bgp_dynamic_neighbors

RT-1.103: DUT iBGP passive listener FNT with common router id

Summary

Validate the iBGP passive listener functionality on DUT using dynamic peering and verify consistent router-id usage across multiple sessions.

Note

This requirement is discussed/aligned in PR #5620.

Testbed type

• TESTBED_DUT_ATE_2LINKS (ATE simulating multiple internal peers).

Topology

graph LR;
  ate1[ATE Port 1] -- "BGP Initiator (Listen Range)" --> dut1[DUT Port 1]
  ate2[ATE Port 2] -- "BGP Initiator (Listen Range)" --> dut2[DUT Port 2]

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• Connect ATE Port 1 to DUT Port 1.
• Connect ATE Port 2 to DUT Port 2.
• ATE will initiate multiple BGP sessions from different source IPs within the configured listen range.
• Simulated ATE peers may use the same BGP Identifier (Router ID) to verify standard transport separation behavior (identified by source IP).
• One of the ports (e.g., ATE Port 1) will also establish a static BGP session using a direct interface IP/port IP address (outside the listen range).

Procedure

Configuration

1. Configure DUT with a global router-id.
2. Configure a peer-group for dynamic neighbors (e.g., RM_DYNAMIC_PEERS).
3. Configure dynamic neighbor prefixes (listen range, e.g., 2001:db8:1::/64) associated with the peer-group.
4. Configure MD5 authentication on the peer-group.
5. Configure a static BGP neighbor (outside the listen range, e.g., 2001:db8:0:1::2).

Tests

RT-1.103.1 - Dynamic Peering and Router-ID Validation

• Step 1: Enable dynamic neighbor prefix on DUT (e.g., 2001:db8:1::/64).
• Step 2: Initiate BGP sessions from multiple ATE interfaces using different specific source IPs (e.g., 2001:db8:1::1, 2001:db8:1::2) within the listen range.
• Step 3: Verify that sessions transition to ESTABLISHED.
• Step 4: Verify that the DUT uses the configured router-id (e.g., 192.0.2.1) for all dynamically established sessions.
• Step 5: Verify concurrent session handling (e.g., 5-10 sessions established simultaneously).
• Step 6: Attempt to initiate a BGP session from an IP in the listen range but using an incorrect/Different ASN (e.g., 64501 instead of 64500).
• Step 7: Verify that the DUT rejects the connection or that it fails to transition to ESTABLISHED state.

RT-1.103.2 - Telemetry for Dynamic Neighbors

• Step 1: Verify that the established dynamic peers (e.g., 2001:db8:1::1) are instantiated and visible under the neighbors/neighbor container in telemetry.
• Step 2: Query the state leaf /network-instances/network-instance/protocols/protocol/bgp/neighbors/neighbor/state/dynamically-configured for the dynamic peer and verify it returns true.
• Step 3: Verify that standard statically configured neighbors return false for this leaf.

RT-1.103.3 - Secured Dynamic Peers (iBGP MD5)

• Step 1: Configure the peer group RM_DYNAMIC_PEERS with auth-password.
• Step 2: Initiate BGP sessions from ATE using the correct MD5 password.
• Step 3: Verify that sessions transition to ESTABLISHED.
• Step 4: Attempt to initiate a session from ATE with an incorrect password or no password.
• Step 5: Verify that the session FAILS to establish.

RT-1.103.4 - Duplicate ATE Router-ID (Transport Separation)

• Step 1: Establish a BGP session from ATE Peer 1 (Source IP 2001:db8:1::1) with a specific Router-ID (e.g., 192.0.2.200).
• Step 2: Initiate a BGP session from ATE Peer 2 (Source IP 2001:db8:1::2) using the same Router-ID (192.0.2.200).
• Step 3: Verify that both sessions transition to ESTABLISHED and are maintained independently, relying on transport address separation.

RT-1.103.5 - Overlapping Prefix Best-Path Selection and Reconvergence

Verifies that the DUT correctly evaluates BGP best-path parameters (e.g., MED) and executes seamless route reconvergence when the same prefix is received concurrently from both static and dynamic BGP peers.

• Step 1: Establish a static BGP session on one of the current ports (e.g., Port 1) using an IP address outside the listen range (e.g., the direct port IP address/subnet 2001:db8:0:1::2).
• Step 2: Establish a dynamic BGP session (e.g., on Port 2 or behind Port 1) using an IP within the listen range (e.g., 2001:db8:1::1).
• Step 3: Advertise the exact same prefix (e.g., 2001:db8:2::/64 for IPv6 or 198.51.100.0/24 for IPv4) from both ATE ports/peers to DUT.
• Step 4: Configure Multi-Exit Discriminator (MED) to influence best-path selection: set MED = 50 on the static peer and MED = 100 on the dynamic peer.
• Step 5: Verify DUT selects the best path based on standard BGP decision process (favors path with lower MED, i.e., the static peer).
• Step 6: Withdraw/Disable the preferred path from ATE.
• Step 7: Verify seamless reconvergence to the alternative path on DUT.

Canonical OC

{
  "network-instances": {
    "network-instance": [
      {
        "config": {
          "name": "DEFAULT"
        },
        "name": "DEFAULT",
        "protocols": {
          "protocol": [
            {
              "bgp": {
                "global": {
                  "config": {
                    "as": 64500,
                    "router-id": "192.0.2.1"
                  },
                  "dynamic-neighbor-prefixes": {
                    "dynamic-neighbor-prefix": [
                      {
                        "config": {
                          "prefix": "2001:db8:1::/64",
                          "peer-group": "RM_DYNAMIC_PEERS"
                        },
                        "prefix": "2001:db8:1::/64"
                      }
                    ]
                  }
                },
                "peer-groups": {
                  "peer-group": [
                    {
                      "config": {
                        "peer-group-name": "RM_DYNAMIC_PEERS",
                        "peer-as": 64500,
                        "auth-password": "secret_md5_key"
                      },
                      "peer-group-name": "RM_DYNAMIC_PEERS"
                    },
                    {
                      "config": {
                        "peer-group-name": "STATIC_PEERS",
                        "peer-as": 64500
                      },
                      "peer-group-name": "STATIC_PEERS"
                    }
                  ]
                },
                "neighbors": {
                  "neighbor": [
                    {
                      "config": {
                        "neighbor-address": "2001:db8:0:1::2",
                        "peer-as": 64500,
                        "peer-group": "STATIC_PEERS"
                      },
                      "neighbor-address": "2001:db8:0:1::2"
                    }
                  ]
                }
              },
              "config": {
                "identifier": "BGP",
                "name": "BGP"
              },
              "identifier": "BGP",
              "name": "BGP"
            }
          ]
        }
      }
    ]
  }
}

OpenConfig Path and RPC Coverage

paths:
  # BGP Global Config
  /network-instances/network-instance/protocols/protocol/bgp/global/config/as:
  /network-instances/network-instance/protocols/protocol/bgp/global/config/router-id:
  /network-instances/network-instance/protocols/protocol/bgp/global/state/router-id:

  # BGP Dynamic Neighbors
  /network-instances/network-instance/protocols/protocol/bgp/global/dynamic-neighbor-prefixes/dynamic-neighbor-prefix/config/prefix:
  /network-instances/network-instance/protocols/protocol/bgp/global/dynamic-neighbor-prefixes/dynamic-neighbor-prefix/config/peer-group:

  # BGP Peer Group Auth
  /network-instances/network-instance/protocols/protocol/bgp/peer-groups/peer-group/config/auth-password:

  # BGP Neighbor State (Dynamic)
  /network-instances/network-instance/protocols/protocol/bgp/neighbors/neighbor/state/session-state:
  /network-instances/network-instance/protocols/protocol/bgp/neighbors/neighbor/state/dynamically-configured:

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

Required DUT platform

• FFF (Fixed Form Factor) or MFF supporting dynamic BGP peers.