C9800 HA-SSO RP vs RP+RMI for Redundancy Port connection via L2-VLAN

[merilcerpos]

according to high availability deployment guide 17.3 for C9800 WLCs there are 2 options for Redundancy:

via RP

Connecting a C9800 wireless controller HA pair to upstream switches Prior to 17.1 following topologies were supported in terms of upstream connectivity to the network:

1. SSO pair connected to upstream VSS pair with split links and RP connected back to back.
2. SSO pair connected to upstream VSS pair with RP connected via the upstream set of switches in order to detect gateway down scenario.
3. SSO pair connected to upstream HSRP active and standby and RP connected via upstream set of switches in order to detect gateway down scenario

and via RP+RMI, which is suggested and supported. This requires according to the guide back to back connection between the 2 WLCs. Does this mean if you can connect redundancy port only via L2 switched VLAN only RP without RMI is best choice?

With the option of RMI and default gateway check feature available in release 17.1, the following topologies are now supported and recommended:

1. SSO pair connected to upstream VSS pair with split links and RP connected back to back.
2. SSO pair connected to upstream VSS pair and RP connected back to back.
3. SSO pair connected to upstream HSRP active and standby and RP connected back to back.

https://www.cisco.com/c/dam/en/us/td/docs/wireless/controller/9800/17-3/deployment-guide/c9800-ha-sso-deployment-guide-rel-17-3.pdf

[Haydn Andrews]

Perered method is that the RP port be connected back to back in either scenario.

If that is not possible then the RP port needs to be connected via a non routed layer 2 VLAN (with just that RP port on it).

RP vs RP+RMI

Basically RP+RMI will also check reachability of the gateway from the WLCs management interface, where as RP only uses the RP port to check the redundant WLC.

For VSS, If able i split the WLC ports to a port channel accross the stack. One port channel per WLC.

In HSRP the port channel accross different switches/blade within the primary HSRP switch for the primary WLC and same for the secondary WLC to the secondary HSRP switch