[vlanmgrd]: Preventing VLAN interfaces from going down when all of their member ports are down #3370
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…ed to the bridge are down, the bridge interface still remains up (and as a result, VLAN interfaces connected to the bridge also remain up). Signed-off-by: Mahdi Ramezani <[email protected]>
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@dgsudharsan , fyi |
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If I understand, this Vlan interface without neighbors is used only for decapsulation purpose? Why can't we use Loopback interface? |
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/azp run |
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Azure Pipelines successfully started running 1 pipeline(s). |
no, we use Vlan GW IP as well for decap in addition to Loopback. |
dgsudharsan
previously approved these changes
Nov 23, 2024
…ce's subnet is added to the 'ASIC_STATE:SAI_OBJECT_TYPE_ROUTE_ENTRY' table upon creation of the VLAN interface. Signed-off-by: Mahdi Ramezani <[email protected]>
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What I did
Started up the "dummy" interface that is already connected to the bridge named "Bridge" so that when all ports connected to the bridge are DOWN, the bridge interface remains UP. This ensures that when there is one VLAN interface connected to the bridge, it remains UP even when all of the VLAN's member ports are DOWN.
Since the VLAN interface is UP immediately after creation (because the "dummy" interface is UP), at least one route to the VLAN's subnet is added to the
ASIC_STATE:SAI_OBJECT_TYPE_ROUTE_ENTRYtable (one route if the VLAN is created in a peerless Vnet, and two routes if it is created in a VNet with one peer). Tests intests/test_vnet.pyhave been updated to reflect this fact.Why I did it
Before this change, when all member ports of a VLAN interface went down, the VLAN interface also went operationally down. This effectively disabled the advertisement of the VLAN interface's subnet IP to neighbors and prevented the IP-in-IP decapsulation feature for the VLAN interface from working properly.
How I verified it
I ran the tests submitted in PR #15244 for sonic-mgmt repo on a T0 testbed and verified that when all member ports of a VLAN are brought down, the VLAN interface remains operationally UP and BGP advertisement and IP-in-IP decapsulation features work as expected.
I also ran all tests in
tests/test_vnet.pyon a local DVS container after starting up the "dummy" interface and verified that all of them pass (except fortest_vnet_orch_4, which is skipped).