You truncate received packets to preprare them for analysis tool.
Packet truncation is performed at either ingress or egress before packets are forwarded to analysyis tools, depending on the policy configuration. When the incoming packet length is greater than the configured truncation value, the packet is truncated to the length specified in a policy. The following figure is a conceptual representation of before and after packet truncation.
Because ingress policy actions are applied before those specified in the egress policy, the incoming packet may be terminated or truncated at ingress. Egress policy match criteria are applied to received tunneled or non-tunneled packets. The following lists the order of operations on packets upon ingress to the application: