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End-to-End Fragmentation and Reassembly

The fragmentation and reassembly feature reduces excessive delays of Frame Relay packets by breaking them up into smaller fragments and interleaving them with real-time frames. By doing this, real-time and non-real-time data frames can be carried together on lower-speed links without causing excessive delays to the real-time traffic. On receiving the smaller fragments by the peer interface, the fragments are reassembled into their original packet. For example, short delay-sensitive packets, such as packetized voice, can race ahead of larger delay-insensitive packets, such as common data packets.

E-series routers support end-to-end fragmentation according to the FRF.12 Implementation Agreement standard. Unlike UNI and NNI fragmentation, end-to-end supports fragmentation only at the endpoints. End-to-end fragmentation and reassembly are supported only on non-multilink Frame Relay interfaces on cOC12/STM4 and CT3 12 FO modules.

You configure end-to-end fragmentation at the Frame Relay subinterface level. Fragmentation is applied to all PVCs associated with the subinterface. In most cases, fragmentation and reassembly are used together. Fragmentation and reassembly, however, can be configured separately for each map class.

For additional information, see Frame Relay Forum—Frame Relay Fragmentation Implementation Agreement, FRF.12 (December 1997).

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