How to Enable Jumbo Frame support in SonicOS (6.2 and above). Please note that since 6.2 we have support for jumbo frame for GEN6 firewall - NSA3600 or higher.
A Jumbo frame is an Ethernet frame with a payload greater than the standard maximum transmission unit (MTU) of 1,500 bytes. Jumbo frames are used on local area networks that support at least 1 Gbps and can be as large as 9,000 bytes.
Enabling Jumbo Frame support option increases throughput and reduces the number of Ethernet frames to be processed. Throughput increase may not be seen in some cases. However, there will be some improvement in throughput if the packets traversing are really jumbo size.
Note: Due to jumbo frame packet buffer size requirements (9000 kilobytes), jumbo frames increase memory requirements by a factor of 4.
Step 1: Login to the SonicWall Management Interface
Firewall Settings | Advanced page
Step 2: Navigate to Firewall Settings | Advanced page. Step 3:Enable Jumbo Support checkbox and then click on Accept button on top of the page.
Enabling jumbo frames allows the SonicOS to process Ethernet frames with payloads ranging from 1500-9000 bytes.
NOTE: The enable Jumbo Frame support option will prompt you to Restart your SonicWall firewall appliance, when you are ready go to System | Restart page.
Increase the MTU on the Network | Interfaces page
Interface MTU - Specifies the largest packet size that the interface can forward without fragmenting the packet. Identify the size of the packets that the port will receive and transmit:
1500 Standard packets (default) 9000 Jumbo frame packets
Step 4: Edit the desired Interface, click on the Advanced tab and set the MTU to 9,000 bytes. Click on OK when done.
NOTE: You can set the MTU of a jumbo frame with the value from 1500 to 9000 (not include 1500).
Step 5: Ensure that the Switches and computer's Network Interface Card also supports Jumbo Frames:
How to Test:
- Enable Jumbo Frame Support on the SonicWall firewall and then restart when you are ready. - Edit an unused Interface (e.g. X3 ) and configure an IP address (e.g. 10.10.20.1/24) and enable the Ping option below, in the Advanced tab set the MTU to 9000 bytes. - Connect a computer directly to the SonicWall's X3 Interface (computer's IP must be in the same subnet e.g. 10.10.20.5/24) - You must also Enable Jumbo Frame support on the computer's NIC card. - Open the Command Prompt and ping the SonicWall's X3 Interface IP with the following syntax. - The ping with large bytes should succeed.