Configuring Jumbo Frames

In RTX64, jumbo frame sizes are configured for an interface with Maximum Packet Size, which includes 14 bytes of Ethernet header and does not include FCS. The IP MTU must be configured to be less than or equal to (Maximum Packet Size – 14).

The TCP/IP stack supports Path MTU Discovery. RTX64 devices will successfully communicate over TCP with another device that supports Path MTU Discovery, even if MTUs are configured to different sizes.

NOTE: All tested drivers support Jumbo Packets. To view a list of supported network cards, go to the IntervalZero Customer Center or contact IntervalZero Customer Support.

To configure the stack and your NIC cards to use jumbo frames:

NOTE: Maximum frame size is hardware-specific, and you should consult your NIC card's hardware documentation for acceptable values.

UDP or ICMP over Fragmented IP

For User Datagram Protocol (UDP) or Internet Control Message Protocol (ICMP) over fragmented IP, if two devices are configured with different MTUs, they can only communicate with IP frame sizes of smaller MTU. In order to run UDP or ICMP over fragmented IP protocol, the IP MTU must be configured to the same number. Windows devices typically configure JUMBO frame sizes of IP MTU + 14 bytes of Ethernet header.

Example:

The Intel(R) Gigabit CT Desktop Adapter Windows driver includes 14 bytes of layer 2 frame header in Jumbo Packet size configuration. To run UDP or ICMP over fragmented IP between this driver and any RTX64 interface, you would:

Or

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