Cisco Nexus 7000 Series Unicast Routing Command Reference
H Commands
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Table of Contents

H Commands

hardware ejector enable

hardware forwarding dynamic-allocation

hardware forwarding l3 resource route non-deterministic

hardware ip glean throttle

hardware ip glean throttle maximum

hardware ip glean throttle syslog

hardware ip glean throttle timeout

hardware ip verify

hardware ip verify address

hardware ip verify length

hardware ipv6 verify

hardware proxy layer-3 forwarding

hello-interval (OSPF virtual link)

hello-interval (OSPFv3 virtual link)

hostname dynamic

hsrp

hsrp ipv6

hsrp mac-refresh

hsrp timers extended-hold

hsrp version 2

H Commands

This chapter describes the Cisco NX-OS unicast routing commands that begin with the letter H.

hardware ejector enable

To enable the hardware when both ejectors are open, card is powered down, use the hardware ejector enable command.

hardware ejector enable

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Enabled

 
Command Modes

Global configuration mode

 
Supported User Roles

network-admin
network-operator
vdc-admin
vdc-operator

 
Command History

Release
Modification

4.2(1)

This command was introduced.

 
Usage Guidelines

This command does not require a license.

Examples

This example shows how to enable the hardware when both ejectors are open:

switch(config)# hardware ejector enable
 
 
 

 
Related Commands

Command
Description

show hardware forwarding dynamic-allocation

Displays information about dynamic TCAM allocation for each module.

hardware forwarding dynamic-allocation

To enable or disable dynamic TCAM block allocation in the Forwarding Information Base (FIB), use the hardware forwarding dynamic-allocation command.

hardware forwarding dynamic-allocation { enable | disable }

 
Syntax Description

enable

Enables dynamic TCAM allocation.

disable

Disables dynamic TCAM allocation.

 
Defaults

Enabled

 
Command Modes

Any command mode

 
Supported User Roles

network-admin
network-operator
vdc-admin
vdc-operator

 
Command History

Release
Modification

4.2(1)

This command was introduced.

5.0(x)

This command was deprecated.

 
Usage Guidelines

As of Cisco NX-OS Release 5.0(x), dynamic TCAM allocation is enabled by default and cannot be disabled.

Use the hardware forwarding dynamic-allocation enable command to reallocate unused blocks in the FIB.

Use the hardware forwarding dynamic-allocation disable command to disable the dynamic TCAM allocation. This command returns the TCAM to the default allocation if there are no routes in the reallocated blocks.

This command does not require a license.

Examples

This example shows how to enable dynamic TCAM allocation:

switch(config)# hardware forwarding dynamic-allocation enable
 
 
 

 
Related Commands

Command
Description

show hardware forwarding dynamic-allocation

Displays information about dynamic TCAM allocation for each module.

hardware forwarding l3 resource route non-deterministic

To expand the number of routes available on the Cisco NX-OS device, use the hardware forwarding l3 resource route non-deterministic command. To set the revert to the default settings, use the no form of the command.

hardware forwarding l3 resource route non-deterministic

no hardware forwarding l3 resource route non-deterministic

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

None

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

5.2(1)

This command was introduced.

 
Usage Guidelines

We recommend that you use the hardware forwarding l3 resource route non-deterministic command only under the advisement of Cisco.

This command does not require a license.

Examples

This example shows how to expand the number of routes available on the Cisco NX-OS device:

switch# configure terminal
switch(config)# hardware forwarding l3 resource route non-deterministic
 
This example shows how to remove the route expansion on the Cisco NX-OS device:

switch(config)# no hardware forwarding l3 resource route non-deterministic
switch(config)#

 
Related Commands

Command
Description

hardware forwarding dynamic-allocation

Enable or disable dynamic TCAM block allocation in the Forwarding Information Base (FIB).

hardware ip glean throttle

To enable Address Resolution Protocol (ARP) throttling, use the hardware ip glean throttle command. To return to the default setting, use the no form of this command.

hardware ip glean throttle

no hardware ip glean throttle

 
Syntax Description

This command has no arguments or keywords.

 
Defaults

Disabled

 
Command Modes

Global configuration

 
Supported User Roles

network-admin

vdc-admin

 
Command History

Release
Modification

5.1(1)

This command was introduced.

4.2(8)

This command was introduced.

 
Usage Guidelines


Note We recommend that you configure the IP glean throttle feature by using the hardware ip glean throttle command to filter the unnecessary glean packets that are sent to the supervisor for ARP resolution for the next hops that are not reachable or do not exist. IP glean throttling boosts software performance and helps to manage traffic more efficiently.


This command does not require a license.

Examples

This example shows how to enable ARP throttling:

switch(config)# hardware ip glean throttle
switch(config)#

 
Related Commands

Command
Description

show hardware proxy layer-3 detail

Displays Layer-3 proxy detail information.

hardware ip glean throttle maximum

To limit the maximum number of drop adjacencies that will be installed in the Forwarding Information Base (FIB), use the hardware ip glean throttle maximum command. If no form is used, default limits will be applied.

hardware ip glean throttle maximum count

no hardware ip glean throttle maximum count

 
Syntax Description

count

Maximum count. The range is from 0 to 2147483647.

 
Defaults

The default value for count is 1000. The minimum value is 0 and the maximum value is 32767 entries

 
Command Modes

Global configuration

 
Supported User Roles

network-admin

vdc-admin

 
Command History

Release
Modification

5.1(1)

This command was introduced.

4.2(8)

This command was introduced.

 
Usage Guidelines

If the maximum number of entries are exceeded, the packets for which ARP is not resolved continue to be processed in the software instead of getting dropped in the hardware.

This command does not require a license.

Examples

This example shows how to limit the maximum number of drop adjacencies that are installed in the FIB:

switch(config)# hardware ip glean throttle maximum 2134
switch(config)#

 
Related Commands

Command
Description

show hardware proxy layer-3 detail

Displays Layer-3 proxy detail information.

hardware ip glean throttle syslog

To generate a syslog if the number of packets that get dropped for a specific flow exceeds the configured packet count, use the hardware ip glean throttle syslog command. To return to the default setting, use the no form of this command.

hardware ip glean throttle syslog pkt-count

no hardware ip glean throttle syslog pkt-count

 
Syntax Description

pkt-count

Packet count. The range is from 0 to 2147483647.

 
Defaults

The default value for count is 10000. The minimum value is 0 and the maximum value is 64 k (65535) packets

 
Command Modes

Global configuration

 
Supported User Roles

network-admin

vdc-admin

 
Command History

Release
Modification

5.1(1)

This command was introduced.

4.2(8)

This command was introduced.

 
Usage Guidelines

After the timeout period is exceeded, the drop adjacencies are removed from the FIB.

This command does not require a license.


Note The Adjmgr generates a syslog for the configured packet count that will not be accurate to the glean packets dropped hit in FIB. The drop statistics collected from the FIB in S/w (Adjmgr) occurs every two minutes. The Adjmgr generates a syslog only after it receives the stats from the FIB every two minutes only for the adjacencies where the drop count exceeds the configured packet count.


Examples

This example shows how to generate a syslog if the number of packets that get dropped for a specific flow exceed the configured packet count:

switch(config)# hardware ip glean throttle syslog 1030
switch(config)#

 

 
Related Commands

Command
Description

show hardware proxy layer-3 detail

Displays Layer-3 proxy detail information.

hardware ip glean throttle timeout

To configure a timeout for the installed drop adjacencies to remain in the Forwarding Information Base (FIB), use the hardware ip glean throttle timeout command. To return to the default setting, use the no form of this command.

hardware ip glean throttle timeout timeout-in-sec

no hardware ip glean throttle timeout timeout-in-sec

 
Syntax Description

timeout -in-sec

Timeout value in seconds. The range is from 300 to 1800.

 
Defaults

300 seconds

 
Command Modes

Global configuration

 
Supported User Roles

network-admin

vdc-admin

 
Command History

Release
Modification

5.1(1)

This command was introduced.

4.2(8)

This command was introduced.

 
Usage Guidelines

After the timeout period is exceeded, the drop adjacencies are removed from the FIB.

This command does not require a license.

Examples

This example shows how to limit the maximum number of drop adjacencies that are installed in the FIB:

switch(config)# hardware ip glean throttle timeout 300
switch(config)#

 
Related Commands

Command
Description

show hardware proxy layer-3 detail

Displays Layer-3 proxy detail information.

hardware ip verify

To configure IP packet verification, use the hardware ip verify command. To disable IP packet verification, use the no form of this command.

hardware ip verify { checksum | fragment | protocol | tcp tiny-frag | version }

no hardware ip verify { checksum | fragment }

 
Syntax Description

checksum

Drops IPv4 or IPv6 packets if the checksum is invalid.

fragment

Drops IPv4 or IPv6 packets if the packet fragment has a nonzero offset and the DF bit is active.

protocol

Drops IPv4 or IPv6 packets if the packet fragment has an invalid IP protocol number.

tcp tiny-frag

Drops IPv4 packets if the IP fragment offset is 1, or if the IP fragment offset is 0 and the IP payload length is less than 16.

version

Drops IPv4 packets if the Ethertype is not set to 4 (IPv4).

 
Defaults

All address tests disabled (since Cisco NX-OS Release 5.1(3)).

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.1(3)

This command was introduced.

4.2(2)

Added protocol keyword.

 
Usage Guidelines

Use the hardware ip verify command to configure packet verification tests on IPv4 and IPv6 packets based on checksum or fragments.

This command is not supported in F Series modules.

This command replaces the platform ip verify command.

This command does not require a license.

Examples

This example shows how to drop fragmented IPv4 or IPv6 packets:

switch(config)# hardware ip verify fragment

 
Related Commands

Command
Description

hardware ip verify address

Configures IPv4 and IPv6 packet verification checks based on addresses.

hardware ip verify length

Configures IPv4 packet verification checks based on length.

hardware ipv6 verify

Configures IPv6 packet verification.

show hardware forwarding ip verify

Displays information about IP packet verification checks.

hardware ip verify address

To enable packet verification tests on IP addresses, use the hardware ip verify address command. To disable packet verification tests, use the no form of this command.

hardware ip verify address { destination zero | identical | reserved | source {broadcast | multicast }}

no hardware ip verify address { destination zero | identical | reserved | source {broadcast | multicast }}

 
Syntax Description

destination zero

Drops IP packets if the destination IPv4 address is 0.0.0.0 or if the IPv6 address is ::.

identical

Drops IP packets if the source IPv4 or IPv6 address is identical to the destination IPv4 or IPv6 address.

reserved

Drops IP packets if the IPv4 address is in the 127.x.x.x range or if the IPv6 address is in the ::1 range.

source

Drops IP packets based on the IP source address.

broadcast

Drops IP packets if the IP source address is 255.255.255.255.

multicast

Drops IP packets if the IPv4 source address is in the 224.x.x.x range or if the IPv6 source address is in the FF00::/8 range.

 
Defaults

All values are disabled (since Cisco NX-OS Release 5.1(3)).

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.1(3)

This command was introduced.

 
Usage Guidelines

Use the hardware ip verify address command to configure packet verification tests on IPv4 and IPv6 packets based on addresses.

This command replaces the platform ip verify address command.

Prior to Cisco NX-OS Release 5.1(3), for Fabric Extender (FEX), you must manually disable the hardware ip verify address reserved option.

In Cisco NX-OS Release 5.1(3), you must disable the hardware ip verify address identical option before enabling the Multiprotocol Label Switching (MPLS) feature.

This command is not supported in F-Series modules.

This command does not require a license.

Examples

This example shows how to drop broadcast IPv4 packets:

switch(config)# hardware ip verify address source broadcast

 
Related Commands

Command
Description

hardware ip verify

Configures IPv4 and IPv6 packet verification checks based on checksum or fragments.

hardware ip verify length

Configures IPv4 packet verification checks based on length.

hardware ipv6 verify

Configures IPv6 packet verification.

show hardware forwarding ip verify

Displays information about IP packet verification checks.

hardware ip verify length

To configure IPv4 packet verification tests based on packet length, use the hardware ip verify length command. To disable the tests, use the no form of this command.

hardware ip verify length { consistent | maximum { max-frag | max-tcp | udp } | minimum }

no hardware ip verify length { consistent | maximum { max-frag | max-tcp | udp } | minimum }

 
Syntax Description

consistent

Drops IPv4 packets where the Ethernet frame size is greater than or equal to the IP packet length plus the Ethernet header.

maximum

Drops IP packets if the Ethernet frame length is more than the IP packet length.

max-frag

Drops IP packets if the maximum fragment offset is greater than 65536.

max-tcp

Drops IP packets if the TCP length is greater than the IP payload length.

udp

Drops IP packets if the IP payload length is less than the UDP packet length.

minimum

Drops IP packets if the Ethernet frame length is less than the IP packet length plus four octets (the CRC length).

 
Defaults

All address tests are enabled.

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.1(3)

This command was introduced.

 
Usage Guidelines

Use the hardware ip verify length command to configure packet verification tests on IPv4 and IPv6 packets based on packet length.

This command replaces the platform ip verify length command.

This command is not supported in F Series modules.

This command does not require a license.

Examples

This example shows how to drop minimum-length IPv4 packets:

switch(config)# hardware ip verify length minimum

 
Related Commands

Command
Description

hardware ip verify

Configures IPv4 packet verification checks based on checksum or fragments.

hardware ip verify address

Configures IPv4 and IPv6 packet verification checks based on addresses.

hardware ipv6 verify

Configures IPv6 packet verification.

show hardware forwarding ip verify

Displays information about IP packet verification checks.

hardware ipv6 verify

To configure IPv6 packet verification tests, use the hardware ipv6 verify command. To disable the tests, use the no form of this command.

hardware ipv6 verify { length { consistent | maximum { max-frag | max-tcp | udp } | tcp tiny-frag | version }

no hardware ip verify { checksum | fragment }

 
Syntax Description

length

Drops IPv6 packets based on length.

consistent

Drops IPv6 packets where the Ethernet frame size is greater than or equal to the IPv6 packet length plus the Ethernet header.

maximum

Drops IP packets if the Ethernet frame length is more than the IP packet length.

max-frag

Drops IP packets if the maximum fragment offset is greater than 65536.

max-tcp

Drops IP packets if the TCP length is greater than the IP payload length.

udp

Drops IP packets if the IP payload length is less than the UDP packet length.

tcp tiny-frag

Drops IPv6 packets if the IP fragment offset is 1, or if the IPv6 fragment offset is 0 and the IPv6 payload length is less than 16.

version

Drops IPv6packets if the Ethertype is not set to 6 (IPv6).

 
Defaults

All address tests are enabled.

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.1(3)

This command was introduced.

 
Usage Guidelines

Use the hardware ipv6 verify command to configure packet verification tests on IPv6 packets.

This command replaces the platform ipv6 verify command.

This command does not require a license.

Examples

This example shows how to drop all IPv4 packets:

switch(config)# hardware ipv6 verify version

 
Related Commands

Command
Description

hardware ip verify address

Configures IPv4 and IPv6 packet verification checks based on addresses.

hardware ip verify length

Configures IPv4 packet verification checks based on length.

show hardware forwarding ip verify

Displays information about IP packet verification checks.

hardware proxy layer-3 forwarding

To configure hardware proxy layer 3 forwarding information, use the hardware proxy layer-3 forwarding command. To set the default value, use the no form of the command.

hardware proxy layer-3 forwarding {exclude | use} {{none} {interface ethernet slot/port | module slot-number} [module-type f1]}

no hardware proxy layer-3 forwarding

 
Syntax Description

use

Specifies members.

exclude

Specifies all available members to exclude.

none

Specifies no modules or interface.

module

Specifies modules.

slot-number

Slot number. The range is from 1 to 18.

interface

Specifies interfaces.

slot/port

Slot or port number. The range is from 1 to 253.

module-type f1

(Optional) Specifies type of modules to perform proxyl ayer 3 forwarding for hardware proxy layer 3 forwarding exclude interface ethernet F1 modules.

 
Defaults

None

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

5.1(1)

This command was introduced.

 
Usage Guidelines

The N7K-F132-15 module only runs Layer 2 switching. So, when you have both this module and an M Series module in one Nexus 7000 Series chassis and you are performing Layer 3 procedures, the system uses proxy routing.

This command does not require a license.

Examples

This example shows how to configure hardware proxy forwarding information:

switch(config)# hardware proxy layer-3 forwarding exclude interface ethernet 2/1-16, ethernet 3/1, ethernet 4/1-2

switch(config)#

 
Related Commands

Command
Description

show hardware proxy layer-3 detail

Displays detail information on the proxylayer 3 functionality.

hello-interval (OSPF virtual link)

To specify the interval between hello packets that Cisco NX-OS sends on an Open Shortest Path First (OSPF) virtual link, use the hello-interval command. To return to the default, use the no form of this command.

hello-interval seconds

no hello-interval

 
Syntax Description

seconds

Hello interval (in seconds). The value must be the same for all nodes on a specific virtual link. The range is from 1 to 65535.

 
Defaults

10 seconds

 
Command Modes

Virtual link configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

Use the hello-interval command in virtual link configuration mode to set the hello interval for OSPF across a virtual link. A shorter hello interval detects topological changes faster but causes more routing traffic. The hello interval must be the same for all devices on a virtual link.

This command requires the Enterprise Services license.

Examples

This example shows how to configure the hello interval to 15 seconds:

switch(config)# router ospf 202
switch(config-router)# ip ospf area 99 virtual-link 192.0.2.4
switch(config-router-vlink)# hello-interval 15
 

 
Related Commands

Command
Description

dead-interval (virtual link)

Sets the time period to declare a neighbor as down if the local device receives no hello packets.

hello-interval (OSPFv3 virtual link)

To specify the interval between hello packets that Cisco NX-OS sends on an Open Shortest Path First version 3 (OSPFv3) virtual link, use the hello-interval command. To return to the default, use the no form of this command.

hello-interval seconds

no hello-interval

 
Syntax Description

seconds

Hello interval (in seconds). The value must be the same for all nodes on a specific virtual link. The range is from 1 to 65535.

 
Defaults

10 seconds

 
Command Modes

Virtual link configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

Use the hello-interval command in virtual link configuration mode to set the hello interval for OSPFv3 across a virtual link. A shorter hello interval detects topological changes faster but causes more routing traffic. The hello interval must be the same for all devices on a virtual link.

This command requires the Enterprise Services license.

Examples

This example shows how to configure the hello interval to 15 seconds:

switch(config)# router ospfv3 202
switch(config-router)# ipv6 ospfv3 area 99 virtual-link 192.0.2.4
switch(config-router-vlink)# hello-interval 15
 

 
Related Commands

Command
Description

dead-interval (OSPFv3 virtual link)

Sets the time period to declare a neighbor as down if the local device receives no hello packets.

hostname dynamic

To enable the exchange of the dynamic host name for IS-IS, use the hostname dynamic configuration mode command. To disable the exchange of the dynamic host name for IS-IS, use the no form of this com mand

hostname dynamic

no hostname dynamic

 
Syntax Description

This command has no arguments or keywords.

 
Command Default

Dynamic hostname is disabled by default.

 
Command Modes

Router configuration
VRF configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

 
Usage Guidelines

The hostname dynamic command allows you to enable the IS-IS routers to flood their host name to system ID mapping information across the IS-IS network.

This command requires the Enterprise Services license.

Examples

This example shows how to enable the exchange of the dynamic host name for IS-IS:

switch(config-router)# hostname dynamic
switch(config-router)#
 

This example shows how to disable the exchange of the dynamic host name for IS-IS:

switch(config-router)# no hostname dynamic
switch(config-router)#

 
Related Commands

Command
Description

feature isis

Enables IS-IS on the router.

router isis

Enables IS-IS.

show isis hostname

Displays the IS-IS dynamic host name exchange information.

hsrp

To enter Hot Standby Router Protocol (HSRP) configuration mode and create an HSRP group, use the hsrp command. To disable HSRP, use the no form of this command.

hsrp group-number [ ipv4 | ipv6 ]

no hsrp group-number [ ipv4 | ipv6 ]

 
Syntax Description

group-number

Number of HSRP groups that can be configured on a Gigabit Ethernet port, including the main interfaces and subinterfaces. For HSRP version 1, the range is from 0 to 255. For HSRP version 2, the range is from 0 to 4096. The default value is 0.

ipv4

(Optional) Sets the HSRP group for IPv4.

ipv6

(Optional) Sets the HSRP group for IPv6.

 
Defaults

Disabled

 
Command Modes

Interface configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.0(1)

This command was introduced.

4.1(2)

Added the IPv4 keyword.

5.0(2)

Added the IPv6 keyword.

5.1(1)

Added an example on how to configure an IPv6 HSRP group.

 
Usage Guidelines

You must globally enable HSRP before you can configure any HSRP options or create an HSRP group.

The switch creates an IPv4 HSRP group if ipv6 keyword not specified.

The keyword ipv4 is optional if only IPv4 with the group ID exists on the interface. If both the IPv4 and IPv6 groups exist on the same interface, you must specify the address type as IPv4 or IPv6.

To configure IPv6 HRSP groups, you must configure HSRP version 2 on the interface.

The IPv4 and IPv6 groups can share the same group ID within an interface.

This command does not require a license.

Examples

This example shows how to create and activate an HSRP group:

switch# configure t
switch(config)# interface ethernet 0
switch(config-if)# ip address 172.16.6.5 255.255.255.0
switch(config-if)# hsrp 1
switch(config-if-hsrp)#
 
This example shows how to create and activate an IPv6 HSRP group:
switch# configure t
switch(config)# interface ethernet 5/2
switch(config)# ipv6 address 2001:0DB8:0001:0001:/64
switch(config-if-hsrp)# hsrp version 2
switch(config-if)# hsrp 10 ipv6
switch(config-if-hsrp)#

 
Related Commands

Command
Description

feature hsrp

Enables HSRP configuration.

show hsrp

Displays HSRP information.

ip address

Creates a virtual IP address for the HSRP group. The IP address must be in the same subnet as the interface IP address

hsrp ipv6

To create an Hot Standby Redundancy Protocol (HSRP) group and enter HSRP configuration mode, use the hsrp command. To remove the HSRP group configuration, use the no form of this command.

hsrp group-number [ipv6]

no hsrp group-number [ipv6]

 
Syntax Description

group-number

Group number. The range is from 0 to 4095.

ipv6

(Optional) Specifies the IPv6 address.

 
Defaults

None

 
Command Modes

Interface configuration mode

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

6.2(2)

This command was introduced.

 
Usage Guidelines

This command requires the Enterprise Services license.

Examples

This example shows how to create an HSRP group and enter HSRP configuration mode:

switch# configure terminal
switch(config)# interface ethernet 3/5
switch(config-if)# ip address 11.0.0.1/24
switch(config-if)# hsrp version 2
switch(config-if)# hsrp 10
switch(config-if-hsrp)#
 
This example shows how to remove the HSRP group configuration:
switch(config-if)# no hsrp 10
switch(config-if)#

 
Related Commands

Command
Description

hsrp version 2

Configures the HSRP version 2.

hsrp mac-refresh

To configure the MAC refresh interval for the Hot Standby Redundancy Protocol (HSRP) slave group, use the hsrp mac-refresh command.

hsrp mac-refresh seconds

 
Syntax Description

seconds

Interval in seconds. The range is from 0 to 10000.

 
Defaults

60 seconds

 
Command Modes

Interface configuration mode

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

6.2(2)

This command was introduced.

 
Usage Guidelines

You can use the hsrp mac-refresh command to minimize the number of hello messages that are sent out and reduce HSRP protocol overheads and CPU utilization when multiple subinterfaces are configured.

The hsrp mac-refresh command is not available for individual subinterfaces. It applies to all groups on all subinterfaces.

This command requires the Enterprise Services license.

Examples

This example shows how to configure the MAC refresh interval for an HSRP slave group:

switch# configure terminal
switch(config)# interface ethernet 3/5
switch(config-if)# ip address 11.0.0.1/24
switch(config-if)# hsrp version 2
switch(config-if)# hsrp mac-refresh 90
switch(config-if)#

 
Related Commands

Command
Description

follow

Configures a regular HSRP group as a slave group.

hsrp timers extended-hold

To enabled extended hold timers for the Hot Standby Router Protocol (HSRP), use the hsrp timers extended-hold command. To revert to default, use the no form of this command.

hsrp timers extended-hold [ timer ]

no hsrp timers extended-hold

 
Syntax Description

timer

(Optional) Extended hold time, in seconds. The range is from 10 to 255.

 
Defaults

10 seconds

 
Command Modes

Global configuration

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

4.2(1)

This command was introduced.

 
Usage Guidelines

Use the hsrp timers extended-hold command to configure extended Non-stop Forwarding (NSF) support for HSRP.


Note You must configure extended hold timers on all HSRP routers if you configure non-default extended hold timers. You can configure different extended holdtimer values on each HSRP routers, based on the expected system switchover delays.


This command does not require a license.

Examples

This example shows how to configure the extended hold time for HSRP:

switch(config)# hsrp timers extended-hold 30
 

 
Related Commands

Command
Description

feature hsrp

Enables the HSRP feature.

show hsrp

Displays HSRP information.

hsrp version 2

To configure the Hot Standby Redundancy Protocol (HSRP) version 2, use the hsrp version 2 command.

hsrp version 2

 
Syntax Description

This command has no arguments of keywords.

 
Defaults

Version 1

 
Command Modes

Interface configuration mode

 
Supported User Roles

network-admin
vdc-admin

 
Command History

Release
Modification

6.2(2)

This command was introduced.

 
Usage Guidelines

Because the multiple group optimization (MGO) supports only HSRP version 2, you must set the HSRP version to version 2.

This command requires the Enterprise Services license.

Examples

This example shows how to configures the HSRP version:

switch# configure terminal
switch(config)# interface ethernet 3/5
switch(config-if)# ip address 11.0.0.1/24
switch(config-if)# hsrp version 2
switch(config-if)#

 
Related Commands

Command
Description

hsrp

Configures the HSRP version.