The SmartNIC can be configured to decrement the value of the IPv4 time-to-live (TTL) field or the IPv6 hop-limit field.
Decrementing TTL and hop limit
If decrementing the value of the IPv4 TTL field or the IPv6 hop-limit field is enabled, the value of these fields is reduced by one in the SmartNIC. The frame is discarded, if the value of a frame reaches zero. IP checksum is recalculated after decrementing the value.
The RTE_FLOW_ACTION_TYPE_MODIFY_FIELD action type and the
rte_flow_action_modify_field structure are supported to decrement IPv4
TTL or IPv6 hope limit. To subtract 1 from the specified field, set
rte_flow_action_modify_field.operation to
RTE_FLOW_MODIFY_SUB. The following field IDs are supported.
- RTE_FLOW_FIELD_IPV4_TTL
- RTE_FLOW_FIELD_IPV6_HOPLIMIT