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Configuration Guide - IP Routing 01

NE05E and NE08E V300R003C10SPC500

This is NE05E and NE08E V300R003C10SPC500 Configuration Guide - IP Routing
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Configuring Association Between Direct Routes and a VRRP Backup Group

Configuring Association Between Direct Routes and a VRRP Backup Group

Association between direct routes and a Virtual Router Redundancy Protocol (VRRP) backup group ensures that both network-to-user traffic and user-to-network traffic that traverse the VRRP backup group travel along the same path, which facilitates network management and improves reliability.

Usage Scenario

On a live network, a VRRP backup group serves as a gateway for users (including common users and base stations) to access the network. User-to-network traffic traverses the master device in the VRRP backup group, while network-to-user traffic travels along a path that a dynamic routing protocol selects. Therefore, user-to-network traffic and network-to-user traffic may along different paths, which interrupts services if firewalls are attached to devices in the VRRP backup group, complicates traffic monitoring or statistics collection, and increases costs.

To address the preceding problems, the routing protocol is expected to select a route passing through the master device so that the user-to-network and network-to-user traffic travels along the same path. Association between direct routes and a VRRP backup group can meet expectations by allowing the dynamic routing protocol to select a route based on the VRRP status.

Pre-configuration Tasks

Before associating direct routes with a VRRP backup group, complete the following tasks:

  • Configure VRRP basic functions and create a VRRP backup group.
  • Configure a dynamic routing protocol to ensure reachable routes among nodes.
NOTE:

With association between direct routes with a VRRP backup group, VRRP and an IGP cannot be configured on the same interface. If VRRP and an IGP are configured on the same interface, the IGP cannot inherit the route costs from the imported direct routes. As a result, the path selected by the IGP for network-to-user traffic may be different from the one on which user-to-network traffic is transmitted.

Configuration Procedures

Figure 2-1 Association between direct routes and a VRRP backup group

Associating Direct Routes with a VRRP Backup Group

Associating direct routes with a VRRP backup group on a VRRP-enabled interface or loopback interface allows the interface to modify the cost of each direct route to the virtual IP network segment based on the VRRP status.

Context

If the master device in a VRRP backup group fails, the VRRP backup group performs a master/backup switchover. After the master device recovers, the direct routes of the master device immediately become available. The VRRP backup group performs a VRRP switchback, which takes some time. To ensure that user-to-network traffic and network-to-user traffic travel along the same path in this period, associate direct routes with the VRRP backup group on both the master and backup devices. The association allows the VRRP-enabled devices to modify the cost of each direct route to the virtual IP network segment based on the VRRP status.

Procedure

  1. Run system-view

    The system view is displayed.

  2. Run interface interface-type interface-name

    VRRP must have been configured on this interface.

    VRRP must run on this interface.

  3. Configure the association between direct routes with the VRRP backup group status.

    • Configure the association between IPv4 direct routes with the VRRP backup group status.

      • On non-loopback interfaces:

        Run direct-route track vrrp vrid virtual-router-id degrade-cost cost-value

      • On loopback interfaces:

        Run direct-route track vrrp interface interface-type interface-number vrid virtual-router-id degrade-cost cost-value

    • To configure association between IPv6 direct routes with the VRRP6 backup group status, run the direct-route ipv6 track vrrp6 vrid virtual-router-id degrade-cost cost-value command.

    After the command is run, the cost of direct routes is adjusted based on the VRRP backup group status, with details as follows:

    • If the VRRP backup group status is Master, 0 (the highest priority) is used as the cost of the direct routes.

    • If the VRRP backup group status is Backup or Initialize, the cost-value specified in the command is used as the cost of the direct routes.

  4. Run commit

    The configuration is committed.

Configuring a Dynamic Routing Protocol to Import Direct Routes

After you associate direct routes with a Virtual Router Redundancy Protocol (VRRP) backup group, configure a dynamic routing protocol to import the direct routes so that the path selection by the dynamic routing protocol can be controlled.

Context

After direct routes are associated with a VRRP backup group, VRRP-enabled devices modify the cost of each direct route to the virtual IP network segment based on the VRRP status. To control the path by a dynamic routing protocol, enable the dynamic routing protocol to import direct routes and inherit the costs from the imported direct routes.

Currently, dynamic routing protocols include the Interior Gateway Protocol (IGP) and Border Gateway Protocol (BGP). If an IGP is configured to import direct routes, routing information protocol (RIP) cannot inherit costs from the imported direct routes. This section describes how to configure Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS), and BGP to import direct routes.

Procedure

  • Configure OSPF to import direct routes.
    1. Run system-view

      The system view is displayed.

    2. Run ospf [ process-id ]

      The OSPF process view is displayed.

    3. Run import-route direct

      OSPF is configured to import direct routes.

    4. Run default cost inherit-metric

      OSPF is enabled to inherit the costs from the imported direct routes.

      NOTE:
      • The default (OSPF) command has a lower priority than the apply cost command. If the apply cost command is run, it overrides the default (OSPF) command. Therefore, before running the default (OSPF) command, ensure that the apply cost command is not run.

      • Do not run the default cost cost-value command after you run the default cost inherit-metric command. If the default cost cost-value command is run after the default cost inherit-metric command, the default cost cost-value command overrides the default cost inherit-metric command.

    5. Run commit

      The configuration is committed.

  • Configure IS-IS to import direct routes.
    1. Run system-view

      The system view is displayed.

    2. Run isis [ process-id ]

      The IS-IS process view is displayed.

    3. Run import-route direct inherit-cost

      IS-IS is configured to import direct routes and to inherit the costs from the imported direct routes.

    4. Run commit

      The configuration is committed.

  • Configure BGP to import direct routes.
    1. Run system-view

      The system view is displayed.

    2. Run bgp as-number

      The BGP process view is displayed.

    3. Run import-route direct

      BGP is configured to import direct routes.

      BGP automatically inherits the costs from the imported direct routes. The inherited costs are shown as the multi-exit discrimination (MED) values.

    4. Run commit

      The configuration is committed.

Verifying the Configuration of Association Between Direct Routes and a VRRP Backup Group

After you associate direct routes with a Virtual Router Redundancy Protocol (VRRP) backup group, you can view information about the VRRP backup group and information in the routing table of the previous-hop device on the network side.

Prerequisites

Direct routes have been associated with a VRRP backup group.

Procedure

  • Run the display ip routing-table command on the backup device in the VRRP backup group to check the modified direct route costs in the IP routing table.
  • Run the display ip routing-table ip-address command on the VRRP backup group's previous-hop device on the network side to check whether network-to-user traffic lows through the master device in the VRRP backup group.

Example

When you associate direct routes with a VRRP backup group, set the cost of direct routes to the virtual IP network segment to 300 when the VRRP state is Backup or Initialize. On the VRRP backup group's previous-hop device on the network side, the next hop IP address of the route passing through the master device is 10.1.3.1, and the next hop IP address of the route passing through the backup device is 10.1.2.1. Check the configurations as follows:

# Run the display ip routing-table command on the backup device in the VRRP backup group to view information in the IP routing table.

<HUAWEI> display ip routing-table
Route Flags: R - relay, D - download
to fib, T - to vpn-instance, B - black hole route
------------------------------------------------------------------------------
Routing Table : _public_
         Destinations : 12       Routes : 12        

Destination/Mask    Proto  Pre  Cost        Flags NextHop         Interface

     10.1.1.0/24  Direct 0    300           D  10.1.1.2        GigabitEthernet0/1/0
       10.1.1.2/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/0
     10.1.1.111/32  O_ASE  150  0             D  10.1.2.2        GigabitEthernet0/1/1
     10.1.1.255/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/0
       10.1.2.0/24  Direct 0    0             D  10.1.2.1        GigabitEthernet0/1/1
       10.1.2.1/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/1
     10.1.2.255/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/1
       10.1.3.0/24  OSPF   10   2             D  10.1.2.2        GigabitEthernet0/1/1
      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
127.255.255.255/32  Direct 0    0             D  127.0.0.1       InLoopBack0
255.255.255.255/32  Direct 0    0             D  127.0.0.1       InLoopBack0

# Run the display ip routing-table ip-address command on the previous-hop device on the network side to view information about the route destined for the user network segment 10.1.1.0/24.

<HUAWEI> display ip routing-table 10.1.1.0
Route Flags: R - relay, D - download
to fib, T - to vpn-instance, B - black hole route
------------------------------------------------------------------------------
Routing Table : _public_
Summary Count : 1

Destination/Mask    Proto  Pre  Cost        Flags NextHop         Interface

       10.1.1.0/24  O_ASE  150  0             D  10.1.3.1        GigabitEthernet0/1/0
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Updated: 2019-01-14

Document ID: EDOC1100058916

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