ArubaOS and Controllers

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Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Standby master and OSPF

Before I open (another) case with TAC, is a standby master controller supposed to be able to form an OSPF neighbor relationship?
Regular Contributor I
Posts: 163
Registered: ‎04-11-2011

Re: Standby master and OSPF

I have this same scenario, what did you find out?
Guru Elite
Posts: 20,553
Registered: ‎03-29-2007

Re: Standby master and OSPF

Only the active master controller can form an OSPF adjacency. The backup master cannot.

This is by design. A backup master cannot answer traffic from access points, so it should also not be advertising reachability. The purpose of OSPF in an Aruba Network is to advertise reachability so that access points can be terminated to a controller. Since a backup master cannot service access points, it should not be advertising reachability.


Colin Joseph
Aruba Customer Engineering

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Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: Standby master and OSPF

Like Colin says, no a backup master will not establish an adjacency.

However, adjacencies and advertising reachability are two different things. A backup master could certainly have an adjacency and probably always should, but that's not the way Aruba designed it. Since APs can't connect to a backup controller, the AP VLANs will be down anyway and wouldn't be advertised by OSPF regardless.
Guru Elite
Posts: 20,553
Registered: ‎03-29-2007

Re: Standby master and OSPF


Like Colin says, no a backup master will not establish an adjacency.

However, adjacencies and advertising reachability are two different things. A backup master could certainly have an adjacency and probably always should, but that's not the way Aruba designed it. Since APs can't connect to a backup controller, the AP VLANs will be down anyway and wouldn't be advertised by OSPF regardless.




That is interesting. What would be the utility of a WLAN device forming a routing adjacency if it cannot terminate access points? Local controllers, on the other hand, CAN participate in the OSPF process. If there is a need to form that adjacency, that is probably what should be used.


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: Standby master and OSPF

Two reasons off the top of my head.

First, you know that OSPF is configured properly and is functioning properly. So, in case of failover, we know that OSPF won't be an issue. I fear someone could muck with the OSPF config on the backup controller or its upstream router and you won't know until it's too late.

Second, what about the controller's upstream router sending routes to the controller? Just because it's backup doesn't mean it doesn't need routes. Why deal with statics when I shouldn't have to?
Guru Elite
Posts: 20,553
Registered: ‎03-29-2007

Re: Standby master and OSPF

Which is why a local controller should be used in that situation.

OSPF was introduced for when you have a Remote AP controller that backed up another Remote AP contoroller in a geographically separated datacenter and the clients, especially wired ones, needed to maintain the same ip address space. OSPF is not necessary in a campus network and is not worth the complexity of OSPF since campus WLAN should be just an overlay to a highly available routed network.

That is why in the Campus Validated Reference Design document here: http://www.arubanetworks.com/pdf/technology/VRD_Campus_Networks.pdf, you will not find a word about OSPF.


Colin Joseph
Aruba Customer Engineering

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Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: Standby master and OSPF

I am talking about a geographically diverse RAP controller deployment.
Guru Elite
Posts: 20,553
Registered: ‎03-29-2007

Re: Standby master and OSPF

In that situation you would have a very low-end master-backup master pair (3200s) in your datacenter strictly to replicate and provide high availability for the RAP whitelist, AP database information and cap database and would terminate no APs. To terminate RAP traffic, you would have 2 controllers, locals, running OSPF to maintain client ip addressing information.

That master-backup master pair could also service actual WLAN controllers, as well.


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: Standby master and OSPF

That's not what we do for RAPs. We have two 6000s with M3s, one master one backup. I don't like locals in a RAP deployment because RAP whitelists aren't synced to them.
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