Branch Gateway supports IP fragmentation and reassembly. The Branch Gateway router can fragment and reassemble IP packets according to RFC 791. This feature allows the router to send and receive large IP packets where the underlying data link protocol constrains the Maximum Transport Unit (MTU).

IP fragmentation involves breaking a datagram into a number of pieces that can be reassembled later. The IP source, destination, identification, total length, and fragment offset fields, along with the more fragment and don’t fragment flags in the IP header, are used for IP fragmentation and reassembly.

IP fragmentation works as follows:

• Each IP packet is divided into fragments

• Each fragment becomes its own IP packet

• Each packet has same identifier, source, and destination address

Fragments are usually not reassembled until final destination. The Branch Gateway supports fragmentation of IP packets according to RFC 791, and reassembly of IP packets destined only to its interfaces.