Contents

Introduction· 1

Prerequisites· 1

Example: Configuring GRE with OSPF· 1

Network configuration· 1

Applicable hardware and software versions· 2

Restrictions and guidelines· 2

Procedures· 2

Configuring Device A· 2

Configuring Device B· 3

Configuring Device C· 4

Verifying the configuration· 5

Configuration files· 6

 

Introduction

This document provides GRE with OSPF configuration examples.

Prerequisites

The configuration examples in this document were created and verified in a lab environment, and all the devices were started with the factory default configuration. When you are working on a live network, make sure you understand the potential impact of every command on your network.

This document assumes that you have basic knowledge of GRE and OSPF.

Example: Configuring GRE with OSPF

Network configuration

As shown in Figure 1, Device A is the gateway of the headquarters. Device B and Device C are the gateways of Branch 1 and Branch 2, respectively. The gateways have obtained public IP addresses from an ISP and can communicate with one another. Configure GRE with OSPF to meet the following requirements:

·     The headquarters and the branches communicate with one another through the GRE tunnels established between the headquarters and the branches.

·     The gateways learn the routes reaching the destination networks through the tunnel interfaces.

Figure 1 Network diagram

 

 

Table 1 Interface and IP address assignment

Device	Interface	IP address	Device	Interface	IP address
Device A	Vlan-int10	191.2.1.1/24	Device B	Vlan-int10	191.3.1.1/24
	Vlan-int20	10.1.1.1/24		Vlan-int20	10.7.1.1/24
	Tunnel1	10.5.1.1/24		Tunnel1	10.5.1.2/24
	Tunnel2	10.6.1.1/24
Device C	Vlan-int10	191.4.1.1/24
	Vlan-int20	10.8.1.1/24
	Tunnel2	10.6.1.2/24

 

Applicable hardware and software versions

The following matrix shows the hardware and software versions to which this configuration example is applicable:

 

Hardware	Software version
S6550X-HI switch series	Release 1116 and later
S6880 switch series	Release 1116 and later
S9820-8M switch	Release 1116 and later
S9855 switch series	Not supported
S9825 switch series	Not supported

 

Restrictions and guidelines

Encapsulated packets cannot be forwarded on Layer 3 according to the destination IP addresses and routing tables. You must create a service loopback group of the tunnel service type to loop encapsulated packets back to the forwarding module for Layer 3 forwarding.

Procedures

Before configuring GRE and OSPF, configure an IPv4 routing protocol on the gateways so that they can reach one another. (Details not shown.)

Configuring Device A

# Configure VLAN-interface 10.

<DeviceA> system-view

[DeviceA] vlan 10

[DeviceA-vlan10] port Twenty-FiveGigE 1/0/1

[DeviceA-vlan10] quit

[DeviceA] interface vlan-interface 10

[DeviceA-vlan-interface10] ip address 191.2.1.1 255.255.255.0

[DeviceA-vlan-interface10] quit

# Configure other interfaces in the same way VLAN-interface 10 is configured. (Details not shown.)

# Create service loopback group 1, and specify its service type as Tunnel.

[DeviceA] service-loopback group 1 type tunnel

# Add Twenty-FiveGigE 1/0/3 to service loopback group 1.

[DeviceA] interface Twenty-FiveGigE 1/0/3

[DeviceA-Twenty-FiveGigE1/0/3] port service-loopback group 1

[DeviceA-Twenty-FiveGigE1/0/3] quit

# Create a tunnel interface Tunnel 1, and specify the tunnel mode as GRE/IPv4.

[DeviceA] interface tunnel 1 mode gre

# Configure an IP address for the tunnel interface Tunnel 1.

[DeviceA-Tunnel1] ip address 10.5.1.1 24

# Configure the source interface of the tunnel interface Tunnel 1 as VLAN-interface 10.

[DeviceA-Tunnel1] source vlan-interface 10

# Configure the destination address of the tunnel interface Tunnel 1 as the IP address of VLAN-interface 10 on Device B.

[DeviceA-Tunnel1] destination 191.3.1.1

[DeviceA-Tunnel1] quit

# Create a tunnel interface Tunnel 2, and specify the tunnel mode as GRE/IPv4.

[DeviceA] interface tunnel 2 mode gre

# Configure an IP address for the tunnel interface Tunnel 2.

[DeviceA-Tunnel2] ip address 10.6.1.1 24

# Configure the source interface of the tunnel interface Tunnel 2 as VLAN-interface 10.

[DeviceA-Tunnel2] source vlan-interface 10

# Configure the destination address of the tunnel interface Tunnel 2 as the IP address of VLAN-interface 10 on Device C.

[DeviceA-Tunnel2] destination 191.4.1.1

[DeviceA-Tunnel2] quit

# Configure the OSPF router ID as 10.6.1.1.

[DeviceA] router id  10.6.1.1

# Enable OSPF process 1.

[DeviceA] ospf 1

# Create OSPF area 0.

[DeviceA-ospf-1] area 0

# Enable OSPF on interfaces whose primary IP addresses are on network 10.1.1.0/24, 10.5.1.0/24, or 10.6.1.0/24 in area 0.

[DeviceA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255

[DeviceA-ospf-1-area-0.0.0.0] network 10.5.1.0 0.0.0.255

[DeviceA-ospf-1-area-0.0.0.0] network 10.6.1.0 0.0.0.255

Configuring Device B

# Configure VLAN-interface 10.

<DeviceB> system-view

[DeviceB] vlan 10

[DeviceB-vlan10] port Twenty-FiveGigE 1/0/1

[DeviceB-vlan10] quit

[DeviceB] interface vlan-interface 10

[DeviceB-vlan-interface10] ip address 191.3.1.1 255.255.255.0

[DeviceB-vlan-interface10] quit

# Configure other interfaces in the same way VLAN-interface 10 is configured. (Details not shown.)

# Create service loopback group 1, and specify its service type as Tunnel.

[DeviceB] service-loopback group 1 type tunnel

# Add Twenty-FiveGigE 1/0/3 to service loopback group 1.

[DeviceB] interface Twenty-FiveGigE 1/0/3

[DeviceB-Twenty-FiveGigE1/0/3] port service-loopback group 1

[DeviceB-Twenty-FiveGigE1/0/3] quit

# Create a tunnel interface Tunnel 1, and specify the tunnel mode as GRE/IPv4.

[DeviceB] interface tunnel 1 mode gre

# Configure an IP address for the tunnel interface Tunnel 1.

[DeviceB-Tunnel1] ip address 10.5.1.2 24

# Configure the source interface of the tunnel interface Tunnel 1 as VLAN-interface 10.

[DeviceB-Tunnel1] source Vlan-interface 10

# Configure the destination address of the tunnel interface Tunnel 1 as the IP address of VLAN-interface 10 on Device A.

[DeviceB-Tunnel1] destination 191.2.1.1

[DeviceB-Tunnel1] quit

# Configure the OSPF router ID as 10.7.1.1.

[DeviceB] router id 10.7.1.1

# Enable OSPF process 1.

[DeviceB] ospf 1

# Create OSPF area 0.

[DeviceB-ospf-1] area 0

# Enable OSPF on interfaces whose primary IP addresses are on network 10.7.1.0/24 or 10.5.1.0/24 in area 0.

[DeviceB-ospf-1-area-0.0.0.0] network 10.7.1.0 0.0.0.255

[DeviceB-ospf-1-area-0.0.0.0] network 10.5.1.0 0.0.0.255

Configuring Device C

# Configure VLAN-interface 10.

<DeviceC> system-view

[DeviceC] vlan 10

[DeviceC-vlan10] port Twenty-FiveGigE 1/0/1

[DeviceC-vlan10] quit

[DeviceC] interface Vlan-interface 10

[DeviceC-Vlan-interface10] ip address 191.4.1.1 255.255.255.0

[DeviceC-Vlan-interface10] quit

# Configure other interfaces in the same way VLAN-interface 10 is configured. (Details not shown.)

# Create service loopback group 1, and specify its service type as Tunnel.

[DeviceC] service-loopback group 1 type tunnel

# Add Twenty-FiveGigE 1/0/3 to service loopback group 1.

[DeviceC] interface Twenty-FiveGigE 1/0/3

[DeviceC-Twenty-FiveGigE1/0/3] port service-loopback group 1

[DeviceC-Twenty-FiveGigE1/0/3] quit

# Create a tunnel interface Tunnel 2, and specify the tunnel mode as GRE/IPv4.

[DeviceC] interface tunnel 2 mode gre

# Configure an IP address for the tunnel interface Tunnel 2.

[DeviceC-Tunnel2] ip address 10.6.1.2 24

# Configure the source interface of the tunnel interface Tunnel 2 as VLAN-interface 10.

[DeviceC-Tunnel2] source Vlan-interface 10

# Configure the destination address of the tunnel interface Tunnel 2 as the IP address of VLAN-interface 10 on Device A.

[DeviceC-Tunnel2] destination 191.2.1.1

[DeviceC-Tunnel2] quit

# Configure the OSPF router ID as 10.8.1.1.

[DeviceC] router id 10.8.1.1

# Enable OSPF process 1.

[DeviceC] ospf 1

# Create OSPF area 0.

[DeviceC-ospf-1] area 0

# Enable OSPF on interfaces whose primary IP addresses are on network 10.8.1.0/24 or 10.6.1.0/24 in area 0.

[DeviceC-ospf-1-area-0.0.0.0] network 10.8.1.0 0.0.0.255

[DeviceC-ospf-1-area-0.0.0.0] network 10.6.1.0 0.0.0.255

Verifying the configuration

# Verify that Host A can ping Host B successfully.

C:\> ping 10.7.1.2

 

Pinging 10.7.1.2 with 32 bytes of data:

 

Reply from 10.7.1.2: bytes=32 time=19ms TTL=253

Reply from 10.7.1.2: bytes=32 time<1ms TTL=253

Reply from 10.7.1.2: bytes=32 time<1ms TTL=253

Reply from 10.7.1.2: bytes=32 time<1ms TTL=253

 

Ping statistics for 10.7.1.2:

    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 19ms, Average = 4ms

 

# Verify that Host A can ping Host C successfully.

C:\> ping 10.8.1.2

 

Pinging 10.8.1.2 with 32 bytes of data:

 

Reply from 10.8.1.2: bytes=32 time=18ms TTL=253

Reply from 10.8.1.2: bytes=32 time<1ms TTL=253

Reply from 10.8.1.2: bytes=32 time<1ms TTL=253

Reply from 10.8.1.2: bytes=32 time<1ms TTL=253

 

Ping statistics for 10.8.1.2:

    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 19ms, Average = 4ms

# Verify that Host B can ping Host C successfully.

C:\> ping 10.8.1.2

 

Pinging 10.8.1.2 with 32 bytes of data:

 

Reply from 10.8.1.2: bytes=32 time=20ms TTL=251

Reply from 10.8.1.2: bytes=32 time<1ms TTL=251

Reply from 10.8.1.2: bytes=32 time<1ms TTL=251

Reply from 10.8.1.2: bytes=32 time<1ms TTL=251

 

Ping statistics for 10.8.1.2:

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 19ms, Average = 4ms

Configuration files

·     Device A

#

 service-loopback group 1 type tunnel

#

vlan 10

#

vlan 20

#

interface Vlan-interface10

 ip address 191.2.1.1 255.255.255.0

#

interface Vlan-interface20

 ip address 10.1.1.1 255.255.255.0

#

interface Twenty-FiveGigE1/0/1

 port link-mode bridge

 port access vlan 10

#

interface Twenty-FiveGigE1/0/2

 port link-mode bridge

 port access vlan 20

#

interface Twenty-FiveGigE1/0/3

 port link-mode bridge

 port service-loopback group 1

#

interface Tunnel1 mode gre

 source vlan-interface10

 destination 191.3.1.1

 ip address 10.5.1.1 255.255.255.0

#

interface Tunnel2 mode gre

 source vlan-interface10

 destination 191.4.1.1

 ip address 10.6.1.1 255.255.255.0

#

router id 10.6.1.1

#

ospf 1

 area 0.0.0.0

  network 10.1.1.0 0.0.0.255

  network 10.5.1.0 0.0.0.255

  network 10.6.1.0 0.0.0.255

#

·     Device B

#

 service-loopback group 1 type tunnel

#

vlan 10

#

vlan 20

#

interface Vlan-interface10

 ip address 191.3.1.1 255.255.255.0

#

interface Vlan-interface20

 ip address 10.7.1.1 255.255.255.0

#

interface Twenty-FiveGigE1/0/1

 port link-mode bridge

 port access vlan 10

#

interface Twenty-FiveGigE1/0/2

 port link-mode bridge

 port access vlan 20

#

interface Twenty-FiveGigE1/0/3

 port link-mode bridge

 port service-loopback group 1

#

interface Tunnel1 mode gre

 source Vlan-interface10

 destination 191.2.1.1

 ip address 10.5.1.2 255.255.255.0

#

router id 10.7.1.1

#

ospf 1

 area 0.0.0.0

  network 10.7.1.0 0.0.0.255

  network 10.5.1.0 0.0.0.255

#

·     Device C

#

 service-loopback group 1 type tunnel

#

vlan 10

#

vlan 20

#

interface Vlan-interface10

 ip address 191.4.1.1 255.255.255.0

#

interface Vlan-interface20

 ip address 10.8.1.1 255.255.255.0

#

interface Twenty-FiveGigE1/0/1

 port link-mode bridge

 port access vlan 10

#

interface Twenty-FiveGigE1/0/2

 port link-mode bridge

 port access vlan 20

#

interface Twenty-FiveGigE1/0/3

 port link-mode bridge

 port service-loopback group 1

#

interface Tunnel2 mode gre

 source Vlan-interface10

 destination 191.2.1.1

 ip address 10.6.1.2 255.255.255.0

#

router id 10.8.1.1

#

ospf 1

 area 0.0.0.0

  network 10.8.1.0 0.0.0.255

  network 10.6.1.0 0.0.0.255

#