Add a note about stats-collect-rx and stats-collect-tx

docs/DETAILS.md

@@ -188,6 +188,32 @@ snmpget -v2c -c public localhost 1.3.6.1.2.1.31.1.1.1.6.2000
 - Stats socket accessible at `/var/run/vpp/stats.sock` (or custom path)
 - Application must have read permissions on the stats socket
 
+### VPP Packet Counter Configuration
+
+For accurate unicast, multicast, and broadcast packet counters, VPP requires specific feature arc configurations:
+
+#### Receive Packet Counters
+To enable detailed RX packet counters (RxUnicast, RxMulticast, RxBroadcast), configure:
+```
+set interface feature <interface> stats-collect-rx arc device-input
+```
+
+#### Transmit Packet Counters
+To enable detailed TX packet counters (TxUnicast, TxMulticast, TxBroadcast), configure:
+```
+set interface feature <interface> stats-collect-tx arc interface-output
+```
+
+#### Fallback Behavior
+If these features are not enabled, the detailed packet counters will be zero. The SNMP agent automatically falls back to using the total packet counters (Rx.Packets and Tx.Packets) for unicast packet reporting to maintain SNMP compatibility.
+
+**Example Configuration:**
+```bash
+# Enable detailed packet counters for GigabitEthernet0/8/0
+vppctl set interface feature GigabitEthernet0/8/0 stats-collect-rx arc device-input
+vppctl set interface feature GigabitEthernet0/8/0 stats-collect-tx arc interface-output
+```
+
 ### SNMP Requirements
 
 - SNMP master agent running (net-snmp's snmpd)
@@ -314,9 +340,3 @@ upstream PR is merged.
 3. Make your changes
 4. Add tests if applicable
 5. Submit a pull request
-
-## Version History
-
-- **v1.0.0**: Initial release with IF-MIB support
-- **v1.1.0**: Added configurable interface index offset
-- **v1.2.0**: Added Unix socket support for AgentX