The Virtual Router Redundancy Protocol (VRRP) is a fault tolerant protocol, and it groups several routers into a virtual router. If the next hop router of a host is defective, VRRP uses a mechanism to switch traffic to another router. This ensures continuity and reliability of communications.




In this example, by configuring a VRRP backup group in master/backup mode, you can use the master device of the VRRP backup group to transmit all network traffic.


Networking Requirements

As shown in Figure 1, Host A accesses Host B through the default gateway.
The requirements are as follows:
  • CX-A and CX-B form a VRRP backup group that serves as the default gateway for Host A.
  • Normally, CX-A serves as the gateway. When CX-A fails, CX-B serves as the gateway.
  • CX-A continues to function as the master CX device within 20 seconds after it recovers.
Figure 1 Networking diagram of configuring VRRP in the master/backup mode

Configuration Roadmap

The configuration roadmap is as follows:
  1. Create the backup group 1 on the GE 2/0/0 on CX-A and configure CX-A with the highest priority in the backup group to be the master CX device. Configure the preemption mode.
  2. Create backup group 1 on the GE 2/0/0 interface on CX-B and use the default priority.

Data Preparation

To complete the configuration, you need the following data:
  • Virtual router ID and virtual IP address
  • Priority of each CX device in the backup group
  • Preemption mode

Procedure

  1. Configure network interconnection between devices.
    # Configure the default gateway of Host A with 10.1.1.111 and the default gateway of Host B with 20.1.1.1.
    # Configure CX-A, CX-B and CX-C to use OSPF for interconnection.
  2. Configure VRRP.
    # On CX-A, configure the IP address of the interface, create backup group 1 and configure the priority of CX-A in this group with 120 (as the master CX device).
    <CX-A> system-view
    [CX-A] interface gigabitethernet 2/0/0
    [CX-A-GigabitEthernet2/0/0] undo shutdown
    [CX-A-GigabitEthernet2/0/0] ip address 10.1.1.1 24
    [CX-A-GigabitEthernet2/0/0] vrrp vrid 1 virtual-ip 10.1.1.111
    [CX-A-GigabitEthernet2/0/0] vrrp vrid 1 priority 120
    [CX-A-GigabitEthernet2/0/0] vrrp vrid 1 preempt-mode timer delay 20
    [CX-A-GigabitEthernet2/0/0] quit
    [CX-A] quit
    # On CX-B, configure the IP address of the interface, create backup group 1 and configure the priority of CX-B in this group with the default value 100 (as the backup CX device).
    <CX-B> system-view
    [CX-B] interface gigabitethernet 2/0/0
    [CX-B-GigabitEthernet2/0/0] undo shutdown
    [CX-B-GigabitEthernet2/0/0] ip address 10.1.1.2 24
    [CX-B-GigabitEthernet2/0/0] vrrp vrid 1 virtual-ip 10.1.1.111
    [CX-B] quit
  3. Verify the configuration.
    • Check that the VRRP backup group can serve as a gateway.
      After the previous configuration, Host A can ping through Host B.
      Running the display vrrp command on CX-A, you can view that the status of CX-A is Master. Running thedisplay vrrp command on CX-B, you can view that the CX-B is Backup.
      <CX-A> display vrrp
        GigabitEthernet2/0/0 | Virtual CX-1
          state          : Master
          Virtual IP     : 10.1.1.111
          Master IP       : 10.1.1.1
          PriorityRun    : 120
          PriorityConfig : 120
          MasterPriority : 120
          Preempt        : YES        Delay Time : 20
          TimerRun       : 1
          TimerConfig    : 1
          Auth Type      : NONE
          Virtual Mac    :  0000-5e00-0101
          Check TTL      : YES
          Config type    : normal-vrrp
      <CX-B> display vrrp
        GigabitEthernet2/0/0 | Virtual CX-1
          state          : Backup
          Virtual IP     : 10.1.1.111
          Master IP      : 10.1.1.1
          PriorityRun    : 100
          PriorityConfig : 100
          MasterPriority : 120
          Preempt        : YES      Delay Time : 0
          TimerRun       : 1
          TimerConfig    : 1
          Auth Type      : NONE
          Virtual Mac    :  0000-5e00-0101
          Check TTL      : YES
          Config type    : normal-vrrp
      Running the display ip routing-table command on CX-A and CX-B, you can view a direct route with the destination address being the virtual IP address on CX-A, and an OSPF route to the same destination on CX-B.
      The displays on CX-A and CX-B are as follows.
      <CX-A> display ip routing-table
      Route Flags: R - relied, D - download to fib
      ------------------------------------------------------------------------------
      Routing Tables: Public
               Destinations : 10       Routes : 10
      Destination/Mask    Proto    Pre  Cost     Flags    NextHop         Interface
           10.1.1.0/24    Direct   0     0         D      10.1.1.1        GigabitEthernet2/0/0
           10.1.1.1/32    Direct   0     0         D      127.0.0.1       InLoopBack0
           10.1.1.111/32    Direct  0     0         D      127.0.0.1      InLoopBack0
           20.1.1.0/24    OSPF     10    2         D      192.168.1.2     Pos1/0/0
           127.0.0.0/8    Direct   0     0         D      127.0.0.1       InLoopBack0
          127.0.0.1/32    Direct   0     0         D      127.0.0.1       InLoopBack0
        192.168.1.0/24    Direct   0     0         D      192.168.1.1     Pos1/0/0
        192.168.1.1/32    Direct   0     0         D      127.0.0.1       InLoopBack0
        192.168.1.2/32    Direct   0     0         D      192.168.1.2     Pos1/0/0
        192.168.2.0/24    OSPF     10    2         D      10.1.1.2        GigabitEthernet2/0/0
      <CX-B> display ip routing-table
      Route Flags: R - relied, D - download to fib
      ------------------------------------------------------------------------------
      Routing Tables: Public
               Destinations : 10       Routes : 10
      Destination/Mask    Proto    Pre  Cost     Flags   NextHop         Interface
           10.1.1.0/24    Direct   0     0         D     10.1.1.2        InLoopBack0
           10.1.1.2/32    Direct   0     0         D     127.0.0.1       InLoopBack0
           10.1.1.111/32    OSPF    10    2         D     10.1.1.1       InLoopBack0
           20.1.1.0/24    OSPF     10    2         D     192.168.2.2     Pos1/0/0
           127.0.0.0/8    Direct   0     0         D     127.0.0.1       InLoopBack0
          127.0.0.1/32    Direct   0     0         D     127.0.0.1       InLoopBack0
        192.168.1.0/24    OSPF     10    2         D     10.1.1.1        GigabitEthernet2/0/0
        192.168.2.0/24    Direct   0     0         D     192.168.2.1     Pos1/0/0
        192.168.2.1/32    Direct   0     0         D     127.0.0.1       InLoopBack0
        192.168.2.2/32    Direct   0     0         D     192.168.2.2     Pos1/0/0
    • Check whether CX- B can become the master when CX-A fails.
      To simulate the election of the master CX device when CX-A fails, run the shutdown command on the GE 2/0/0 on CX-A.
      Running the display vrrp command on CX-B to view the VRRP status, you can view that CX-B is in the Master state. The command output is as follows:
      <CX-B> display vrrp
      GigabitEthernet2/0/0 | Virtual CX-1
          state          : Master
          Virtual IP     : 10.1.1.111
          Master IP       : 10.1.1.2
          PriorityRun    : 100
          PriorityConfig : 100
          MasterPriority : 100
          Preempt        : YES      Delay Time : 0
          TimerRun       : 1
          TimerConfig    : 1
          Auth Type      : NONE
          Virtual Mac    :  0000-5e00-0101
          Check TTL      : YES
          Config type    : normal-vrrp
    • Check that CX-A can perform preemption after recovering.
      Run the undo shutdown command on GE 2/0/0. On CX-A, run the display vrrp command to view VRRP status 20 seconds after GE 2/0/0 being Up. You can view that CX-A restores to be the master CX device.

Configuration Files

  • Configuration file of CX-A
    #
     sysname CX-A
    #
    interface GigabitEthernet2/0/0
     undo shutdown
     ip address 10.1.1.1 255.255.255.0
     vrrp vrid 1 virtual-ip 10.1.1.111
     vrrp vrid 1 priority 120
     vrrp vrid 1 preempt-mode timer delay 20
    #
    interface Pos1/0/0
     link-protocol ppp
     undo shutdown
     ip address 192.168.1.1 255.255.255.0
    #
    ospf 1
     area 0.0.0.0
      network 192.168.1.0 0.0.0.255
      network 10.1.1.0 0.0.0.255
    #
    return
  • Configuration file of CX-B
    #
     sysname CX-B
    #
    interface GigabitEthernet2/0/0
     undo shutdown
     ip address 10.1.1.2 255.255.255.0
     vrrp vrid 1 virtual-ip 10.1.1.111
    #
    interface Pos1/0/0
     link-protocol ppp
     undo shutdown
     ip address 192.168.2.1 255.255.255.0
    #
    ospf 1
     area 0.0.0.0
      network 192.168.2.0 0.0.0.255
      network 10.1.1.0 0.0.0.255
    #
    return
  • Configuration file of CX-C
    #
     sysname CX-C
    #
    interface Ethernet3/0/0
     undo shutdown
     ip address 20.1.1.1 255.255.255.0
    #
    interface Pos1/0/0
     link-protocol ppp
     undo shutdown
     ip address 192.168.1.2 255.255.255.0
    #
    interface Pos2/0/0
     link-protocol ppp
     undo shutdown
     ip address 192.168.2.2 255.255.255.0
    #
    ospf 1
     area 0.0.0.0
      network 192.168.1.0 0.0.0.255
      network 192.168.2.0 0.0.0.255
      network 20.1.1.0 0.0.0.255
    #
    return

from the best of networking http://ift.tt/1AR2dhs


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