C5210 failover options

[Rahman_Duran1]

Hi,

We have C5210 controller with 100 AP license. We use B@EWC topologies and don't want clients lose connection if controller is down. If we want some redundancy what are our options?

Do we need an identical C5210? Do wee need all AP licences on the hot-standby controller? Can we use virtual controller appliance as hot standby controller?

Thanks,

Rahman

[Paulo_Francisco]

if High Availability is of importance, the recommended configuration is always to pair controllers of the same characteristics. So, C52110 should always be paired whenever possible with another C5210. Un-matched configurations are not recommended, and caution would be advised in pairing physical (especially high end appliances) and virtual appliances.

Although un-matched configurations will work (to a set of capacity variables) , it is not hard for customers to overlook the capacity of the smallest system and then realize during a failover event that some APs are not connected, or that some users are disconnected and un-able to re-associate (oversubscribe user limits). The responsibility is on the administrator/IT to ensure that the HA-Pair is operated and configured within the limits of the smallest system. Also, even though one admin may be aware of the restrictions of an un-matching pair, IT staff changes can easily miss this restriction and load the larger controller beyond the capabilities of the HA pair. These situations will no doubt end up un-necessarily as escalations to GTAC

There are significant differences across the wireless appliance portfolio beyond just the number of APs that are supported (#services, #Policies, #Topologies, supported Data rates). For HA we recommend keeping configuration synchronized in the HA pair. If the systems are un-matched it is easy to oversaturate the peer's other capacity limits and therefore end up in situations where certain services are not available or behave inconsistent after failover (and then back to GTAC...) . Note that V2110 is only asserted for 2 Gbps (2 x 1) throughput, whereas a C5210 has been asserted up to 18.6 Gbps. Also, a V2110 installation is typically not alone on the host, so even the available processing and network resources can be further restricted.

There are way to many variables to consider in an un-matched HA pair - it will likely work under special circumstances, but also raises the possibility for failure during an HA event. For those reasons I would not recommend such un-matched installations unless absolutely necessary.

Per this inquiry, my strong recommendation would be to pair with another C5210.However, if absolutely necessary to pair with a virtual appliance, then I suggest that at minimum deploy the 9.21 VMWARE-V2110 configured for Large (8 core, 4 GB RAM, 25 GB) category*.

V2110 is available for VMware (EXSi 5.5) and Microsoft Hyper-V (Windows Server 2012 R2). No other hypervisor technology is currently supported, including KVM. We have no committed plans to support KVM in a near term release, but will consider prioritizing backlog if business case warrants it.

*System limits and system performance characteristics do not match, so administrator needs to exercise care in the configuration and monitor operational states to avoid surprises if/when a Failover is required.

Paulo

[Karthik1]

Hi Rahman,

Linux/KVM is not officially tested and so no support will be available if you use it. Besides, NMS, NAC are basically Linux distributions with NMS, NAC software preinstalled for quick deployment. But V2110 is heavily customized, so chances of V2110 running on KVM is very low.

Thanks
Karthik.

[Rahman_Duran1]

Thank you, I will evaluate it on VMware.

[Rahman_Duran1]

Hi Ronald,

Thank you for your suggestions. We have 50 AP's at the moment and we saw ~700 clients at peak times. I don't think we will have more than 300-350 AP's and 3000 simultaneous clients ever. VMWare is free as I know and we have some spare rack server. So it seems V2110 can handle our wifi service until C5210 comes back online.

P.S. Does V2110 run on KVM even if it is unsupported officialy? We evaluate our NAC and NMS appliances on Linux/KVM without any problem.

Thanks,

Rahman