Test changes for fboss neighbor scale #1037
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itskittycisco wants to merge 1 commit intofacebook:mainfrom
Open
Test changes for fboss neighbor scale #1037itskittycisco wants to merge 1 commit intofacebook:mainfrom
itskittycisco wants to merge 1 commit intofacebook:mainfrom
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pip install -r requirements-dev.txt && pre-commit installpre-commit runclang-format.............................................................Passed
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Summary
In the fboss test logs there are 1024 SAI_API_CREATE::create_neighbor_entry calls, all successful (no OOR).
They create all 1024 neighbors with same dst MAC (logged as 02:03:04:05:06:07).
Why no OOR
The SDK’s get_next_hop_host() reuses one nexthop host for all neighbors with the same MAC.
So it allocates one GID per unique MAC (one host nexthop per MAC).
Creating 1024 neighbors all with the same destination MAC uses only one host nexthop (one GID).
The limit is applied to number of host nexthops (GIDs), not number of neighbor entries, so the 1024th create still succeeds and we never see OOR.
With the changes in PR: 512 neighbors were created and programmed in hardware. The 513th and 514th add attempts hit OOR and did not create new entries.
Different MAC per neighbor
SAI: create_neighbor_entry shows DST_MAC increasing by index, e.g.
1::2 → 02:00:00:00:00:00, 1::3 → 02:00:00:00:00:01, 1::4 → 02:00:00:00:00:02, … up to 02:00:00:00:01:ff for the last successful one.
SDK: add_ipv6_host shows mac_addr= (flat=0x20000000000), 0x20000000001, 0x20000000002, … (same pattern: one MAC per IP).
So all created neighbors use unique MACs (one IP host / GID per neighbor).
Results: the 513th (1::204) and 514th (1::205) attempts hit IP_HOSTS OOR; the test sees the OOR via getNeighborTableUpdateFailure() = 1 and passes.
Test Plan
Manually verified the neighbor test -
AgentNeighborResolutionOverFlowTest.neighborResolutionOverFlow