feat: add LLDP topology discovery support

Adds LLDP (Link Layer Discovery Protocol) topology discovery capability
to the agent for local network neighbor detection.

New Features:
- LLDP-MIB walker for discovering network neighbors via SNMP
- New LLDP_TOPOLOGY job type for topology discovery jobs
- Automatic IPv4 and IPv6 management address parsing
- Bulk neighbor discovery with full port information

Protocol Buffers:
- Added LldpTopologyResult message for topology data
- Added LldpNeighbor message for individual neighbor info
- Extended JobType enum with LLDP_TOPOLOGY (value 5)

Implementation:
- lldp.go: LLDP discovery logic with SNMP walking
- agent.go: Job dispatch and result channel handling
- Updated handleMessage signature to support LLDP results
- Result sent to Phoenix via "lldp_topology_result" event

LLDP-MIB OIDs:
- 1.0.8802.1.1.2.1.3.3.0 (lldpLocSysName)
- 1.0.8802.1.1.2.1.3.7.1.4 (lldpLocPortDesc)
- 1.0.8802.1.1.2.1.4.1.1.7 (lldpRemPortId)
- 1.0.8802.1.1.2.1.4.1.1.8 (lldpRemPortDesc)
- 1.0.8802.1.1.2.1.4.1.1.9 (lldpRemSysName)
- 1.0.8802.1.1.2.1.4.2.1.3 (lldpRemManAddr)

This enables the Phoenix web application to dispatch LLDP discovery
jobs to agents for local neighbor detection, reducing SNMP load on the
Phoenix server and improving discovery performance.

agent.go

@@ -106,6 +106,7 @@ func runSession(ctx context.Context, baseURL, token string) error {
 	credTestResultCh := make(chan *pb.CredentialTestResult, 5000)
 	monitoringCheckCh := make(chan *pb.MonitoringCheck, 10000)
 	checkResultCh := make(chan *pb.CheckResult, 10000)
+	lldpTopologyResultCh := make(chan *pb.LldpTopologyResult, 1000)
 
 	// Ref counter for outbound messages
 	var refCounter atomic.Uint64
@@ -277,7 +278,7 @@ func runSession(ctx context.Context, baseURL, token string) error {
 				slog.Warn("invalid message", "error", err)
 				continue
 			}
-			if handleMessage(ctx, msg, pools, snmpResultCh, mikrotikResultCh, credTestResultCh, monitoringCheckCh, checkResultCh) {
+			if handleMessage(ctx, msg, pools, snmpResultCh, mikrotikResultCh, credTestResultCh, monitoringCheckCh, checkResultCh, lldpTopologyResultCh) {
 				flushSnmpBatch()
 				return errRestartRequested
 			}
@@ -304,6 +305,10 @@ func runSession(ctx context.Context, baseURL, token string) error {
 			sendBinaryResult("check_result", result)
 			slog.Info("sent check result", "check", result.CheckId, "status", result.Status)
 
+		case result := <-lldpTopologyResultCh:
+			sendBinaryResult("lldp_topology_result", result)
+			slog.Info("sent LLDP topology result", "device", result.DeviceId, "neighbors", len(result.Neighbors))
+
 		case <-flushTicker.C:
 			flushSnmpBatch()
 
@@ -345,6 +350,7 @@ func handleMessage(
 	credTestResultCh chan<- *pb.CredentialTestResult,
 	monitoringCheckCh chan<- *pb.MonitoringCheck,
 	checkResultCh chan<- *pb.CheckResult,
+	lldpTopologyResultCh chan<- *pb.LldpTopologyResult,
 ) bool {
 	switch msg.Event {
 	case "phx_reply":
@@ -374,7 +380,7 @@ func handleMessage(
 		}
 		slog.Info("received jobs", "count", len(jobList.Jobs))
 		for _, job := range jobList.Jobs {
-			dispatchJob(ctx, job, pools, snmpResultCh, mikrotikResultCh, credTestResultCh, monitoringCheckCh, checkResultCh)
+			dispatchJob(ctx, job, pools, snmpResultCh, mikrotikResultCh, credTestResultCh, monitoringCheckCh, checkResultCh, lldpTopologyResultCh)
 		}
 
 	case "check_jobs":
@@ -442,6 +448,7 @@ func dispatchJob(
 	credTestResultCh chan<- *pb.CredentialTestResult,
 	monitoringCheckCh chan<- *pb.MonitoringCheck,
 	checkResultCh chan<- *pb.CheckResult,
+	lldpTopologyResultCh chan<- *pb.LldpTopologyResult,
 ) {
 	slog.Info("starting job", "job_id", job.JobId, "type", job.JobType)
 
@@ -453,6 +460,8 @@ func dispatchJob(
 		ok = pools.snmp.submit(ctx, func() { executeCredentialTest(ctx, job, credTestResultCh) })
 	case pb.JobType_PING:
 		ok = pools.ping.submit(ctx, func() { executePingJob(ctx, job, monitoringCheckCh) })
+	case pb.JobType_LLDP_TOPOLOGY:
+		ok = pools.snmp.submit(ctx, func() { executeLldpTopologyJob(ctx, job, lldpTopologyResultCh) })
 	default:
 		ok = pools.snmp.submit(ctx, func() { executeSnmpJob(ctx, job, snmpResultCh) })
 	}

agent_test.go

@@ -108,7 +108,7 @@ func TestHandleMessage(t *testing.T) {
 		credCh := make(chan *pb.CredentialTestResult, 1)
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
-		handleMessage(context.Background(), channelMsg{Event: "phx_reply", Payload: json.RawMessage(`{}`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "phx_reply", Payload: json.RawMessage(`{}`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Just verify it doesn't panic
 	})
 
@@ -136,7 +136,7 @@ func TestHandleMessage(t *testing.T) {
 			SnmpDevice: &pb.SnmpDevice{Ip: "10.0.0.1", Port: 161},
 		})
 
-		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Wait for goroutine to finish
 		select {
 		case <-snmpCh:
@@ -151,7 +151,7 @@ func TestHandleMessage(t *testing.T) {
 		credCh := make(chan *pb.CredentialTestResult, 1)
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
-		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: json.RawMessage(`not json`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: json.RawMessage(`not json`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Should log error but not panic
 	})
 
@@ -162,7 +162,7 @@ func TestHandleMessage(t *testing.T) {
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
 		payload, _ := json.Marshal(map[string]string{"binary": "not-base64!!!"})
-		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 	})
 
 	t.Run("invalid protobuf", func(t *testing.T) {
@@ -172,7 +172,7 @@ func TestHandleMessage(t *testing.T) {
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
 		payload, _ := json.Marshal(map[string]string{"binary": base64.StdEncoding.EncodeToString([]byte{0xFF, 0xFF, 0xFF})})
-		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 	})
 
 	t.Run("restart", func(t *testing.T) {
@@ -181,7 +181,7 @@ func TestHandleMessage(t *testing.T) {
 		credCh := make(chan *pb.CredentialTestResult, 1)
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
-		shouldEnd := handleMessage(context.Background(), channelMsg{Event: "restart", Payload: json.RawMessage(`{}`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		shouldEnd := handleMessage(context.Background(), channelMsg{Event: "restart", Payload: json.RawMessage(`{}`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		if !shouldEnd {
 			t.Error("expected handleMessage to return true for restart")
@@ -204,7 +204,7 @@ func TestHandleMessage(t *testing.T) {
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
 		payload, _ := json.Marshal(map[string]string{"url": "https://example.com/agent", "checksum": "abc123"})
-		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		if calledURL != "https://example.com/agent" {
 			t.Errorf("expected update URL %q, got %q", "https://example.com/agent", calledURL)
@@ -228,7 +228,7 @@ func TestHandleMessage(t *testing.T) {
 		checkCh := make(chan *pb.CheckResult, 1)
 		// Missing URL field
 		payload, _ := json.Marshal(map[string]string{"checksum": "abc123"})
-		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		if called {
 			t.Error("selfUpdate should not be called with empty URL")
@@ -249,7 +249,7 @@ func TestHandleMessage(t *testing.T) {
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
 		payload, _ := json.Marshal(map[string]string{"url": "https://example.com/agent", "checksum": "abc123"})
-		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Should log error but not panic
 	})
 
@@ -269,7 +269,7 @@ func TestHandleMessage(t *testing.T) {
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
 		payload, _ := json.Marshal(map[string]string{"url": "https://example.com/agent"})
-		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "update", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		if called {
 			t.Error("selfUpdate should not be called with empty checksum")
@@ -282,7 +282,7 @@ func TestHandleMessage(t *testing.T) {
 		credCh := make(chan *pb.CredentialTestResult, 1)
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
-		handleMessage(context.Background(), channelMsg{Event: "some_unknown_event", Payload: json.RawMessage(`{}`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "some_unknown_event", Payload: json.RawMessage(`{}`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Should just log and not panic
 	})
 
@@ -299,7 +299,7 @@ func TestHandleMessage(t *testing.T) {
 		credCh := make(chan *pb.CredentialTestResult, 1)
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
-		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		select {
 		case <-checkCh:
 		case <-time.After(5 * time.Second):
@@ -313,7 +313,7 @@ func TestHandleMessage(t *testing.T) {
 		credCh := make(chan *pb.CredentialTestResult, 1)
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
-		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: json.RawMessage(`not json`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: json.RawMessage(`not json`)}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Should log error but not panic
 	})
 
@@ -324,7 +324,7 @@ func TestHandleMessage(t *testing.T) {
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
 		payload, _ := json.Marshal(map[string]string{"binary": "not-base64!!!"})
-		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Should log error but not panic
 	})
 
@@ -335,7 +335,7 @@ func TestHandleMessage(t *testing.T) {
 		monCh := make(chan *pb.MonitoringCheck, 1)
 		checkCh := make(chan *pb.CheckResult, 1)
 		payload, _ := json.Marshal(map[string]string{"binary": base64.StdEncoding.EncodeToString([]byte{0xFF, 0xFF, 0xFF})})
-		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "check_jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		// Should log error but not panic
 	})
 
@@ -362,7 +362,7 @@ func TestHandleMessage(t *testing.T) {
 			JobType:    pb.JobType_DISCOVER,
 			SnmpDevice: &pb.SnmpDevice{Ip: "10.0.0.1"},
 		})
-		handleMessage(context.Background(), channelMsg{Event: "discovery_job", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "discovery_job", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		select {
 		case <-snmpCh:
 		case <-time.After(2 * time.Second):
@@ -390,7 +390,7 @@ func TestHandleMessage(t *testing.T) {
 			JobType:        pb.JobType_MIKROTIK,
 			MikrotikDevice: &pb.MikrotikDevice{Ip: "10.0.0.1", SshPort: 22, Username: "admin", Password: "pass"},
 		})
-		handleMessage(context.Background(), channelMsg{Event: "backup_job", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		handleMessage(context.Background(), channelMsg{Event: "backup_job", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 		select {
 		case result := <-mtCh:
 			if result.Error != "" {
@@ -414,7 +414,7 @@ func TestHandleMessageRejectsOversizedPayload(t *testing.T) {
 	encoded := base64.StdEncoding.EncodeToString(oversized)
 	payload, _ := json.Marshal(map[string]string{"binary": encoded})
 
-	handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+	handleMessage(context.Background(), channelMsg{Event: "jobs", Payload: payload}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 	// Verify no jobs were dispatched
 	select {
@@ -518,7 +518,7 @@ func TestDispatchJob(t *testing.T) {
 			JobId:          "mt1",
 			JobType:        pb.JobType_MIKROTIK,
 			MikrotikDevice: &pb.MikrotikDevice{Ip: "10.0.0.1", Port: 8728},
-		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		select {
 		case result := <-mtCh:
@@ -547,7 +547,7 @@ func TestDispatchJob(t *testing.T) {
 			JobId:      "tc1",
 			JobType:    pb.JobType_TEST_CREDENTIALS,
 			SnmpDevice: &pb.SnmpDevice{Ip: "10.0.0.1"},
-		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		select {
 		case result := <-credCh:
@@ -576,7 +576,7 @@ func TestDispatchJob(t *testing.T) {
 			JobId:      "p1",
 			JobType:    pb.JobType_PING,
 			SnmpDevice: &pb.SnmpDevice{Ip: "127.0.0.1"},
-		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		select {
 		case result := <-monCh:
@@ -609,7 +609,7 @@ func TestDispatchJob(t *testing.T) {
 			JobId:      "s1",
 			JobType:    pb.JobType_POLL,
 			SnmpDevice: &pb.SnmpDevice{Ip: "10.0.0.1"},
-		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh)
+		}, testPools(t), snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 		select {
 		case <-snmpCh:
@@ -792,19 +792,19 @@ func TestDispatchJobCancelledContext(t *testing.T) {
 	// All dispatch types should hit the "pool full" warning
 	dispatchJob(ctx, &pb.AgentJob{
 		JobId: "s1", JobType: pb.JobType_POLL, SnmpDevice: &pb.SnmpDevice{Ip: "10.0.0.1"},
-	}, p, snmpCh, mtCh, credCh, monCh, checkCh)
+	}, p, snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 	dispatchJob(ctx, &pb.AgentJob{
 		JobId: "m1", JobType: pb.JobType_MIKROTIK, MikrotikDevice: &pb.MikrotikDevice{Ip: "10.0.0.1"},
-	}, p, snmpCh, mtCh, credCh, monCh, checkCh)
+	}, p, snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 	dispatchJob(ctx, &pb.AgentJob{
 		JobId: "tc1", JobType: pb.JobType_TEST_CREDENTIALS, SnmpDevice: &pb.SnmpDevice{Ip: "10.0.0.1"},
-	}, p, snmpCh, mtCh, credCh, monCh, checkCh)
+	}, p, snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 	dispatchJob(ctx, &pb.AgentJob{
 		JobId: "p1", JobType: pb.JobType_PING, SnmpDevice: &pb.SnmpDevice{Ip: "10.0.0.1"},
-	}, p, snmpCh, mtCh, credCh, monCh, checkCh)
+	}, p, snmpCh, mtCh, credCh, monCh, checkCh, make(chan *pb.LldpTopologyResult, 1))
 
 	close(done)
 }

lldp.go

@@ -0,0 +1,249 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"net"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/gosnmp/gosnmp"
+	"github.com/towerops-app/towerops-agent/pb"
+)
+
+// LLDP-MIB OIDs (IEEE 802.1AB)
+const (
+	oidLocSysName  = "1.0.8802.1.1.2.1.3.3.0"
+	oidLocPortDesc = "1.0.8802.1.1.2.1.3.7.1.4"
+	oidRemPortId   = "1.0.8802.1.1.2.1.4.1.1.7"
+	oidRemPortDesc = "1.0.8802.1.1.2.1.4.1.1.8"
+	oidRemSysName  = "1.0.8802.1.1.2.1.4.1.1.9"
+	oidRemManAddr  = "1.0.8802.1.1.2.1.4.2.1.3"
+)
+
+// executeLldpTopologyJob performs LLDP neighbor discovery via SNMP.
+func executeLldpTopologyJob(ctx context.Context, job *pb.AgentJob, resultCh chan<- *pb.LldpTopologyResult) {
+	deviceID := job.DeviceId
+	jobID := job.JobId
+
+	if job.SnmpDevice == nil {
+		slog.Error("missing SNMP config for LLDP job", "job_id", jobID, "device_id", deviceID)
+		return
+	}
+
+	snmpDev := job.SnmpDevice
+	client, err := newSnmpConn(snmpDev)
+	if err != nil {
+		slog.Error("failed to create SNMP client for LLDP", "job_id", jobID, "device_id", deviceID, "error", err)
+		return
+	}
+	defer func() {
+		if err := client.Conn.Close(); err != nil {
+			slog.Debug("SNMP close error", "error", err)
+		}
+	}()
+
+	if err := client.Connect(); err != nil {
+		slog.Error("SNMP connect failed for LLDP", "job_id", jobID, "device_id", deviceID, "error", err)
+		return
+	}
+
+	result, err := discoverLldpNeighbors(client, deviceID, jobID)
+	if err != nil {
+		slog.Error("LLDP discovery failed", "job_id", jobID, "device_id", deviceID, "error", err)
+		return
+	}
+
+	select {
+	case resultCh <- result:
+		slog.Info("LLDP topology discovered", "job_id", jobID, "device_id", deviceID, "neighbors", len(result.Neighbors))
+	case <-ctx.Done():
+		slog.Warn("LLDP result send cancelled", "job_id", jobID)
+	}
+}
+
+// discoverLldpNeighbors walks LLDP-MIB tables and returns discovered neighbors.
+func discoverLldpNeighbors(client *gosnmp.GoSNMP, deviceID, jobID string) (*pb.LldpTopologyResult, error) {
+	now := time.Now().Unix()
+	result := &pb.LldpTopologyResult{
+		DeviceId:  deviceID,
+		JobId:     jobID,
+		Timestamp: now,
+	}
+
+	// Get local system name
+	sysNamePkt, err := client.Get([]string{oidLocSysName})
+	if err == nil && len(sysNamePkt.Variables) > 0 {
+		result.LocalSystemName = snmpValueToString(sysNamePkt.Variables[0])
+	}
+
+	// Walk local port descriptions (indexed by port number)
+	localPorts := make(map[string]string)
+	if err := client.Walk(oidLocPortDesc, func(pdu gosnmp.SnmpPDU) error {
+		portNum := extractSuffix(pdu.Name, oidLocPortDesc)
+		if portNum != "" {
+			localPorts[portNum] = snmpValueToString(pdu)
+		}
+		return nil
+	}); err != nil {
+		slog.Warn("failed to walk local ports", "error", err)
+	}
+
+	// Walk remote system names (indexed by timeMark.portNum.remIndex)
+	sysNames := make(map[string]string)
+	if err := client.Walk(oidRemSysName, func(pdu gosnmp.SnmpPDU) error {
+		key := parseRemoteKey(pdu.Name, oidRemSysName)
+		if key != "" {
+			sysNames[key] = snmpValueToString(pdu)
+		}
+		return nil
+	}); err != nil {
+		slog.Warn("failed to walk remote sys names", "error", err)
+		return result, nil // Return empty result, not an error
+	}
+
+	// If no neighbors found, return early
+	if len(sysNames) == 0 {
+		return result, nil
+	}
+
+	// Walk remote port descriptions
+	remotePorts := make(map[string]string)
+	_ = client.Walk(oidRemPortDesc, func(pdu gosnmp.SnmpPDU) error {
+		key := parseRemoteKey(pdu.Name, oidRemPortDesc)
+		if key != "" {
+			remotePorts[key] = snmpValueToString(pdu)
+		}
+		return nil
+	})
+
+	// Walk remote port IDs (fallback when description is empty)
+	remotePortIds := make(map[string]string)
+	_ = client.Walk(oidRemPortId, func(pdu gosnmp.SnmpPDU) error {
+		key := parseRemoteKey(pdu.Name, oidRemPortId)
+		if key != "" {
+			remotePortIds[key] = snmpValueToString(pdu)
+		}
+		return nil
+	})
+
+	// Walk management addresses (indexed by timeMark.portNum.remIndex.addrSubtype.addrLen.addr[bytes])
+	mgmtAddrs := make(map[string][]string)
+	_ = client.Walk(oidRemManAddr, func(pdu gosnmp.SnmpPDU) error {
+		key, ip := parseMgmtAddr(pdu.Name)
+		if key != "" && ip != "" {
+			mgmtAddrs[key] = append(mgmtAddrs[key], ip)
+		}
+		return nil
+	})
+
+	// Assemble neighbor list
+	for key, neighborName := range sysNames {
+		if neighborName == "" {
+			continue
+		}
+
+		parts := strings.Split(key, ".")
+		if len(parts) < 2 {
+			continue
+		}
+		portNum := parts[1] // timeMark.portNum.remIndex -> parts[1] is portNum
+
+		localPort := localPorts[portNum]
+		if localPort == "" {
+			localPort = "port-" + portNum
+		}
+
+		neighbor := &pb.LldpNeighbor{
+			NeighborName:        neighborName,
+			LocalPort:           localPort,
+			RemotePort:          remotePorts[key],
+			RemotePortId:        remotePortIds[key],
+			ManagementAddresses: mgmtAddrs[key],
+		}
+
+		result.Neighbors = append(result.Neighbors, neighbor)
+	}
+
+	return result, nil
+}
+
+// extractSuffix strips the base OID prefix and returns the suffix.
+func extractSuffix(oid, base string) string {
+	prefix := "." + base + "."
+	if strings.HasPrefix(oid, prefix) {
+		return strings.TrimPrefix(oid, prefix)
+	}
+	// Try without leading dot on oid
+	prefix = base + "."
+	if strings.HasPrefix(oid, prefix) {
+		return strings.TrimPrefix(oid, prefix)
+	}
+	return ""
+}
+
+// parseRemoteKey extracts a remote table key from OID: timeMark.portNum.remIndex
+func parseRemoteKey(oid, base string) string {
+	suffix := extractSuffix(oid, base)
+	if suffix == "" {
+		return ""
+	}
+	parts := strings.SplitN(suffix, ".", 4)
+	if len(parts) < 3 {
+		return ""
+	}
+	// Return full key as string: timeMark.portNum.remIndex
+	return parts[0] + "." + parts[1] + "." + parts[2]
+}
+
+// parseMgmtAddr parses a management address OID.
+// Format: timeMark.portNum.remIndex.addrSubtype.addrLen.addr[bytes]
+// addrSubtype 1 = IPv4 (4 bytes), 2 = IPv6 (16 bytes)
+func parseMgmtAddr(oid string) (key string, ip string) {
+	suffix := extractSuffix(oid, oidRemManAddr)
+	if suffix == "" {
+		return "", ""
+	}
+
+	parts := strings.Split(suffix, ".")
+	// Minimum: timeMark(1) portNum(1) remIndex(1) addrSubtype(1) addrLen(1) addr(>=4)
+	if len(parts) < 9 {
+		return "", ""
+	}
+
+	// timeMark.portNum.remIndex
+	key = parts[0] + "." + parts[1] + "." + parts[2]
+	addrSubtype := parts[3]
+	// parts[4] is addrLen (we trust the subtype to determine length)
+
+	switch addrSubtype {
+	case "1": // IPv4
+		if len(parts) < 9 {
+			return key, ""
+		}
+		ip = strings.Join(parts[5:9], ".")
+	case "2": // IPv6
+		if len(parts) < 21 {
+			return key, ""
+		}
+		// Convert 16 octets to IPv6 hex format
+		var ipv6Parts []string
+		for i := 0; i < 16; i += 2 {
+			a, _ := strconv.Atoi(parts[5+i])
+			b, _ := strconv.Atoi(parts[5+i+1])
+			ipv6Parts = append(ipv6Parts, fmt.Sprintf("%x", a*256+b))
+		}
+		ip = strings.Join(ipv6Parts, ":")
+	default:
+		return key, ""
+	}
+
+	// Validate IP address
+	if net.ParseIP(ip) == nil {
+		return key, ""
+	}
+
+	return key, ip
+}

pb/agent.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
 // 	protoc-gen-go v1.36.11
-// 	protoc        v6.32.1
+// 	protoc        v7.34.0
 // source: proto/agent.proto
 
 package pb
@@ -29,6 +29,7 @@ const (
 	JobType_MIKROTIK         JobType = 2
 	JobType_TEST_CREDENTIALS JobType = 3
 	JobType_PING             JobType = 4
+	JobType_LLDP_TOPOLOGY    JobType = 5 // Discover all LLDP neighbors for topology mapping
 )
 
 // Enum value maps for JobType.
@@ -39,6 +40,7 @@ var (
 		2: "MIKROTIK",
 		3: "TEST_CREDENTIALS",
 		4: "PING",
+		5: "LLDP_TOPOLOGY",
 	}
 	JobType_value = map[string]int32{
 		"DISCOVER":         0,
@@ -46,6 +48,7 @@ var (
 		"MIKROTIK":         2,
 		"TEST_CREDENTIALS": 3,
 		"PING":             4,
+		"LLDP_TOPOLOGY":    5,
 	}
 )
 
@@ -2512,6 +2515,158 @@ func (x *MikrotikSentence) GetAttributes() map[string]string {
 	return nil
 }
 
+type LldpTopologyResult struct {
+	state           protoimpl.MessageState `protogen:"open.v1"`
+	DeviceId        string                 `protobuf:"bytes,1,opt,name=device_id,json=deviceId,proto3" json:"device_id,omitempty"`
+	JobId           string                 `protobuf:"bytes,2,opt,name=job_id,json=jobId,proto3" json:"job_id,omitempty"`
+	LocalSystemName string                 `protobuf:"bytes,3,opt,name=local_system_name,json=localSystemName,proto3" json:"local_system_name,omitempty"`
+	Neighbors       []*LldpNeighbor        `protobuf:"bytes,4,rep,name=neighbors,proto3" json:"neighbors,omitempty"`
+	Timestamp       int64                  `protobuf:"varint,5,opt,name=timestamp,proto3" json:"timestamp,omitempty"`
+	unknownFields   protoimpl.UnknownFields
+	sizeCache       protoimpl.SizeCache
+}
+
+func (x *LldpTopologyResult) Reset() {
+	*x = LldpTopologyResult{}
+	mi := &file_proto_agent_proto_msgTypes[31]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *LldpTopologyResult) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*LldpTopologyResult) ProtoMessage() {}
+
+func (x *LldpTopologyResult) ProtoReflect() protoreflect.Message {
+	mi := &file_proto_agent_proto_msgTypes[31]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use LldpTopologyResult.ProtoReflect.Descriptor instead.
+func (*LldpTopologyResult) Descriptor() ([]byte, []int) {
+	return file_proto_agent_proto_rawDescGZIP(), []int{31}
+}
+
+func (x *LldpTopologyResult) GetDeviceId() string {
+	if x != nil {
+		return x.DeviceId
+	}
+	return ""
+}
+
+func (x *LldpTopologyResult) GetJobId() string {
+	if x != nil {
+		return x.JobId
+	}
+	return ""
+}
+
+func (x *LldpTopologyResult) GetLocalSystemName() string {
+	if x != nil {
+		return x.LocalSystemName
+	}
+	return ""
+}
+
+func (x *LldpTopologyResult) GetNeighbors() []*LldpNeighbor {
+	if x != nil {
+		return x.Neighbors
+	}
+	return nil
+}
+
+func (x *LldpTopologyResult) GetTimestamp() int64 {
+	if x != nil {
+		return x.Timestamp
+	}
+	return 0
+}
+
+type LldpNeighbor struct {
+	state               protoimpl.MessageState `protogen:"open.v1"`
+	NeighborName        string                 `protobuf:"bytes,1,opt,name=neighbor_name,json=neighborName,proto3" json:"neighbor_name,omitempty"`
+	LocalPort           string                 `protobuf:"bytes,2,opt,name=local_port,json=localPort,proto3" json:"local_port,omitempty"`
+	RemotePort          string                 `protobuf:"bytes,3,opt,name=remote_port,json=remotePort,proto3" json:"remote_port,omitempty"`
+	RemotePortId        string                 `protobuf:"bytes,4,opt,name=remote_port_id,json=remotePortId,proto3" json:"remote_port_id,omitempty"`
+	ManagementAddresses []string               `protobuf:"bytes,5,rep,name=management_addresses,json=managementAddresses,proto3" json:"management_addresses,omitempty"`
+	unknownFields       protoimpl.UnknownFields
+	sizeCache           protoimpl.SizeCache
+}
+
+func (x *LldpNeighbor) Reset() {
+	*x = LldpNeighbor{}
+	mi := &file_proto_agent_proto_msgTypes[32]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *LldpNeighbor) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*LldpNeighbor) ProtoMessage() {}
+
+func (x *LldpNeighbor) ProtoReflect() protoreflect.Message {
+	mi := &file_proto_agent_proto_msgTypes[32]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use LldpNeighbor.ProtoReflect.Descriptor instead.
+func (*LldpNeighbor) Descriptor() ([]byte, []int) {
+	return file_proto_agent_proto_rawDescGZIP(), []int{32}
+}
+
+func (x *LldpNeighbor) GetNeighborName() string {
+	if x != nil {
+		return x.NeighborName
+	}
+	return ""
+}
+
+func (x *LldpNeighbor) GetLocalPort() string {
+	if x != nil {
+		return x.LocalPort
+	}
+	return ""
+}
+
+func (x *LldpNeighbor) GetRemotePort() string {
+	if x != nil {
+		return x.RemotePort
+	}
+	return ""
+}
+
+func (x *LldpNeighbor) GetRemotePortId() string {
+	if x != nil {
+		return x.RemotePortId
+	}
+	return ""
+}
+
+func (x *LldpNeighbor) GetManagementAddresses() []string {
+	if x != nil {
+		return x.ManagementAddresses
+	}
+	return nil
+}
+
 var File_proto_agent_proto protoreflect.FileDescriptor
 
 const file_proto_agent_proto_rawDesc = "" +
@@ -2733,13 +2888,28 @@ const file_proto_agent_proto_rawDesc = "" +
 	"attributes\x1a=\n" +
 	"\x0fAttributesEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
-	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01*O\n" +
+	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"\xce\x01\n" +
+	"\x12LldpTopologyResult\x12\x1b\n" +
+	"\tdevice_id\x18\x01 \x01(\tR\bdeviceId\x12\x15\n" +
+	"\x06job_id\x18\x02 \x01(\tR\x05jobId\x12*\n" +
+	"\x11local_system_name\x18\x03 \x01(\tR\x0flocalSystemName\x12:\n" +
+	"\tneighbors\x18\x04 \x03(\v2\x1c.towerops.agent.LldpNeighborR\tneighbors\x12\x1c\n" +
+	"\ttimestamp\x18\x05 \x01(\x03R\ttimestamp\"\xcc\x01\n" +
+	"\fLldpNeighbor\x12#\n" +
+	"\rneighbor_name\x18\x01 \x01(\tR\fneighborName\x12\x1d\n" +
+	"\n" +
+	"local_port\x18\x02 \x01(\tR\tlocalPort\x12\x1f\n" +
+	"\vremote_port\x18\x03 \x01(\tR\n" +
+	"remotePort\x12$\n" +
+	"\x0eremote_port_id\x18\x04 \x01(\tR\fremotePortId\x121\n" +
+	"\x14management_addresses\x18\x05 \x03(\tR\x13managementAddresses*b\n" +
 	"\aJobType\x12\f\n" +
 	"\bDISCOVER\x10\x00\x12\b\n" +
 	"\x04POLL\x10\x01\x12\f\n" +
 	"\bMIKROTIK\x10\x02\x12\x14\n" +
 	"\x10TEST_CREDENTIALS\x10\x03\x12\b\n" +
-	"\x04PING\x10\x04*\x1e\n" +
+	"\x04PING\x10\x04\x12\x11\n" +
+	"\rLLDP_TOPOLOGY\x10\x05*\x1e\n" +
 	"\tQueryType\x12\a\n" +
 	"\x03GET\x10\x00\x12\b\n" +
 	"\x04WALK\x10\x01B+Z)github.com/towerops-app/towerops-agent/pbb\x06proto3"
@@ -2757,7 +2927,7 @@ func file_proto_agent_proto_rawDescGZIP() []byte {
 }
 
 var file_proto_agent_proto_enumTypes = make([]protoimpl.EnumInfo, 2)
-var file_proto_agent_proto_msgTypes = make([]protoimpl.MessageInfo, 36)
+var file_proto_agent_proto_msgTypes = make([]protoimpl.MessageInfo, 38)
 var file_proto_agent_proto_goTypes = []any{
 	(JobType)(0),                 // 0: towerops.agent.JobType
 	(QueryType)(0),               // 1: towerops.agent.QueryType
@@ -2792,11 +2962,13 @@ var file_proto_agent_proto_goTypes = []any{
 	(*MikrotikCommand)(nil),      // 30: towerops.agent.MikrotikCommand
 	(*MikrotikResult)(nil),       // 31: towerops.agent.MikrotikResult
 	(*MikrotikSentence)(nil),     // 32: towerops.agent.MikrotikSentence
-	nil,                          // 33: towerops.agent.Sensor.MetadataEntry
+	(*LldpTopologyResult)(nil),   // 33: towerops.agent.LldpTopologyResult
-	nil,                          // 34: towerops.agent.HttpCheckConfig.HeadersEntry
+	(*LldpNeighbor)(nil),         // 34: towerops.agent.LldpNeighbor
-	nil,                          // 35: towerops.agent.SnmpResult.OidValuesEntry
+	nil,                          // 35: towerops.agent.Sensor.MetadataEntry
-	nil,                          // 36: towerops.agent.MikrotikCommand.ArgsEntry
+	nil,                          // 36: towerops.agent.HttpCheckConfig.HeadersEntry
-	nil,                          // 37: towerops.agent.MikrotikSentence.AttributesEntry
+	nil,                          // 37: towerops.agent.SnmpResult.OidValuesEntry
+	nil,                          // 38: towerops.agent.MikrotikCommand.ArgsEntry
+	nil,                          // 39: towerops.agent.MikrotikSentence.AttributesEntry
 }
 var file_proto_agent_proto_depIdxs = []int32{
 	3,  // 0: towerops.agent.AgentConfig.devices:type_name -> towerops.agent.Device
@@ -2804,7 +2976,7 @@ var file_proto_agent_proto_depIdxs = []int32{
 	4,  // 2: towerops.agent.Device.snmp:type_name -> towerops.agent.SnmpConfig
 	5,  // 3: towerops.agent.Device.sensors:type_name -> towerops.agent.Sensor
 	6,  // 4: towerops.agent.Device.interfaces:type_name -> towerops.agent.Interface
-	33, // 5: towerops.agent.Sensor.metadata:type_name -> towerops.agent.Sensor.MetadataEntry
+	35, // 5: towerops.agent.Sensor.metadata:type_name -> towerops.agent.Sensor.MetadataEntry
 	8,  // 6: towerops.agent.MetricBatch.metrics:type_name -> towerops.agent.Metric
 	9,  // 7: towerops.agent.Metric.sensor_reading:type_name -> towerops.agent.SensorReading
 	10, // 8: towerops.agent.Metric.interface_stat:type_name -> towerops.agent.InterfaceStat
@@ -2814,7 +2986,7 @@ var file_proto_agent_proto_depIdxs = []int32{
 	14, // 12: towerops.agent.Check.http:type_name -> towerops.agent.HttpCheckConfig
 	15, // 13: towerops.agent.Check.tcp:type_name -> towerops.agent.TcpCheckConfig
 	16, // 14: towerops.agent.Check.dns:type_name -> towerops.agent.DnsCheckConfig
-	34, // 15: towerops.agent.HttpCheckConfig.headers:type_name -> towerops.agent.HttpCheckConfig.HeadersEntry
+	36, // 15: towerops.agent.HttpCheckConfig.headers:type_name -> towerops.agent.HttpCheckConfig.HeadersEntry
 	13, // 16: towerops.agent.CheckList.checks:type_name -> towerops.agent.Check
 	22, // 17: towerops.agent.AgentJobList.jobs:type_name -> towerops.agent.AgentJob
 	0,  // 18: towerops.agent.AgentJob.job_type:type_name -> towerops.agent.JobType
@@ -2824,15 +2996,16 @@ var file_proto_agent_proto_depIdxs = []int32{
 	30, // 22: towerops.agent.AgentJob.mikrotik_commands:type_name -> towerops.agent.MikrotikCommand
 	1,  // 23: towerops.agent.SnmpQuery.query_type:type_name -> towerops.agent.QueryType
 	0,  // 24: towerops.agent.SnmpResult.job_type:type_name -> towerops.agent.JobType
-	35, // 25: towerops.agent.SnmpResult.oid_values:type_name -> towerops.agent.SnmpResult.OidValuesEntry
+	37, // 25: towerops.agent.SnmpResult.oid_values:type_name -> towerops.agent.SnmpResult.OidValuesEntry
-	36, // 26: towerops.agent.MikrotikCommand.args:type_name -> towerops.agent.MikrotikCommand.ArgsEntry
+	38, // 26: towerops.agent.MikrotikCommand.args:type_name -> towerops.agent.MikrotikCommand.ArgsEntry
 	32, // 27: towerops.agent.MikrotikResult.sentences:type_name -> towerops.agent.MikrotikSentence
-	37, // 28: towerops.agent.MikrotikSentence.attributes:type_name -> towerops.agent.MikrotikSentence.AttributesEntry
+	39, // 28: towerops.agent.MikrotikSentence.attributes:type_name -> towerops.agent.MikrotikSentence.AttributesEntry
-	29, // [29:29] is the sub-list for method output_type
+	34, // 29: towerops.agent.LldpTopologyResult.neighbors:type_name -> towerops.agent.LldpNeighbor
-	29, // [29:29] is the sub-list for method input_type
+	30, // [30:30] is the sub-list for method output_type
-	29, // [29:29] is the sub-list for extension type_name
+	30, // [30:30] is the sub-list for method input_type
-	29, // [29:29] is the sub-list for extension extendee
+	30, // [30:30] is the sub-list for extension type_name
-	0,  // [0:29] is the sub-list for field type_name
+	30, // [30:30] is the sub-list for extension extendee
+	0,  // [0:30] is the sub-list for field type_name
 }
 
 func init() { file_proto_agent_proto_init() }
@@ -2858,7 +3031,7 @@ func file_proto_agent_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_proto_agent_proto_rawDesc), len(file_proto_agent_proto_rawDesc)),
 			NumEnums:      2,
-			NumMessages:   36,
+			NumMessages:   38,
 			NumExtensions: 0,
 			NumServices:   0,
 		},

proto/agent.proto

@@ -173,6 +173,7 @@ enum JobType {
   MIKROTIK = 2;
   TEST_CREDENTIALS = 3;
   PING = 4;
+  LLDP_TOPOLOGY = 5;  // Discover all LLDP neighbors for topology mapping
 }
 
 enum QueryType {
@@ -273,3 +274,21 @@ message MikrotikResult {
 message MikrotikSentence {
   map<string, string> attributes = 1;
 }
+
+// LLDP Topology Discovery Results
+
+message LldpTopologyResult {
+  string device_id = 1;
+  string job_id = 2;
+  string local_system_name = 3;
+  repeated LldpNeighbor neighbors = 4;
+  int64 timestamp = 5;
+}
+
+message LldpNeighbor {
+  string neighbor_name = 1;
+  string local_port = 2;
+  string remote_port = 3;
+  string remote_port_id = 4;
+  repeated string management_addresses = 5;
+}