Cisco WLC C9800-L HA的配置方式RMI+RP

16.x 只能支持RP

https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/213915-configure-catalyst-9800-wireless-control.html

17.X 支持RP 和RMI 2种

https://www.cisco.com/c/dam/en/us/td/docs/wireless/controller/9800/17-2/deployment-guide/c9800-ha-sso-deployment-guide-rel-17-2.pdf

为什么推荐RP上连到交换机而不是WLC直连？

网关检测

Default Gateway Check
Default Gateway check is done by periodically sending Internet Control Message Protocol (ICMP) ping to the gateway. Both
the active and the standby controllers use the RMI IP as the source IP. These messages are sent at 1 second interval. If
there are 8 consecutive failures in reaching the gateway, the controller will declare the gateway as non-reachable.
After 4 ICMP Echo requests fail to get ICMP Echo responses, ARP requests are attempted. If there is no response for 8
seconds (4 ICMP Echo Requests followed by 4 ARP Requests), the gateway is assumed to be non-reachable. Currently, this feature supports IPv4 only.

The Catalyst 9800 Wireless controller has two recovery states to prevent an active-active scenario.
Recovery mode logically means a state where the controller does not have all “resources” available to provide the service.
Currently, RP, RMI and Gateway are the resources. Ports will be in admin down in recovery mode, so no traffic goes
through.
■ Standby-Recovery: If Gateway goes down, standby goes to standby-recovery mode. Standby means, its state is
up to date with the active. But since it does not have the other resource (Gateway) it goes to Standby-Recovery.
The standby shall not be in a position to take over the active functionality when it is in standby-recovery mode.
Standby-Recovery will go back to Standby without a reload, once it detects that the Gateway reachability is
restored.
■ Active-Recovery is when the RP goes down. Active-Recovery does not have its internal state in sync with the
Active. Active-Recovery will reload when the RP link comes up so that it can come up as Standby with bulk sync.
Switchover history will show switchover reason as Gateway down in the event of a switchover triggered as a result of the
gateway going down.

Default Gateway Check WebUI Configuration

The default gateway check option can be configured under Administration > Device > Redundancy > Management Gateway Failover

Default Gateway Check CLI Configuration

The following CLIs need to be configured for the gateway check functionality to be enabled and to specify the default
gateway IP used by this feature

WLC-9800(config)#management gateway-failover enable
WLC-9800#ip default-gateway 
To verify if gateway check is enabled, use the CLI show redundancy state
WLC-9800#show redundancy states
 my state = 13 -ACTIVE
 peer state = 8 -STANDBY HOT
 Mode = Duplex
 Unit = Primary
Unit ID = 2
Redundancy Mode (Operational) = sso
Redundancy Mode (Configured) = sso
Redundancy State = sso
…
Gateway Monitoring = Enabled

With 17.2, usage of “ip default-gateway ” shall be removed . Gateway IP will be picked up from the static IP routes configured. The HA infrastructure will choose the static route IP that matches the RMI network. If there are multiple static routes configured, the route configured for the broadest network scope shall be selected. It is possible to configure multiple gateways for the same network scope. If there are multiple gateways for the same network, broadest mask and least gateway IP is chosen. The gateway IP shall be reevaluated, if necessary, when config update to static routes happens.

Note:

•Physical port down scenario takes 8 seconds to be detected as it is detected via GW check mechanism
•Physical port status is synced from the active to standby controller in release 17.1. This has been fixed in release 17.2 and
the active and standby controllers maintain their own port status.