feat(lldp-mib): add SNMP subagent handlers for lldpPortConfigTable, lldpStats scalars, lldpStatsTxPortTable, lldpStatsRxPortTable

[shongal-uai]

Problem

In the current `sonic_ax_impl/mibs/ieee802_1ab.py` implementation, the following LLDP-MIB subtrees have no registered handler and return empty responses:

• `lldpPortConfigTable` (`.1.0.8802.1.1.2.1.1.7`) — per-port admin status configuration
• `lldpStatistics` scalars (`.1.0.8802.1.1.2.1.2.1–5`) — remote table change counters and last-change time
• `lldpStatsTxPortTable` (`.1.0.8802.1.1.2.1.2.6`) — per-port TX statistics
• `lldpStatsRxPortTable` (`.1.0.8802.1.1.2.1.2.7`) — per-port RX statistics

Verified on `upscaleai-202511` (Mellanox SN5610, 130 ports): `snmpwalk 1.0.8802.1.1.2.1.1.7` and `snmpwalk 1.0.8802.1.1.2.1.2` return no data.

Fix

`src/sonic_ax_impl/mibs/ieee802_1ab.py`

Adds four new handler classes:

Class	MIB table	OID root	Data source
`LLDPPortConfigTable`	`lldpPortConfigTable`	`1.0.8802.1.1.2.1.1.7`	`APPL_DB LLDP_ENTRY_TABLE` (per-port admin status)
`LLDPStatisticsGroup`	`lldpStatistics` scalars	`1.0.8802.1.1.2.1.2.1–5`	`APPL_DB LLDP_LOC_COUNTERS`
`LLDPStatsTxPortTable`	`lldpStatsTxPortTable`	`1.0.8802.1.1.2.1.2.6`	`APPL_DB LLDP_LOC_COUNTERS` (per-port TX frames)
`LLDPStatsRxPortTable`	`lldpStatsRxPortTable`	`1.0.8802.1.1.2.1.2.7`	`APPL_DB LLDP_LOC_COUNTERS` (per-port RX frames, discards, errors, TLVs, ageouts)

`src/sonic_ax_impl/main.py`

Registers the four new handler classes in the MIB instance map.

Test evidence

fanout7 — upscaleai-202511 (Mellanox SN5610, 130 ports)

Without patch (base image):

```
snmpwalk -v2c -c public 1.0.8802.1.1.2.1.1.7 # endOfMibView
snmpwalk -v2c -c public 1.0.8802.1.1.2.1.2 # endOfMibView
```

Automated test result: 15 tests xfail (UPSW-LLDP-GAP-005)

With patch applied:

```
snmpwalk -v2c -c public 1.0.8802.1.1.2.1.1.7 # → 130 rows (lldpPortConfigAdminStatus per port)
snmpwalk -v2c -c public 1.0.8802.1.1.2.1.2.1 # → Timeticks scalar
snmpwalk -v2c -c public 1.0.8802.1.1.2.1.2.6 # → 130 rows (TX frames per port)
snmpwalk -v2c -c public 1.0.8802.1.1.2.1.2.7 # → 780 rows (6 RX columns × 130 ports)
```

Automated test result: 15 xpassed, 0 failed

Note: `lldpStatistics` scalars (`lldpStatsRemTablesInserts`, `Deletes`, `Drops`, `Ageouts`) are also used as varbinds in `lldpRemTablesChange` SNMP trap notifications — the notification implementation (upscale-ai-network/ucli#351) reads these counters from `LLDP_LOC_COUNTERS` and includes them in each trap PDU.

Data availability note

`lldpPortConfigTable` reads admin status from `APPL_DB LLDP_ENTRY_TABLE` (present on any SONiC build with lldpd running). `lldpStats*` counters read from `APPL_DB LLDP_LOC_COUNTERS` (written by lldpd-syncd). Both sources are present on standard SONiC builds.

References

• Tracked in: UPSW-LLDP-GAP-005
• SNMP test framework: upscale-ai-network/ucli#340 (workaround patches), upscale-ai-network/ucli#351 (lldpRemTablesChange notifications that use lldpStatistics counters as varbinds)
• Test file: `NetworkManagementStack/snmp_tests/tests/ieee8021ab_lldp_mib/test_ieee8021ab_lldp_stats_config.py`

Made with Cursor

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[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[shongal-uai]

Closing for now — will revisit when upstream fix is prioritized (UPSW-LLDP-GAP-005).