Service Router vs Distributed Router in NSX-T (aka NSX 4.x)

In VMware NSX-T, both Service Router (SR) and Distributed Router (DR) are integral components of the networking architecture that play distinct roles in providing routing and connectivity within the virtualized network environment. Let’s delve into the differences between these two router types:

  1. Service Router (SR):
    • Role: The Service Router is a centralized routing component that provides north-south (external to internal) routing and connectivity in the NSX-T environment.
    • Functionality: It connects the NSX-T overlay network to external networks, which can include physical networks and traditional network infrastructure. The SR performs tasks like NAT (Network Address Translation), load balancing, and VPN (Virtual Private Network) termination.
    • Placement: Service Routers are typically deployed at the edge of the NSX-T environment, serving as the gateway between the virtual overlay network and the external network.
    • Scale: The SR is designed for relatively lower traffic volume and is well-suited for smaller environments where centralized routing control is sufficient.
  2. Distributed Router (DR):
    • Role: The Distributed Router is an integral part of NSX-T’s data plane, providing east-west (internal to internal) routing and connectivity between virtual machines (VMs) and segments within the NSX-T overlay network.
    • Functionality: It enables seamless and efficient routing of traffic between VMs and segments within the same NSX-T environment without the need to traverse a centralized device.
    • Placement: Distributed Routers are instantiated on each hypervisor host in the NSX-T environment, allowing for distributed and optimized routing directly at the host level.
    • Scale: The DR is designed for high-throughput and low-latency routing within the NSX-T overlay, making it suitable for larger environments and scenarios where efficient communication between VMs is essential.

In summary, the key differences between Service Router and Distributed Router in NSX-T include their roles, functionalities, placements, and scaling capabilities:

  • Service Router (SR):
    • Provides north-south routing (external to internal).
    • Connects NSX-T overlay network to external networks.
    • Performs tasks like NAT, load balancing, and VPN.
    • Centralized routing component.
    • Typically placed at the edge of the network.
    • Suitable for smaller environments with lower traffic volume.
  • Distributed Router (DR):
    • Provides east-west routing (internal to internal).
    • Enables routing between VMs and segments within NSX-T overlay.
    • Distributed routing at the hypervisor host level.
    • Optimized for high-throughput and low-latency routing.
    • Suitable for larger environments and efficient internal communication.

Both Service Routers and Distributed Routers have distinct purposes within the NSX-T networking architecture, working together to provide comprehensive routing and connectivity capabilities for virtualized environments.

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