H3C S5500-EI series User manual

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Table of Contents
i
Table of Contents
Chapter 1 VRRP Configuration....................................................................................................1-1
1.1 Introduction to VRRP.........................................................................................................1-1
1.1.1 VRRP Overview ......................................................................................................1-1
1.1.2 VRRP Standby Group Overview.............................................................................1-2
1.1.3 VRRP Timers ..........................................................................................................1-4
1.1.4 Format of VRRP Packets........................................................................................1-5
1.1.5 Principles of VRRP..................................................................................................1-7
1.1.6 VRRP Interface Tracking ........................................................................................1-7
1.1.7 VRRP Application (Taking IPv4-Based VRRP for Example) ..................................1-7
1.2 Configuring VRRP for IPv4................................................................................................1-9
1.2.1 VRRP for IPv4 Configuration Task List...................................................................1-9
1.2.2 Enabling Users to Ping Virtual IP Addresses........................................................1-10
1.2.3ConfiguringtheAssociationBetweenVirtualIPAddressandMACAddress..................... 1-10
1.2.4 Creating Standby Group and Configuring Virtual IP Address...............................1-11
1.2.5ConfiguringStandbyGroupPriority,PreemptionModeandInterfaceTracking.................1-12
1.2.6 Configuring VRRP Packet Attributes ....................................................................1-13
1.2.7 Displaying and Maintaining VRRP for IPv4...........................................................1-14
1.3 Configuring VRRP for IPv6..............................................................................................1-15
1.3.1 VRRP for IPv6 Configuration Task List.................................................................1-15
1.3.2 Enabling Users to Ping Virtual IPv6 Addresses....................................................1-15
1.3.3ConfiguringtheAssociationBetweenVirtualIPv6AddressandMACAddress................. 1-16
1.3.4 Creating Standby Group and Configuring Virtual IPv6 Address...........................1-17
1.3.5ConfiguringStandbyGroupPriority,PreemptionModeandInterfaceTracking.................1-18
1.3.6 Configuring VRRP Packet Attributes ....................................................................1-19
1.3.7 Displaying and Maintaining VRRP for IPv6...........................................................1-20
1.4 IPv4-Based VRRP Configuration Examples....................................................................1-20
1.4.1 Single VRRP Standby Group Configuration Example .......................................... 1-20
1.4.2 VRRP Interface Tracking Configuration Example.................................................1-23
1.4.3 Multiple VRRP Standby Group Configuration Example........................................1-26
1.5 IPv6-Based VRRP Configuration Examples....................................................................1-29
1.5.1 Single VRRP Standby Group Configuration Example .......................................... 1-29
1.5.2 VRRP Interface Tracking Configuration Example.................................................1-32
1.5.3 Multiple VRRP Standby Group Configuration Example........................................1-36
1.6 Troubleshooting VRRP....................................................................................................1-39

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-1
Chapter 1 VRRP Configuration
When configuring VRRP, go to these sections for information you are interested in:
zIntroduction to VRRP
zConfiguring VRRP for IPv4
zConfiguring VRRP for IPv6
zIPv4-Based VRRP Configuration Examples
zIPv6-Based VRRP Configuration Examples
zTroubleshooting VRRP
Note:
At present, the interfaces that VRRP involves can only be VLAN interfaces unless
otherwise specified.
1.1 Introduction to VRRP
1.1.1 VRRP Overview
Normally, as shown in Figure 1-1, you can configure a default route with the gateway as
the next hop for every host on a network segment, allowing all packets destined to the
other network segments to be sent over the default route to the gateway and then be
forwarded by the gateway. This enables hosts on a network segment to communicate
with external networks. However, when the gateway fails, all the hosts using the
gateway as the default next-hop switch fail to communicate with the external network.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-2
Gateway
Network
Host A
Host B
Host C
Figure 1-1 LAN networking
Apparently, this approach to enabling hosts on a network to communicate with external
networks is easy to configure but it imposes a very high requirement of performance
stability on the device acting as the gateway. A common way to improve system
reliability is to use more egress gateways, introducing the problem ofrouting among the
multiple egresses.
Virtual Router Redundancy Protocol (VRRP) is an error-tolerant protocol designed to
address this problem through separating physical devices from logical devices.
Deploying VRRP on multicast and broadcast LANs such as Ethernet, you can ensure
that the system can still provide highly reliable default links without changing
configurations (such as dynamic routing protocols, route discovery protocols) when a
device fails and prevent network interruption due to a single link failure.
There are two VRRPversions: VRRPv2 and VRRPv3. VRRPv2 isbased on IPv4, while
VRRPv3 is based on IPv6. The two versions implement the same functions but provide
different commands.
1.1.2 VRRP Standby Group Overview
VRRP combines a group of switches (including a master and multiple backups) on a
LAN into a virtual router called standby group.
The VRRP standby group has the following features:
zA virtual router has an IP address. A host on the LAN only needs to know the IP
address of the virtual router and uses the IP address as the next hop of the default
route.
zEvery host on the LAN communicates with external networks through the virtual
router.
zSwitches in the standby group elect the gateway according to their priorities. Once
the master switch acting as the gateway fails, the other switches in the standby

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-3
group elect a new gateway to undertake the responsibility of the failed switch, thus
ensuring that the hosts in the network segment cancommunicatewith the external
networks uninterruptedly.
Host A
Host B
Host C
Switch A
Switch B
Switch C
Virtual router
Network
Figure 1-2 Network diagram for VRRP
As shown in Figure 1-2, Switch A, Switch B, and Switch C form a virtual router, which
has its own IP address. Hosts on the Ethernet use the virtual router as the default
gateway.
The switch with the highest priority of thethree switches is electedas the masterswitch
to act as the gateway, and the other two are backup switches.
Caution:
zThe IP address of the virtual router can be either an unused IP address on the
segment where
zthe standby group resides or the IP address of an interface on a switch in the
standby group. In the latter case, the switch is called the IP address owner.
zIn a VRRP standby group, there can only be one IP address owner.
I. VRRP priority
VRRP determines the role (master or backup) of each switch in the standby group by
priority. A switch with a higher priority has more opportunity to become the master.
VRRP priority is in the range of 0 to 255. A bigger number means a higher priority.
Priorities 1 to 254 are configurable. Priority 0 is reserved for special uses and priority
255 for the IP address owner. When a switch acts as the IP address owner, its priority

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-4
remains 255. That is, if there is an IP address owner in a standby group, it acts as the
master as long as it works properly.
II. Working mode
A switch in a standby group can work in one of the following two modes:
zNon-preemption mode
Once a switch in the standby group becomes the master, it stays as the master as long
as it operates normally, even if a backup switch is assigned a higher priority later.
zPreemption mode
Once a backup switch finds its priority higher than that of the switch acting as the
master, it sends VRRP advertisements to start a new master switch election in the
standby group and becomes the master. Accordingly, the original master switch
becomes a backup.
III. Authentication mode
VRRP provides two authentication modes:
zsimple: Simple text authentication
You can adopt the simple text authentication mode in a network facing possiblesecurity
problems. Aswitch sendinga packet fills the authentication key into the packet, and the
switch receiving the packet compares its local authentication key with that of the
received packet. If the two authentication keys are the same, the received VRRP
packet is considered real and valid; otherwise, the received packet is considered an
invalid one.
zmd5: MD5 authentication
You can adopt MD5 authentication in a network facing severe security problems. The
switch encrypts a packet to be sent using the authentication key and MD5 algorithm
and saves the encrypted packet in the authentication header. The switch receiving the
packet uses the authentication key to decrypt the packet and checks whether the
packet is valid.
On a secure network, you need not set the authentication mode.
1.1.3 VRRP Timers
VRRP timers include VRRP advertisement interval timer and VRRP preemption delay
timer.
I. VRRP advertisement interval timer
The master switch in a VRRP standby group sends VRRP advertisements periodically
to inform the other switches in the standby group that it operates properly.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-5
You can adjust the interval of sending VRRP advertisements by setting the VRRP
advertisement interval timer. If a backup switch receives no advertisements in three
times the interval, the backup switch regards itself as the master switch and sends
VRRP advertisements to start a new master switch election.
II. VRRP preemption delay timer
In an unstable network, a backup switch may fail to receive the packets from the master
switch due to network congestion, thus causing the members in the group to change
their states frequently. This problem can be addressed through setting the VRRP
preemption delay timer.
With the VRRP preemption delay timer set, if a backup switch receives no
advertisement in three times the advertisement interval and then in preemption delay, it
considers that the master fails. In this case, it regards itself as the master and sends
VRRP advertisements to start a new master switch election in a standby group.
1.1.4 Format of VRRP Packets
VRRP uses multicast packets. The switch acting as the master sends VRRP packets
periodically to declare its existence. VRRP packets are also used for checking the
parameters of the virtual router and electing the master.
I. IPv4-based VRRP packet format
...
Version Type Virtual Rtr ID Priority Count IP Addrs
Auth Type Adver Int Checksum
IP address 1
IP address n
Authentication data 1
Authentication data 2
0 7 15 23 313
Figure 1-3 IPv4-based VRRP packet format
As shown in Figure 1-3, an IPv4-based VRRP packet consists of the following fields:
zVersion: Version number of the protocol, 2 for VRRPv2.
zType: Type of the VRRP packet. Only one VRRP packet type is present, that is,
VRRP advertisement, which is represented by 1.
zVirtual Rtr ID (VRID): Number of the virtual router, that is, number of the standby
group. It ranges from 1 to 255.
zPriority: Priority of the switch in the standby group, in the range 0 to 255. A greater
value represents a higher priority.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-6
zCount IP Addrs: Number of virtual IP addresses for the standby group. A standby
group can have multiple virtual IP addresses.
zAuth Type: Authentication type. 0 means no authentication, 1 means simple
authentication, and 2 means MD5 authentication.
zAdver Int: Interval for sending advertisement packets, in seconds. The default is 1.
zChecksum: 16-bit checksum for validating the data in VRRP packets.
zIP Address: Virtual IP address entry of the standby group. The allowed number is
given by the Count IP Addrs field.
zAuthentication Data: Authentication key. Currently, this field is used only for simple
authentication and is 0 for any other authentication modes.
II. IPv6-based VRRP packet format
Version Type Virtual Rtr ID Priority Count IPv6 Addrs
Auth Type Adver Int Checksum
IPv6 address 1
Authentication data 1
Authentication data 2
IPv6 address n
0 7 15 23 313
Figure 1-4 IPv6-based VRRP packet format
As shown in Figure 1-4, an IPv6-based VRRP packet consists of the following fields:
zVersion: Version number of the protocol, 3 for VRRPv3.
zType: Type of the VRRP packet. Only one VRRP packet type is present, that is,
VRRP advertisement, which is represented by 1.
zVirtual Rtr ID (VRID): Number of the virtual router, that is, number of the standby
group. It ranges from 1 to 255.
zPriority: Priority of the switch in the standby group, in the range 0 to 255. A greater
value represents a higher priority.
zCount IPv6 Addrs: Number of virtual IPv6 addresses for the standby group. A
standby group can have multiple virtual IPv6 addresses.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-7
zAuth Type: Authentication type. 0 means no authentication, 1 means simple
authentication. VRRPv3 does not support MD5 authentication.
zAdver Int: Interval for sending advertisement packets, in centiseconds. The default
is 100.
zChecksum: 16-bit checksum for validating the data in VRRPv3 packets.
zIPv6 Address: Virtual IPv6 address entry of the standby group. The allowed
number is given by the Count IPv6 Addrs field.
zAuthentication Data: Authentication key. Currently, this field is used only for simple
authentication and is 0 for any other authentication modes.
1.1.5 Principles of VRRP
zWith VRRP enabled, the switches determine their respective roles in the standby
group by priority. The switch with the highest priority becomes the master, while
the others are the backups. The master sends VRRP advertisement packets
periodically to notify the backups that it is working properly, and each of the
backups starts a timer to wait for advertisement packets from the master.
zIn preemption mode, when a backup receives a VRRP advertisement packet, it
compares the priority in the packet with that of its own. If its priority is higher, it
becomes the master; otherwise, it remains a backup.
zIn non-preemption mode, the switch in the standby group remains as a master or
backup as long as the master does not fail. The backup will no become the master
even if the former is configured with a higher priority.
zIf the timer of a backup expires but the backup still does not receive any VRRP
advertisement packet, it considers that the master fails. In this case, the backup
switch considers itself as the master switch and sends VRRP advertisements to
start the election process to elect a new master switch for forwarding packets.
1.1.6 VRRP Interface Tracking
The interface tracking function expands the backup functionality of VRRP. It provides
backup not only when the interface to which a standby group is assigned fails but also
when other interfaces on the switch become unavailable. This is achieved by tracking
interfaces. When a monitored interface goes down, the priority of the switch owning the
interface is automatically decreased by a specified value,allowing a higher priority
switch in the standby group to become the master.
1.1.7 VRRP Application (Taking IPv4-Based VRRP for Example)
I. Master/backup
In master/backup mode, only one switch, the master, provides services. When the
master fails, a new master is elected from the original backups. This mode requires

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-8
only one standby group, in which each switch holds different priorities and the one with
the highest priority becomes the master, as shown in Figure 1-5.
Figure 1-5 VRRP in master/backup mode
At the beginning, Switch A is the master and therefore can forward packets to external
networks, while Switch B and Switch C are backups and are thus in the state of
listening. If Switch Afails, Switch B and Switch C will elect for the new master. The new
master takes over the forwarding task to provide services to hosts on the LAN.
II. Load balancing
You can create more than one standby group on an interface of a switch, allowing the
switch to be the master of one standby group but a backup of another at the same time.
In load balancing mode, multiple switches provide services at the same time. This
mode requires two or more standby groups, each of which includes a master and one
or more backups. The masters of the standby groups can be assumed by different
switches, as shown in Figure 1-6.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-9
Host A
Host B
Host C
Switch A
Backup
Switch B
Backup
Switch C
Master
Virtual router 2 Virtual router 3Virtual router 1
Master
Backup
Backup Backup
Master
Backup
Network
Figure 1-6 VRRP in load balancing mode
A switch can be in multiple standby groups and hold a different priority in different
group.
In Figure 1-6, three standby groups are present:
zStandby group 1: Switch A is the master; Switch B and Switch C are the backups.
zStandby group 2: Switch B is the master; Switch A and Switch C are the backups.
zStandby group 3: Switch C is the master; Switch A and Switch B are the backups.
For load balancing among SwitchA, Switch B, and Switch C, hosts on the LAN need to
be configured to use standby group 1, 2, and 3 as the default gateways respectively.
When configuring VRRPpriorities, ensure that each switch holds such a priority in each
standby group that it will take the expected role in the group.
1.2 Configuring VRRP for IPv4
1.2.1 VRRP for IPv4 Configuration Task List
Complete these tasks to configure VRRP for IPv4:
Task Remarks
Enabling Users to Ping Virtual IP Addresses Optional
Configuring the Association Between Virtual IP Address and
MAC Address Optional
Creating Standby Group and Configuring Virtual IP Address Required
Configuring Standby Group Priority, Preemption Mode and
Interface Tracking Optional

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-10
Task Remarks
Configuring VRRP Packet Attributes Optional
1.2.2 Enabling Users to Ping Virtual IP Addresses
You can configure whether the master switch responds to the received ICMP echo
requests, that is, whether the virtual IP address of a standby group can be successfully
pinged.
Follow these steps to enable a user to successfully ping the virtual IP addresses of
standby groups:
To do… Use the command… Remarks
Enter system view system-view —
Enable users to ping
virtual IP address of the
standby group vrrp ping-enable Optional
Enabled by default.
Caution:
Configure this function before creating a standby group. Otherwise, your configuration
will fail.
1.2.3 Configuring the Association Between Virtual IP Address and MAC Address
After the virtual IP address of a standup group is associated with a MAC address, the
master switch takes the configured MAC address as the source MAC address of the
packets to be sent, so that the hosts in the internal network can learn the association
between the IP address and the MAC address and thus forward the packets to be
forwarded to the other network segments to the master switch properly.
There are two types of association between virtual IP address and MAC address:
zVirtual IP address is associated with virtual router MAC address
By default, a MAC address is created for a standby group after the standby group is
created, and the virtual IP address is associated with the virtual MAC address. With
such association adopted, the hosts in the internal network need not update the
association between IP address and MAC address when the master switch changes.
zVirtual IP address is associated with real MAC address of the interface

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-11
When an IP address owner exists in a standby group, if you associate the virtual IP
address with the virtual MAC address, two MAC addresses are associated with an IP
address. In this case, you can associate the virtual IPaddress of the standby group with
the real MAC address, so that the packets from a host are forwarded to the IP address
owner according the real MAC address.
Follow these steps to configure the association between MAC address and virtual IP
address:
To do… Use the command… Remarks
Enter system view system-view —
Configure the association
between virtual IP
address and MAC
address
vrrp method { real-mac |
virtual-mac }
Optional
The virtual MAC address
is associated with the
virtual IP address by
default.
Caution:
You should configure this function before creating a standby group. Otherwise, you
cannot modify the mapping between the virtual IP address and the MAC address.
1.2.4 Creating Standby Group and Configuring Virtual IP Address
You need to configure a virtual IP address for a standby group when creating the
standby group. A VRRP standby group is created automatically when you specify the
first virtual IP address for the standby group. If you specify a virtual IP address for the
standby group later, the virtual IP address is only added to the virtual IP address list of
the VRRP standby group.
I. Configuration prerequisites
Before creating standby group and configuring virtual IP address, you should first
configure the IP address of the interface and ensure that the virtual IP address to be
configured is in the same network segment as the IP address of the interface.
II. Configuration procedure
Follow these steps to create standby group and configure virtual IP address:

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-12
To do… Use the command… Remarks
Enter system view system-view —
Enter the specified
interface view interface interface-type
interface-number —
Create standby group and
configure virtual IP
address of the standby
group
vrrp vrid virtual-router-id
virtual-ip virtual-address
Required
Standup group is not
created by default.
Caution:
zThe maximum number of standby groups on an interface and the maximum number
of virtual IP addresses in a standby group vary by device.
zA standby group is removed after you remove all the virtual IP addresses in it. In
addition, configurations on that standby group no longer take effect.
zThe virtual IP address of thevirtual router can be either an unused IP address on the
segment where the standby group resides or the IP address of an interface on a
switch in the standby group. In the latter case, the switch is called the IP address
owner.
zThe virtual IP address of the standby group cannot be 0.0.0.0, 255.255.255.255,
loopback address, non A/B/C address and other illegal IP addresses such as
0.0.0.1.
zOnly when the configured virtual IP address and the interface IP address belong to
the same segment and are legal host addresses can the standby group operate
normally. If the configured virtual IP address and the interface IP address do not
belong to the same network segment, or the configured IP address is the network
address or network broadcast address of the network segment that the interface IP
address belongs to, the state of the standby group is always initialize though you
can perform the configuration successfully, that is, VRRP does not take effect in this
case.
1.2.5 Configuring Standby Group Priority, Preemption Mode and Interface Tracking
I. Configuration prerequisites
Before you configure these features, you should first create a standby group on the
interface and configure virtual IP address for it.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-13
II. Configuration procedure
By configuring switch priority, preemption mode and interface tracking, you can decide
which switch in the standby group serves as the Master.
Follow these steps to configure standby group priority, preemption mode and interface
tracking: To do… Use the command… Remarks
Enter system view system-view —
Enter interface view interface interface-type
interface-number —
Configure switch priority
in the standby group vrrp vrid virtual-router-id
priority priority-value Optional
100 by default.
Configure the switch in
the standby group to work
in preemption mode and
configure preemption
delay
vrrp vrid virtual-router-id
preempt-mode [ timer
delay delay-value ]
Optional
The switch in the standby
group works in
preemption mode and the
preemption delay is 0
seconds by default.
Configure the interface to
be tracked
vrrp vrid virtual-router-id
track interface
interface-type
interface-number
[reduced
priority-reduced ]
Optional
No interface is being
tracked by default.
Caution:
zThe priority of an IP address owner is always 255 and not configurable.
zInterface tracking is not configurable to an IP address owner.
zThe priority of a device is restored if the state of the interface under tracking
changes from down to up.
1.2.6 Configuring VRRP Packet Attributes
I. Configuration prerequisites
Before configuring the relevant attributes of VRRP packets, you should first create the
standby group and configure the virtual IP address.
II. Configuration procedure
Follow these steps to configure VRRP packet attributes:

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-14
To do… Use the command… Remarks
Enter system view system-view —
Enter the specified
interface view interface interface-type
interface-number —
Configure the
authentication mode and
authentication key when
the standby groups send
and receive VRRP
packets
vrrp vrid virtual-router-id
authentication-mode
{ md5 | simple } key
Optional
Authentication is not
performed by default
Configure the time interval
for the Master in the
standby group to send
VRRP advertisement
vrrp vrid virtual-router-id
timer advertise
adver-interval
Optional
1 second by default
Disable TTL check on
VRRP packets vrrp un-check ttl
Optional
Enabled by default
Do not create a standby
group before executing
this command.
Note:
zYou may configure different authentication modes and authentication keys for the
standby groups on an interface. However, the members of the same standby group
must use the same authentication mode and authentication key.
zFactors like excessive traffic or different timer setting on switches can cause the
Backup timer to time-out abnormally and trigger a change of the state. To solve this
problem, you can prolong the time interval to send VRRP packets and configure a
preemption delay.
1.2.7 Displaying and Maintaining VRRP for IPv4
To do… Use the command… Remarks
Display VRRP status
display vrrp [ verbose ]
[ interface interface-type
interface-number [ vrid
virtual-router-id ] ]
Available in any view
Display VRRP statistics
display vrrp statistics
[ interface interface-type
interface-number [ vrid
virtual-router-id ] ]
Available in any view

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-15
To do… Use the command… Remarks
Remove VRRP statistics
reset vrrp statistics
[ interface interface-type
interface-number [ vrid
virtual-router-id ] ]
Available in user view
1.3 Configuring VRRP for IPv6
1.3.1 VRRP for IPv6 Configuration Task List
Complete these tasks to configure VRRP for IPv6:
Task Remarks
Enabling Users to Ping Virtual IPv6 Addresses Optional
Configuring the Association Between Virtual IPv6 Address and
MAC Address Optional
Creating Standby Group and Configuring Virtual IPv6 Address Required
Configuring Standby Group Priority, Preemption Mode and
Interface Tracking Optional
Configuring VRRP Packet Attributes Optional
1.3.2 Enabling Users to Ping Virtual IPv6 Addresses
You can configure whether the master switch responds to the received ICMPv6 echo
requests, that is, whether the virtual IPv6 address of a standby group can be pinged
through.
Follow these steps to enable a user to successfully ping the virtual IPv6 addresses of
standby groups:
To do... Use the command... Remarks
Enter system view system-view —
Enable a user to ping
virtual IPv6 address of the
standby group vrrp ipv6 ping-enable Optional
Enabled by default

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-16
Caution:
You should configure this function before creating a standby group. Otherwise, you
cannot ping the virtual IPv6 addresses of standby groups.
1.3.3 Configuring the Association Between Virtual IPv6 Address and MAC Address
After the virtual IPv6 address of a standup group is associated with the MAC address,
the master switch takes the configured MAC address as the source MAC address of the
packets to be sent, so that the hosts in the internal network can learn the association
between the IPv6 address and the MAC address and thus forward the packets to be
forwarded to the other network segments to the master switch properly.
There are two types of association between virtual IPv6 address and MAC address:
zVirtual IPv6 address is associated with virtual router MAC address
By default, a MAC address is created for a standby group after the standby group is
created, and the virtual IPv6 address is associated with the virtual MAC address. With
such association adopted, the hosts in the internal network need not update the
association between IPv6 address and MAC address when the master switch changes.
zVirtual IPv6 address is associated with real MAC address of the interface
When an IP address owner exists in a standby group, if you associate the virtual IPv6
address with the virtual MAC address, two MAC addresses are associated with an IPv6
address. In this case, you can associate the virtual IPv6 address of the standby group
with the real MAC address, so that the packets from a host is forwarded to the IP
address owner according the real MAC address.
Follow these steps to configure the association between MAC address and virtual IPv6
address:
To do… Use the command… Remarks
Enter system view system-view —
Configure the association
between virtual IPv6
address and MAC
address
vrrp ipv6 method
{ real-mac | virtual-mac }
Optional
The virtual MAC address
of the standby group is
associated with the virtual
IPv6 address by default.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-17
Caution:
You should configure this function before creating a standby group. Otherwise, you
cannot modify the mapping between the virtual IPv6 address and the MAC address.
1.3.4 Creating Standby Group and Configuring Virtual IPv6 Address
You need to configure a virtual IPv6 address for a standby group when creating the
standby group. A VRRP standby group is created automatically when you specify the
first virtual IPv6 address for the standby group. If you specify a virtual IPv6 address for
the standby group later, the virtual IPv6 address is only added to the virtual IPv6
address list of the VRRP standby group.
I. Configuration prerequisites
Before creating standby group and configuring virtual IPv6 address, you should first
configure the IPv6 address of the interface and ensure that the virtual IPv6 address to
be configured is in the same network segment as the IPv6 address of the interface.
II. Configuration procedure
Follow these steps to create standby group and configure its virtual IPv6 address:
To do… Use the command… Remarks
Enter system view system-view —
Enter the specified
interface view interface interface-type
interface-number —
Create standby group and
configure its virtual IPv6
address
vrrp ipv6 vrid
virtual-router-id virtual-ip
virtual-address
[ link-local ]
Required
No standby group is
created by default.
The first virtual IPv6
address of the standby
group must be a link local
address. Only one link
local address is allowed in
a standby group, and
must be removed the last.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-18
Caution:
zThe maximum number of standby groups on an interface and the maximum number
of virtual IPv6 addresses in a standby group vary by device.
zA standby group is removed after you remove all the virtual IPv6 addresses in it. In
addition, configurations on that standby group no longer take effect.
1.3.5 Configuring Standby Group Priority, Preemption Mode and Interface Tracking
I. Configuration prerequisites
Before configuring these features, you should first create the standby group and
configure the virtual IPv6 address.
II. Configuration procedure
By configuring standby group priority, preemption mode and interface tracking, you can
decide which switch in the standby group serves as the Master.
Follow these steps to configure standby group priority, preemption mode and interface
tracking:
To do… Use the command… Remarks
Enter system view system-view —
Enter the specified
interface view interface interface-type
interface-number —
Configure the priority of
the switch in the standby
group
vrrp ipv6 vrid
virtual-router-id priority
priority-value
Optional
100 by default
Configure the switch in
the standby to work in
preemption mode and
configure preemption
delay of the standby
group
vrrp ipv6 vrid
virtual-router-id
preempt-mode [ timer
delay delay-value ]
Optional
The switch in the standby
group works in
preemption mode and the
preemption delay is zero
seconds by default.
Configure the interface to
be tracked
vrrp ipv6 vrid
virtual-router-id track
interface interface-type
interface-number
[reduced
priority-reduced ]
Optional
No interface is being
tracked by default.

Operation Manual – VRRP
H3C S5500-EI Series Ethernet Switches Chapter 1 VRRP Configuration
1-19
Caution:
zThe priority of an IP address owner is always 255 and not configurable.
zInterface tracking is not configurable on an IP address owner.
zThe priority of a device is reset if the state of the interface under tracking changes
from down to up.
1.3.6 Configuring VRRP Packet Attributes
I. Configuration prerequisites
Before configuring the relevant attributes of VRRP packets, you should first create the
standby group and configure the virtual IPv6 address.
II. Configuration procedure
Follow these steps to configure VRRP packet attributes:
To do… Use the command… Remarks
Enter system view system-view —
Enter the specified
interface view interface interface-type
interface-number —
Configure the
authentication mode and
authentication key when
the standby groups send
and transmit VRRP
packets
vrrp ipv6 vrid
virtual-router-id
authentication-mode
simple key
Optional
Authentication is not
performed by default
Configure the time interval
for the Master in the
standby group to send
VRRP advertisement
vrrp ipv6 vrid
virtual-router-id timer
advertise adver-interval
Optional
100 centiseconds by
default
You may configure different authentication modes and authentication keys for the
standby groups on an interface. However, the members of the same standby group
must use the same authentication mode and authentication key.
Factors like excessive traffic or different timer setting on switches can cause the
Backup timer to time-out abnormally and change the state. To solve this problem, you
can prolong the time interval to send VRRP packets and configure a delay for
preemption.