5508 HA

[Michael Bredell]

Hi guys,

A client of ours has 2 x AIR-CT5508-K9. Both are running 8.0.120.0 (can't upgrade the software as they have some outdated AP's). Both controllers are connected to 2 6509's running in VSS.Both controllers have licensing for 250AP's

Anyways, they have asked if they can run them in HA. Do they need to buy an HA controller specifically?. I don't see anything online stating you specifically need an HA controller? Am I wrong here?

Thanks in advance.

[Sandeep Choudhary]

Hi ,

Yes you can run HA:

HA N+1 ---> its currently you are using..

HA AP/Client SSO --> for it you need to convert secondary WLC to HA (for that you need atleast 50 AP license on it.) 

Regards

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[Jhosbell Verdesca De Aguiar · Accepted solution]

There are two types of HA for WLCs.

You have 250 Licenses on both WLCs. So depending on the number of APs you have, there are few options:

1. If you have IN TOTAL less than 250 APs. You can simply configure HA SSO and one of the WLCs will be set as Secondary WLC. Keep in mind, that for 5508 to become secondary WLC it requires at least 50 AP licenses (You have 250 so you're good). However, the secondary WLC inherits the licenses from the primary WLC once they're configured as HA SSO. So you will have a total of 250 AP licenses. (even when you have 500 right now). Whenever the ACTIVE WLC fails, the STANDBY WLC takes over with minimal downtime. (APs and authenticated clients remain connected)

2. If you have more than 250 APs, then, you can load balance the APs between both WLCs and set the other as secondary WLC for those APs. This is called N+1. Both WLCs will be standalone and independent. Meaning, every configuration change needs to be done in both boxes. Keep in mind that if you have more than 250 APs whenever one of the WLC fails, the other won't have enough licenses to accept all the APs. You can set AP priority to make sure the most critical APs join tho. When the Primary WLC fails, the APs need to wait for the keepalives to timeout and then join the Secondary WLC. So there is a downtime.

3. If you have less than 250 APs but do not want to have HA SSO (I don't see a reason for it - but it is an option), then you can configure N+1 as described above.

[Michael Bredell]

Thank you! This makes perfect sense.

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@Jhosbell Verdesca De Aguiar wrote:
There are two types of HA for WLCs.

You have 250 Licenses on both WLCs. So depending on the number of APs you have, there are few options:

1. If you have IN TOTAL less than 250 APs. You can simply configure HA SSO and one of the WLCs will be set as Secondary WLC. Keep in mind, that for 5508 to become secondary WLC it requires at least 50 AP licenses (You have 250 so you're good). However, the secondary WLC inherits the licenses from the primary WLC once they're configured as HA SSO. So you will have a total of 250 AP licenses. (even when you have 500 right now). Whenever the ACTIVE WLC fails, the STANDBY WLC takes over with minimal downtime. (APs and authenticated clients remain connected)

2. If you have more than 250 APs, then, you can load balance the APs between both WLCs and set the other as secondary WLC for those APs. This is called N+1. Both WLCs will be standalone and independent. Meaning, every configuration change needs to be done in both boxes. Keep in mind that if you have more than 250 APs whenever one of the WLC fails, the other won't have enough licenses to accept all the APs. You can set AP priority to make sure the most critical APs join tho. When the Primary WLC fails, the APs need to wait for the keepalives to timeout and then join the Secondary WLC. So there is a downtime.

3. If you have less than 250 APs but do not want to have HA SSO (I don't see a reason for it - but it is an option), then you can configure N+1 as described above.

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@Jhosbell Verdesca De Aguiar wrote:
There are two types of HA for WLCs.

You have 250 Licenses on both WLCs. So depending on the number of APs you have, there are few options:

1. If you have IN TOTAL less than 250 APs. You can simply configure HA SSO and one of the WLCs will be set as Secondary WLC. Keep in mind, that for 5508 to become secondary WLC it requires at least 50 AP licenses (You have 250 so you're good). However, the secondary WLC inherits the licenses from the primary WLC once they're configured as HA SSO. So you will have a total of 250 AP licenses. (even when you have 500 right now). Whenever the ACTIVE WLC fails, the STANDBY WLC takes over with minimal downtime. (APs and authenticated clients remain connected)

2. If you have more than 250 APs, then, you can load balance the APs between both WLCs and set the other as secondary WLC for those APs. This is called N+1. Both WLCs will be standalone and independent. Meaning, every configuration change needs to be done in both boxes. Keep in mind that if you have more than 250 APs whenever one of the WLC fails, the other won't have enough licenses to accept all the APs. You can set AP priority to make sure the most critical APs join tho. When the Primary WLC fails, the APs need to wait for the keepalives to timeout and then join the Secondary WLC. So there is a downtime.

3. If you have less than 250 APs but do not want to have HA SSO (I don't see a reason for it - but it is an option), then you can configure N+1 as described above.

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