[lldp] Fix LLDP_ENTRY_TABLE key comparison for dualtor topology#23193
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StormLiangMS merged 1 commit intosonic-net:masterfrom Mar 24, 2026
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In dualtor-aa topology, uplink ports receive LLDP PDUs from both the T1 neighbor switch and the fanout switch. This causes `show lldp table` to list multiple rows per interface (e.g., Ethernet224 appears twice - once for ARISTA01T1, once for fanout). The test compared sorted lists of interfaces from APPL_DB LLDP_ENTRY_TABLE (which stores one entry per interface) against the parsed `show lldp table` output (which has duplicate entries). This always failed on dualtor testbeds (29 DB keys vs 32 CLI rows). Changes: - Deduplicate interface list in get_show_lldp_table_output() using dict.fromkeys() to handle multiple LLDP neighbors per port - Use set comparison instead of sorted list comparison in check_lldp_table_keys() and assert_lldp_interfaces() - Add diff details to assertion error message for easier debugging Signed-off-by: Zhaohui Sun <zhaohuisun@microsoft.com>
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LGTM — correct fix for dualtor LLDP test. dict.fromkeys() for dedup and set comparison with diff-based error messages are clean improvements. CI all green.
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…c-net#23193) In dualtor-aa topology, uplink ports receive LLDP PDUs from both the T1 neighbor switch and the fanout switch. This causes `show lldp table` to list multiple rows per interface (e.g., Ethernet224 appears twice - once for ARISTA01T1, once for fanout). The test compared sorted lists of interfaces from APPL_DB LLDP_ENTRY_TABLE (which stores one entry per interface) against the parsed `show lldp table` output (which has duplicate entries). This always failed on dualtor testbeds (29 DB keys vs 32 CLI rows). Changes: - Deduplicate interface list in get_show_lldp_table_output() using dict.fromkeys() to handle multiple LLDP neighbors per port - Use set comparison instead of sorted list comparison in check_lldp_table_keys() and assert_lldp_interfaces() - Add diff details to assertion error message for easier debugging Signed-off-by: Zhaohui Sun <zhaohuisun@microsoft.com>
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Description of PR
Summary:
Fix
test_lldp_entry_table_contentfailure on dualtor-aa topology caused by duplicate LLDP neighbors from fanout switches.In dualtor-aa topology, uplink ports (e.g., Ethernet224/232/240) receive LLDP PDUs from both the T1 ARISTA switch and the fanout switch.
show lldp tablelists multiple rows per port, butLLDP_ENTRY_TABLEin APPL_DB stores only one entry per interface. The sorted list comparison (29 DB keys vs 32 CLI rows) always fails.Fixes https://msazure.visualstudio.com/One/_workitems/edit/36796797
Type of change
Back port request
Approach
What is the motivation for this PR?
test_lldp_entry_table_contentconsistently fails on dualtor-aa topology testbeds (e.g., Arista-720DT-48CQ, Cisco-8101-C32) becauseget_show_lldp_table_output()returns duplicate interface entries when a port has multiple LLDP neighbors.Example from
show lldp tableon dualtor-aa:The comparison
sorted(lldp_entry_keys) == sorted(show_lldp_table_int_list)fails because:LLDP_ENTRY_TABLEhas 29 unique interface keysshow lldp tableparsed output has 32 entries (3 interfaces duplicated due to fanout)How did you do it?
get_show_lldp_table_output(): Usedict.fromkeys()to remove duplicate interface names while preserving ordercheck_lldp_table_keys(): Replacesorted()list comparison withset()comparison for robustnessassert_lldp_interfaces(): Use set comparison and include diff details (which interfaces are in DB but not CLI, and vice versa) for easier debuggingHow did you verify/test it?
show lldp table(once for T1 neighbor ARISTA0xT1, once for fanout str3-8101-fanout-10)Any platform specific information?
Affects dualtor-aa topology testbeds where uplink ports are connected through fanout switches that also advertise LLDP. Confirmed on:
Supported testbed topology if it's a new test case?
N/A (bug fix for existing test)
Documentation
N/A