Configure an IPv6 address which is in link local scope. Verify the link local IPv6 address exists by checking the state path.

• Subtest #1 - Configure IPv6 link local

  • Configure DUT port 1 and OTG port 1 with an IPv6 link local scope IP address
  • Configure DUT port 2 and OTG port 2 with an IPv6 link local scope IP address
  • Validate config and state paths are set

• Subtest #2 - Verify the interface will pass IPv6 traffic as expected

  • Send IPv6 traffic from OTG port 1 to OTG port 2, validate OTG port 2 does not receive the traffic
  • Send IPv6 traffic from OTG port 1 to DUT port 1, validate DUT port 1 receives the traffic

• Subtest #3 - Verify adding and removing global unicast address does not affect link local address

  • Add configuration for a global unicast address on DUT port 1 and DUT port 2
  • Validate config and state paths are set
  • Send IPv6 traffic from OTG port 1 to OTG port 2, validate OTG port 2 receives the traffic
  • Remove configuration for the global unitcast address on DUT port 1
  • Validate that DUT port 1 link local address is still configured
  • Send IPv6 traffic from OTG port 1 to DUT port 1, validate DUT port 1 receives the traffic
  • Send IPv6 traffic from OTG port 1 to OTG port 2, validate OTG port 2 does not receive the traffic

• Subtest #4 - Verify enable/disable of DUT port 1 does not affect link local address

  • Disable/enable the port and see if the configured link-local address stays?
  • Validate that DUT port 1 link local address config and state paths continue to contain the address assignment
  • Send IPv6 traffic from OTG port 1 to DUT port 1, validate DUT port 1 receives the traffic

• Subtest #5 - IPv6 Neighbor Discovery REACHABLE to STALE state transition

  • Test setup:
    • DUT port 1 connected to ATE port 1.
    • DUT port 2 connected to ATE port 2.
    • Configure DUT port 1 with IPv6 global unicast address 2001:db8:1::1/64 on subinterface 0 (/interfaces/interface/subinterfaces/subinterface/config/index).
    • Configure DUT port 2 with IPv6 global unicast address 2001:db8:2::1/64 on subinterface 0.
    • Configure ATE port 1 with IPv6 address 2001:db8:1::2/64, MAC address 02:00:01:01:01:01, and gateway 2001:db8:1::1.
    • Configure the ATE port 1 gateway MAC statically (OTG gateway_mac) with the DUT port 1 MAC address from /interfaces/interface/ethernet/state/mac-address instead of resolving it with Neighbor Discovery. ATE port 1 then does not send Neighbor Solicitations (NS) to resolve DUT port 1, while its interface stays up and still replies to NS from DUT port 1 with solicited Neighbor Advertisements (NA).
    • Configure ATE port 2 with IPv6 address 2001:db8:2::2/64, MAC address 02:00:01:02:01:01, and gateway 2001:db8:2::1.
  • Step 1: Send ICMPv6 Echo Requests between ATE port 1 and DUT port 1 (2001:db8:1::1) and between ATE port 2 and DUT port 2 (2001:db8:2::1).
  • Step 2: Validate via gNMI state telemetry that neighbor discovery is complete and neighbor state is REACHABLE:
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/ip is 2001:db8:1::2.
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/link-layer-address is 02:00:01:01:01:01.
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state is REACHABLE.
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/origin is DYNAMIC.
  • Step 3: Stop all traffic flows and ICMPv6 Echo Requests toward DUT port 1. Keep the ATE port 1 link and protocols up (do not stop protocols or flap the link) so that ATE port 1 sends no traffic or NS toward DUT port 1 but still replies to NS from DUT port 1.
  • Step 4: Wait for the IPv6 neighbor reachability timer (BaseReachableTime, default 30 seconds) to expire without positive reachability confirmation.
  • Step 5: Validate via gNMI state telemetry that the neighbor entry on DUT port 1 transitions from REACHABLE to STALE:
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state is STALE.
  • Step 6: Validate via gNMI state telemetry that the cached link-layer address is preserved in the neighbor table while in STALE state:
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/link-layer-address remains 02:00:01:01:01:01.

• Subtest #6 - Forwarding to an IPv6 neighbor in STALE state

  • Step 1: While neighbor 2001:db8:1::2 on DUT port 1 remains in STALE state, generate an IPv6 data traffic flow from ATE port 2 destined to ATE port 1 (2001:db8:1::2) routed through DUT port 1.
  • Step 2: Validate that DUT immediately forwards data packets out of port 1 using the cached link-layer address 02:00:01:01:01:01 without dropping packets (0% packet loss, confirming the switch does not blackhole or drop traffic to stale neighbors).

• Subtest #7 - Verify IPv6 neighbor state transition from STALE back to REACHABLE state

  • Step 1: Stop traffic and allow neighbor 2001:db8:1::2 on DUT port 1 to transition back to STALE state after reachability timer expiry (repeat Subtest #5 Steps 3 to 5).
  • Step 2: Start the IPv6 data traffic flow from ATE port 2 to ATE port 1 (2001:db8:1::2) routed through DUT port 1.
  • Step 3: Validate that sending data traffic to the stale neighbor triggers the DUT neighbor state machine to initiate reachability verification per RFC 4861:
    • The neighbor state transitions from STALE to DELAY and then PROBE.
    • DUT transmits unicast Neighbor Solicitation (NS) probes out of port 1 toward ATE port 1.
  • Step 4: ATE port 1 replies to the NS probe with a solicited Neighbor Advertisement (NA). The ATE emulated interface does this by default, so no additional ATE configuration is needed.
  • Step 5: Validate via gNMI state telemetry that upon receiving the NA, the neighbor state on DUT port 1 transitions back to REACHABLE:
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state is REACHABLE.
  • Step 6: Validate continuous traffic forwarding across DUT port 2 to port 1 achieves 100% packet delivery with 0% loss during and after the transition.

• Subtest #8 - Neighbor cache update via unsolicited Neighbor Advertisement and control plane stability under load

  • Step 1: Halt traffic and allow neighbor 2001:db8:1::2 on DUT port 1 to transition back to STALE state after reachability timer expiry.
  • Step 2: Validate via gNMI state telemetry that neighbor state is STALE:
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state is STALE.
  • Step 3: Transmit an unsolicited Neighbor Advertisement (NA) from ATE port 1 (source 2001:db8:1::2) to the all-nodes multicast address ff02::1, with target IPv6 address 2001:db8:1::2, a new target link-layer address 02:00:01:01:01:02, the Override flag set, and the Solicited and Router flags clear. OTG has no native NA header, so send the NA as an ATE raw packet flow on ATE port 1: Ethernet and IPv6 headers (Next Header 58, Hop Limit 255) followed by an OTG custom header that carries the ICMPv6 NA bytes, with the ICMPv6 checksum precomputed by the test.
  • Step 4: Validate via gNMI state telemetry that the DUT applies the unsolicited NA per RFC 4861 (sections 7.2.5 and 7.2.6): it updates the cached link-layer address but does not treat the NA as reachability confirmation:
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/link-layer-address is 02:00:01:01:01:02.
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state is STALE (an unsolicited NA must not move the entry to REACHABLE).
  • Step 5: Transmit a second unsolicited NA, identical to the one in Step 3 except that it carries the original target link-layer address 02:00:01:01:01:01, and validate via gNMI state telemetry that the neighbor entry is restored:
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/link-layer-address is 02:00:01:01:01:01.
    • /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state is STALE.
  • Step 6: Generate continuous bidirectional data traffic between ATE port 1 and ATE port 2 at line rate across the DUT.
  • Step 7: While data traffic is actively flowing, transmit periodic ICMPv6 Echo Requests from ATE port 1 directed to the DUT interface IP (2001:db8:1::1).
  • Step 8: Validate that the DUT control plane responds to 100% of ICMPv6 Echo Requests without packet timeout or unreachability.
  • Step 9: Validate via gNMI state telemetry that the IPv6 neighbor table remains healthy, entries do not get stuck in STALE, and the switch remains consistently reachable throughout the duration of the test.

• Stop all ATE traffic flows, including the raw Neighbor Advertisement flows, and stop ATE protocols.
• Register and execute t.Cleanup() routines that ensure DUT port 1 and DUT port 2 are administratively enabled (/interfaces/interface/config/enabled is true) and remove all IPv6 link-local and global unicast addresses configured on them during the test, so the DUT is returned to its exact pre-test baseline state even if the test fails.

{
  "interfaces": {
    "interface": [
      {
        "config": {
          "description": "DUT Port 1 to ATE Port 1",
          "enabled": true,
          "name": "port1"
        },
        "name": "port1",
        "subinterfaces": {
          "subinterface": [
            {
              "config": {
                "enabled": true,
                "index": 0
              },
              "index": 0,
              "ipv6": {
                "addresses": {
                  "address": [
                    {
                      "config": {
                        "ip": "2001:db8:1::1",
                        "prefix-length": 64
                      },
                      "ip": "2001:db8:1::1"
                    }
                  ]
                },
                "config": {
                  "enabled": true
                }
              }
            }
          ]
        }
      },
      {
        "config": {
          "description": "DUT Port 2 to ATE Port 2",
          "enabled": true,
          "name": "port2"
        },
        "name": "port2",
        "subinterfaces": {
          "subinterface": [
            {
              "config": {
                "enabled": true,
                "index": 0
              },
              "index": 0,
              "ipv6": {
                "addresses": {
                  "address": [
                    {
                      "config": {
                        "ip": "2001:db8:2::1",
                        "prefix-length": 64
                      },
                      "ip": "2001:db8:2::1"
                    }
                  ]
                },
                "config": {
                  "enabled": true
                }
              }
            }
          ]
        }
      }
    ]
  }
}

/interfaces/interface/subinterfaces/subinterface/config/index
/interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/config/ip
/interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/config/prefix-length
/interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/config/type

/interfaces/interface/subinterfaces/subinterface/state/index
/interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/state/ip
/interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/state/prefix-length
/interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/state/type
/interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/ip
/interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/is-router
/interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/link-layer-address
/interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state
/interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/origin

paths:
  /interfaces/interface/config/enabled:
  /interfaces/interface/state/counters/in-pkts:
  /interfaces/interface/state/enabled:
  /interfaces/interface/state/oper-status:
  /interfaces/interface/subinterfaces/subinterface/config/enabled:
  /interfaces/interface/subinterfaces/subinterface/config/index:
  /interfaces/interface/subinterfaces/subinterface/state/admin-status:
  /interfaces/interface/subinterfaces/subinterface/state/counters/in-pkts:
  /interfaces/interface/subinterfaces/subinterface/state/counters/out-pkts:
  /interfaces/interface/subinterfaces/subinterface/state/enabled:
  /interfaces/interface/subinterfaces/subinterface/state/index:
  /interfaces/interface/subinterfaces/subinterface/state/oper-status:
  /interfaces/interface/subinterfaces/subinterface/ipv4/config/enabled:
  /interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/config/ip:
  /interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/config/prefix-length:
  /interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/config/type:
  /interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/state/ip:
  /interfaces/interface/subinterfaces/subinterface/ipv6/addresses/address/state/prefix-length:
  /interfaces/interface/subinterfaces/subinterface/ipv6/config/enabled:
  /interfaces/interface/subinterfaces/subinterface/ipv6/state/enabled:
  /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/ip:
  /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/is-router:
  /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/link-layer-address:
  /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/neighbor-state:
  /interfaces/interface/subinterfaces/subinterface/ipv6/neighbors/neighbor/state/origin:
rpcs:
  gnmi:
    gNMI.Get:
    gNMI.Set:
    gNMI.Subscribe:

• FFF - fixed form factor