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Example for Configuring a Static Route for GRE to Implement Interworking Between IPv4 Networks

Networking Requirements

As shown in Figure 1:
  • SwitchA, SwitchB, and SwitchC communicate with each other through a public network. (The OSPF protocol is used in this example.)
  • PC1 and PC2 run the IPv4 proprietary protocol and communicate with each other over the public network.

  • PC1 uses SwitchA and PC2 uses SwitchC as a default gateway.

Figure 1 Configuring a static route for GRE

Configuration Roadmap

To allow PC1 to communicate with PC2, you can configure a direct link between SwitchA and SwitchC. This allows you to set up a GRE tunnel and configure a static route to forward packets through tunnel interfaces to the peer.

The configuration roadmap is as follows:

  1. Run OSPF on the devices to implement interworking among them.

  2. Create tunnel interfaces on SwitchA and SwitchC to set up a GRE tunnel, and configure a static route passing through tunnel interfaces on SwitchA and SwitchC, so that traffic between PC1 and PC2 can be transmitted over the GRE tunnel.

Procedure

  1. Configure an IP address for each physical interface.

    # Configure SwitchA.

    <HUAWEI> system-view
[HUAWEI] sysname SwitchA
[SwitchA] vlan batch 10 30
[SwitchA] interface gigabitethernet 0/0/1
[SwitchA-GigabitEthernet0/0/1] port link-type trunk
[SwitchA-GigabitEthernet0/0/1] port trunk allow-pass vlan 10
[SwitchA-GigabitEthernet0/0/1] quit
[SwitchA] interface gigabitethernet 0/0/2
[SwitchA-GigabitEthernet0/0/2] port link-type access
[SwitchA-GigabitEthernet0/0/2] port default vlan 30
[SwitchA-GigabitEthernet0/0/2] quit
[SwitchA] interface vlanif 10
[SwitchA-Vlanif10] ip address 20.1.1.1 24
[SwitchA-Vlanif10] quit
[SwitchA] interface vlanif 30
[SwitchA-Vlanif30] ip address 10.1.1.2 24
[SwitchA-Vlanif30] quit

    # Configure SwitchB.

    <HUAWEI> system-view
[HUAWEI] sysname SwitchB
[SwitchB] vlan batch 10 20
[SwitchB] interface gigabitethernet 0/0/1
[SwitchB-GigabitEthernet0/0/1] port link-type trunk
[SwitchB-GigabitEthernet0/0/1] port trunk allow-pass vlan 10
[SwitchB-GigabitEthernet0/0/1] quit
[SwitchB] interface gigabitethernet 0/0/2
[SwitchB-GigabitEthernet0/0/2] port link-type trunk
[SwitchB-GigabitEthernet0/0/2] port trunk allow-pass vlan 20
[SwitchB-GigabitEthernet0/0/2] quit
[SwitchB] interface vlanif 10
[SwitchB-Vlanif10] ip address 20.1.1.2 24
[SwitchB-Vlanif10] quit
[SwitchB] interface vlanif 20
[SwitchB-Vlanif20] ip address 30.1.1.1 24
[SwitchB-Vlanif20] quit

    # Configure SwitchC.

    <HUAWEI> system-view
[HUAWEI] sysname SwitchC
[SwitchC] vlan batch 20 30
[SwitchC] interface gigabitethernet 0/0/1
[SwitchC-GigabitEthernet0/0/1] port link-type trunk
[SwitchC-GigabitEthernet0/0/1] port trunk allow-pass vlan 20
[SwitchC-GigabitEthernet0/0/1] quit
[SwitchC] interface gigabitethernet 0/0/2
[SwitchC-GigabitEthernet0/0/2] port link-type access
[SwitchC-GigabitEthernet0/0/2] port default vlan 30 
[SwitchC-GigabitEthernet0/0/2] quit
[SwitchC] interface vlanif 20
[SwitchC-Vlanif20] ip address 30.1.1.2 24
[SwitchC-Vlanif20] quit
[SwitchC] interface vlanif 30
[SwitchC-Vlanif30] ip address 10.2.1.2 24
[SwitchC-Vlanif30] quit

  2. Configure OSPF on the devices.

    # Configure SwitchA.

    [SwitchA] ospf 1
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 20.1.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
[SwitchA-ospf-1] quit

    # Configure SwitchB.

    [SwitchB] ospf 1
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 20.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] network 30.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] quit

    # Configure SwitchC.

    [SwitchC] ospf 1
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 30.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit

    # After the configuration is complete, run the display ip routing-table command on SwitchA and SwitchC. The command output shows that they have learned the OSPF route destined for the network segment of the peer.

  3. Configure a tunnel interface.

    # Configure SwitchA.

    [SwitchA] interface tunnel 1
[SwitchA-Tunnel1] tunnel-protocol gre
[SwitchA-Tunnel1] ip address 40.1.1.1 255.255.255.0
[SwitchA-Tunnel1] source 20.1.1.1
[SwitchA-Tunnel1] destination 30.1.1.2
[SwitchA-Tunnel1] quit

    # Configure SwitchC.

    [SwitchC] interface tunnel 1
[SwitchC-Tunnel1] tunnel-protocol gre
[SwitchC-Tunnel1] ip address 40.1.1.2 255.255.255.0
[SwitchC-Tunnel1] source 30.1.1.2
[SwitchC-Tunnel1] destination 20.1.1.1
[SwitchC-Tunnel1] quit

    # After the configuration is complete, the tunnel interfaces turn Up and can ping each other. This indicates that a direct tunnel has been set up.

    # The command output on SwitchA is used as an example.

    [SwitchA] ping -a 40.1.1.1 40.1.1.2
  PING 40.1.1.2: 56  data bytes, press CTRL_C to break
    Reply from 40.1.1.2: bytes=56 Sequence=1 ttl=255 time=1 ms
    Reply from 40.1.1.2: bytes=56 Sequence=2 ttl=255 time=1 ms
    Reply from 40.1.1.2: bytes=56 Sequence=3 ttl=255 time=1 ms
    Reply from 40.1.1.2: bytes=56 Sequence=4 ttl=255 time=1 ms
    Reply from 40.1.1.2: bytes=56 Sequence=5 ttl=255 time=1 ms

  --- 40.1.1.2 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 1/1/1 ms

  4. Configure a static route.

    # Configure SwitchA.

    [SwitchA] ip route-static 10.2.1.0 255.255.255.0 tunnel 1

    # Configure SwitchC.

    [SwitchC] ip route-static 10.1.1.0 255.255.255.0 tunnel 1

    # After the configuration is complete, run the display ip routing-table command on SwitchA and SwitchC. The command output shows the static route from the tunnel interface to the user-side network segment.

    # The command output on SwitchA is used as an example.

    [SwitchA] display ip routing-table 10.2.1.0
Route Flags: R - relay, D - download to fib, T - to vpn-instance
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1
Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

       10.2.1.0/24  Static  60   0           D   40.1.1.1        Tunnel1

    PC1 and PC2 can ping each other.

Configuration Files

  • SwitchA configuration file

    #
sysname SwitchA
#
vlan batch 10 30
#
interface Vlanif10
 ip address 20.1.1.1 255.255.255.0
#
interface Vlanif30
 ip address 10.1.1.2 255.255.255.0
#
interface GigabitEthernet0/0/1
 port link-type trunk
 port trunk allow-pass vlan 10
#
interface GigabitEthernet0/0/2
 port link-type access
 port default vlan 30
#
interface Tunnel1
 ip address 40.1.1.1 255.255.255.0
 tunnel-protocol gre
 source 20.1.1.1
 destination 30.1.1.2
#
ospf 1
 area 0.0.0.0
  network 20.1.1.0 0.0.0.255
#
ip route-static 10.2.1.0 255.255.255.0 Tunnel1
#
return

  • SwitchB configuration file

    #
sysname SwitchB
#
vlan batch 10 20
#
interface Vlanif10
 ip address 20.1.1.2 255.255.255.0
#
interface Vlanif20
 ip address 30.1.1.1 255.255.255.0
#
interface GigabitEthernet0/0/1
 port link-type trunk
 port trunk allow-pass vlan 10
#
interface GigabitEthernet0/0/2
 port link-type trunk
 port trunk allow-pass vlan 20
#
ospf 1
 area 0.0.0.0
  network 20.1.1.0 0.0.0.255
  network 30.1.1.0 0.0.0.255
#
return

  • SwitchC configuration file

    #
sysname SwitchC
#
vlan batch 20 30
#
interface Vlanif20
 ip address 30.1.1.2 255.255.255.0
#
interface Vlanif30
 ip address 10.2.1.2 255.255.255.0
#
interface GigabitEthernet0/0/1
 port link-type trunk
 port trunk allow-pass vlan 20
#
interface GigabitEthernet0/0/2
 port link-type access
 port default vlan 30
#
interface Tunnel1
 ip address 40.1.1.2 255.255.255.0
 tunnel-protocol gre
 source 30.1.1.2
 destination 20.1.1.1
#
ospf 1
 area 0.0.0.0
  network 30.1.1.0 0.0.0.255
#
ip route-static 10.1.1.0 255.255.255.0 Tunnel1
#
return
Parent Topic: Configuration Examples for GRE
Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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