## 5 Proof-of-Concept Results
### The P4 Algorithm
Figure 12 shows an example of P4 parser code. This packet is then sent to the match-action pipeline where the majority of the processing logic is held. The match-action pipeline contains the primary processing and forwarding logic of the data plane. It is in this stage of the program where tables can be created to rows of keys and actions. An incoming packet is matched to a row with its designated matching key (e.g., IPv4 address matched to keys with longest-prefix match (LPM)), and then actions are performed here on the packet (e.g., dropping the packet or declaring what egress port this packet should go to). The actions that can be performed are custom defined and can involve manipulating the entire packet. This match-action pipeline is also where the control plane can directly interface with the data plane to manipulate a switch's behavior. Once a P4 program is compiled and running on a target, the control plane is able to send messages to the data plane via an API to manipulate the rows of these tables. It is in this way that the control plane is able to control the logic of the data plane, however it is up to the data plane programmer to provide tables that provide the sufficient amount of control required by the control plane [32]. The P4 program in Figure 13 showcases a match-action pipeline that has a simple table for IPv4 forwarding. This table matches packets to rows based on IPv4 destination addresses. When a match is found, it is assigned a specified egress port. Figure 12: Example P4 Hader Declaration. Figure 13: Example P4 Hader Declaration. ## References

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* (10) [PERSON]; [PERSON] _Bundle Protocol Specification_; RFC 5050; IETF: Fremont, CA, USA, 2007. [CrossRef]
* (11) [PERSON]; [PERSON]; [PERSON] _Bundle Protocol Version 7_; RFC 9171; IETF: Fremont, CA, USA, 2022. [CrossRef]
* (12) NASA Jet Propulsion Laboratory. Interplanetary Overlay Network (IONN).