🧪 Lab 03 · SR-PCE & BGP Color Traffic Steering

✅ Validated on Arista cEOS 4.32.0F. All outputs captured live from fabric in OrbStack.

Time: ~50 minutes · Nodes: 5 (2 Edge PEs, 3 Core P Routers)

Quick Start — Step-by-Step Execution Guide (Location: labs/segment-routing-lab/)

Step 1 · Deploy the Lab Fabric (if not already running)

cd labs/segment-routing-lab
sudo containerlab deploy -t topology.clab.yml --max-workers 1

Step 2 · Launch the Fully Guided Interactive Walkthrough

./run.sh --guided

Alternative Execution Options (Automated Push or Manual CLI)

• Fast Automated Script Push:

  ./run.sh 01          # apply + verify step 01 automatically
  ./run.sh --all       # run all steps in order
  

• Manual Line-by-Line CLI Execution: Interactive CLI shell on any container node:

  docker exec -it clab-segment-routing-lab-pe1 Cli
  

SR-PCE Traffic Steering Architecture

graph TD
    subgraph TrafficSteering["BGP Color Extended Community Steering"]
        PE1["pe1 (Headend PE)<br/>Color 100 Policy"] ===>|Color 100 Low-Latency Segment List| P1["p1 (Core P)"]
        P1 ===> PE2["pe2 (Tailend PE)<br/>10.255.0.5/32"]
    end

    classDef pe fill:#1b5e20,stroke:#81c784,color:#ffffff,stroke-width:2px,font-weight:bold;
    classDef p fill:#0d47a1,stroke:#64b5f6,color:#ffffff,stroke-width:2px,font-weight:bold;

    class PE1,PE2 pe; class P1 p;

---

Step 1 · Segment Routing Policy & Color Mapping

Define an explicit Segment Routing Policy matching Color 100 (Low-Latency Path $\le 10\,\text{ms}$) on pe1.

pe1pe2

configure
router bgp 65000
   router-id 10.255.0.1
   neighbor 10.255.0.5 remote-as 65000
   neighbor 10.255.0.5 update-source Loopback0
   !
   address-family ipv4
      neighbor 10.255.0.5 activate
!
router traffic-engineering
   segment-routing
      policy COLOR-100-LATENCY
         binding-sid 500100
         color 100 endpoint 10.255.0.5
         segment-list
            index 10 label 16002
            index 20 label 16005

configure
router bgp 65000
   router-id 10.255.0.5
   neighbor 10.255.0.1 remote-as 65000
   neighbor 10.255.0.1 update-source Loopback0
   !
   address-family ipv4
      neighbor 10.255.0.1 activate

---

Clean up

sudo containerlab destroy -t topology.clab.yml