OcNOS SP : Layer 3
Layer 3
 
Overview
Target Users
Key Capabilities
Overview
Layer 3 (L3) refers to the comprehensive suite of routing protocols and services integrated into OcNOS (Open Compute Network Operating System). Based on the ZebOS platform, OcNOS provides carrier-grade Layer 3 functionality for service providers, data centers, and enterprise networks.
Target Users
This document targets network operators, platform engineers, and system administrators responsible for managing OcNOS-based deployments. It assumes working knowledge of standard networking practices, CLI navigation, and basic system administration.
Key Capabilities
OcNOS supports a full range of industry-standard IPv4 and IPv6 routing protocols to ensure high interoperability with legacy and modern hardware:
• BGP (Border Gateway Protocol): Supports MP-BGP (Multiprotocol BGP), BGP-LU (Labeled Unicast), and advanced BGP features like 4-byte ASNs, Graceful Restart (NSF-GR), and complex routing policies.
• OSPF (Open Shortest Path First): Supports OSPFv2 (IPv4) and OSPFv3 (IPv6).
• IS-IS (Intermediate System to Intermediate System): A link-state protocol used for both IPv4 and IPv6 routing.
• RIP (Routing Information Protocol): Legacy support for RIPv1 and RIPv2.
• ECMP (Equal-Cost Multi-Path): Optimized for high-bandwidth scaling with a large fan-out for load balancing across multiple paths.
Ensures carrier-grade reliability Layer 3 services include:
• BFD (Bidirectional Forwarding Detection): Provides sub-50ms failure detection, often with hardware offload support.
• VRRP (Virtual Router Redundancy Protocol): Supports VRRPv2 and VRRPv3 for gateway redundancy.
• TI-LFA (Topology-Independent Loop-Free Alternate): A fast reroute mechanism used in Segment Routing to minimize packet loss during link or node failures.
Supports advanced L3 services and virtualization
• L3VPN over MPLS/SR: Provides secure Layer 3 connectivity across a provider backbone using MPLS or Segment Routing (SR-MPLS).
• EVPN-L3VPN: A modern approach that leverages the BGP EVPN control plane to provide Layer 3 connectivity and multihoming.
• 6PE & 6VPE: Allows IPv6 islands to be interconnected over an IPv4-only MPLS core, facilitating a smooth transition to IPv6.
• L3 Sub-interfaces: Allows a single physical port to be partitioned into multiple logical Layer 3 termination points, enabling service density and VLAN reuse.
Data Center & Web-Scale L3
• In Data Center environments (OcNOS-DC), Layer 3 is typically deployed in a CLOS Topology (L3 eBGP):
• Routed Fabric: A pure L3 design from the Top-of-Rack (TOR) switch up to the Spine, simplifying operations and limiting failure domains.
• EVPN-VXLAN Overlay: Uses a Layer 3 routed network (Underlay) to support virtualized Layer 2 and Layer 3 services (Overlay) for multi-tenant environments.
Security and Management
• Access Control Lists (ACLs): Layer 3 ingress/egress filtering based on IP addresses, protocol types, and TCP/UDP ports.
• Control Plane Protection: Mechanisms to safeguard the CPU from excessive Layer 3 control traffic.
• Interoperability: Because OcNOS uses a standard Cisco-like CLI, management of these Layer 3 features is consistent with industry norms, reducing training time for engineers.
• This Layer 3 stack is designed to run on a variety of white-box hardware (using Broadcom and other merchant silicon), decoupling the networking software from the hardware to reduce TCO.
 
For detailed information on Layer 3 topics and configurations, refer to the Layer 3 Configuration Guide.