Specifications

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Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, Release 5.0(3)U2(2)
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Chapter 1 Overview
Layer 3 Virtualization
OSPF is an example of a link-state protocol.
Layer 3 Virtualization
Cisco NX-OS supports multiple Virtual Routing and Forwarding Instances (VRFs) and multiple routing
information bases (RIBs) to support multiple address domains. Each VRF is associated with a routing
information base (RIB) and this information is collected by the Forwarding Information Base (FIB). A
VRF represents a Layer 3 addressing domain. Each Layer 3 interface (logical or physical) belongs to one
VRF. For more information, see Chapter 11, “Configuring Layer 3 Virtualization.”
Cisco NX-OS Fowarding Architecture
The Cisco NX-OS forwarding architecture is responsible for processing all routing updates and
populating the forwarding information on the switch.
This section includes the following topics:
• Unicast RIB, page 1-10
• Adjacency Manager, page 1-11
• Unicast Forwarding Distribution Module, page 1-11
• FIB, page 1-11
• Hardware Forwarding, page 1-12
• Software Forwarding, page 1-12
Unicast RIB
The Cisco NX-OS forwarding architecture consists of multiple components, as shown in Figure 1-3.
Figure 1-3 Cisco NX-OS Forwarding Architecture
URIB
Unicast FIB Distribution Module (uFDM)
Unicast Forwarding Information Base (UFIB)
Adjacency Manager (AM)
EIGRP BGP OSPF ARP
Switch components
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