Cisco NX-OS/IOS HSRP Comparison

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<font size = "3">'''Configuration Comparison'''</font>
<font size = "3">'''Configuration Comparison'''</font>
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The following sample code shows configuration similarities and differences between the Cisco NX-OS and Cisco IOS Software CLIs. There are two significant differences: Cisco NX-OS uses a hierarchical configuration, and it uses the '''hsrp''' keyword instead of the '''standby''' keyword for configuration and verification. Both enhancements make the configuration easier to read.
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The following sample code shows configuration similarities and differences between the Cisco NX-OS and Cisco IOS Software CLIs. There are two significant differences: Cisco NX-OS uses a hierarchical configuration, and it uses the '''hsrp''' keyword instead of the '''standby''' keyword for configuration and verification commands. Both enhancements make the configuration easier to read.

Revision as of 22:14, 12 August 2009

Objective

This tech note outlines the main differences in Hot Standby Routing Protocol (HSRP) (IPv4) support between Cisco® NX-OS Software and Cisco IOS® Software. Sample configurations are included for Cisco NX-OS and Cisco IOS Software for some common features to demonstrate the similarities and differences. Please refer to the NX-OS documentation on Cisco.com for a complete list of supported features.


Hot Standby Routing Protocol (HSRP) Overview

HSRP is a Cisco proprietary First Hop Redundancy Protocol (FHRP) designed to allow transparent failover for an IP client’s default gateway (first-hop router).


Important Cisco NX-OS and Cisco IOS Software Differences

In Cisco NX-OS:

  • HSRP command-line interface (CLI) configuration and verification commands are not available until you enable the HSRP feature with the feature hsrp command.
  • HSRP is hierarchical. All related commands for an HSRP group are configured under the group number.
  • The HSRP configuration commands use the format hsrp <option> instead of standby <option>.
  • The HSRP verification commands use the format show hsrp <option> instead of show standby <option>.
  • HSRP supports stateful process restart by default.
  • The hello and hold-time timer ranges for the millisecond options are different. In Cisco NX-OS, hello = 250 to 999 milliseconds, and hold time = 750 to 3000 milliseconds. In Cisco IOS Software, hello = 15 to 999 milliseconds, and hold time = 50 to 3000 milliseconds.


Things You Should Know

The following list provides some additional facts about Cisco NX-OS that should be helpful when designing, configuring, and maintaining HSRP-enabled networks.


  • If you remove the feature hsrp command, all relevant HSRP configuration information is also removed.
  • HSRPv1 is enabled by default (HSRPv2 can be enabled per interface).
  • HSRPv1 supports 256 group numbers (0 to 255). HSRPv2 supports 4096 group numbers (0 to 4095).
  • HSRPv1 and HSRPv2 are not compatible. However, a device can be configured to run a different version on different interfaces.
  • The show running-config hsrp command displays the current HSRP configuration.
  • Configuration of more than one FHRP on an interface is not recommended.
  • Object tracking is supported. Tracking can be configured for an interface’s line protocol state, IP address state, and for IP route reachability (determining whether a route is available in the routing table).
  • An interface can track multiple objects.
  • Secondary IP addresses are supported in the same or a different group as the interface’s primary IP address.
  • Load sharing can be accomplished by using multiple HSRP groups per interface.


Configuration Comparison

The following sample code shows configuration similarities and differences between the Cisco NX-OS and Cisco IOS Software CLIs. There are two significant differences: Cisco NX-OS uses a hierarchical configuration, and it uses the hsrp keyword instead of the standby keyword for configuration and verification commands. Both enhancements make the configuration easier to read.


Cisco IOS CLI Cisco NX-OS CLI
Enabling the HSRP Feature
Cisco IOS Software does not have the ability to enable or disable HSRP. feature hsrp
Configuring HSRP on an Interface
interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby 0 ip 192.168.10.1

interface Ethernet2/1

ip address 192.168.10.2/24

hsrp 0

ip 192.168.10.1

Configuring the priority and preempt Options
interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby 0 ip 192.168.10.1

standby 0 priority 110

standby 0 preempt

interface Ethernet2/1

ip address 192.168.10.2/24

hsrp 0

preempt

priority 110

ip 192.168.10.1

Modifying the Hello and Holdtime Timers (Seconds)
interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby 0 ip 192.168.10.1

standby 0 timers 1 3

interface Ethernet2/1

ip address 192.168.10.2/24

hsrp 0

timers 1 3

ip 192.168.10.1

Modifying the Hello and Holdtime Timers (Milliseconds)
interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby 0 ip 192.168.10.1

standby 0 timers msec 250 msec 750

interface Ethernet2/1

ip address 192.168.10.2/24

hsrp 0

timers msec 250 msec 750

ip 192.168.10.1

Configuring MD5 Authentication
interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby 0 ip 192.168.10.1

standby 0 authentication md5 key-string cisco123

interface Ethernet2/1

ip address 192.168.10.2/24

hsrp 0

authentication md5 key-string cisco123

ip 192.168.10.1

Configuring HSRP Version 2 on an Interface
interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby version 2

interface Ethernet2/1

ip address 192.168.10.2/24

hsrp version 2

Configuring Minimum and Reload Initialization Delay
interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby delay minimum 5 reload 10

interface Ethernet2/1

ip address 192.168.10.2/24

hsrp delay minimum 5 reload 10

Configuring Object Tracking (Interface Line-Protocol)
track 1 interface Ethernet2/2 line-protocol


interface Ethernet2/1

ip address 192.168.10.2 255.255.255.0

standby 0 ip 192.168.10.1

standby 0 track 1 decrement 20

track 1 interface ethernet 2/2 line-protocol


interface Ethernet2/1

ip address 192.168.10.2/24

hsrp 0

track 1 decrement 20

ip 192.168.10.1



Verification Command Comparison

The following table compares some useful show commands for verifying and troubleshooting an HSRP configuration.


Cisco NX-OS HSRP Cisco IOS Software HSRP Command Description
show hsrp show standby <#> Displays detailed information for all HSRP groups
show hsrp active - Displays all of the groups in the “active” state
show hsrp brief show standby brief Displays a summary of all the HSRP groups
show hsrp delay - Displays minimum and maximum delay times for preempting
show hsrp group - Displays detailed information for a specified group
show hsrp init - Displays all the groups in the "init" state
show hsrp interface - Displays detailed information for a specific interface
show hsrp learn - Displays all the groups in the "learn" state
show hsrp listen - Displays all the groups in the "listen" state
show hsrp speak - Displays all the groups in the "speak" state
show hsrp standby - Displays all the groups in the "standby" state
show hsrp summary - Displays summary information for HSRP groups
- - -
show track show track Displays the configured tracked objects
show track brief show track brief Displays a brief list of tracked objects
show track interface show track interface Displays the status of tracked interfaces
show track ip show track ip Displays the IP protocol objects that are tracked

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