Slow Negotiated Speed for AP-515 Access Points

[stevenjacobs]

We have recently deployed a new Instant cluster, based on AP-515 access points, running ArubaOS 8.5.0.2.

We noticed that actual perceived speeds for clients were low, even though the signal was very good.

Based on the client's association to the network, a client should be at 173Mbps (VHT, 2SS, 20Mhz, 256QAM, SGI).

However, the maximum speed for -any- client, even those with an SNR of 50 or higher, never exceeds 86Mbps in the Instant UI.

Setting the channel width to 40Mhz doubles the speed, but it's still much lower than what is should be: this time 173 instead of 400.
Basically, it looks as if only 1 spatial stream is being utilized. But this conflicts from what we see in the association table.

We tried downgrading to 8.4.0.4 to see if this fixes the issue (8.4 is the lowest supported for this type of AP), to no avail.

We manage lots of IAP clusters, all with nearly identical configurations. The config of this cluster is based on a cluster of IAP-305s running 6.5.4.12.

On any other cluster running 6.5.4.12, the speeds (both perceived as well as in the UI) are much better than on this new cluster with newer APs.

Any ideas?

[stevenjacobs · Accepted solution]

Hi Colin,

They are powered by PoE+.

And that's when the penny dropped... We forgot to enable LLDP.

After enabling it I noticed the inline power went up from 15.4 to 30, and speeds went up as well.

Once again, you saved the day! Cheers!

[cjoseph]

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@stevenjacobs wrote:

We have recently deployed a new Instant cluster, based on AP-515 access points, running ArubaOS 8.5.0.2.

We noticed that actual perceived speeds for clients were low, even though the signal was very good.

Based on the client's association to the network, a client should be at 173Mbps (VHT, 2SS, 20Mhz, 256QAM, SGI).

However, the maximum speed for -any- client, even those with an SNR of 50 or higher, never exceeds 86Mbps in the Instant UI.

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What channel width was it on initially when you observed this?

[stevenjacobs]

Hello Colin,

We had the cluster configured at 20Mhz from day one. Only yesterday we discovered this symptom after we received some complaints about the speeds.

[cjoseph]

Do you have broadcast filtering enabled on all of your SSIDs?

How many SSIDs do you have configured?

How are your IAP-515s powered?

[stevenjacobs · Accepted solution]

Hi Colin,

They are powered by PoE+.

And that's when the penny dropped... We forgot to enable LLDP.

After enabling it I noticed the inline power went up from 15.4 to 30, and speeds went up as well.

Once again, you saved the day! Cheers!