SPRUIM2H May 2020 – October 2023 AM2431 , AM2432 , AM2434 , AM6411 , AM6412 , AM6421 , AM6422 , AM6441 , AM6442
The CPSW module supports wire rate InterVLAN routing for a small number of routes, that is the host will setup an ALE classifier with an associated egress operation that will cause the CPSW to perform particular egress operations. The ALE can optionally check time to live validity as well.
The ALE uses the classifier along with an egress opcode, destination port mask and TTL check field to tell the CPSW to manipulate the packet on the egress. The CPSW will use the opcode along with a per port operation table to process the packet. By setting up the CPSW egress operation table you can replace the DA, SA and VLAN along with optionally updating the time to live IP header field. This allows the CPSW to perform the routing function for a small set of routes without getting the local host/CPU involved.
The Egress opcode will only be use for a classifier match and the packet would normally be sent only to the host. That is the host would have routed the packet but the CPSW has been configured to do the work instead. In the event that the time-to-live check feature is enabled and the time-to-live is either 0 or 1, the packet will not get the egress opcode and instead be sent to the host as if the route is not setup. This allows the host to deal with invalid TTL fields.