Jumbo Frame Support
A Jumbo Frame is an ethernet frame containing a data field larger than the maximum 1500 bytes specified by the IEEE 802.3 Ethernet standard. A 1500-byte data field yields a 1518-byte Ethernet_II frame size, after adding the DA/SA/Type/FCS fields.
Typically a jumbo frame will be between 9k-64k bytes in size. Jumbo frames are a result of the need to be able to increase data transfer rates across larger data paths. With the increased usage of Gigabit and 10 Gigabit Ethernet, the 1500 MTU limit is not the most useful in terms of processing of packets and effective use of the bandwidth. With Jumbo frames there is less fragmentation requiring the use of processing resources.
9K Jumbo frames are typically used because Ethernet uses a 32 bit CRC. Frames larger than that make the use of the CRC ineffective. A 9K frame size easily handles an 8K block size used with NFS. A 64K Frame size is the maximum limit for IPV4 datagrams. IPV6 will theoretically support a maximum framesize of 4GB.
Devices supporting Jumbo frames:
- X-pedition, T-Series gigabit linecards only, 64K frames
- Matrix E1, f/w 3.00.14+, gigabit ports only; 6K frames
- 1G694-13, f/w 1.02.04+, h/w rev 0H+), gigabit ports only; 6K frames
- Matrix DFE (4th Generation); gigabit ports only; 10K (10,239 byte) frames (12390)
- Matrix X-Series; at least 9K
- SecureStack; 9K (9,216 byte) frames (11750)
- G-Series; 9K (9,216 byte) frames (11750)