooping trust ! interface TenGigabitEthernet1/0/6 switchport mode trunk channel-group 1 mode on ip dhcp snooping trust ! interface TenGigabitEthernet2/0/1 switchport mode trunk channel-group 2 mode on ip dhcp snooping trust ! interface TenGigabitEthernet2/0/2 switchport mode trunk channel-group 2 mode on ip dhcp snooping trust ! interface TenGigabitEthernet2/0/3 switchport mode trunk channel-group 2 mode on ip dhcp snooping trust ! interface TenGigabitEthernet2/0/4 switchport mode trunk channel-group 2 mode on ip dhcp snooping trust ! interface TenGigabitEthernet2/0/5 switchport mode trunk channel-group 2 mode on ip dhcp snooping trust ! interface TenGigabitEthernet2/0/6 switchport mode trunk channel-group 2 mode on ip dhcp snooping trust ! interface Vlan1 no ip address Controller# show etherchannel summary Flags: D - down P - bundled in port-channel I - stand-alone s - suspended H - Hot-standby (LACP only) R - Layer3 S - Layer2 U - in use f - failed to allocate aggregator M - not in use, minimum links not met u - unsuitable for bundling w - waiting to be aggregated d - default port Number of channel-groups in use: 2 Number of aggregators: 2 Group Port-channel Protocol Ports ------+-------------+-----------+----------------------------------------------- 1 Po1(SU) - Te1/0/1(P) Te1/0/2(P) Te1/0/3(P) Te1/0/4(P) Te1/0/5(P) Te1/0/6(P) 2 Po2(SU) - Te2/0/1(P) Te2/0/2(P) Te2/0/3(D) Te2/0/4(P) Te2/0/5(P) Te2/0/6(P)
Step 1 | Click
The Redundancy States page is displayed. The values for the following parameters are displayed in the page:
| ||||||||||||
Step 2 | Click Apply. |
Step 1 | Click
The Redundancy States page is displayed. The values for the following parameters are displayed in the page:
| ||||||||||||||||||||||||||||||||
Step 2 | Click Apply. |