Wireless Access

Hello Airheads,

I'm currently exploring the idea of enabling jumbo frames on a new AOS10 Gateway based wireless network, as per customer requirements.

I have a few specific questions and would appreciate any insights from those who have experience with this:

1. Is enabling jumbo frames on Aruba APs and controllers considered a best practice?
   I understand there may be performance benefits for data transfer between the controllers and APs themselves (and switches in between), but is there a downside to enabling it? I'd love to hear about real-world experiences or any potential challenges.

2. Client Devices and Fragmentation:
   Since most client devices don't support jumbo frames (or difficult to control), I assume they will still send standard Ethernet frame sizes. In this case, does fragmentation occur when jumbo frames are sent back to the client? How does the infrastructure handle this?

3. Where to Enable Jumbo Frames:
   There are several places to enable jumbo frames on an AOS10 Gateway, such as the global setting, per-interface settings, port-channel, Global Firewall settings (Jumbo Frame processing). What are the best practices for determining where to enable jumbo frames?
   
   
4. How is Jumbo Frames enabled on the AP in AOS10?
   AOS8 used to have a SAP profile under the AP group where you could specify the MTU. I can't find a similar setting in AOS10.

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Brett V
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Hi BrettV

I will try to give my opinion on here.

By enabling jumbo frames you can have performance improvements, however it requires careful planning in order to avoid potential downsides.
So related to your question No.1:

In a high-throughput, controller-based network, enabling jumbo frames (typically MTU 9000) between APs, switches, and controllers can reduce overhead and improve efficiency, especially for high-speed traffic such as:

• AP ↔ Controller communication
• AP ↔ Gateway uplinks (AOS10-based environments)
• High-bandwidth applications (e.g., VoIP, video streaming, large file transfers

You must be careful in making sure the compatibility issues with non-jumbo-frame devices. If any switches or links in the network don't support jumbo frames, it can lead to packet drops or fragmentation. Some firewall policies and ACLs may need adjustments for jumbo frame handling.

What would the best practice in my opinion is to enable jumbo frames on wired infrastructure (switches, controllers, gateways) first before enabling it on the APs. Ensure the entire path supports jumbo frames (AP → Switch → Gateway → Controller → Core Switch). Avoid enabling jumbo frames on client VLANs as most client devices use standard MTU sizes (typically 1500 bytes).

Related to your question No.2:

Since most wireless client devices do not support jumbo frames, here's what could happen. Clients send traffic with standard MTU (1500 bytes). Then the AP will forward these frames as-is, without fragmentation. If the AP, gateway, or switch uses jumbo frames (9000 bytes) for uplinks, it won't affect the clients because the AP can handle smaller frames natively and jumbo frames only apply to the infrastructure (AP↔Switch↔Gateway). If jumbo frames are sent directly to a client that doesn't support them, packets may be dropped so make sure client VLANs remain at standard MTU (1500 bytes). If the infrastructure uses jumbo frames for inter-device communication but needs to send a response to a client (which only supports 1500-byte frames), fragmentation does not occur at the AP level. The AP will reassemble and transmit standard MTU-sized packets to the client.

Related to your question No.3:

You have Global settings, where you can use jumbo-frame enable c command. You can verify the mtu in interfaces with show interface mtu. If you want per interface settings then you enter in the interface configuration as an example:
interface ethernet 1/1/1
mtu 9000

If you have portchannel / LAG you have to do it there:
interface port-channel 1
mtu 9000

Also, you have global firewall settings where the jumbo frame processing can be configured. 

Related to your question No.4:

Try to check AP MTU with show ap debug system-status ap-name <AP_NAME>

You don't need to configure MTU on APs since the APs in AOS10 do not require a separate MTU Settings configuration. The MTU configuration will be inherited from the gateway/switch uplink as the AP is just a "CABLE" connectivity from Client →Switch

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Shpat | ACEP | ACMP | ACCP | ACDP
Just an Aruba enthusiast and contributor by cases
If you find my comment helpful, KUDOS are appreciated.
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1. AOS 8, yes.  Up to 30% performance increase when you allow full jumbo, up to 9000 byte MTU.  AOS 10, at this point not a recommendation but you may see some minor benefit from reduced fragmentation but the tunnel will only negotiate up to 1578 byte.
2. The point of jumbo is to allow more efficient communication between AP and controller/gateway, client MTU has nothing to do with the setup.
3. Covered in the user guide.  https://arubanetworking.hpe.com/techdocs/ArubaOS_8.12.0_Web_Help/Content/arubaos-solutions/nwk-params/jumb-fram-supp.htm
4. Gateway side, same as AOS 8.  AP will automatically attempt jumbo negotiation same as AOS 8.  There is not a static MTU setting for the AOS 10 AP.

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Carson Hulcher, ACEX#110
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