fix(cisco_nxos): record LLDP detail blocks that carry no Port id line - #2355
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`show lldp neighbors detail` parsed to zero rows on NX-OS releases that do not emit a `Port id:` line. Not a partial result -- the whole command came back empty, and nothing raised. `NEIGHBOR_INTERFACE` is Required and comes from a rule anchored at the start of the line, so `Local Port id:` correctly does not match it. On a release emitting `Local Port id:` and `Port Description:` and no bare `Port id:`, the value is never filled, and being Required it discards every block. Measured on two Nexus 3064s in one estate: 6.0(2)U2(9Z) returns 250 lines describing 18 neighbours and parses to 0 rows, while 7.0(3)I4(9) returns 208 lines and parses to 14. All 18 blocks on the 6.x switch carry `Local Port id:` and `Port Description:` and none carries `Port id:`. An empty parse from a switch with 18 neighbours is indistinguishable from a switch that has none, so a consumer reports no LLDP adjacency and is believed. Dropping Required lets a block record with the fields the device did send. `NEIGHBOR_NAME` and `LOCAL_INTERFACE` stay Required and still guard against recording junk. Both existing fixtures parse byte-identically before and after, so releases that already worked are unaffected.
jacqueswindt-gif
requested review from
itdependsnetworks,
jmcgill298,
jvanderaa,
matt852 and
mjbear
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August 27, 2026 11:25
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Problem
On NX-OS releases that do not emit a
Port id:line,show lldp neighbors detailparses to zero rows. Not a partial result — the whole command comes back empty, and nothing raises.NEIGHBOR_INTERFACEisRequiredand is sourced from:That rule is anchored at the start of the line, so
Local Port id:correctly does not match it (it is caught by the rule below). On a release that emitsLocal Port id:andPort Description:but no barePort id:line,NEIGHBOR_INTERFACEis therefore never filled — and because it isRequired, every block is discarded.Where this was seen
Two Cisco Nexus 3064s, same estate:
show lldp neighbors detailOn the 6.x switch all 18 blocks carry
Local Port id:andPort Description:, and none carriesPort id:.The silence is the awkward part: an empty parse from a switch with 18 LLDP neighbours is indistinguishable from a switch that genuinely has none, so a consumer reports "no LLDP adjacency" and is believed.
Fix
Drop
RequiredfromNEIGHBOR_INTERFACE. A block then records with the fields the device did send, instead of the command yielding nothing.NEIGHBOR_NAMEandLOCAL_INTERFACEstayRequired, so they still guard against recording junk.Verification
cisco_nxos_show_lldp_neighbors_detail_no_port_id.{raw,yml}— the block shape that release emits. It parses to 0 rows before this change and 2 rows after.show_lldp_neighbors_detailfixtures parse byte-identically before and after; releases that already worked are unaffected.1896 passedfor the parsed-reference tests and2929 passedfor index/testcase/capture-group.Not included, deliberately
Port Description:is present in this output and currently discarded, and on this release it happens to hold the remote interface name. Mapping it toNEIGHBOR_INTERFACEwould be wrong in general — in the existing..._detail2.rawfixture,Port id: Ethernet1/52sits besidePort Description: SW-NEXUS-UPLINK, where the description is a description. Adding a separatePORT_DESCRIPTIONvalue would be a reasonable follow-up but changes the parsed schema for every consumer, so it is left out of a bug fix.🤖 Generated with Claude Code