Pre-Tunnel fragmentation at VPC-DI
The pre tunnel fragmentation feature and its maximal MTU size will be defined under WSG service. This MTU size is stored with other WSG service parameters. During IPsec SA creation, the MTU is passed to crypto driver subsystem. The crypto driver will calculate the crypto overhead to determine the effective MTU size for plaintext based on given MTU size and SA information. When crypto driver receives a packet for encryption and packet length is longer than effective MTU, the packet will be fragmented before deliver to crypto chip.
MTU range is between intiger 576 to 2048, default is 1400.