Fragmentation packet ordering using NP session cache

A session can consist of both normal and fragmented packets. With hash-based distribution, 5-tuple and 3-tuple keys can be used to distribute normal and fragmented packets to different SPUs. All the session packets are forwarded to the SPU. Due to latency, the SPU might not guarantee packet ordering. NP cache on IOCs ensures fragmentation ordering. An NP cache entry is allocated for normal packets of the session and the 5-tuple keyis used to find the fragmented packet. When the first fragmented packet is received,the IOC updates the NP cache entry. The IOC forwards all subsequent packets to the SPU to ensure fragmentation packet ordering. To enable NP cache on the IOC, you need to run the set chassis fpc <fpc-slot> np-cache command.