Verify that configuration changes made via gNMI to an interface (e.g., MTU, speed, enabling/disabling) used by an active gRIBI NextHop are handled gracefully.

When an interface state changes due to gNMI configuration (like shutting down the interface or changing its MTU), any gRIBI-programmed NextHop relying on that interface must react gracefully. The gRIBI-routed traffic stream state should be predictable, recovering via backup paths or restoring once the interface is back online. The viability of the gRIBI NextHop should be correctly reflected in gNMI telemetry, and the system must remain stable without causing switch instability.

• TESTBED_DUT_ATE_4LINKS

• Connect ATE port-1 to DUT port-1, ATE port-2 to DUT port-2, ATE port-3 to DUT port-3, and ATE port-4 to DUT port-4.
• Configure IPv4 and IPv6 addresses on the interfaces.
  • DUT port-1 (Ethernet1/1/1): 192.0.2.1/30 and 2001:db8:1::1/126
  • ATE port-1: 192.0.2.2/30 and 2001:db8:1::2/126
  • DUT port-2 (Ethernet1/1/2): 198.51.100.1/30 and 2001:db8:2::1/126
  • ATE port-2: 198.51.100.2/30 and 2001:db8:2::2/126
  • DUT port-3 (Ethernet1/1/3): 198.51.100.5/30 and 2001:db8:3::1/126
  • ATE port-3: 198.51.100.6/30 and 2001:db8:3::2/126
  • DUT port-4 (Ethernet1/1/4): 198.51.100.9/30 and 2001:db8:4::1/126
  • ATE port-4: 198.51.100.10/30 and 2001:db8:4::2/126
• Enable gNMI, gRIBI, and gNOI services on the DUT.

• Step 1 - Generate DUT configuration

Configure the baseline interfaces on the DUT.

{
  "openconfig-interfaces:interfaces": {
    "interface": [
      {
        "name": "Ethernet1/1/2",
        "config": {
          "name": "Ethernet1/1/2",
          "enabled": true,
          "mtu": 1500
        },
        "subinterfaces": {
          "subinterface": [
            {
              "index": 0,
              "ipv4": {
                "addresses": {
                  "address": [
                    {
                      "ip": "198.51.100.1",
                      "config": {
                        "ip": "198.51.100.1",
                        "prefix-length": 30
                      }
                    }
                  ]
                }
              },
              "ipv6": {
                "addresses": {
                  "address": [
                    {
                      "ip": "2001:db8:2::1",
                      "config": {
                        "ip": "2001:db8:2::1",
                        "prefix-length": 126
                      }
                    }
                  ]
                }
              }
            }
          ]
        }
      }
    ]
  }
}

• Step 2 - Establish gRIBI client session.
• Step 3 - Program gRIBI NextHops, NextHopGroup, and 1,000 IPv4/IPv6 entries pointing to a NextHopGroup (NHG) containing DUT port-2, port-3, and port-4 for ECMP validation.
  • NextHop 1 (Index 10): DUT port-2 (Ethernet1/1/2), MAC 00:1A:11:00:1A:BC
  • NextHop 2 (Index 11): DUT port-3 (Ethernet1/1/3), MAC 00:1A:11:00:1A:BD
  • NextHop 3 (Index 12): DUT port-4 (Ethernet1/1/4), MAC 00:1A:11:00:1A:BE
  • NextHopGroup (Index 100): Contains NextHops 10, 11, and 12 with equal weights.
  • IPv4 Prefixes: 203.0.113.1/32 through 203.0.116.232/32 (1,000 prefixes) pointing to NHG 100.
  • IPv6 Prefixes: 2001:db8:a::1/128 through 2001:db8:a::3e8/128 (1,000 prefixes) pointing to NHG 100.
• Step 4 - Send continuous IPv4 and IPv6 traffic at 1000 pps from ATE port-1 to the programmed prefixes. Verify traffic hashes evenly across ATE port-2, port-3, and port-4.
• Step 5 - Disable DUT port-2 via gNMI Set replacing /interfaces/interface[name=Ethernet1/1/2]/config/enabled to false.
• Step 6 - Subscribe via gNMI ON_CHANGE to /interfaces/interface[name=Ethernet1/1/2]/state/oper-status and verify it transitions to DOWN.
• Step 7 - Subscribe via gNMI ON_CHANGE to /network-instances/network-instance[name=DEFAULT]/afts/next-hops/next-hop[index=10]/state/index and verify it reflects the failure or viability change (if supported).
• Step 8 - Verify traffic to ATE port-2 drops to exactly 0 pps, and traffic from ATE port-1 redistributes to ATE port-3 and ATE port-4. Monitor for 30 seconds to ensure no switch instability or route flapping.
• Step 9 - Enable DUT port-2 via gNMI Set replacing /interfaces/interface[name=Ethernet1/1/2]/config/enabled to true.
• Step 10 - Subscribe via gNMI ON_CHANGE to /interfaces/interface[name=Ethernet1/1/2]/state/oper-status and verify it transitions to UP.
• Step 11 - Verify traffic resumes hashing evenly across ATE port-2, port-3, and port-4. Monitor for 30 seconds to confirm 0% loss and stable ECMP distribution.

• Step 1 - Continuing from TE-1.7.1 without tearing down gRIBI or gNMI sessions, ensure continuous traffic is flowing from ATE port-1 and hashing across ATE port-2, port-3, and port-4.
• Step 2 - Change the MTU of DUT port-2 via gNMI Set replacing /interfaces/interface[name=Ethernet1/1/2]/config/mtu to 9000.
• Step 3 - Subscribe via gNMI ON_CHANGE to /interfaces/interface[name=Ethernet1/1/2]/state/mtu and verify it reflects 9000.
• Step 4 - Verify the switch remains stable and traffic continues to hash across all three egress ports. (A brief flap on port-2 during MTU change is acceptable depending on vendor implementation, but traffic must fully recover across all ports). Monitor for 30 seconds.
• Step 5 - Revert the MTU of DUT port-2 via gNMI Set replacing /interfaces/interface[name=Ethernet1/1/2]/config/mtu to 1500.
• Step 6 - Subscribe via gNMI ON_CHANGE to /interfaces/interface[name=Ethernet1/1/2]/state/mtu and verify it reflects 1500 and traffic fully recovers across all ports.

• Step 1 - Continuing from TE-1.7.2, disable DUT port-2 via gNMI Set replacing /interfaces/interface[name=Ethernet1/1/2]/config/enabled to false.
• Step 2 - Subscribe via gNMI ON_CHANGE to verify /interfaces/interface[name=Ethernet1/1/2]/state/oper-status is DOWN.
• Step 3 - Program a new gRIBI NextHop (Index 20) pointing to DUT port-2 (Ethernet1/1/2) and a new IPv4 prefix 203.0.113.255/32 pointing to it.
• Step 4 - Subscribe via gNMI ON_CHANGE to /network-instances/network-instance[name=DEFAULT]/afts/next-hops/next-hop[index=20]/state/index and verify it is either rejected or correctly reflects an unviable state in telemetry.
• Step 5 - Send continuous IPv4 traffic at 1000 pps from ATE port-1 to 203.0.113.255.
• Step 6 - Verify 100% traffic drop to this prefix.
• Step 7 - Re-enable DUT port-2 via gNMI Set and verify via ON_CHANGE subscription that it transitions to UP.
• Step 8 - Verify traffic to 203.0.113.255 now successfully forwards to ATE port-2.

• Step 1 - Continuing from TE-1.7.3, ensure traffic is flowing steadily to all programmed prefixes.
• Step 2 - Change the MTU of DUT port-2 via gNMI Set replacing /interfaces/interface[name=Ethernet1/1/2]/config/mtu to 500.
• Step 3 - Send continuous IPv4 traffic with a packet size of 1500 bytes from ATE port-1 to a prefix solely destined to DUT port-2 (e.g., 203.0.113.255).
• Step 4 - Verify traffic drops to exactly 0 pps for this prefix.
• Step 5 - Verify via gNMI Get that the interface error counters (e.g., /interfaces/interface[name=Ethernet1/1/2]/ethernet/state/counters/in-oversize-frames or in-errors) increment correspondingly to the dropped traffic.
• Step 6 - Revert the MTU of DUT port-2 to 1500 via gNMI Set and verify traffic resumes with 0% loss.

paths:
  /interfaces/interface/config/enabled:
  /interfaces/interface/state/oper-status:
  /interfaces/interface/config/mtu:
  /interfaces/interface/state/mtu:
  /interfaces/interface/ethernet/state/counters/in-oversize-frames:
  /interfaces/interface/state/counters/in-errors:
  /network-instances/network-instance/afts/next-hops/next-hop/state/index:
  /network-instances/network-instance/afts/ipv4-unicast/ipv4-entry/state/next-hop-group:
  /network-instances/network-instance/afts/ipv6-unicast/ipv6-entry/state/next-hop-group:
  /network-instances/network-instance/afts/next-hop-groups/next-hop-group/next-hops/next-hop/state/index:

rpcs:
  gnmi:
    gNMI.Get:
    gNMI.Set:
    gNMI.Subscribe:
      on_change: true

• FFF