Contents

Introduction· 1

Prerequisites· 1

Restrictions and guidelines· 1

Example: Configuring IP unnumbered· 1

Network configuration· 1

Applicable hardware and software versions· 2

Procedures· 3

Configuring Device A· 3

Configuring Device B· 4

Configuring Device C·· 4

Verifying the configuration· 5

Configuration files· 6

 

Introduction

This document provides IP unnumbered configuration examples.

This feature enables an interface to borrow an IP address from another interface on the device when the borrowing interface does not have any IP addresses. The borrowing interface is called IP unnumbered interface.

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 IP unnumbered.

Restrictions and guidelines

When you configure IP unnumbered, follow these restrictions and guidelines:

·     Loopback interfaces cannot borrow IP addresses of other interfaces.

·     An interface cannot borrow an IP address from an unnumbered interface.

·     If an interface has multiple manually configured IP addresses, only the manually configured primary IP address can be borrowed.

Example: Configuring IP unnumbered

Network configuration

As shown in Figure 1, Group A and Group B are two private IPv4 networks. Device A and Device C will establish a GRE tunnel to interconnect Group 1 and Group 2.

To save IP address space, configure tunnel interface Tunnel 1 to borrow an IP address from the loopback interface loopback 0.

Figure 1 Network diagram

 

Applicable hardware and software versions

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

 

Hardware	Software version
S6520XE-HI switch series	Supported in Release 11xx
S5560X-EI switch series	Supported in Release 111x
S5500V2-EI switch series	Supported in Release 111x
MS4520V2-30F switch	Supported in Release 111x
S5560S-EI switch series S5560S-SI switch series	Supported in Release 612x
S5130S-HI switch series S5130S-EI switch series S5130S-SI switch series S5130S-LI switch series	Not supported
S5120V2-SI switch series S5120V2-LI switch series	Not supported
S3100V3-EI switch series S3100V3-SI switch series	Not supported
S5110V2 switch series	Not supported
S5110V2-SI switch series	Not supported
S5000V3-EI switch series	Not supported
S5000E-X switch series	Not supported
WAS6000 switch series	Not supported
E128C switch E152C switch E500C switch series E500D switch series	Not supported
MS4520V2 switch series (except the MS4520V2-30F switch)	Supported in Release 612x
MS4320V2 switch series MS4300V2 switch series MS4320 switch series MS4200 switch series	Not supported
WS5850-WiNet switch series	Supported in Release 612x
WS5820-WiNet switch series WS5810-WiNet switch series	Not supported

 

Procedures

IMPORTANT: For the S6520XE-HI switch series, create a service loopback group and specify the unicast tunnel service for the group before you create a GRE tunnel.

 

Configuring Device A

1.     Assign IP addresses to the interfaces:

# Assign IP addresses to GigabitEthernet 1/0/1 and loopback 0.

<DeviceA> system-view

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] ip address 12.12.12.1 24

[DeviceA-GigabitEthernet1/0/1] quit

[DeviceA] interface loopback 0

[DeviceA-LoopBack0] ip address 8.8.8.8 32

[DeviceA-LoopBack0] quit

# Assign IP addresses to other interfaces in the same way an IP address is assigned to GigabitEthernet 1/0/1. (Details not shown.)

2.     Configure OSPF:

# Enable OSPF process 1.

[DeviceA] ospf 1

# Create Area 0 and specify GigabitEthernet 1/0/1 whose IP address is on network 12.12.12.0/24 to run OSPF in Area 0.

[DeviceA-ospf-1] area 0

[DeviceA-ospf-1-area-0.0.0.0] network 12.12.12.0 0.0.0.255

[DeviceA-ospf-1-area-0.0.0.0] quit

[DeviceA-ospf-1] quit

3.     Configure a GRE tunnel:

# Create service loopback group 1 and specify the unicast tunnel service for the group.

[DeviceA] service-loopback group 1 type tunnel

# Assign GigabitEthernet 1/0/3 to the service loopback group.

[DeviceA] interface gigabitethernet 1/0/3

[DeviceA-GigabitEthernet1/0/3] port service-loopback group 1

[DeviceA-GigabitEthernet1/0/3] quit

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

[DeviceA] interface tunnel 1 mode gre

# Specify 12.12.12.1 as the source address of interface Tunnel 1.

[DeviceA-Tunnel1] source 12.12.12.1

# Specify 23.23.23.3 as the destination address of interface Tunnel 1.

[DeviceA-Tunnel1] destination 23.23.23.3

# Configure interface Tunnel 1 to borrow an IP address from loopback 0.

[DeviceA-Tunnel1] ip address unnumbered interface loopback 0

[DeviceA-Tunnel1] quit

# Configure a static route from Device A through the tunnel interface to Group B.

[DeviceA] ip route-static 10.2.1.0 255.255.255.0 tunnel 1

Configuring Device B

1.     Assign IP addresses to the interfaces:

# Assign an IP address to GigabitEthernet 1/0/1.

<DeviceB> system-view

[DeviceB] interface gigabitethernet 1/0/1

[DeviceB-GigabitEthernet1/0/1] ip address 12.12.12.2 24

[DeviceB-GigabitEthernet1/0/1] quit

# Assign an IP address to GigabitEthernet 1/0/2 in the same way an IP address is assigned to GigabitEthernet 1/0/1. (Details not shown.)

2.     Configure OSPF:

# Enable OSPF process 1.

[DeviceB] ospf 1

# Create Area 0 and specify GigabitEthernet 1/0/1 whose IP address is on network 12.12.12.0/24 to run OSPF in Area 0.

[DeviceB-ospf-1] area 0

[DeviceB-ospf-1-area-0.0.0.0] network 12.12.12.0 0.0.0.255

# Create Area 0 and specify GigabitEthernet 1/0/2 whose IP address is on network 23.23.23.0/24 to run OSPF in Area 0.

[DeviceB-ospf-1-area-0.0.0.0] network 23.23.23.0 0.0.0.255

[DeviceB-ospf-1-area-0.0.0.0] quit

[DeviceB-ospf-1] quit

Configuring Device C

1.     Assign IP addresses to the interfaces:

# Assign IP addresses to GigabitEthernet 1/0/1 and loopback 0.

<DeviceC> system-view

[DeviceC] interface gigabitethernet 1/0/1

[DeviceC-GigabitEthernet1/0/1] ip address 23.23.23.3 24

[DeviceC-GigabitEthernet1/0/1] quit

[DeviceC] interface loopback 0

[DeviceC-LoopBack0] ip address 9.9.9.9 32

[DeviceC-LoopBack0] quit

# Assign IP addresses to other interfaces in the same way an IP address is assigned to GigabitEthernet 1/0/1. (Details not shown.)

2.     Configure OSPF:

# Enable OSPF process 1.

[DeviceC] ospf 1

# Create Area 0 and specify GigabitEthernet 1/0/1 whose IP address is on network 23.23.23.0/24 to run OSPF in Area 0.

[DeviceC-ospf-1] area 0

[DeviceC-ospf-1-area-0.0.0.0] network 23.23.23.0 0.0.0.255

[DeviceC-ospf-1-area-0.0.0.0] quit

[DeviceC-ospf-1] quit

3.     Configure a GRE tunnel:

# Create service loopback group 1 and specify the unicast tunnel service for the group.

[DeviceC] service-loopback group 1 type tunnel

# Assign GigabitEthernet 1/0/3 to the service loopback group.

[DeviceC] interface gigabitethernet 1/0/3

[DeviceC-GigabitEthernet1/0/3] port service-loopback group 1

[DeviceC-GigabitEthernet1/0/3] quit

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

[DeviceC] interface tunnel 1 mode gre

# Specify 23.23.23.3 as the source address of interface Tunnel 1.

[DeviceC-Tunnel1] source 23.23.23.3

# Specify 12.12.12.1 as the destination address of interface Tunnel 1.

[DeviceC-Tunnel1] destination 12.12.12.1

# Configure interface Tunnel 1 to borrow an IP address from loopback 0.

[DeviceC-Tunnel1] ip address unnumbered interface loopback 0

[DeviceC-Tunnel1] quit

# Configure a static route from Device C through the tunnel interface to Group A.

[DeviceC] ip route-static 10.1.1.0 255.255.255.0 tunnel 1

Verifying the configuration

This example uses Device A to verify the configuration.

# Verify that the interface Tunnel 1 has borrowed the IP address 8.8.8.8/32 from loopback 0.

[DeviceA] display interface tunnel 1

Tunnel1

Current state: UP

Line protocol state: UP

Description: Tunnel1 Interface

Bandwidth: 64kbps

Maximum transmission unit: 1476

Internet Address: 8.8.8.8/32 (Unnumbered)

Tunnel source 12.12.12.1, destination 23.23.23.3

Tunnel keepalive disabled

Tunnel TTL 255

Tunnel protocol/transport GRE/IP

    GRE key disabled

    Checksumming of GRE packets disabled

Last clearing of counters: Never

Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

Last 300 seconds output rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

Input: 11 packets, 924 bytes, 0 drops

Output: 10 packets, 840 bytes, 0 drops

# Verify that GigabitEthernet 1/0/2 on Device A can ping the IP address of GigabitEthernet 1/0/2 on Device C.

[DeviceA] ping -a 10.1.1.1 10.2.1.1

Ping 10.2.1.1 (10.2.1.1) from 10.1.1.1: 56 data bytes, press CTRL_C to break

56 bytes from 10.2.1.1: icmp_seq=0 ttl=255 time=32.641 ms

56 bytes from 10.2.1.1: icmp_seq=1 ttl=255 time=4.881 ms

56 bytes from 10.2.1.1: icmp_seq=2 ttl=255 time=4.816 ms

56 bytes from 10.2.1.1: icmp_seq=3 ttl=255 time=26.393 ms

56 bytes from 10.2.1.1: icmp_seq=4 ttl=255 time=43.003 ms

 

--- Ping statistics for 10.2.1.1 ---

5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss

round-trip min/avg/max/std-dev = 4.816/22.347/43.003/15.241 ms

Configuration files

IMPORTANT: The port link-mode bridge command is available only on the following switches: ·     S6520XE-HI switch series. ·     S5560X-EI switch series. ·     S5500V2-EI switch series. ·     MS4520V2-30F switch. For the S6520XE-HI switch series, a service loopback group of the unicast tunnel service type is required before you create a GRE tunnel.

 

·     Device A:

#

 service-loopback group 1 type tunnel

#

ospf 1

 area 0.0.0.0

  network 12.12.12.0 0.0.0.255

#

interface LoopBack0

 ip address 8.8.8.8 255.255.255.255

#

interface GigabitEthernet1/0/1

 port link-mode route

 ip address 12.12.12.1 255.255.255.0

#

interface GigabitEthernet1/0/2

 port link-mode route

 ip address 10.1.1.1 255.255.255.0

#

interface GigabitEthernet1/0/3

 port link-mode bridge

 port service-loopback group 1

#

interface Tunnel1 mode gre

 ip address unnumbered interface LoopBack0

 source 12.12.12.1

 destination 23.23.23.3

#

 ip route-static 10.2.1.0 24 Tunnel1

#

·     Device B:

#

ospf 1

 area 0.0.0.0

  network 12.12.12.0 0.0.0.255

  network 23.23.23.0 0.0.0.255

#

interface GigabitEthernet1/0/1

 port link-mode route

 ip address 12.12.12.2 255.255.255.0

#

interface GigabitEthernet1/0/2

 port link-mode route

 ip address 23.23.23.2 255.255.255.0

#

·     Device C:

#

 service-loopback group 1 type tunnel

#

ospf 1

 area 0.0.0.0

  network 23.23.23.0 0.0.0.255

#

interface LoopBack0

 ip address 9.9.9.9 255.255.255.255

#

interface GigabitEthernet1/0/1

 port link-mode route

 ip address 23.23.23.3 255.255.255.0

#

interface GigabitEthernet1/0/2

 port link-mode route

 ip address 10.2.1.1 255.255.255.0

#

interface GigabitEthernet1/0/3

 port link-mode bridge

 port service-loopback group 1

#

interface Tunnel1 mode gre

 ip address unnumbered interface LoopBack0

 source 23.23.23.3

 destination 12.12.12.1

#

 ip route-static 10.1.1.0 24 Tunnel1

#