CLI Example: Configuring DSVPN NAT traversal

Networking Requirements

An enterprise has a central office (Hub) and multiple branches which are located in different areas (this example shows only two Spokes Spoke1 and Spoke2). The subnets of the branches frequently change. The Spokes use addresses translated by NAT devices to connect to the public network. Open Shortest Path First (OSPF) is used on the enterprise network.

The enterprise wants to establish a VPN between the Spokes.

Figure 1 Networking diagram for DSVPN NAT traversal configuration

Configuration Roadmap

The configuration roadmap is as follows:

Because a Spoke uses a translated address to connect to the public network, it does not know the translated public address of the other Spoke. DSVPN NAT traversal is implemented to establish a VPN between the Spokes.
Shortcut Scenario of DSVPN is implemented because the enterprise has a large number of branches.
The networks of the central office and branches frequently change. OSPF is deployed to realize communication between the Hub and Spokes and to simplify maintenance.

Procedure

Assign an IP address to each interface.

Configure IP addresses for the interfaces of each FW.

# Configure IP addresses for interfaces of Hub.

<sysname> system-view
[sysname] sysname Hub
[Hub] interface GigabitEthernet 0/0/0
[Hub-GigabitEthernet0/0/0] ip address 1.1.1.10 255.255.255.0
[Hub-GigabitEthernet0/0/0] quit
[Hub] interface tunnel 0
[Hub-Tunnel0] ip address 172.16.1.1 255.255.255.0
[Hub-Tunnel0] quit
[Hub] interface loopback 0
[Hub-LoopBack0] ip address 192.168.0.1 255.255.255.0
[Hub-LoopBack0] quit

Configure IP addresses for interfaces of the Spoke1 and Spoke2 as shown in Figure 1. The specific configuration is not mentioned here.

Configure security zones and security policies.

# Configure security zones on each device. The configuration commands are the same, and the Hub is used as an example.

[Hub] firewall zone untrust
[Hub-zone-untrust] add interface GigabitEthernet 0/0/0
[Hub-zone-untrust] add interface tunnel 0
[Hub-zone-untrust] quit

# Configure security policies on each device. The configuration commands are the same, and the Hub is used as an example.

In this example, loopback interfaces in the Local zone are used to simulate subnet users. Therefore, the interzone policy between the Local zone and security zone where the tunnel interface resides needs to be configured (in this example, policy rule1 is configured). Actually, the interzone policy between the security zones where subnets reside needs to be configured. For example, if the subnet of the enterprise resides in the Trust zone, configure the interzone policy between the Trust zone and security zone where the tunnel interface resides.

[Hub] security-policy
[Hub-policy-security] rule name rule1
[Hub-policy-security-rule-rule1] source-zone untrust local
[Hub-policy-security-rule-rule1] destination-zone untrust local
[Hub-policy-security-rule-rule1] sourse-address 192.168.0.0 mask 255.255.0.0
[Hub-policy-security-rule-rule1] action permit
[Hub-policy-security-rule-rule1] quit
[Hub-policy-security] rule name rule2
[Hub-policy-security-rule-rule2] source-zone untrust local
[Hub-policy-security-rule-rule2] destination-zone untrust local
[Hub-policy-security-rule-rule2] service gre ospf
[Hub-policy-security-rule-rule2] action permit
[Hub-policy-security-rule-rule2] quit
[Hub-policy-security] quit

Configure routes between the FWs.

Configure OSPF on each FW to provide reachable routes to the public network.

# Configure OSPF on Hub.

[Hub] ospf 2 router-id 1.1.1.10
[Hub-ospf-2] area 0.0.0.1
[Hub-ospf-2-area-0.0.0.1] network 1.1.1.0 0.0.0.255
[Hub-ospf-2-area-0.0.0.1] quit
[Hub-ospf-2] quit

# Configure OSPF on NAT1.

[NAT1] ospf 2 router-id 1.1.2.1
[NAT1] import-route unr
[NAT1-ospf-2] area 0.0.0.1
[NAT1-ospf-2-area-0.0.0.1] network 1.1.2.0 0.0.0.255
[NAT1-ospf-2-area-0.0.0.1] network 10.1.1.0 0.0.0.255
[NAT1-ospf-2-area-0.0.0.1] quit
[NAT1-ospf-2] quit

# Configure OSPF on NAT2.

[NAT2] ospf 2 router-id 1.1.3.1
[NAT2] import-route unr
[NAT2-ospf-2] area 0.0.0.1
[NAT2-ospf-2-area-0.0.0.1] network 1.1.3.0 0.0.0.255
[NAT2-ospf-2-area-0.0.0.1] network 10.2.2.0 0.0.0.255
[NAT2-ospf-2-area-0.0.0.1] quit
[NAT2-ospf-2] quit

# Configure OSPF on Spoke1.

[Spoke1] ospf 2 router-id 10.1.1.1
[Spoke1-ospf-2] area 0.0.0.1
[Spoke1-ospf-2-area-0.0.0.1] network 10.1.1.0 0.0.0.255
[Spoke1-ospf-2-area-0.0.0.1] quit
[Spoke1-ospf-2] quit

# Configure OSPF on Spoke2.

[Spoke2] ospf 2 router-id 10.2.2.2
[Spoke2-ospf-2] area 0.0.0.1
[Spoke2-ospf-2-area-0.0.0.1] network 10.2.2.0 0.0.0.255
[Spoke2-ospf-2-area-0.0.0.1] quit
[Spoke2-ospf-2] quit

Configure NAT.
Configure addresses before and after NAT traversal.

# Configure NAT1.
```
[NAT1] nat server server1 global 1.1.2.10 inside 10.1.1.1
```
# Configure NAT2.
```
[NAT2] nat server server1 global 1.1.3.10 inside 10.2.2.2
```
The NAT devices must be configured with an NAT server. NAT traversal cannot be implemented if source NAT PAT is configured on the NAT devices.

Configure the basic OSPF functions.

# Configure Hub.

[Hub] ospf 1 router-id 172.16.1.1
[Hub-ospf-1] area 0.0.0.0
[Hub-ospf-1-area-0.0.0.0] network 172.16.1.0 0.0.0.255
[Hub-ospf-1-area-0.0.0.0] network 192.168.0.0 0.0.0.255
[Hub-ospf-1-area-0.0.0.0] quit
[Hub-ospf-1] quit

# Configure Spoke1.

[Spoke1] ospf 1 router-id 172.16.1.2
[Spoke1-ospf-1] area 0.0.0.0
[Spoke1-ospf-1-area-0.0.0.0] network 172.16.1.0 0.0.0.255
[Spoke1-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[Spoke1-ospf-1-area-0.0.0.0] quit
[Spoke1-ospf-1] quit

# Configure Spoke2.

[Spoke2] ospf 1 router-id 172.16.1.3
[Spoke2-ospf-1] area 0.0.0.0
[Spoke2-ospf-1-area-0.0.0.0] network 172.16.1.0 0.0.0.255
[Spoke2-ospf-1-area-0.0.0.0] network 192.168.2.0 0.0.0.255
[Spoke2-ospf-1-area-0.0.0.0] quit
[Spoke2-ospf-1] quit

Configure tunnel interfaces.

Configure the OSPF network type to Point-to-Multipoint (P2MP) on Hub and Spokes. Enable the NHRP redirect function on Hub. Configure NHRP mapping entries of Hub and enable the NHRP shortcut function on Spoke1 and Spoke2.

# On Hub, configure a tunnel interface, configure OSPF, and enable the NHRP redirect function.

[Hub] interface tunnel 0
[Hub-Tunnel0] tunnel-protocol gre p2mp
[Hub-Tunnel0] source GigabitEthernet 0/0/0
[Hub-Tunnel0] nhrp entry multicast dynamic
[Hub-Tunnel0] ospf network-type p2mp
[Hub-Tunnel0] nhrp redirect
[Hub-Tunnel0] quit

# On Spoke1, configure a tunnel interface, OSPF, and a static NHRP mapping entry of Hub, and enable the NHRP shortcut function.

[Spoke1] interface tunnel 0
[Spoke1-Tunnel0] tunnel-protocol gre p2mp
[Spoke1-Tunnel0] source GigabitEthernet 0/0/0
[Spoke1-Tunnel0] nhrp entry 172.16.1.1 1.1.1.10 register
[Spoke1-Tunnel0] ospf network-type p2mp
[Spoke1-Tunnel0] nhrp shortcut
[Spoke1-Tunnel0] quit

# On Spoke2, configure a tunnel interface, OSPF, and a static NHRP mapping entry of Hub, and enable the NHRP shortcut function.

[Spoke2] interface tunnel 0
[Spoke2-Tunnel0] tunnel-protocol gre p2mp
[Spoke2-Tunnel0] source GigabitEthernet 0/0/0
[Spoke2-Tunnel0] nhrp entry 172.16.1.1 1.1.1.10 register
[Spoke2-Tunnel0] ospf network-type p2mp
[Spoke2-Tunnel0] nhrp shortcut
[Spoke2-Tunnel0] quit

Verify the configuration.

After the preceding configurations are complete, check the NHRP mapping entries of Spoke1 and Spoke2.

# Run the display nhrp peer all command on Spoke1. The command output is as follows:

[Spoke1] display nhrp peer all
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.1      32    1.1.1.10        172.16.1.1       hub          up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:10:58
Expire time     : -- HostName        : Hub HostEsn         : 210235G7G610F1000002

Number of nhrp peers: 1

# Run the display nhrp peer all command on Spoke2. The command output is as follows:

[Spoke2] display nhrp peer all
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.1      32    1.1.1.10        172.16.1.1       hub          up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:07:55
Expire time     : -- HostName        : Hub HostEsn         : 210235G7G610F1000002

Number of nhrp peers: 1

If you run the display nhrp peer all command on Spoke1 and Spoke2, you can view only the static NHRP mapping entry of Hub.

On Hub, check the NHRP mapping entries of Spoke1 and Spoke2.

# Run the display nhrp peer all command on Hub. The command output is as follows:

[Hub] display nhrp peer all
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.2      32    1.1.2.10        172.16.1.2      registered   up|unique
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:02:02
Expire time     : 01:57:58 HostName        : Spoke1 HostEsn         : 210235G7G610F1000013
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.3      32    1.1.3.10        172.16.1.3      registered   up|unique
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:01:53
Expire time     : 01:59:35 HostName        : Spoke2 HostEsn         : 210235G7G610F3000017

Number of nhrp peers: 2

Run the ping command to check the configuration result.

To use the ping command for link detection, run the service-manage ping permit command in the interface view to set the ping service of all firewall interfaces on the link to permit.

Ping 192.168.2.1 on Spoke1. You can see that Spoke1 and Spoke2 have learned dynamic NHRP mapping entries from each other.

# Run the ping -a 192.168.1.1 192.168.2.1 command on Spoke1. The command output is as follows:

[Spoke1] ping -a 192.168.1.1 192.168.2.1
  PING 192.168.2.1: 56  data bytes, press CTRL_C to break
    Reply from 192.168.2.1: bytes=56 Sequence=1 ttl=254 time=2 ms
    Reply from 192.168.2.1: bytes=56 Sequence=2 ttl=255 time=2 ms
    Reply from 192.168.2.1: bytes=56 Sequence=3 ttl=255 time=1 ms
    Reply from 192.168.2.1: bytes=56 Sequence=4 ttl=255 time=2 ms
    Reply from 192.168.2.1: bytes=56 Sequence=5 ttl=255 time=1 ms

  --- 192.168.2.1 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 1/1/2 ms

# Run the display nhrp peer all command on Spoke1. The command output is as follows:

[Spoke1] display nhrp peer all
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.1      32    1.1.1.10        172.16.1.1      hub           up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:39:32
Expire time     : -- HostName        : Hub HostEsn         : 210235G7G610F1000002
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type           Flag
-------------------------------------------------------------------------------
192.168.2.1     32    1.1.3.10        172.16.1.3      remote-network up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Before NAT NBMA-addr: 10.2.2.2
Created time    : 00:00:13
Expire time     : 01:59:47 HostName        : -- HostEsn         : --
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.3      32    1.1.3.10        172.16.1.3      remote       up

-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Before NAT NBMA-addr: 10.2.2.2
Created time    : 00:00:13
Expire time     : 01:59:47 HostName        : -- HostEsn         : --
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
192.168.1.1     32    10.1.1.1        172.16.1.2      local        up

-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:00:13
Expire time     : 01:59:47 HostName        : -- HostEsn         : --

Number of nhrp peers: 4

# Run the display nhrp peer all command on Spoke2. The command output is as follows:

[Spoke2] display nhrp peer all
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.1      32    1.1.1.10        172.16.1.1      hub           up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:41:08
Expire time     : -- HostName        : Hub HostEsn         : 210235G7G610F1000002
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type           Flag
-------------------------------------------------------------------------------
192.168.1.1     32    1.1.2.10        172.16.1.2      remote-network up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Before NAT NBMA-addr: 10.1.1.1
Created time    : 00:00:52
Expire time     : 01:59:08 HostName        : -- HostEsn         : --
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
172.16.1.2      32    1.1.2.10        172.16.1.2      remote       up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Before NAT NBMA-addr: 10.1.1.1
Created time    : 00:00:52
Expire time     : 01:59:08 HostName        : -- HostEsn         : --
-------------------------------------------------------------------------------
Protocol-addr   Mask  NBMA-addr       NextHop-addr    Type         Flag
-------------------------------------------------------------------------------
192.168.2.1     32    10.2.2.2        172.16.1.3      local        up
-------------------------------------------------------------------------------
Tunnel interface: Tunnel0
Created time    : 00:00:52
Expire time     : 01:59:08 HostName        : -- HostEsn         : --

Number of nhrp peers: 4

Configuration Files

Hub configuration file

#
 sysname Hub
# 
 interface GigabitEthernet0/0/0
 ip address 1.1.1.10 255.255.255.0
# 
 interface LoopBack0
 ip address 192.168.0.1 255.255.255.0
# 
 interface Tunnel0
 ip address 172.16.1.1 255.255.255.0
 tunnel-protocol gre p2mp
 source GigabitEthernet0/0/0
 ospf network-type p2mp
 nhrp redirect
 nhrp entry multicast dynamic
# 
 ospf 1 router-id 172.16.1.1
 area 0.0.0.0
 network 172.16.1.0 0.0.0.255
 network 192.168.0.0 0.0.0.255
# 
 ospf 2 router-id 1.1.1.10
 area 0.0.0.1
 network 1.1.1.0 0.0.0.255
# 
firewall zone untrust
 add interface GigabitEthernet0/0/0   
 add interface Tunnel0 
# 
 security-policy 
  rule name rule1
   source-zone local
   source-zone untrust
   destination-zone local
   destination-zone untrust
   source-address 192.168.0.0 mask 255.255.0.0
   action permit
  rule name rule2
   source-zone local
   source-zone untrust
   destination-zone local
   destination-zone untrust
   service gre
   service ospf
   action permit
# 
return

Spoke1 configuration file

#
 sysname Spoke1
# 
 interface GigabitEthernet0/0/0
 ip address 10.1.1.1 255.255.255.0
# 
 interface LoopBack0
 ip address 192.168.1.1 255.255.255.0
# 
 interface Tunnel0
 ip address 172.16.1.2 255.255.255.0
 tunnel-protocol gre p2mp
 source GigabitEthernet0/0/0
 ospf network-type p2mp
 nhrp shortcut
 nhrp entry 172.16.1.1 1.1.1.10 register
# 
 ospf 1 router-id 172.16.1.2
 area 0.0.0.0
 network 192.168.1.0 0.0.0.255
 network 172.16.1.0 0.0.0.255
# 
 ospf 2 router-id 10.1.1.1
 area 0.0.0.1
 network 10.1.1.0 0.0.0.25
# 
firewall zone untrust
 add interface GigabitEthernet0/0/0   
 add interface Tunnel0 
# 
 security-policy 
  rule name rule1
   source-zone local
   source-zone untrust
   destination-zone local
   destination-zone untrust
   source-address 192.168.0.0 mask 255.255.0.0
   action permit
  rule name rule2
   source-zone local
   source-zone untrust
   destination-zone local
   destination-zone untrust
   service gre
   service ospf
   action permit
# 
return

Spoke2 configuration file

#
sysname Spoke2
#
interface GigabitEthernet0/0/0
 ip address 10.2.2.2 255.255.255.0
#
interface LoopBack0
 ip address 192.168.2.1 255.255.255.0
#
interface Tunnel0
 ip address 172.16.1.3 255.255.255.0
 tunnel-protocol gre p2mp
 source GigabitEthernet0/0/0
 ospf network-type p2mp
 nhrp shortcut
 nhrp entry 172.16.1.1 1.1.1.10 register
#
ospf 1 router-id 172.16.1.3
 area 0.0.0.0
  network 192.168.2.0 0.0.0.255
  network 172.16.1.0 0.0.0.255
#
ospf 2 router-id 10.2.2.2
 area 0.0.0.1
  network 10.2.2.0 0.0.0.255
# 
firewall zone untrust
 add interface GigabitEthernet0/0/0   
 add interface Tunnel0 
# 
 security-policy 
  rule name rule1
   source-zone local
   source-zone untrust
   destination-zone local
   destination-zone untrust
   source-address 192.168.0.0 mask 255.255.0.0
   action permit
  rule name rule2
   source-zone local
   source-zone untrust
   destination-zone local
   destination-zone untrust
   service gre
   service ospf
   action permit
# 
return

NAT1 configuration file

#
sysname NAT1
# 
interface GigabitEthernet0/0/0
 ip address 1.1.2.1 255.255.255.0
# 
interface GigabitEthernet0/0/10
 ip address 10.1.1.254 255.255.255.0
# 
ospf 2 router-id 1.1.2.1
 import-route unr
 area 0.0.0.1
  network 10.1.1.0 0.0.0.255
  network 1.1.2.0 0.0.0.255 
# 
 nat server server1 0 global 1.1.2.10 inside 10.1.1.1
# 
 
firewall zone untrust 
 set priority 5
 add interface GigabitEthernet0/0/0  
# 
firewall zone trust 
 set priority 85 
 add interface GigabitEthernet0/0/10 
# security-policy
 rule name rule1
 source-zone trust
 source-zone untrust
 destination-zone trust
 destination-zone untrust
 action permit
# 
return

NAT2 configuration file

#
sysname NAT2
# 
interface GigabitEthernet0/0/0
 ip address 1.1.3.1 255.255.255.0
# 
interface GigabitEthernet0/0/10
 ip address 10.2.2.254 255.255.255.0
# 
ospf 2 router-id 1.1.3.1
 import-route unr
 area 0.0.0.1
  network 10.2.2.0 0.0.0.255
  network 1.1.3.0 0.0.0.255 
#  
nat server server1 0 global 1.1.3.10 inside 10.2.2.2
 action permit

# 
return