Examkin

Question

Difficulty: Very hardNetwork Topology Architectures

An enterprise network operations team is replacing a legacy 3-Tier campus architecture with a 2-Tier Spine-Leaf (Clos) topology in their data center to optimize East-West traffic performance for containerized microservices. Which of the following architectural characteristics and operational design principles correctly describe this Spine-Leaf fabric when compared to the traditional 3-Tier model? (Select TWO.)

  1. Every Leaf switch connects to every Spine switch in a full mesh layout, guaranteeing a deterministic two-hop latency path for inter-leaf traffic.Answer
  2. Equal-Cost Multi-Pathing (ECMP) routing is implemented across Layer 3 uplinks to enable active-active load sharing without Spanning Tree Protocol port blocking.Answer
  3. C
    Leaf switches maintain direct horizontal 802.1Q trunk connections with neighboring Leaf switches to create a Layer 2 ring for local traffic protection.
  4. D
    Spine switches terminate host VLAN default gateways and provide direct access ports for high-density physical server connections.

Answer

The correct statements are that every Leaf switch connects directly to every Spine switch to provide a deterministic two-hop path for inter-leaf traffic, and that Layer 3 routing with Equal-Cost Multi-Pathing (ECMP) enables active-active load balancing across uplinks without Spanning Tree Protocol link blocking.
In a 2-Tier Spine-Leaf fabric, every Leaf switch connects directly to every Spine switch without horizontal intra-tier links. This structural layout provides a predictable two-hop transport path for East-West traffic across Leaf switches. Furthermore, deploying Layer 3 routing with Equal-Cost Multi-Pathing (ECMP) allows active-active forwarding across all Leaf-Spine links, eliminating Spanning Tree Protocol blocking.

Step-by-Step Solution

1
Analyze physical cabling topology constraints in a 2-Tier Spine-Leaf (Clos) architecture.
Verify that Spine-Leaf requires every Leaf node to connect to every Spine node, with zero direct links between nodes of the same tier.
This bipartite graph layout ensures a predictable, fixed path length of exactly two hops (Leaf to Spine to Leaf) for any East-West communication.
2
Evaluate control plane mechanisms and bandwidth utilization across the fabric.
Determine that Layer 3 routing combined with ECMP replaces Layer 2 Spanning Tree Protocol loop-prevention mechanisms.
ECMP utilizes all available uplinks simultaneously in an active-active forwarding state, avoiding the bandwidth degradation caused by STP port blocking.
3
Differentiate device roles and boundary placements between Leaf and Spine switches.
Confirm that end-system access ports and broadcast domain boundaries reside strictly on Leaf switches, while Spine switches act solely as high-speed transport infrastructure.
Isolating Spine switches from direct host connectivity and Layer 2 broadcast domains keeps the core stateless, fast, and scalable.

Key Concept

2-Tier Spine-Leaf (Clos) Architecture Characteristics vs 3-Tier Campus Design
Rate this question

Topics

Network Topology Architectures

More questions from this topic