The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
This chapter contains the following sections:
Your software release might not support all the features documented in this module. For the latest caveats and feature information, see the Bug Search Tool at https://tools.cisco.com/bugsearch/ and the release notes for your software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "New and Changed Information"chapter or the Feature History table in this chapter.
HSRP is a first-hop redundancy protocol (FHRP) that allows a transparent failover of the first-hop IP router. HSRP provides first-hop routing redundancy for IP hosts on Ethernet networks configured with a default router IP address. You use HSRP in a group of routers for selecting an active router and a standby router. In a group of routers, the active router is the router that routes packets; the standby router is the router that takes over when the active router fails or when preset conditions are met.
Many host implementations do not support any dynamic router discovery mechanisms but can be configured with a default router. Running a dynamic router discovery mechanism on every host is not practical for many reasons, including administrative overhead, processing overhead, and security issues. HSRP provides failover services to these hosts.
When you use HSRP, you configure the HSRP virtual IP address as the host default router (instead of the IP address of the actual router). The virtual IP address is an IPv4 or IPv6 address that is shared among a group of routers that run HSRP.
When you configure HSRP on a network segment, you provide a virtual MAC address and a virtual IP address for the HSRP group. You configure the same virtual address on each HSRP-enabled interface in the group. You also configure a unique IP address and MAC address on each interface that acts as the real address. HSRP selects one of these interfaces to be the active router. The active router receives and routes packets destined for the virtual MAC address of the group.
HSRP detects when the designated active router fails. At that point, a selected standby router assumes control of the virtual MAC and IP addresses of the HSRP group. HSRP also selects a new standby router at that time.
HSRP uses a priority designator to determine which HSRP-configured interface becomes the default active router. To configure an interface as the active router, you assign it with a priority that is higher than the priority of all the other HSRP-configured interfaces in the group. The default priority is 100, so if you configure just one interface with a higher priority, that interface becomes the default active router.
Interfaces that run HSRP send and receive multicast User Datagram Protocol (UDP)-based hello messages to detect a failure and to designate active and standby routers. When the active router fails to send a hello message within a configurable period of time, the standby router with the highest priority becomes the active router. The transition of packet forwarding functions between the active and standby router is completely transparent to all hosts on the network.
You can configure multiple HSRP groups on an interface.
A network configured for HSRP. By sharing a virtual MAC address and a virtual IP address, two or more interfaces can act as a single virtual router.
The virtual router does not physically exist but represents the common default router for interfaces that are configured to provide backup to each other. You do not need to configure the hosts on the LAN with the IP address of the active router. Instead, you configure them with the IP address of the virtual router (virtual IP address) as their default router. If the active router fails to send a hello message within the configurable period of time, the standby router takes over, responds to the virtual addresses, and becomes the active router, assuming the active router duties. From the host perspective, the virtual router remains the same.
Packets received on a routed port destined for the HSRP virtual IP address terminate on the local router, regardless of whether that router is the active HSRP router or the standby HSRP router. This includes ping and Telnet traffic. Packets received on a Layer 2 (VLAN) interface destined for the HSRP virtual IP address terminate on the active router.
HSRP routers communicate with each other by exchanging HSRP hello packets. These packets are sent to the destination IP multicast address 224.0.0.2 (reserved multicast address used to communicate to all routers) on UDP port 1985. The active router sources hello packets from its configured IP address and the HSRP virtual MAC address while the standby router sources hellos from its configured IP address and the interface MAC address, which might be the burned-in address (BIA). The BIA is the last six bytes of the MAC address that is assigned by the manufacturer of the network interface card (NIC).
Because hosts are configured with their default router as the HSRP virtual IP address, hosts must communicate with the MAC address associated with the HSRP virtual IP address. This MAC address is a virtual MAC address, 0000.0C07.ACxy, where xy is the HSRP group number in hexadecimal based on the respective interface. For example, HSRP group 1 uses the HSRP virtual MAC address of 0000.0C07.AC01. Hosts on the adjoining LAN segment use the normal Address Resolution Protocol (ARP) process to resolve the associated MAC addresses.
HSRP version 2 uses the new IP multicast address 224.0.0.102 to send hello packets instead of the multicast address of 224.0.0.2, which is used by version 1. HSRP version 2 permits an expanded group number range of 0 to 4095 and uses a new MAC address range of 0000.0C9F.F000 to 0000.0C9F.FFFF.
 Note |
On the HSRP Standby, HSRP adds the HSRP virtual IP address with a cookie "deadbeef". |
IPv6 hosts learn of available IPv6 routers through IPv6 neighbor discovery (ND) router advertisement (RA) messages. These messages are multicast periodically, or might be solicited by hosts, but the time delay for detecting when a default route is down might be 30 seconds or more. HSRP for IPv6 provides a much faster switchover to an alternate default router than the IPv6 ND protocol provides, less than a second if the milliseconds timers are used. HSRP for IPv6 provides a virtual first hop for IPv6 hosts.
When you configure an IPv6 interface for HSRP, the periodic RAs for the interface link-local address stop after IPv6 ND sends a final RA with a router lifetime of zero. No restrictions occur for the interface IPv6 link-local address. Other protocols continue to receive and send packets to this address.
IPv6 ND sends periodic RAs for the HSRP virtual IPv6 link-local address when the HSRP group is active. These RAs stop after a final RA is sent with a router lifetime of 0 when the HSRP group leaves the active state. HSRP uses the virtual MAC address for active HSRP group messages only (hello, coup, and redesign).
HSRP version 2
UDP port 2029
Virtual MAC address range from 0005.73A0.0000 through 0005.73A0.0FFF
Multicast link-local IP destination address of FF02::66
Hop limit set to 255
An HSRP IPv6 group has a virtual MAC address that is derived from the HSRP group number and a virtual IPv6 link-local address that is derived, by default, from the HSRP virtual MAC address. The default virtual MAC address for an HSRP IPv6 group is always used to form the virtual IPv6 link-local address, regardless of the actual virtual MAC address used by the group.
| Packet | MAC Source Address | IPv6 source Address | IPv6 Destination Address | Link-layer Address Option |
|---|---|---|---|---|
|
Neighbor solicitation (NS) |
Interface MAC address |
Interface IPv6 address |
— |
Interface MAC address |
|
Router solicitation (RS) |
Interface MAC address |
Interface IPv6 address |
— |
Interface MAC address |
|
Neighbor advertisement (NA) |
Interface MAC address |
Interface IPv6 address |
Virtual IPv6 address |
HSRP virtual MAC address |
|
Route advertisement (RA) |
Interface MAC address |
Interface IPv6 address |
— |
HSRP virtual MAC address |
|
HSRP (inactive) |
Interface MAC address |
Interface IPv6 address |
— |
— |
|
HSRP (active) |
Virtual MAC address |
Interface IPv6 address |
— |
— |
HSRP does not add IPv6 link-local addresses to the Unicast Routing Information Base (URIB). There are also no secondary virtual IP addresses for link-local addresses.
For global unicast addresses, HSRP adds the virtual IPv6 address to the URIB and IPv6, but does not register the virtual IPv6 addresses to ICMPv6. ICMPv6 redirects are not supported for HSRP IPv6 groups.
Beginning with Cisco NX-OS Release 6.2(2), HSRP supports multiple group optimization (MGO). MGO optimizes performance and bandwidth when multiple HSRP groups are configured on many subinterfaces. MGO requires only one HSRP group, known as the master group, on the physical interface for the purpose of electing active and standby routers.
You can create other HSRP groups on subinterfaces of the physical interface or a different interface, such as an SVI interface, and link these to the master HSRP group. These groups are known as slave groups. Slave groups follow their master group state so that they do not participate in any HSRP election mechanisms. Master groups send hello messages at their configured rates. Slave groups send hello messages at a reduced rate, which is called the mac-refresh interval rate. This process is required so that the slave groups can send out periodic messages in order to refresh MAC addresses in switches and learning bridges.
Cisco NX-OS supports HSRP version 1 by default. You can configure an interface to use HSRP version 2.
HSRP version 2 has the following enhancements to HSRP version 1:
Expands the group number range. HSRP version 1 supports group numbers from 0 to 255. HSRP version 2 supports group numbers from 0 to 4095.
For IPv4, uses the IPv4 multicast address 224.0.0.102 or the IPv6 multicast address FF02::66 to send hello packets instead of the multicast address of 224.0.0.2, which is used by HSRP version 1.
Uses the MAC address range from 0000.0C9F.F000 to 0000.0C9F.FFFF for IPv4 and 0005.73A0.0000 through 0005.73A0.0FFF for IPv6 addresses. HSRP version 1 uses the MAC address range 0000.0C07.AC00 to 0000.0C07.ACFF.
Adds support for MD5 authentication.
When you change the HSRP version, Cisco NX-OS reinitializes the group because it now has a new virtual MAC address.
HSRP version 2 has a different packet format than HSRP version 1. The packet format uses a type-length-value (TLV) format. HSRP version 2 packets received by an HSRP version 1 router are ignored.
HSRP message digest 5 (MD5) algorithm authentication protects against HSRP-spoofing software and uses the industry-standard MD5 algorithm for improved reliability and security. HSRP includes the IPv4 or IPv6 address in the authentication TLVs.
Hello—The hello message conveys the HSRP priority and state information of the router to other HSRP routers.
Coup—When a standby router wants to assume the function of the active router, it sends a coup message.
Resign—A router that is the active router sends this message when it is about to shut down or when a router that has a higher priority sends a hello or coup message.
HSRP allows you to configure multiple groups on an interface. You can configure two overlapping IPv4 HSRP groups to load share traffic from the connected hosts while providing the default router redundancy expected from HSRP. The following figure shows an example of a load-sharing HSRP IPv4 configuration.
Note |
HSRP for IPv6 load-balances by default. If there are two HSRP IPv6 groups on the subnet, then hosts learn of both groups from their router advertisements and choose to use one so that the load is shared between the advertised routers. |
You can use object tracking to modify the priority of an HSRP interface based on the operational state of another interface. Object tracking allows you to route to a standby router if the interface to the main network fails.
Two objects that you can track are the line protocol state of an interface or the reachability of an IP route. If the specified object goes down, Cisco NX-OS reduces the HSRP priority by the configured amount.
HSRP interoperates with virtual port channels (vPCs). vPCs allow links that are physically connected to two different Cisco Nexus devices to appear as a single port channel by a third device. See the Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, for more information on vPCs.
vPC forwards traffic through both the active HSRP router and the standby HSRP router.
Note |
You should configure HSRP on the primary vPC peer device as active and HSRP on the vPC secondary device as standby. |
Some third-party devices can ignore the HSRP virtual MAC address and instead use the source MAC address of an HSRP router. in a vPC environment, the packets using this source MAC address may be sent across the vPC peer link, causing a potential dropped packet. Configure the vPC peer gateway to enable the HSRP routers to directly handle packets sent to the local vPC peer MAC address and the remote vPC peer MAC address, as well as the HSRP virtual MAC address. See the Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, for more information on the vPC peer gateway.
For mixed-chassis configurations where the vPC peer link is configured on an F-series module, configure the vPC peer gateway exclude option to exclude the Layer 3 backup route that traverses the vPC peer link. See the Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, for more information on the vPC peer gateway exclude option.
Cisco NX-OS Release 6.2(2) and later releases facilitate further scalability at the spine layer by providing support for more than two nodes. You can create an anycast bundle, which is an association between a set of VLANs and an anycast switch ID. The set of VLANs or the HSRP group elects an active router and a standby router. The remaining routers in the group are in listen state.
All of the HSRP routers that have a configured anycast switch ID advertise the ID through FabricPath IS-IS. The active HSRP router is the only router that uses the anycast switch ID in its hello packets. The leaf switches learn that the anycast switch ID is reachable by all of the routers in the group.
All of the first hop gateways at the spine layer need to function in active-active forwarding mode. IP packets are received by any of the spine switches with the destination set as the gateway MAC address, and these packets are terminated and locally forwarded.
This feature supports bidirectional forwarding detection (BFD). BFD is a detection protocol that provides fast-forwarding and path-failure detection times. BFD provides subsecond failure detection between two adjacent devices and can be less CPU-intensive than protocol hello messages because some of the BFD load can be distributed onto the data plane on supported modules. See the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide, for more information.
HSRP supports stateful restarts and stateful switchovers. A stateful restart occurs when the HSRP process fails and is restarted. A stateful switchover occurs when the active supervisor switches to the standby supervisor. Cisco NX-OS applies the run-time configuration after the switchover.
If HSRP hold timers are configured for short time periods, these timers might expire during a controlled switchover or in-service software upgrade (ISSU). Ping to a virtual IP is also unreachable during this timer expiry period. HSRP supports extended non-stop forwarding (NSF) to temporarily extend these HSRP hold timers during a controlled switchover or ISSU.
With extended NSF configured, HSRP sends hello messages with the extended timers. HSRP peers update their hold timers with these new values. The extended timers prevent unnecessary HSRP state changes during the switchover or ISSU. After the switchover or ISSU event, HSRP restores the hold timers to their original configured values. If the switchover fails, HSRP restores the hold timers after the extended hold timer values expire.
HSRP supports virtual routing and forwarding (VRF) instances. VRFs exist within virtual device contexts (VDCs). By default, Cisco NX-OS places you in the default VDC and default VRF unless you specifically configure another VDC and VRF.
If you change the VRF membership of an interface, Cisco NX-OS removes all Layer 3 configuration, including HSRP.
Starting with Cisco NX-OS Release 7.2(0)D1(1), the Hot Standby Router Protocol (HSRP) Virtual IP (VIP) feature provides support for an HSRP Virtual IP configuration to be in a different subnet than that of the interface subnet. This feature is supported only for IPv4 address and not for IPv6. The following are the enhancements:
Enhance ARP to source with VIP from Supervisor Engine (SUP) for hosts, when the hosts in VIP subnet are referenced by static route to VLAN configuration.
Support periodic ARP synchronization to vPC peer if the HSRP VIP feature is enabled.
Allow VIP address as the Layer 3 source address and gateway address for all communications with a Dynamic Host Configuration Protocol (DHCP) server.
Enhance DHCP relay agent to relay DHCP packets with VIP address as source address instead of SVI IP address.
Note |
HSRP subnet VIP should be configured in the virtual port channel (vPC) topology. The HSRP VIP feature works only on HSRP with vPC topologies. |
Note |
In a subnet VIP configuration, the VIP address must be in a different subnet than the interface IP subnet. Without the subnet VIP configuration, the VIP address must be in the same subnet of the interface IP subnet. |
The following is an example for VIP subnet address configuration wherein the VIP address is not configured in the same subnet of the interface IP subnet.
switch# configure terminal
switch(config)# feature hsrp
switch(config)# feature interface-vlan
switch(config)# interface vlan 2
switch(config-if)# ip address 192.0.2.1/24
switch(config-if)# hsrp 2
switch(config-if-hsrp)# ip 209.165.201.1/24The following is an example for VIP address mismatch. Here the VIP address is not in the same subnet of the interface IP subnet.
switch# configure terminal
switch(config)# feature hsrp
switch(config)# feature interface-vlan
switch(config)# interface vlan 2
switch(config-if)# ip address 192.0.2.1/24
switch(config-if)# hsrp 2
switch(config-if-hsrp)# ip 209.165.201.1
!ERROR: Invalid IP address(Mismatch with IP subnet)!The following is an example for VIP address mismatch. Here the VIP subnet address is configured along with VIP address in the same subnet of the interface IP subnet.
switch# configure terminal
switch(config)# feature hsrp
switch(config)# feature interface-vlan
switch(config)# interface vlan 2
switch(config-if)# ip address 192.0.2.1/24
switch(config-if)# hsrp 2
switch(config-if-hsrp)# ip 192.0.2.10/24
!ERROR: Invalid IP address(Mismatch with IP subnet)!You must enable the HSRP feature in a device before you can configure and enable any HSRP groups.
When host connected to HSRP standby sends ping to HSRP Virtual IP, HSRP Active responds to the ping however the ping packets (transient traffic) get punted to the SUP on HSRP standby before reaching HSRP Active.
You must configure an IP address for the interface on which you configure HSRP and enable that interface before HSRP becomes active.
You must configure HSRP version 2 when you configure an IPv6 interface for HSRP.
For IPv4, the virtual IP address must be in the same subnet as the interface IP address.
The value of the first 2 digits of a type 7 key string configured by using the key-string 7 text-string command has to be between 0 and 15. For example, you can configure 07372b557e2c1a as the key string value in which case the sum value of the first 2 digits will be 7. But, you cannot configure 85782916342021 as the key string value because the value of the first 2 digits will be 85. We recommend unconfiguring any type 7 key strings that do not adhere to this value or to configure a type 0 string.
We recommend that you do not configure more than one first-hop redundancy protocol on the same interface.
HSRP version 2 does not interoperate with HSRP version 1. An interface cannot operate both version 1 and version 2 because both versions are mutually exclusive. However, the different versions can be run on different physical interfaces of the same router.
You cannot change from version 2 to version 1 if you have configured groups above the group number range allowed for version 1 (0 to 255).
HSRP for IPv4 is supported with BFD. HSRP for IPv6 is not supported with BFD.
Cisco NX-OS removes all Layer 3 configurations on an interface when you change the interface VRF membership, port channel membership, or when you change the port mode to Layer 2.
If you configure virtual MAC addresses with vPC, you must configure the same virtual MAC address on both vPC peers.
For mixed-chassis configurations where the vPC peer link is configured on an F-series module, configure the vPC peer gateway exclude option to exclude the Layer 3 backup route that traverses the vPC peer link.
You cannot use the HSRP MAC address burned-in option on a VLAN interface that is a vPC member.
If you have not
configured authentication, the
show
hsrp command displays the following string:
Authentication text "cisco"
The following is
the default behavior of HSRP as defined in RFC 2281: If no authentication data is
configured, the RECOMMENDED default value is 0x63 0x69 0x73 0x63 0x6F 0x00 0x00
0x00.
Anycast HSRP does not support BFD.
HSRP for MGO has the following limitations:
Master groups and slave groups are not restricted to the same interface.
HSRP for MGO supports only HSRP version 2.
Master and slave groups must have the same address types.
Configuring an HSRP group as a slave group clears the group's other configurations, such as its virtual IP address, without notification, so you must enter the follow command before you enter the ipip-address command.
Bidirectional forwarding (BFD) is not applicable to slave groups.
HSRP for MGO supports both IPv4 and IPv6 interfaces and works for all Layer 3 interfaces on which a regular HSRP group works.
An HSRP group cannot be configured as both a master and slave group at the same time.
| Parameters | Default |
|---|---|
|
HSRP |
Disabled |
|
Authentication |
Enabled as text for version 1, with cisco as the password |
|
HSRP version |
Version 1 |
|
Preemption |
Disabled |
|
Priority |
100 |
|
Virtual MAC address |
Derived from HSRP group number |
Configuring HSRP
You must globally enable HSRP before you can configure and enable any HSRP groups.
Confirm that you are in the correct VDC. To change the VDC, use the switchto vdc command.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# [no] feature hsrp |
Enables the HSRP feature. Use the no form of this command to disable this feature. You can use this command to enable or disable the HSRP feature and remove all associated configurations in a VDC in the global configuration mode. |
| Step 3 |
(Optional) switch(config)# copy running-config startup-config |
(Optional)
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
The following example enables HSRP:
switch # configure terminal
switch(config)# feature hsrp
switch(config)# copy running-config startup-configYou can configure the HSRP version. If you change the version for existing groups, Cisco NX-OS reinitializes HSRP for those groups because the virtual MAC address changes. The HSRP version applies to all groups on the interface
Note |
IPv6 HSRP groups must be configured as HSRP version 2. |
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface type number |
Enters interface configuration mode. |
| Step 3 |
switch(config-if)# hsrp version {1 | 2} |
Confirms the HSRP version. Version 1 is the default. |
| Step 4 |
(Optional) switch(config-if)# copy running-config startup-config |
(Optional)
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
The following example shows how to configure an HSRP version:
switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# hsrp version 2
switch(config-if)# copy running-config startup-configYou can configure an HSRP group on an IPv4 interface and configure the virtual IP address and virtual MAC address for the HSRP group.
You must enable HSRP.
Cisco NX-OS enables an HSRP group once you configure the virtual IP address on any member interface in the group. You must configure HSRP attributes such as authentication, timers, and priority before you enable the HSRP group.
Confirm that you are in the correct VDC. To change the VDC, use the switchto vdc command.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface type number |
Enters interface configuration mode. |
| Step 3 |
switch(config-if)# ip ip-address/length |
Configures the IPv4 address of the interface. |
| Step 4 |
switch(config-if)# hsrp group-number [ipv4] |
Creates an HSRP group and enters hsrp configuration mode. The range for HSRP version 1 is from 0 to 255. The range is for HSRP version 2 is from 0 to 4095. The default value is 0. |
| Step 5 |
switch(config-if-hsrp)# ip [ip-address [secondary]] |
Configures the virtual IP address for the HSRP group and enables the group. This address should be in the same subnet as the IPv4 address of the interface. |
| Step 6 |
switch(config-if-hsrp)# exit |
Exits HSRP configuration mode. |
| Step 7 |
switch(config-if)# no shutdown |
Enables the interface. |
| Step 8 |
(Optional) switch(config-if)# copy running-config startup-config |
(Optional)
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
| Step 9 |
(Optional) switch(config-if)# show hsrp [group group-number] [ipv4] |
(Optional)
Displays HSRP information. |
switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# ip 192.0.2.2/8
switch(config-if)# hsrp 2
switch(config-if-hsrp)# ip 192.0.2.1
switch(config-if-hsrp)# exit
switch(config-if)# no shutdown
switch(config-if)# copy running-config startup-configYou can configure an HSRP group on an IPv6 interface and configure the virtual IP address and virtual MAC address for the HSRP group. When you configure an HSRP group for IPv6, HSRP generates a link-local address from the link-local prefix. HSRP also generates a modified EUI-64 format interface identifier in which the EUI-64 interface identifier is created from the relevant HSRP virtual MAC address. There are no HSRP IPv6 secondary addresses.
You must enable HSRP.
Ensure that you have enabled HSRP version 2 on the interface where you want to configure an IPv6 HSRP group.
Ensure that you have configured HSRP attributes such as authentication, timers, and priority before you enable the HSRP group.
Confirm that you are in the correct VDC. To change the VDC, use the switchto vdc command.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
|
|
| Step 2 |
switch# configure terminal |
Enters global configuration mode. |
| Step 3 |
switch(config)# interface type number |
Enters interface configuration mode. |
| Step 4 |
switch(config-if)# ipv6 address ipv6-address/length |
Configures the IPv6 address of the interface. |
| Step 5 |
switch(config-if)# hsrp version 2 |
Configures the group for HSRP version 2. |
| Step 6 |
switch(config-if)# hsrp group-number [ipv6] |
Creates an IPv6 HSRP group and enters hsrp configuration mode. The range for HSRP version 2 is from 0 to 4095. The range is for HSRP version 2 is from 0 to 4095. The default value is 0. |
| Step 7 |
switch(config-if-hsrp)# ip [ipv6-address [secondary]] |
Configures the virtual IPv6 address for the HSRP group and enables the group. |
| Step 8 |
switch(config-if-hsrp)# ip autoconfig |
Autoconfigures the virtual IPv6 address for the HSRP group from the calculated link-local virtual IPv6 address and enables the group. |
| Step 9 |
switch(config-if-hsrp)# no shutdown |
Enables the interface. |
| Step 10 |
switch(config-if-hsrp)# copy running-config startup-config |
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
| Step 11 |
(Optional) switch(config-if-hsrp)# show hsrp [group group-number] [ipv6] |
(Optional)
Displays HSRP information. |
switch# configure terminal
switch(config)# interface ethernet 3/2
switch(config-if)# ipv6 address 2001:0DB8:0001:0001:/64
switch(config-if)# hsrp version 2
switch(config-if)# hsrp 2 ipv6
switch(config)# ip 2001:DB8::1
switch(config-if-hsrp)# exit
switch(config-if-hsrp)# no shutdown
switch(config-if-hsrp)# copy running-config startup-configYou can configure HSRP for MGO to optimize performance when scaling by configuring master and slave groups. Slave groups follow the master group state, which minimizes the number of hello messages that are sent. Cisco NX-OS enables an HSRP group once you configure its virtual IP address.
We recommend that you configure master groups on the same parent interface as their slave groups to allow the slave groups to have the same redundancy requirements as the master group. If a failure occurs on the master link, all the slave groups are brought down as well, even if the links on which they are configured remain up.
Ensure that you have enabled the HSRP feature.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface type/number |
Enters interface configuration mode and configures an interface type. |
| Step 3 |
switch(config-if)# ip addressip-address/length |
Configures the IP address of the interface. |
| Step 4 |
switch(config-if)# hsrp version 2 |
Configures the HSRP version. Because MGO supports only HSRP version 2, you must set the HSRP version to version 2. Version 1 is the default. |
| Step 5 |
switch(config-if)# hsrp group-number [ipv6] |
Creates an HSRP group and enters HSRP configuration mode. The range for the HSRP group number is from 0 to 4095. The no form of this command removes the group. |
| Step 6 |
switch(config-if-hsrp)# name [master-group-name] |
Specifies a master group name. The name command changes a regular HSRP group into a master group. If you do not specify a name, a unique name is automatically generated. The no form of this command returns the master group to a regular HSRP group. |
| Step 7 |
switch(config-if-hsrp)# ip [ip-address [secondary]] |
Configures the virtual IP address for the HSRP group and enables the master group. |
| Step 8 |
switch(config-if-hsrp)# exit |
Exits the HSRP configuration mode. |
| Step 9 |
switch(config-if)# no shutdown |
Enables the interface. |
| Step 10 |
switch(config-if)# show hsrp [brief] [group group-number] [ipv4] [ipv6] |
(Optional) Displays HSRP information. |
| Step 11 |
switch(config-if)# show hsrp mgo [name name] [brief] |
(Optional) Displays the relationships between HSRP groups that are in use for MGO and their slave sessions. The name keyword restricts the output to the session with a matching configured name. The brief keyword provides a summary of each MGO session with the associated slave sessions. |
The following example shows how to configure an HSRP master group on Ethernet interface 1/1:
switch# configure terminal
switch(config)# interface ethernet 1/1
switch(config-if)# ip address 11.0.0.1/24
switch(config-if)# hsrp version 2
switch(cofig-if)# hsrp 11
switch(config-if-hsrp)# name master1
switch(config-if-hsrp)# ip 11.0.0.100
switch(config-if-hsrp)# exit
switch(config-if)# no shutdown
switch(config-if)# show hsrp group 11
switch(config-if)# show hsrp mgo name master1If a failure occurs in a slave link that belongs to a different interface than the master group, the slave group is brought down, regardless of the state of the group it is following.
You can configure HSRP for MGO to optimize performance when scaling by configuring master and slave groups. Slave groups follow the master group state, which minimizes the number of hello messages that are sent. Cisco NX-OS enables an HSRP group once you configure its virtual IP address.
We recommend that you configure master groups on the same parent interface as their slave groups to allow the slave groups to have the same redundancy requirements as the master group. If a failure occurs on the master link, all the slave groups are brought down as well, even if the links on which they are configured remain up.
Ensure that you have enabled the HSRP feature.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface type/number |
Enters interface configuration mode and configures an interface type. |
| Step 3 |
switch(config-if)# ip addressip-address/length |
Configures the IP address of the interface. |
| Step 4 |
switch(config-if)# hsrp version 2 |
Configures the HSRP version. Because MGO supports only HSRP version 2, you must set the HSRP version to version 2. Version 1 is the default. |
| Step 5 |
switch(config-if)# hsrp mac refresh seconds |
(Optional) Configures the MAC refresh interval for the HSRP slave group. You can use this 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. This command is not available for individual subinterfaces. It applies to all groups on all subinterfaces. The default is 60 seconds. The range is from 0 to 10000. |
| Step 6 |
switch(config-if)# hsrp group-number [ipv6] |
Creates an HSRP group and enters HSRP configuration mode. The range for the HSRP group number is from 0 to 4095. The no form of this command removes the group. |
| Step 7 |
switch(config-if-hsrp)# follow [master-group-name] |
Configures a regular HSRP group as a slave group. Configuring an HSRP group as a slave group clears the group’s other configurations, such as its virtual IP address without notification, so you must enter the follow command before you enter the ip ip-address command. Slave groups may forward reference master group names that are undefined. The no form of this command returns the slave group to a regular HSRP group. |
| Step 8 |
switch(config-if-hsrp)# ip [ip-address] |
Configures the virtual IP address for the HSRP group and enables the slave group. |
| Step 9 |
switch(config-if-hsrp)# exit |
Exits the HSRP configuration mode. |
| Step 10 |
switch(config-if)# no shutdown |
Enables the interface. |
| Step 11 |
switch(config-if)# show hsrp [brief] [group group-number] [ipv4] [ipv6] |
(Optional) Displays HSRP information. |
| Step 12 |
switch(config-if)# show hsrp mgo [name name] [brief] |
(Optional) Displays the relationships between HSRP groups that are in use for MGO and their slave sessions. The name keyword restricts the output to the session with a matching configured name. The brief keyword provides a summary of each MGO session with the associated slave sessions. |
The following example shows how to configure an HSRP slave group on Ethernet interface 1/2:
switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# ip address 12.0.0.1/24
switch(config-if)# hsrp version 2
switch(cofig-if)# hsrp 12
switch(config-if-hsrp)# follow master1
switch(config-if-hsrp)# ip 12.0.0.100
switch(config-if-hsrp)# exit
switch(config-if)# no shutdown
switch(config-if)# show hsrp group 11
switch(config-if)# show hsrp mgo name master1You can override the default virtual MAC address that HSRP derives from the configured group number. You must configure the same virtual MAC address on both vPC peers of a vPC link.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface type number |
Enters interface configuration mode. |
| Step 3 |
switch(config-if)# hsrp group-number [ipv4] |
Creates an HSRP group and enters hsrp configuration mode. The range for HSRP version 1 is from 0 to 255. The range is for HSRP version 2 is from 0 to 4095. The default value is 0. |
| Step 4 |
switch(config-if-hsrp)# mac-address string |
Configures the virtual MAC address for an HSRP group. The string uses the standard MAC address format (xxxx.xxxx.xxxx). |
| Step 5 |
switch(config-if-hsrp)# copy running-config startup-config |
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
The following example configures the HSRP virtual MAC address manually:
switch # configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# hsrp 2
switch(config-if-hsrp)# mac-address 5000.1000.1060
switch(config-if-hsrp)# copy running-config startup-configYou can override the default virtual MAC address that HSRP derives from the configured group number. You must configure the same virtual MAC address on both vPC peers of a vPC link.
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
||
| Step 2 |
switch(config)# interface type number |
Enters interface configuration mode. |
||
| Step 3 |
switch(config-if)# hsrp use-bia [scope interface] |
Configures HSRP to use the burned-in MAC address of the interface for the HSRP virtual MAC address. Optionally, you can configure HSRP to use the burned-in MAC address for all groups on this interface by using the scope interface keyword.
|
||
| Step 4 |
switch(config-if)# copy running-config startup-config |
(Optional) Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration |
The following example configures the HSRP virtual MAC address manually:
switch # configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# hsrp use-bia
switch(config-if)# copy running-config startup-configYou can configure HSRP to authenticate the protocol using cleartext or MD5 digest authentication. MD5 authentication uses a key chain. For more details, see the Cisco Nexus 7000 Series NX-OS Security Configuration Guide.
You must enable HSRP.
You must configure the same authentication and keys on all members of the HSRP group.
Ensure that you have created the key chain if you are using MD5 authentication.
Confirm that you are in the correct VDC. To change the VDC, use the switchto vdc command.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface interface-type slot/port |
Enters interface configuration mode. |
| Step 3 |
switch(config-if)# hsrp group-number [ipv4 | ipv6] |
Creates an HSRP group and enters HSRP configuration mode. |
| Step 4 |
switch(config-if-hsrp)# authentication {text string | md5 {key-chain key-chain | key-string {0 | 7} text [timeout seconds]}} |
Configures cleartext authentication for HSRP on this interface by using the authentication text command, or you can configure MD5 authentication for HSRP on this interface using the authentication md5 command. If you configure MD5 authentication, you can use a key chain or key string. If you use a key string, you can optionally set the timeout for when HSRP only accepts a new key. The range is from 0 to 32767 seconds. |
| Step 5 |
switch(config-if-hsrp)# copy running-config startup-config |
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
| Step 6 |
(Optional) switch(config-if-hsrp)# show hsrp [group group-number] |
(Optional)
Displays HSRP information. |
The following example shows how to configure MD5 authentication for HSRP on Ethernet 1/2 after creating the key chain:
switch# configure terminal
switch (config)# interface ethernet 1/2
switch(config)# key chain hsrp-keys
switch(config-keychain)# key 0
switch(config-keychain-key)# key-string 7 zqdest
switch(config-keychain-key) accept-lifetime 00:00:00 Jun 01 2010 23:59:59 Sep 12 2010
switch(config-keychain-key) send-lifetime 00:00:00 Jun 01 2010 23:59:59 Aug 12 2010
switch(config-keychain-key) key 1
switch(config-keychain-key) key-string 7 uaeqdyito
switch(config-keychain-key) accept-lifetime 00:00:00 Aug 12 2010 23:59:59 Dec 12 2010
switch(config-keychain-key) send-lifetime 00:00:00 Sep 12 2010 23:59:59 Nov 12 2010
switch(config-keychain-key)# interface ethernet 1/2
switch(config-if)# hsrp 2
switch(config-if-hsrp)# authenticate md5 key-chain hsrp-keys
switch(config-if-hsrp)# copy running-config startup-configYou can configure an HSRP group to adjust its priority based on the availability of other interfaces or routes. The priority of a device can change dynamically if it has been configured for object tracking and the object that is being tracked goes down.
The tracking process periodically polls the tracked objects and notes any value change. The value change triggers HSRP to recalculate the priority. The HSRP interface with the higher priority becomes the active router if you configure the HSRP interface for preemption.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
Perform one of the following tasks: |
|
| Step 3 |
switch(config)# interface interface-type slot/port |
Enters interface configuration mode. |
| Step 4 |
switch(config-if)# hsrp group-number [ipv4 | ipv6] |
Creates an HSRP group and enters hsrp configuration mode. |
| Step 5 |
switch(config-if-hsrp)# priority [value] |
Sets the priority level used to select the active router in an HSRP group. The range is from 0 to 255. The default is 100. |
| Step 6 |
switch(config-if-hsrp)# track object-number [decrement value] |
Specifies an object to be tracked that affects the weighting of an HSRP interface. The value argument specifies a reduction in the priority of an HSRP interface when a tracked object fails. The range is from 1 to 255. The default is 10. |
| Step 7 |
switch(config-if-hsrp)# preempt [delay [minimum seconds] [reload seconds] [sync seconds]] |
Configures the router to take over as the active router for an HSRP group if it has a higher priority than the current active router. This command is disabled by default. The range is from 0 to 3600 seconds. |
| Step 8 |
switch(config-if-hsrp)# copy running-config startup-config |
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
| Step 9 |
(Optional) switch(config-if-hsrp)# show hsrp interface interface-type number |
(Optional)
Displays HSRP information for an interface. |
The following example shows how to configure HSRP object tracking on Ethernet 1/2:
switch# configure terminal
switch(config)# track 1 interface ethernet 2/2 line-protocol
switch(config)# interface ethernet 1/2
switch(config-if)# hsrp 2
switch(config-if-hsrp)# track 1 decrement 20
switch(config-if-hsrp)# copy running-config startup-configYou can configure the HSRP priority on an interface. HSRP uses the priority to determine which HSRP group member acts as the active router. If you configure HSRP on a vPC-enabled interface, you can optionally configure the upper and lower threshold values to control when to fail over to the vPC trunk. If the standby router priority falls below the lower threshold, HSRP sends all standby router traffic across the vPC trunk to forward through the active HSRP router. HSRP maintains this scenario until the standby HSRP router priority increases above the upper threshold.
For IPv6 HSRP groups, if all group members have the same priority, HSRP selects the active router based on the IPv6 link-local address.
For IPv4 HSRP groups, HSRP selects the active router based on the interface IP address when the priority is same.
Note |
Prior to Cisco NX-OS Release 7.2(0)D1(1), if the HSRP peer has a higher source interface IP address than the existing HSRP active peer and if preemption is enabled, the HSRP peer that has the same priority as the existing HSRP active peer preempts the existing HSRP active peer in the network. |
After Cisco NX-OS Release 7.2(0)D1(1), even if the HSRP peer has a higher source interface IP address than the existing HSRP active peer and if preemption is enabled, the HSRP peer that has the same priority as the existing HSRP active peer does not preempt the existing HSRP active peer in the network.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface type number |
Enters interface configuration mode. |
| Step 3 |
switch(config-if)# hsrp group-number [ipv4] |
Creates an HSRP group and enters hsrp configuration mode. The range for HSRP version 1 is from 0 to 255. The range is for HSRP version 2 is from 0 to 4095. The default value is 0. |
| Step 4 |
switch(config-if-hsrp)# priority level [forwarding-threshold lower lower-value upper upper-value] |
Sets the priority level used to select the active router in an HSRP group in interface configuration mode. The level range is from 0 to 255. The default is 100. Optionally, sets the upper and lower threshold values used by vPC to determine when to fail over to the vPC trunk. The lower-value range is from 1 to 255. The default is 1. The upper-value range is from 1 to 255. The default is 255. |
| Step 5 |
switch(config-if-hsrp)# copy running-config startup-config |
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
The following example configures the HSRP prioritylevel to 60 and the upper and lower threshold values used by vPC:
switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# hsrp 2
switch(config-if-hsrp)# priority 60 forwarding-threshold lower 40 upper 50
switch(config-if-hsrp)# copy running-config startup-configYou can optionally customize the behavior of HSRP. Be aware that as soon as you enable an HSRP group by configuring a virtual IP address, that group is now operational. If you first enable an HSRP group before customizing HSRP, the router could take control over the group and become the active router before you finish customizing the feature. If you plan to customize HSRP, you should do so before you enable the HSRP group. To customize HSRP, use the following commands in HSRP configuration mode.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch(config-if-hsrp)# name string |
Specifies the IP redundancy name for an HSRP group. The string is from 1 to 255 characters. The default string has the following format: hsrp-interface short-name group-id. For example, hsrp-Eth2/1-1. |
| Step 2 |
switch(config-if-hsrp)# preempt [delay [minimum seconds] [reload seconds] [sync seconds]] |
Configures the router to take over as an active router for an HSRP group if it has a higher priority than the current active router. This command is disabled by default. The range is from 0 to 3600 seconds. |
| Step 3 |
switch(config-if-hsrp)# timers [msec] hellotime [msec] holdtime |
|
The following example shows how to customize HSRP in HSRP configuration mode:
switch(config-if-hsrp)# name HSRP-1
switch(config-if-hsrp)# preempt delay minimum 60
switch(config-if-hsrp)# timers 5 18You can optionally customize the behavior of HSRP. Be aware that as soon as you enable an HSRP group by configuring a virtual IP address, that group is now operational. If you first enable an HSRP group before customizing HSRP, the router could take control over the group and become the active router before you finish customizing the feature. If you plan to customize HSRP, you should do so before you enable the HSRP group. To customize HSRP, use the following commands in interface configuration mode.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
| Step 2 |
switch(config)# interface interface-type slot/port |
Enters interface configuration mode. |
| Step 3 |
switch(config-if)# hsrp delay minimum seconds |
Specifies the minimum amount of time that HSRP waits after a group is enabled before participating in the group. The range is from 0 to 10000 seconds. The default is 0. |
| Step 4 |
switch(config-if)# hsrp delay reload seconds |
Specifies the minimum amount of time that HSRP waits after reload before participating in the group. The range is from 0 to 10000 seconds. The default is 0. |
The following example shows how to customize HSRP in interface configuration mode:
switch # configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# hsrp delay minimum 30
switch(config-if)# hsrp delay reload 30You can configure HSRP to use extended hold timers to support extended NSF during a controlled (graceful) switchover or ISSU, including software upgrades and supervisor switchovers. You should configure extended hold timers on all HSRP routers.
You must configure extended hold timers on all HSRP routers if you configure extended hold timers. If you configure a nondefault hold timer, you should configure the same value on all HSRP routers when you configure HSRP extended hold timers.
HSRP extended hold timers are not applied if you configure millisecond hello and hold timers for HSRPv1. This statement does not apply to HSRPv2.
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
switch# configure terminal |
Enters global configuration mode. |
||
| Step 2 |
switch(config)# hsrp timers extended-hold [timer] |
Sets the HSRP extended hold timer, in seconds, for both IPv4 and IPv6 groups. The timer range is from 10 to 255. The default is 10.
|
||
| Step 3 |
(Optional) switch(config)# copy running-config startup-config |
(Optional)
Saves the change persistently through reboots and restarts by copying the running configuration to the startup configuration. |
The following example shows how to configure extended hold timers for HSRP:
switch # configure terminal
switch(config)# hsrp timers extended-hold
switch(config)# copy running-config startup-configUse one of the following commands to verify the configuration:
|
Command |
Purpose |
|---|---|
| show hsrp [group group-number] |
Displays the HSRP status for all groups or one group. |
| show hsrp delay [interface interface-type slot/port] |
Displays the HSRP delay value for all interfaces or one interface. |
| show hsrp [interface interface-type slot/port] |
Displays the HSRP status for an interface. |
| show hsrp [group group-number] [interface interface-type slot/port] [active] [all] [init] [learn] [listen] [speak] [standby] |
Displays the HSRP status for a group or interface for virtual forwarders in the active, init, learn, listen, or standby state. Use the all keyword to see all states, including disabled. |
| show hsrp [group group-number] [interface interface-type slot/port] active] [all] [init] [learn] [listen] [speak] [standby] brief |
Displays a brief summary of the HSRP status for a group or interface for virtual forwarders in the active, init, learn, listen, or standby state. Use the all keyword to see all states, including disabled. |
| show hsrp mgo [namename] [brief] |
Displays the relationships between HSRP groups that are in use for MGO and their slave sessions. |
This example shows how to enable HSRP on an interface with MD5 authentication and interface tracking:
key chain hsrp-keys
key 0
key-string 7 zqdest
accept-lifetime 00:00:00 Jun 01 2008 23:59:59 Sep 12 2008
send-lifetime 00:00:00 Jun 01 2008 23:59:59 Aug 12 2008
key 1
key-string 7 uaeqdyito
accept-lifetime 00:00:00 Aug 12 2008 23:59:59 Dec 12 2008
send-lifetime 00:00:00 Sep 12 2008 23:59:59 Nov 12 2008
feature hsrp
track 2 interface ethernet 2/2 ip
interface ethernet 1/2
ip address 192.0.2.2/8
hsrp 1
authenticate md5 key-chain hsrp-keys
priority 90
track 2 decrement 20
ip 192.0.2.10
no shutdownThis example shows how to configure the HSRP priority on an interface:
interface vlan 1
hsrp 0
preempt
priority 100 forwarding-threshold lower 80 upper 90
ip 192.0.2.2
track 1 decrement 30|
Related Topic |
Document Title |
|---|---|
|
Configuring the Gateway Load Balancing protocol |
|
|
Configuring the Virtual Router Redundancy protocol |
|
|
HSRP CLI commands |
Cisco Nexus 7000 Series NX-OS Unicast Routing Command Reference |
|
Configuring high availability |
Cisco Nexus 7000 Series NX-OS High Availability and Redundancy Guide |
|
Related Topic |
Document Title |
|---|---|
|
CISCO-HSRP-MIB |
To locate and download MIBs, go to the following URL: http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml |
This table includes only the updates for those releases that have resulted in additions or changes to the feature.
|
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
MGO |
6.2(2) |
This feature was introduced. |
|
FabricPath anycast HSRP |
6.2(2) |
This feature was introduced. |
|
BFD |
5.0(2) |
Added support for BFD. See the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide for more information. |
|
IPv6 |
5.0(2) |
Added support to IPv6. |
|
Object track lists |
4.2(1) |
Added support for object track lists. |
|
Extended hold timers |
4.2(1) |
Added support for extended hold timers for extended NSF support. |
|
CISCO-HSRP-MIB |
4.2(1) |
Added support for CISCO-HSRP-MIB |
|
Priority thresholds |
4.1(3) |
Added support for vPC threshold values on HSRP priority. |
|
HSRP |
4.0(1) |
This feature was introduced. |
Feedback