Wireless Access

Hello i got a question i got asked by a client... 

He was asking me if you could use both ports of the AP 225 for redundancy

 

I know that the AP 225 port 0 and port 1  you would create a link aggregation to reach high speed( 1.3gb)

 

Now you need to do a link aggregation for that

 

What happen if you got a AP 225 and you got your Link aggregation and you connect it to a switch in a stack(the stack its of 2 switches) and you connect port 0 to switch 1 of the stack and you connect port 1 to switch 2 of the stack.  Both switches are POE

 

Let say one switch die, let say switch 1 die so port 0 dies... will the AP will keep working? on port 1 with Poe and everything? 

I mean will this work for redundancy? just as i explained it or this is just not possible or not recommended for that?

He asked me that because he got a place in which it seems that for some reason the uptime needs to be 100% so they are trying to design something in which everything is redundand...

 

Cheers

Carlos

#AP225

If the switch that is providing the power dies, the AP will reboot and come up on the second switch.

If the switch that is providing a second data link dies, the AP will stay up and continue forwarding.

I rarely deploy LAGs on 225s for speed, only for switch redundancy.

Thanks,
Tim

Tim

So you deploy this for redundancy more than for speed?

 

So this scanenario is possible ? the only thing that will happen is that if for example the poe at that time is being provided by the switch that die the AP will reboot but after that it will continue working? the only thing is that the the other switch will start provising POE?  in this case if switch 1 die then it will start providing POE in switch 2 for port 1 and the AP will just work at that time on the port 1 but it will work, just that migh reboot?

 

Right?

 

Cheers

Carlos

Yes. The AP only has one PD circuit so only one interface can pull power at a time.

If you lose the port providing power, the AP will negotiate power from the other switch and boot back up and forward traffic.

I treat the 2G agg as an added bonus when providing redundancy.


Thanks,
Tim

I would like to add 1 further question.

 

If the setup was only a single switch (with good POE budget), what is the best configuration to provide resilience for a single cable failing ? Power rather than speed.

So, for example both eth0 and eth1 of AP are connected to the switch on port 1 and 2 respectively. If eth0 failed, will AP only reboot on eth1 cable if LAG has been configured ?

 

Is this a configurable option or if no LAG configured would 1 of the switch ports need to be disabled ?

The AP will always reboot if the ethernet that is powering it goes down.  When the AP boots, even if it forms a LAG, only a single ethernet actually provides the power.  If that interface goes down, the AP must reboot.

Hi Colin

Thanks for the speedy reply.

I understand the re-boot scenario. So just to clarify in my own mind.

Putting LAG asside, if i connected an AP225 to a single switch, by using eth0 and eth1 of the AP connected to (example) ports 1 and 2 of the powered switch (both ports POE enabled) i will have power redundancy should a single cable fail. Albeit with a reboot of the AP.

My understanding also is that on initial boot with both cat5/6 cables operational, the eth0 and eth 1 would be in a race condition to provide power. not necessarily always eth0. Is that also correct ?

Correct.

Thankyou