Add -vppcfg flag to set ifAlias from the 'description' fields in vppcfg.yaml

README.md

@@ -75,6 +75,7 @@ CGO_ENABLED=0 go build -ldflags "-X main.version=${VERSION} -X main.buildTime=${
 |------|---------|-------------|
 | `-agentx-addr` | `localhost:705` | AgentX master agent address (hostname:port or Unix socket path) |
 | `-debug` | `false` | Enable debug logging |
+| `-vppcfg` | `""` | VPP configuration YAML file to read interface descriptions from |
 
 #### VPP Statistics Module Flags
 
@@ -99,15 +100,48 @@ CGO_ENABLED=0 go build -ldflags "-X main.version=${VERSION} -X main.buildTime=${
 # Custom interface index offset (start at 2000)
 ./vpp-snmp-agent -vppstats.ifindex-offset 2000
 
+# With VPP configuration file for interface descriptions
+./vpp-snmp-agent -vppcfg /etc/vpp/vppcfg.yaml
+
 # Full configuration
 ./vpp-snmp-agent \
   -agentx-addr /var/agentx/master \
   -debug \
+  -vppcfg /etc/vpp/vppcfg.yaml \
   -vppstats.addr /var/run/vpp/stats.sock \
   -vppstats.period 5 \
   -vppstats.ifindex-offset 1000
 ```
 
+## VPP Configuration File
+
+The `-vppcfg` flag accepts a YAML configuration file that describes VPP interfaces and their descriptions. This file is used to populate the `ifAlias` (.18) field in the ifXTable with meaningful interface descriptions.
+
+### YAML Format Example
+
+```yaml
+interfaces:
+  GigabitEthernet82/0/0:
+    description: 'Infra: Management interface'
+  TenGigabitEthernet1/0/2:
+    description: 'Infra: Core uplink'
+    sub-interfaces:
+      100:
+        description: 'Cust: Customer VLAN 100'
+      200:
+        description: 'Transit: Provider VLAN 200'
+loopbacks:
+  loop0:
+    description: 'Core: Router loopback'
+```
+
+### Description Mapping
+
+- **Main interfaces**: Use the `description` field directly
+- **Sub-interfaces**: Use the `description` field from the `sub-interfaces` section
+- **Loopbacks**: Use the `description` field from the `loopbacks` section
+- **Fallback**: If no description is found, the interface name is used as the alias
+
 ## SNMP Interface Mapping
 
 VPP interfaces are mapped to SNMP indices with a configurable offset (default 1000):
@@ -135,6 +169,7 @@ The application implements the ifXTable (1.3.6.1.2.1.31.1.1.1) with the followin
 | `.11.{index}` | ifHCOutUcastPkts | Counter64 | TX unicast packets (high capacity) |
 | `.12.{index}` | ifHCOutMulticastPkts | Counter64 | TX multicast packets (high capacity) |
 | `.13.{index}` | ifHCOutBroadcastPkts | Counter64 | TX broadcast packets (high capacity) |
+| `.18.{index}` | ifAlias | DisplayString | Interface description/alias (from VPP config or interface name) |
 
 ## SNMP Query Examples
 
@@ -148,6 +183,16 @@ snmpwalk -v2c -c public localhost 1.3.6.1.2.1.31.1.1.1.1
 snmpget -v2c -c public localhost 1.3.6.1.2.1.31.1.1.1.1.1000
 ```
 
+### Query Interface Descriptions
+
+```bash
+# Get all interface descriptions/aliases
+snmpwalk -v2c -c public localhost 1.3.6.1.2.1.31.1.1.1.18
+
+# Get specific interface description (interface 0 with default offset)
+snmpget -v2c -c public localhost 1.3.6.1.2.1.31.1.1.1.18.1000
+```
+
 ### Query Interface Counters
 
 ```bash