hashing_test

Hashing: Dataplane Hashing with Physical/Software Loopbacks

Summary

Verify Dataplane Hashing using a mix of physical loopback ports and software loopback interfaces across multiple Network Instances.

Topology

The test requires a DUT and an ATE. The topology uses a multiple looped back ports configuration to route traffic through multiple hashing stages on the DUT.

graph TD
    Ingress["ATE Ingress: Port 2 (ixia2)"] -->|Traffic| IngressPort["DUT Ingress: lc2_p10"]
    IngressPort --> DefaultVRF{Default VRF}
    
    subgraph Stage1 ["Stage 1: Default VRF (WCMP 7:1:1:1)"]
        DefaultVRF -->|70%| Loop1["Loop 1: lc1_p3 -> lc2_p3"]
        DefaultVRF -->|10%| SL0["Soft Loop 0: lag118"]
        DefaultVRF -->|10%| SL1["Soft Loop 1: lag119"]
        DefaultVRF -->|10%| SL2["Soft Loop 2: lag120"]
    end
    
    SL0 --> Drop1["ACL Drop"]
    SL1 --> Drop1
    SL2 --> Drop1
    
    Loop1 -->|VRF Assignment: lc2_p3 in Transit| TransitVRF{Transit VRF}
    
    subgraph Stage2 ["Stage 2: Transit VRF (ECMP 8-wide)"]
        TransitVRF --> Loop2["Loop 2: lc1_p4 -> lc2_p4"]
        TransitVRF --> Loop3["Loop 3: lc1_p5 -> lc2_p5"]
        TransitVRF --> Loop4["Loop 4: lc1_p6 -> lc2_p6"]
        TransitVRF --> Loop5["Loop 5: lc1_p1 -> lc2_p1"]
        TransitVRF --> SL3["Soft Loop 3: lag121"]
        TransitVRF --> SL4["Soft Loop 4: lag122"]
        TransitVRF --> SL5["Soft Loop 5: lag123"]
        TransitVRF --> SL6["Soft Loop 6: lag124"]
    end
    
    SL3 --> Drop2["ACL Drop"]
    SL4 --> Drop2
    SL5 --> Drop2
    SL6 --> Drop2
    
    Loop2 -->|VRF Assignment: lc2_p4 in Egress| EgressVRF{Egress VRF}
    Loop3 -->|VRF Assignment: lc2_p5 in Egress| EgressVRF
    
    Loop4 -->|VRF Assignment: lc2_p6 in Self-Site| SelfSiteVRF{Self-Site VRF}
    Loop5 -->|VRF Assignment: lc2_p1 in Self-Site| SelfSiteVRF
    
    subgraph Stage3 ["Stage 3: Self-Site VRF (ECMP 8-wide)"]
        SelfSiteVRF --> Loop6["Loop 6: lc2_p8 -> lc1_p8"]
        SelfSiteVRF --> Loop7["Loop 7: lc2_p7 -> lc1_p7"]
        SelfSiteVRF --> Loop8["Loop 8: lc2_p2 -> lc1_p2"]
        SelfSiteVRF --> SL7["Soft Loop 7: lag125"]
        SelfSiteVRF --> SL8["Soft Loop 8: lag126"]
        SelfSiteVRF --> SL9["Soft Loop 9: lag127"]
        SelfSiteVRF --> SL10["Soft Loop 10: lag128"]
        SelfSiteVRF --> SL11["Soft Loop 11: lag129"]
    end
    
    SL7 --> Drop3["ACL Drop"]
    SL8 --> Drop3
    SL9 --> Drop3
    SL10 --> Drop3
    SL11 --> Drop3
    
    Loop6 -->|VRF Assignment: lc1_p8 in Egress| EgressVRF
    Loop7 -->|VRF Assignment: lc1_p7 in Egress| EgressVRF
    Loop8 -->|VRF Assignment: lc1_p2 in Egress| EgressVRF
    
    EgressVRF --> EgressPort["DUT Egress: lc2_p9"] --> Egress["ATE Egress: Port 1 (ixia1)"]

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Port Details and Loopbacks

The test utilizes physical loopback cables and software terminal loopbacks. Physical loopbacks are formed by connecting two ports on the same DUT:

• Loop 1: lc1_p3 <-> lc2_p3
• Loop 2: lc1_p4 <-> lc2_p4
• Loop 3: lc1_p5 <-> lc2_p5
• Loop 4: lc1_p6 <-> lc2_p6
• Loop 5: lc1_p1 <-> lc2_p1
• Loop 6: lc2_p8 <-> lc1_p8
• Loop 7: lc2_p7 <-> lc1_p7
• Loop 8: lc2_p2 <-> lc1_p2

Software loopbacks (Terminal Loopbacks) are configured on the DUT ports:

• Stage 1 Soft Loops: 3 ports configured in TERMINAL loopback mode, with each port assigned as the sole member of a dedicated Link Aggregation Group (LAG).
• Stage 2 Soft Loops: 4 ports configured in TERMINAL loopback mode, with each port assigned as the sole member of a dedicated Link Aggregation Group (LAG).
• Stage 3 Soft Loops: 5 ports configured in TERMINAL loopback mode, with each port assigned as the sole member of a dedicated Link Aggregation Group (LAG). Total 12 software loopbacks are dynamically discovered from the unused ports on the DUT and configured.

ATE Connection:

• ATE Port 1 (ixia1) connects to DUT Port lc2_p9 (Egress).
• ATE Port 2 (ixia2) connects to DUT Port lc2_p10 (Ingress).

Test Scenario 1: Hash Distribution

1. Baseline Configuration

• Configure all DUT ports as LAG interfaces (each port in its own LAG, e.g., lc2_p10 in lag110).
• Configure 12 discovered unused ports as soft loops (in TERMINAL loopback mode, each in its own LAG).
• Configure Static ARP on all interfaces.
• Configure ACLs on all soft loops to drop ingress traffic (to prevent loops/packet storm).
• Configure Network Instances (VRFs): TRANSIT, SELF_SITE, EGRESS.
• Assign interfaces to VRFs:
  • Default VRF: Ingress lc2_p10, Stage 1 Soft Loops.
  • TRANSIT VRF: lc2_p3 (Loop 1 RX), lc1_p4 (Loop 2 TX), lc1_p5 (Loop 3 TX), lc1_p6 (Loop 4 TX), lc1_p1 (Loop 5 TX), Stage 2 Soft Loops.
  • SELF_SITE VRF: lc2_p6 (Loop 4 RX), lc2_p1 (Loop 5 RX), lc2_p8 (Loop 6 TX), lc2_p7 (Loop 7 TX), lc2_p2 (Loop 8 TX), Stage 3 Soft Loops.
  • EGRESS VRF: lc2_p4 (Loop 2 RX), lc2_p5 (Loop 3 RX), lc1_p8 (Loop 6 RX), lc1_p7 (Loop 7 RX), lc1_p2 (Loop 8 RX), lc2_p9 (Egress).

2. Interface VRF Assignment Configuration

Assign RX ports of the loopbacks to their respective VRFs to route traffic to the next stage VRF:

• On lc2_p3 (Loop 1 RX): Assign to TRANSIT VRF.
• On lc2_p6, lc2_p1 (Loop 4, 5 RX): Assign to SELF_SITE VRF.
• On lc2_p4, lc2_p5 (Loop 2, 3 RX): Assign to EGRESS VRF.
• On lc1_p8, lc1_p7, lc1_p2 (Loop 6, 7, 8 RX): Assign to EGRESS VRF.

3. gRIBI Programming

• Default VRF:
  • Route 198.51.100.0/24 -> NHG 1 (WCMP: lc1_p3 weight 7, 3 soft loops weight 1 each).
• TRANSIT VRF:
  • Route 198.51.100.0/24 -> NHG 2 (ECMP 8-wide: lc1_p4, lc1_p5, lc1_p6, lc1_p1 and 4 soft loops, weight 1 each).
• SELF_SITE VRF:
  • Route 198.51.100.0/24 -> NHG 3 (ECMP 8-wide: lc2_p8, lc2_p7, lc2_p2 and 5 soft loops, weight 1 each).
• EGRESS VRF:
  • Route 198.51.100.0/24 -> NHG 4 (pointing to egress port lc2_p9).

4. Traffic Verification

• Generate Test Traffic: Send traffic from ATE Port 2 targeting random destination IP addresses within the 198.51.100.0/24 subnet. Vary the source IPv4 addresses, source UDP ports, and destination UDP ports to ensure sufficient entropy for hashing.
• Tolerance Threshold: Hashing distribution tolerance is defined as ±2% of the expected value (relative). For example, with an expected value of 12.5%, the acceptable range is 12.25% to 12.75%.
• Verify Packet Distribution:
  • Stage 1 (Default VRF): ~70% to lc1_p3 (acceptable range: 68.6% – 71.4%), and ~10% to each of the 3 soft loops (acceptable range: 9.8% – 10.2%).
  • Stage 2 (Transit VRF): ~12.5% to each of the 8 members of NHG 2 (acceptable range: 12.25% – 12.75%).
  • Stage 3 (Self-Site VRF): ~12.5% to each of the 8 members of NHG 3 (acceptable range: 12.25% – 12.75%).
  • Egress: All traffic routed to EGRESS VRF is received on ATE Port 1 (ixia1).

Canonical OC

{
  "interfaces": {
    "interface": [
      {
        "config": {
          "enabled": true,
          "name": "ae1",
          "type": "ieee8023adLag"
        },
        "name": "ae1"
      },
      {
        "config": {
          "enabled": true,
          "name": "ae2",
          "type": "ieee8023adLag"
        },
        "name": "ae2"
      },
      {
        "config": {
          "enabled": true,
          "name": "eth1",
          "type": "ethernetCsmacd"
        },
        "ethernet": {
          "config": {
            "aggregate-id": "ae1"
          }
        },
        "name": "eth1"
      },
      {
        "config": {
          "enabled": true,
          "loopback-mode": "TERMINAL",
          "name": "eth2",
          "type": "ethernetCsmacd"
        },
        "ethernet": {
          "config": {
            "aggregate-id": "ae2"
          }
        },
        "name": "eth2"
      }
    ]
  },
  "network-instances": {
    "network-instance": [
      {
        "config": {
          "name": "DEFAULT",
          "type": "DEFAULT_INSTANCE"
        },
        "interfaces": {
          "interface": [
            {
              "config": {
                "id": "ae1",
                "interface": "ae1"
              },
              "id": "ae1"
            }
          ]
        },
        "name": "DEFAULT"
      },
      {
        "config": {
          "name": "TRANSIT",
          "type": "L3VRF"
        },
        "interfaces": {
          "interface": [
            {
              "config": {
                "id": "ae2",
                "interface": "ae2"
              },
              "id": "ae2"
            }
          ]
        },
        "name": "TRANSIT"
      }
    ]
  }
}

OpenConfig Path and RPC Coverage

paths:
  /interfaces/interface/config/name:
  /interfaces/interface/config/enabled:
  /interfaces/interface/state/counters/in-pkts:
  /interfaces/interface/state/counters/out-pkts:
  /network-instances/network-instance/config/name:
  /network-instances/network-instance/config/type:
  /network-instances/network-instance/interfaces/interface/config/id:
  /network-instances/network-instance/interfaces/interface/config/interface:
rpcs:
  gribi:
    gRIBI.Modify: