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nx.os.and.cisco.nexus.switching.2nd.edition.1587143046

Nexus Switching 2nd Edition

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Chapter 3. Layer 3 Support <strong>and</strong> Configurations<br />

The Nexus line of switches provides a robust Layer 3 feature set. This chapter features<br />

common implementations <strong>and</strong> syntax for Layer 3 features such as EIGRP, OSPF, IS-IS, <strong>and</strong><br />

BGP <strong>and</strong> FHRPs such as HSRP, VRRP, <strong>and</strong> GLBP <strong>and</strong> covers the following topics:<br />

• EIGRP: Describes the configuration <strong>and</strong> operations of EIGRP<br />

• OSPF: Describes the configuration <strong>and</strong> operations of OSPF<br />

• IS-IS: Describes the configuration <strong>and</strong> operations of IS-IS<br />

• BGP: Describes the configuration <strong>and</strong> operations of BGP<br />

• HSRP: Describes the configuration <strong>and</strong> operations of HSRP<br />

• VRRP: Describes the configuration <strong>and</strong> operations of VRRP<br />

• GLBP: Describes the configuration <strong>and</strong> operations of GLBP<br />

EIGRP<br />

Cisco NX-OS on the Nexus 7000 series switches support Layer 3 routing using dynamic<br />

routing protocols, static routing, <strong>and</strong> policy-based routing. The Nexus 5500 series switches<br />

support Layer 3 routing using dynamic routing protocols <strong>and</strong> static routing. NX-OS also<br />

provides advanced virtualization capabilities using Virtual Routing <strong>and</strong> Forwarding<br />

instances (VRF). Supporting industry-leading protocols such as Enhanced Interior Gateway<br />

Routing Protocol (EIGRP), Open Shortest Path First (OSPF), Border Gateway Protocol<br />

(BGP), Intermediate System-to-Intermediate System (IS-IS), Routing Information Protocol<br />

(RIP), <strong>and</strong> static routing, the Nexus 7000 enables significant flexibility <strong>and</strong> options to<br />

interconnect multiple topologies. The Route Policy Manager supports complex<br />

configurations, tight routing control, <strong>and</strong> migrations from one protocol to another. This<br />

chapter covers common implementations <strong>and</strong> syntax for EIGRP, OSPF, IS-IS, <strong>and</strong> BGP <strong>and</strong><br />

First-Hop Redundancy Protocols (FHRP) such as Hot St<strong>and</strong>by Router Protocol (HSRP),<br />

Virtual Router Redundancy Protocol (VRRP), <strong>and</strong> Gateway Load Balancing Protocol<br />

(GLBP).<br />

EIGRP was developed by Cisco <strong>and</strong> runs only on Cisco devices. EIGRP is a highly<br />

scalable, flexible, <strong>and</strong> robust routing protocol considered a hybrid of distance vector <strong>and</strong><br />

link-state protocols. Considered a hybrid routing protocol, EIGRP implements the best<br />

characteristics of both distance vector <strong>and</strong> link-state protocols such as the hello mechanism<br />

<strong>and</strong> incremental updates. EIGRP is supported on both the Nexus 7000 <strong>and</strong> 5500 series<br />

switches. The Nexus 5500 series switches must be configured with a Layer-3 daughtercard<br />

or module, dependent on the specific platform. The Nexus 5500 series also requires an<br />

Enterprise License for full EIGRP functionality. (The Base license includes EIGRP stub<br />

routing only.) The examples in this chapter focus on EIGRP configuration for the Nexus<br />

7000.<br />

EIGRP Operation<br />

EIGRP calculates routes based on metrics received from neighbors <strong>and</strong> uses an algorithm

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