Jumbogram

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In packet-switching computer networks, a jumbogram is a packet that is larger than the usual size limit for a given technology. The term jumbogram is a portmanteau of jumbo and datagram.

[edit] IPv6 jumbograms

A jumbogram is defined in RFC 2675 as an IPv6 packet containing a payload longer than 65,535 octets.

The payload length field of IPv4 and IPv6 has a size of 16 bits; hence, IP packets are limited to a maximum size of about 64 KiB (= 2¹⁶-1 B). An optional feature of IPv6, the jumbo payload option, allows the exchange of packets of up to 4 GiB, or 4,294,967,296 bytes, by making use of a 32 bit length field. Packets with such long payloads are called jumbograms.

Since both TCP and UDP include fields limited to 16 bits (length, urgent data pointer), support for IPv6 jumbograms requires slight tweaks to the transport layer. Both the jumbo payload options and the transport-layer tweaks are described in RFC 2675.

[edit] See also

• Jumbo frame - large packets for Ethernet