Cisco Nexus 3000 series User manual

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Cisco Nexus 3000 Series NX-OS Unicast
Routing Configuration Guide,
NX-OS Release 5.0(3)U1(1)
May 2011

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Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
©2011 Cisco Systems, Inc. All rights reserved.

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iii
Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
CONTENTS
Preface xix
Audience xix
Supported Switches xix
Cisco Nexus 3000 PlatformSwitches xix
Organization xx
Document Conventions xxi
Related Documentation xxii
Release Notes xxii
Configuration Guides xxii
Maintain and Operate Guides xxii
Installation and Upgrade Guides xxii
Licensing Guide xxii
Command References xxii
Technical References xxiii
Error and System Messages xxiii
Troubleshooting Guide xxiii
Obtaining Documentation and Submitting a Service Request xxiii
CHAPTER 1Overview 1-1
Information About Layer 3 Unicast Routing 1-1
Routing Fundamentals 1-2
Packet Switching 1-2
Routing Metrics 1-3
Path Length 1-4
Reliability 1-4
Routing Delay 1-4
Bandwidth 1-4
Load 1-4
Communication Cost 1-4
Router IDs 1-5
Autonomous Systems 1-5
Convergence 1-6
Load Balancing and Equal Cost Multipath 1-6
Route Redistribution 1-6

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Cisco Nexus3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
Administrative Distance 1-7
StubRouting 1-7
Routing Algorithms 1-8
Static Routes and Dynamic Routing Protocols 1-8
Interior and Exterior Gateway Protocols 1-8
Distance Vector Protocols 1-9
Link-State Protocols 1-9
Layer 3Virtualization 1-10
Cisco NX-OS Fowarding Architecture 1-10
Unicast RIB 1-10
Adjacency Manager 1-11
Unicast Forwarding Distribution Module 1-11
FIB 1-11
Hardware Forwarding 1-12
Software Forwarding 1-12
Summary of Layer 3 Unicast Routing Features 1-12
IPv4 1-13
IP Services 1-13
OSPF 1-13
EIGRP 1-13
BGP 1-13
RIP 1-13
Static Routing 1-13
Layer 3Virtualization 1-14
Route Policy Manager 1-14
First-Hop Redundancy Protocols 1-14
Object Tracking 1-14
Related Topics 1-14
IP
CHAPTER 2Configuring IPv4 2-1
Information About IPv4 2-1
Multiple IPv4 Addresses 2-2
Address ResolutionProtocol 2-2
ARP Caching 2-3
Static and Dynamic Entries in the ARP Cache 2-3
Devices that Do Not Use ARP 2-4
ReverseARP 2-4

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Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
Proxy ARP 2-5
LocalProxy ARP 2-5
Gratuitous ARP 2-5
ICMP 2-5
Virtualization Support 2-6
Licensing Requirements for IPv4 2-6
Prerequisites for IPv4 2-6
Guidelines and Limitations 2-6
Default Settings 2-6
Configuring IPv4 2-7
Configuring IPv4 Addressing 2-7
Configuring Multiple IP Addresses 2-8
Configuring a Static ARP Entry 2-9
Configuring Proxy ARP 2-10
Configuring Local Proxy ARP 2-11
Configuring Gratuitous ARP 2-12
Configuring IP Directed Broadcasts 2-13
Verifying the IPv4 Configuration 2-14
Configuration Examples for IPv4 2-14
Additional References 2-14
Related Documents 2-15
Standards 2-15
Feature History for IP 2-15
Routing
CHAPTER 3Configuring OSPFv2 3-1
Information About OSPFv2 3-1
Hello Packet 3-2
Neighbors 3-2
Adjacency 3-3
Designated Routers 3-3
Areas 3-4
Link-State Advertisements 3-5
LSA Types 3-5
Link Cost 3-6
Flooding and LSA Group Pacing 3-6
Link-State Database 3-7

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Cisco Nexus3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
Opaque LSAs 3-7
OSPFv2 and the Unicast RIB 3-7
Authentication 3-7
Simple Password Authentication 3-8
MD5 Authentication 3-8
Advanced Features 3-8
StubArea 3-8
Not-So-Stubby Area 3-9
VirtualLinks 3-9
Route Redistribution 3-10
Route Summarization 3-10
OSPFv2 Stub RouterAdvertisements 3-11
Multiple OSPFv2 Instances 3-11
SPF Optimization 3-11
Virtualization Support 3-11
Licensing Requirements for OSPFv2 3-11
Prerequisites for OSPFv2 3-12
Guidelines and Limitations 3-12
Default Settings 3-12
Configuring Basic OSPFv2 3-13
Enabling the OSPFv2 Feature 3-13
Creating an OSPFv2 Instance 3-14
Configuring Optional Parameters on an OSPFv2 Instance 3-15
Configuring Networks in OSPFv2 3-16
Configuring Authentication for an Area 3-18
Configuring Authentication for an Interface 3-20
Configuring Advanced OSPFv2 3-22
Configuring Filter Lists for Border Routers 3-23
Configuring Stub Areas 3-24
Configuring a Totally Stubby Area 3-25
Configuring NSSA 3-26
Configuring Virtual Links 3-28
Configuring Redistribution 3-30
Limiting the Number of Redistributed Routes 3-32
Configuring Route Summarization 3-34
Configuring Stub Route Advertisements 3-35
Modifying the Default Timers 3-36
Restarting anOSPFv2 Instance 3-39
Configuring OSPFv2 with Virtualization 3-39

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Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
Verifying the OSPFv2 Configuration 3-41
Displaying OSPFv2 Statistics 3-42
Configuration Examples for OSPFv2 3-42
Additional References 3-43
Related Documents 3-43
MIBs 3-43
Feature History for OSPFv2 3-43
CHAPTER 4Configuring EIGRP 4-1
Information About EIGRP 4-1
EIGRP Components 4-2
Reliable Transport Protocol 4-2
Neighbor Discovery and Recovery 4-2
Diffusing Update Algorithm 4-3
EIGRP Route Updates 4-3
InternalRoute Metrics 4-3
External Route Metrics 4-4
EIGRP and the Unicast RIB 4-4
Advanced EIGRP 4-4
Address Families 4-5
Authentication 4-5
StubRouters 4-5
Route Summarization 4-6
Route Redistribution 4-6
Load Balancing 4-6
Split Horizon 4-6
Virtualization Support 4-7
Licensing Requirements for EIGRP 4-7
Prerequisites for EIGRP 4-7
Guidelines and Limitations 4-7
Default Settings 4-8
Configuring Basic EIGRP 4-9
Enabling the EIGRP Feature 4-9
Creating an EIGRP Instance 4-10
Restarting an EIGRP Instance 4-12
Shutting Down an EIGRP Instance 4-13
Configuring a Passive Interface for EIGRP 4-13
Shutting Down EIGRP on an Interface 4-13

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Contents
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Cisco Nexus3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
Configuring Advanced EIGRP 4-13
Configuring Authentication in EIGRP 4-14
Configuring EIGRP Stub Routing 4-16
Configuring a Summary Address for EIGRP 4-17
Redistributing Routes into EIGRP 4-17
Limiting the Number of Redistributed Routes 4-19
Configuring Load Balancing in EIGRP 4-21
Adjusting the Interval Between Hello Packets and the Hold Time 4-22
Disabling Split Horizon 4-23
Tuning EIGRP 4-23
Configuring Virtualization for EIGRP 4-25
Verifying the EIGRP Configuration 4-27
Displaying EIGRP Statistics 4-27
Configuration Examples for EIGRP 4-28
Related Topics 4-28
Additional References 4-28
Related Documents 4-29
MIBs 4-29
Feature History for EIGRP 4-29
CHAPTER 5Configuring Basic BGP 5-1
Information About Basic BGP 5-1
BGP Autonomous Systems 5-2
4-Byte AS Number Support 5-2
Administrative Distance 5-2
BGP Peers 5-3
BGP Sessions 5-3
Dynamic AS Numbers for Prefix Peers 5-3
BGP Router Identifier 5-4
BGP Path Selection 5-4
Step1—Comparing Pairs ofPaths 5-4
Step 2—Determining theOrderof Comparisons 5-6
Step 3—Determining the Best-Path Change Suppression 5-6
BGP and the Unicast RIB 5-7
BGP Virtualization 5-7
Licensing Requirements for Basic BGP 5-7
Prerequisites for BGP 5-7
Guidelines and Limitations for BGP 5-8

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Contents
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Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
CLI Configuration Modes 5-8
Global Configuration Mode 5-8
Address Family Configuration Mode 5-9
Neighbor Configuration Mode 5-9
Neighbor Address Family Configuration Mode 5-10
Default Settings 5-10
Configuring Basic BGP 5-10
Enabling the BGP Feature 5-11
Creating a BGP Instance 5-12
Restarting a BGP Instance 5-13
Shutting Down BGP 5-14
Configuring BGP Peers 5-14
Configuring Dynamic AS Numbers for Prefix Peers 5-16
Clearing BGP Information 5-18
Verifying the Basic BGP Configuration 5-21
Displaying BGP Statistics 5-23
Configuration Examples for BasicBGP 5-23
Related Topics 5-23
Where to Go Next 5-23
Additional References 5-23
Related Documents 5-24
MIBs 5-24
Feature History for BGP 5-24
CHAPTER 6Configuring Advanced BGP 6-1
Information About Advanced BGP 6-1
Peer Templates 6-2
Authentication 6-2
Route Policies and Resetting BGP Sessions 6-3
eBGP 6-3
iBGP 6-3
AS Confederations 6-4
Route Reflector 6-5
Capabilities Negotiation 6-5
Route Dampening 6-6
Load Sharing and Multipath 6-6
Route Aggregation 6-7
BGP Conditional Advertisement 6-7

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Contents
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Cisco Nexus3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
BGP Next-HopAddress Tracking 6-7
Route Redistribution 6-8
Tuning BGP 6-8
BGP Timers 6-8
Tuning the Best-Path Algorithm 6-8
Multiprotocol BGP 6-9
Virtualization Support 6-9
Licensing Requirements for Advanced BGP 6-9
Prerequisites for BGP 6-9
Guidelines and Limitations for BGP 6-10
Default Settings 6-10
Configuring Advanced BGP 6-10
Configuring BGP Session Templates 6-11
Configuring BGP Peer-Policy Templates 6-13
Configuring BGP Peer Templates 6-16
Configuring Prefix Peering 6-18
Configuring BGP Authentication 6-19
Resetting a BGP Session 6-20
Modifying the Next-Hop Address 6-20
Configuring BGP Next-Hop Address Tracking 6-21
Configuring Next-Hop Filtering 6-21
Disabling Capabilities Negotiation 6-21
Configuring eBGP 6-22
Disabling eBGP Single-Hop Checking 6-22
Configuring eBGP Multihop 6-22
Disabling a Fast External Failover 6-23
Limiting the AS-path Attribute 6-23
Configuring AS Confederations 6-23
Configuring Route Reflector 6-24
Configuring Route Dampening 6-26
Configuring Load Sharing and ECMP 6-26
Configuring Maximum Prefixes 6-27
Configuring Dynamic Capability 6-27
Configuring Aggregate Addresses 6-28
Configuring BGP Conditional Advertisement 6-28
Configuring Route Redistribution 6-30
Configuring Multiprotocol BGP 6-32
Tuning BGP 6-33
Configuring Virtualization 6-36