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Frequent Contributor I

Re: Clustering MD in 8.x. The need for VRRP IP?

This was EXACTLY what I was looking for in order to understand clustering VRRP. Thank you!

 

One question - prior to upgrading to 8.x, one of my interface VLANs was acting as a proxy for IGMP to join multicast groups. How does clustering work with multicast? Not all of my VLANs need to use multicast, only a few. I see that there is an option in the cluster profile to specify the multicast VLAN - which should I choose? My controller management VLAN?

 

Thanks!

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Re: Clustering MD in 8.x. The need for VRRP IP?

Hi everybody,

 

As far as I know remember the following:

 

The cluster manager will use the VRID 220+, so if you are using VRRP for AP discovery please use a VRID below 220!

 

 

Cheers, Frank
AirHeads MVP |AMFX#22| ACCX#613| ACMX#733| ACDX#744

If you like my posts, kudo's are welcome. If it solves your problem, please click 'Accept as Solution'
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Occasional Contributor II

Re: Clustering MD in 8.x. The need for VRRP IP?

So can we use one of the VRRP IP address that was created as part of clustering as the DNS address for controller discovery?

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Re: Clustering MD in 8.x. The need for VRRP IP?

hi,

 

In theory I think you can. There is always a backup VRRP on one of the other members of the cluster.

 

That said, I don't think it is best practise.

 

More important, with a cluster of 4 MC's you can setup the VRRP discovery IP on all four with different prio for VRRP. So you always have that AP discovery IP active. If you use the VRRP from a cluster member (intended for the CoA/Authentication) for the AP discovery you only count on two MC's, not the total of four.

 

Hope this helps

 

 

Cheers, Frank
AirHeads MVP |AMFX#22| ACCX#613| ACMX#733| ACDX#744

If you like my posts, kudo's are welcome. If it solves your problem, please click 'Accept as Solution'
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Frequent Contributor II

Re: Clustering MD in 8.x. The need for VRRP IP?

I wouldn't - there's a catch with VRRP.

 

If you bring up a single controller, the VRRP addresses are not active at all.  This means they won't work for AP discover, and the controllers will only use their directly configured IP addresses for RADIUS/TACACS.  Only once the cluster is up and running, will the VRRP addresses become active.

 

To work around this, I recommend two things.

  1. Put all of the directly configured controller IP addresses into DNS for discovery, not the VRRP ones.
  2. Make sure that your RADIUS server is prepared to handle requests from both VRRP and directly configured addresses.
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Re: Clustering MD in 8.x. The need for VRRP IP?

That’s why it is recommended to have the separate VRRP (redundancy service) set up.

AFAIK the AP will not use all of the configured IP addresses in DNS for discovery so if one MC/MD is down new AP’s might not connect correctly.

Cheers, Frank
AirHeads MVP |AMFX#22| ACCX#613| ACMX#733| ACDX#744

If you like my posts, kudo's are welcome. If it solves your problem, please click 'Accept as Solution'
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Occasional Contributor II

Re: Clustering MD in 8.x. The need for VRRP IP?

Can anyone answer 's question about the multicast VLAN? I'm confused about that too. I have several VLANs that I want to allow multicast on, but I have several others that I don't. The configuration only allows you to add one VLAN as the multicast VLAN, so would that be the management VLAN?

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Frequent Contributor I

Re: Clustering MD in 8.x. The need for VRRP IP?

I worked with TAC on this. You just need to choose one of the VLANs to proxy the traffic for all of the VLANs. For example, I had multicast traffic on VLAN 301-305. I made VLAN 301 the mcast vlan. Everything works automagically.

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Occasional Contributor II

Re: Clustering MD in 8.x. The need for VRRP IP?

OK - That's one of the other ideas I thought about trying. Thanks for the reply efisher214!

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