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---
lastproofread: '2026-02-05'
---
(l2tpv3-interface)=
# L2TPv3
{abbr}`L2TPv3 (Layer 2 Tunneling Protocol version 3)` interfaces let you
establish L2TPv3 tunnels to transport Layer 2 traffic over IP networks.
The L2TPv3 protocol (defined in RFC 3931) wraps Layer 2 frames (e.g., Ethernet,
Frame Relay, HDLC) within IP packets, allowing them to traverse the underlying
IP infrastructure.
Unlike L2TPv2, which strictly requires UDP encapsulation, the L2TPv3 protocol
is more flexible and supports two encapsulation types:
> - **Direct IP:** Tunnel data is encapsulated directly inside IP packets
> (Protocol 115) for lower overhead.
> - **UDP:** Tunnel data is encapsulated inside a UDP datagram. This allows the
> tunnel to traverse NAT more easily.
L2TPv3 tunnels connect geographically separated sites, serving as a simpler
alternative to {ref}`mpls` by operating over basic IP connectivity rather than
requiring a full MPLS infrastructure.
L2TPv3 tunnels can be established over both IPv4 and IPv6 underlying networks.
## Configuration
### Common interface configuration
```{cmdincludemd} /_include/interface-common-without-dhcp.txt
:var0: l2tpv3
:var1: l2tpeth0
```
### L2TPv3 options
Use the following commands to configure the L2TPv3 tunnel's specific parameters.
```{cfgcmd} set interfaces l2tpv3 \<interface\> encapsulation \<udp | ip\>
**Configure the encapsulation type for the L2TPv3 tunnel.**
Valid values are ``udp`` and ``ip``.
The default encapsulation type is ``udp``.
```
:::{note}
The encapsulation type must match on both the local and remote peers
for the tunnel to establish.
:::
```{cfgcmd} set interfaces l2tpv3 \<interface\> source-address \<address\>
**Configure the L2TPv3 tunnel source IP address.**
The specified address must be a local interface IP address and can be either
IPv4 or IPv6.
```
```{cfgcmd} set interfaces l2tpv3 \<interface\> remote \<address\>
**Configure the L2TPv3 tunnel destination IP address.**
The specified address must be a remote peer’s interface IP address and can be
either IPv4 or IPv6.
```
```{cfgcmd} set interfaces l2tpv3 \<interface\> session-id \<id\>
**Configure the local session ID within the L2TPv3 tunnel.**
The ``session-id`` is a 32-bit value that identifies an incoming tunnel session
on the local peer.
The ``peer-session-id`` that identifies this session on the remote peer must be
set to the same value.
```
```{cfgcmd} set interfaces l2tpv3 \<interface\> peer-session-id \<id\>
**Configure the peer session ID within the L2TPv3 tunnel.**
The ``peer-session-id`` is a 32-bit value that identifies an outgoing tunnel
session from the local peer.
The ``peer-session-id`` must match the ``session-id`` configured for this
session on the remote peer.
```
```{cfgcmd} set interfaces l2tpv3 \<interface\> tunnel-id \<id\>
**Configure the local identifier for the L2TPv3 tunnel.**
The ``tunnel-id`` is a 32-bit value that identifies the L2TPv3 tunnel on the
local peer.
The ``peer-tunnel-id`` that identifies this tunnel on the remote peer must be
set to the same value.
```
```{cfgcmd} set interfaces l2tpv3 \<interface\> peer-tunnel-id \<id\>
**Configure the peer identifier for the L2TPv3 tunnel.**
The ``peer-tunnel-id`` is a 32-bit value that identifies the L2TPv3 tunnel on
the remote peer and must correspond to the ``tunnel-id`` configured for that
tunnel on that peer.
The ``peer-tunnel-id`` must match the ``tunnel-id`` that identifies this tunnel
on the remote peer.
```
## Example
### L2TPv3 tunnel with IP encapsulation
The following example shows the configuration of an L2TPv3 tunnel using direct
IP encapsulation:
```none
# show interfaces l2tpv3
l2tpv3 l2tpeth10 {
address 192.168.37.1/27
encapsulation ip
source-address 192.0.2.1
peer-session-id 100
peer-tunnel-id 200
remote 203.0.113.24
session-id 100
tunnel-id 200
}
```
The inverse configuration must be applied to the remote peer.
### L2TPv3 tunnel with UDP encapsulation
The following example shows the configuration of an L2TPv3 tunnel using UDP
encapsulation.
This setup is recommended when the tunnel traverses NAT devices.
Configuration notes:
- Use a local LAN IP address as the `source-address`.
- Configure a forwarding rule to allow tunnel traffic on the specified UDP port
on the upstream NAT device.
- Use a distinct UDP port for each individual tunnel.
```none
# show interfaces l2tpv3
l2tpv3 l2tpeth10 {
address 192.168.37.1/27
destination-port 9001
encapsulation udp
source-address 192.0.2.1
peer-session-id 100
peer-tunnel-id 200
remote 203.0.113.24
session-id 100
source-port 9000
tunnel-id 200
}
```
|
