What Are Jumbo Frames? Definition and Configuration Guidance

What Are Jumbo Frames?

 

The jumbo frame refers to an Ethernet frame with a payload size that's bigger than the standard 1,500 bytes. Jumbo frames are also much larger than the normal maximum transmission unit (MTU) specified in the Ethernet standard. Sometimes, using jumbo frames can improve network performance, but in other cases, it can actually slow them down.

 

The Ethernet standard (IEEE 802.3) sets the normal maximum frame size at 1,518 or 1,522 bytes. This includes 14 bytes of routing info, a 4-byte checksum, and 1,500 bytes of payload (i.e. MTU). Most devices use this standard as a default for sending and receiving data.

 

However, since the Ethernet standard set the MTU, network speeds and processing power have significantly increased. These days, Gigabit Ethernet switches are standard, and 10 Gigabit, 40 Gigabit, and even 100 Gigabit network switches are becoming more common in specific specialized applications. In these high-speed networks, you can get even better performance if you configure your devices to send larger packets called jumbo frames.

 

The most common jumbo frames have an MTU limit of 9,000 bytes. While there's no strict standard, 9,000 bytes became the norm during the development of Gigabit Ethernet and was picked up by most equipment vendors and organizations. Most modern Ethernet devices can easily support jumbo 9,000-byte frames.

 

When the payload size is more than 9,000 bytes, it's a super-jumbo frame. The maximum payload can be up to 65,535 bytes, but it's rarely used. IPv6 supports the jumbo payload or jumbo frame option, allowing payloads of up to 4GB.

 

There's also a type of data frame called a small jumbo frame, which is larger than the standard 1,522 bytes and usually tops out at 1,600 bytes. Small jumbo frames are often used in network routing or encapsulation techniques requiring extra header info. One example is Multi-Protocol Label Switching (MPLS), which adds 4 bytes of label info to each frame, making the packet slightly larger than the standard frame size. This helps avoid packet fragmentation.

 

Importance of Jumbo Frames in Networking

 

Jumbo frames are a complete game changer in networks that need to transmit large amounts of data. They can commonly be applied in video and audio streaming, data backup, and cloud computing applications.

 

Using jumbo frames can help network administrators improve network efficiency and reduce congestion, resulting in better performance and faster data transfers. In addition, jumbo frames minimize the number of packet retransmissions, resulting in lower latency and a better user experience.

 

In short, jumbo frames are an important part of today's network environment. They help organizations keep up with the high-speed demands of the digital age and improve overall network performance.

 

Standard MTU vs. Jumbo framing

 

In Ethernet, the standard maximum transmission unit (MTU) size of 1500 bytes sets an upper limit on the data sent in a single frame. A larger frame size means that more data can be sent in one go, reducing the overhead of data fragmentation and reassembly.

 

Advantages of Jumbo Framing

 

There are many benefits to using jumbo frames in a network. They increase network efficiency, improve performance, and reduce overhead. By sending more data at once, the network hardware has less fragmentation and reorganization to deal with, which reduces the burden on the hardware. This speeds up network operation, accelerates data transfer, and reduces latency. In addition, jumbo frames take pressure off the network, freeing up more bandwidth for other tasks and making the network more stable overall.

When to Use Jumbo Frames?

 

If you're using jumbo frames, you'll need to consider what your network needs to do. Jumbo frames are usually used in places where you need a lot of bandwidth, low latency, and high throughput, like data centers, cloud computing environments, and other high-performance network applications.

 

Network Topology Considerations

How your network is set up is also a significant factor in deciding whether to use jumbo frames. These frames are best suited for networks with dedicated switches because they may need to be compatible with routers with limited MTU sizes. If you have more than one switch or other network device on your network, you need to make sure they all support jumbo frames to get the best performance.

 

Hardware Limitations

Another thing to consider when deciding whether to use jumbo frames is whether your hardware is compatible. Just a heads-up: not all network adapters and switches support jumbo frames. So, it's always a good idea to check your hardware for compatibility before making any changes. Some older devices might not be able to handle larger frames, which could lead to a drop in performance or even packet loss.

 

In summary, if you're considering using jumbo frames, it's essential to think about what your network needs, how it's set up and what hardware you've got. If you weigh all these factors, you can make an informed decision on whether to use jumbo frames.

 

How to Use Jumbo Frames

 

Understanding the network and the correct command procedures is essential before configuring jumbo frames. The following is a step-by-step guide to configuring jumbo frames:

 

1. Check that the network device supports jumbo frames.

 

Before you begin configuration, make sure that your network device supports jumbo frames. You can find this information in the device manufacturer's documentation or on the vendor's website.

 

2. Find the optimal MTU size

 

The MTU for jumbo frames is larger than the standard 1500 bytes. To find the best MTU size for your network, you need to consider its tasks, how it is set up, and what hardware you have.

 

3. Connecting to the Device's Command Line Interface (CLI)

 

To get the jumbo frame up and running, you must first connect to the device's CLI interface via console cable, Telnet, or SSH.

 

4. Configuring Jumbo Frames on the Interface

 

The commands for configuring jumbo frames vary from device to device. For example, if you are using a Cisco switch, you can use this command to set the jumbo frame size for the interface:

 

switch(config)#interface <interface-name>

switch(config-if)#mtu <jumbo-frame-size>

switch(config-if)#end

 

5. Verifying the Configuration of Jumbo Frames:

 

After configuring jumbo frames on a network device, it is a good idea to check that everything is set up correctly. If you are using a Cisco switch, you can use this command to check the MTU size of the interface to make sure the configuration has taken effect:

 

switch#show interfaces <interface-name> | include MTU

 

This command displays the MTU size of the specified interface to help verify that the configuration is correct. Configuring jumbo frames is essential in improving network performance, but you must understand the hardware and software requirements before implementing them.

 

Setting the MTU size on Operating Systems

 

Ensuring that the MTU size is set correctly in the operating system and that jumbo frames are configured on network devices is also essential. This can usually be set through the operating system's network configuration, but it may be necessary to specify a custom MTU size manually. Putting a consistent MTU size on all systems that send and receive data is an excellent idea to ensure that jumbo frames are handled correctly.

 

Network topology, hardware compatibility, and performance requirements must be considered before setting the operating system's MTU size. If all devices on the network support jumbo frames, you can set the MTU size on the operating system.

 

How you set it depends on the operating system you are using.

The following section describes how to set the MTU size on commonly used systems:

 

Windows:

1. Open Command Prompt with Administrator privileges.

2. Enter the following command: “netsh interface ipv4 show subinterface” to display detailed information for all network interfaces.

3. Determine which interface you want to adjust the MTU size for and take note of its index.

4. Use the following command to modify the MTU size: “netsh interface ipv4 set subinterface [index] mtu=xxxx store=persistent”. 

5. Replace [index] with the interface's index and xxxx with the desired MTU size.

 

Linux:

1. Open a terminal window.

2. Determine the name of the network interface you want to change the MTU size for.

3. Enter the following command to adjust the MTU size: “sudo ifconfig [interface] mtu xxxx”. 

4. Replace [interface] with the actual network interface name and xxxx with the desired MTU size.

5. To make the change permanent, enter the following command: “sudo nano /etc/network/interfaces”.

6. In the configuration line for the relevant interface, add the following: “mtu xxxx”. 

7. Replace xxxx with the desired MTU size.

8. Save and exit.

9. Restart the network service by the next command: “sudo service network-manager restart”

 

If you want to take full advantage of jumbo frames, you must ensure that all devices on your network have the same MTU size. Inconsistent configurations can result in broken connections or packet loss. Therefore, testing everything thoroughly before applying the configuration to a production environment is essential.

 

How to Test Jumbo Frame Configuration?

 

Once you've configured jumbo frames on your network devices and set the MTU size on your operating system, it's essential to test everything thoroughly to ensure everything works as it should. You can use network diagnostic tools like ping and traceroute to ensure that jumbo frames are correctly processed and transmitted. The Network performance monitoring tools can also help you see how jumbo frames affect network performance and spot any issues or limits.

 

There are a few key points to keep in mind when testing jumbo frame configurations:

 

Verify that all devices and operating systems can handle jumbo frames. This will ensure that the entire network can handle the frames correctly.

 

Ensure each network device and operating system sets the correct MTU size. This can be done through the network settings.

 

Once you have set the MTU size, running some tests to ensure everything is fine with jumbo frames is a good idea. Use an analysis tool like Wireshark to examine network traffic and see the size of frames sent over the network.

 

Another test is to transfer a large file between two devices on the network and see how long it takes. If set up correctly, transfers using jumbo frames should be faster than transfers using standard MTU sizes.

 

It is a good idea to monitor the network and test the jumbo frame configuration periodically to ensure proper operation. If problems occur during testing, you may need to adjust the MTU size or other network settings.

 

Conclusion

Jumbo frames can help your network data transfer and reduce network overhead. This article helps you when you're looking to configure jumbo frames for your network. Once you've read this article, you'll need to consider whether jumbo frames are right for your network and confirm whether they're suitable for your LAN.