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Table Of Contents
L2TP Client-Initiated Tunneling
Prerequisites for L2TP Client-Initiated Tunneling
Restrictions for L2TP Client-Initiated Tunneling
Information About L2TP Client-Initiated Tunneling
Benefits of L2TP Client-Initiated Tunneling
How to Configure L2TP Client-Initiated Tunneling
Configuring L2TP Client-Initiated Tunneling on the Local Peer
Configuring L2TP Client-Initiated Tunneling on the Remote Peer
Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TP Tunnels
Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TPv3 Tunnels
Configuring L2TP Control Channel Parameters
Configuring L2TP Control Channel Timing Parameters
Configuring L2TP Control Channel Authentication Parameters
Configuring L2TP Control Channel Maintenance Parameters
Configuring the L2TPv3 Pseudowire
Configuration Examples for L2TP Client-Initiated Tunneling
Configuring L2TP Client-Initiated Tunneling on the Local Peer for L2TP Tunnels: Example
Configuring L2TP Client-Initiated Tunneling on the Local Peer for L2TPv3 Tunnels: Example
Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TP Tunnels: Example
Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TPv3 Tunnels: Example
L2TP Client-Initiated Tunneling
The L2TP Client-Initiated Tunneling feature introduces the ability to establish client-initiated Layer 2 Tunnel Protocol (L2TP) tunnels. The client may initiate an L2TP or L2TP Version 3 (L2TPv3) tunnel to the L2TP network server (LNS) without the intermediate network access server (NAS) participating in tunnel negotiation or establishment. The benefit of this feature is that client routers now have the ability to initiate L2TP or L2TPv3 tunnels.
Feature History for the L2TP Client-Initiated Tunneling
Feature
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Contents
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Prerequisites for L2TP Client-Initiated Tunneling
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Prerequisites for L2TP Client-Initiated Tunneling
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Restrictions for L2TP Client-Initiated Tunneling
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Information About L2TP Client-Initiated Tunneling
To configure the L2TP Client-Initiated Tunneling feature, you must understand the following concepts:
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L2TP Client-Initiated Tunnels
L2TP client-initiated tunneling allows the client router to initiate Layer 2 tunnels. The client establishes a tunnel to the customer network without an intermediate NAS participating in the tunnel negotiation and establishment. The customer manages the client software that initiates the tunnel.
In the client-initiated tunneling scenario depicted in Figure 1, the client connects to the L2TP access concentrator (LAC) through a media that supports PPP, such as a dialup modem, digital subscriber line (DSL), ISDN, or a cable modem. The client may initiate an L2TP or L2TPv3 tunnel to the LNS.
Figure 1
Client-Initiated L2TP Tunneling
The L2TP Client-Initiated Tunneling feature uses a virtual-PPP interface. The virtual-PPP interface adds Layer 2 encapsulation to Layer 3 packets, allowing them to be sent to the LNS over an L2TP or L2TPv3 tunnel.
L2 Tunnel Types
The L2TP Client-Initiated Tunneling feature can be configured to establish either an L2TP tunnel or an L2TPv3 tunnel. The type of Layer 2 (L2) tunnel that is established is dependent on the configuration of both the local and remote peers. To establish L2TP tunnels, refer to the sections "Configuring L2TP Client-Initiated Tunneling on the Local Peer" and "Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TP Tunnels" in this document. To establish L2TPv3 tunnels, refer to the sections "Configuring L2TP Client-Initiated Tunneling on the Local Peer" and "Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TPv3 Tunnels" in this document.
Benefits of L2TP Client-Initiated Tunneling
This feature provides the ability for client routers to initiate L2TP or L2TPv3 tunnels. The main advantage of client-initiated L2TP tunneling is that the connection between the client and the internet service provider (ISP) is secure.
How to Configure L2TP Client-Initiated Tunneling
This section contains the following procedures:
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Configuring L2TP Client-Initiated Tunneling on the Local Peer
The L2TP Client-Initiated Tunneling feature can be configured to establish either L2TP or L2TPv3 tunnels. The type of tunnel that is established is dependent on the configuration of both the local and remote peers. The local and remote peers must be configured to establish the same type of tunnel.
To configure the local peer to establish L2TP tunnels, perform the task described in this section. You must also perform the task "Configuring the L2TPv3 Pseudowire" and configure the protocol l2tpv2 option.
To configure the local peer to establish L2TPv3 tunnels, perform the task perform the task described in this section. You must also perform the task "Configuring the L2TPv3 Pseudowire" and configure the protocol l2tpv3 option.
Perform this task to configure the L2TP Client-Initiated Tunneling feature on the local peer.
SUMMARY STEPS
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DETAILED STEPS
Step 1
enable
Example:Router> enable
Enables privileged EXEC mode.
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Step 2
configure terminal
Example:Router# configure terminal
Enters global configuration mode.
Step 3
l2tp-class [l2tp-class-name]
Example:Router(config)# l2tp-class l2tpclass2
Specifies the L2TP class name and enters L2TP class configuration mode.
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Step 4
exit
Example:Router(config-l2tp-class)# exit
Exits L2TP class configuration mode.
Step 5
pseudowire-class [pw-class-name]
Example:Router(config)# pseudowire-class pwclass2
Enters pseudowire class configuration mode and optionally specifies the name of the L2TP pseudowire class.
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Step 6
exit
Example:Router(config-pw)# exit
Exits pseudowire class configuration mode.
Step 7
interface virtual-ppp number
Example:Router(config)# interface virtual-ppp 2
Enters interface configuration mode and assigns a virtual-PPP interface number.
Step 8
ppp authentication {protocol1 [protocol2...]} [if-needed] [list-name | default] [callin] [one-time]
Example:Router(config-if)# ppp authentication chap
Enables Challenge Handshake Authentication Protocol (CHAP) or Password Authentication Protocol (PAP) or both and specifies the order in which CHAP and PAP authentication is selected on the interface.
Step 9
ppp chap hostname [hostname]
Example:Router(config-if)# ppp chap hostname peer2
Creates a pool of dialup routers that all appear to be the same host when authenticating with CHAP.
Step 10
pseudowire peer-ip-address vcid pw-class pw-class-name [sequencing {transmit | receive | both}]
Example:Router(config-if)# pseudowire 172.16.32.24 10 pw-class pwclass2
Specifies the IP address of the peer provider edge (PE) router and the 32-bit virtual circuit identifier shared between the PE at each end of the control channel.
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Step 11
exit
Example:Router(config-if)# exit
Exits interface configuration mode.
Step 12
ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]
Example:Router(config)# ip route 10.20.20.0 255.255.255.0 virtual-PPP1
Establishes static routes.
Configuring L2TP Client-Initiated Tunneling on the Remote Peer
The L2TP Client-Initiated Tunneling feature can be configured to establish either L2TP or L2TPv3 tunnels. The type of tunnel that is established is dependent on the configuration of both the local and remote peers. The local and remote peers must be configured to establish the same type of tunnel.
To configure the remote peer to establish L2TP tunnels, perform the task "Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TP Tunnels" in this section. To configure the remote peer to establish L2TPv3 tunnels, perform the task "Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TPv3 Tunnels" in this section.
This section contains the following tasks:
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Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TP Tunnels
This task configures the L2TP Client-Initiated Tunneling feature on the remote peer. Perform this task to establish L2TP tunnels.
SUMMARY STEPS
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DETAILED STEPS
Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TPv3 Tunnels
This task configures the L2TP Client-Initiated Tunneling feature on the remote peer. Perform this task to establish L2TPv3 tunnels.
SUMMARY STEPS
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DETAILED STEPS
Step 1
enable
Example:Router> enable
Enables privileged EXEC mode.
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Step 2
configure terminal
Example:Router# configure terminal
Enters global configuration mode.
Step 3
l2tp-class [l2tp-class-name]
Example:Router(config)# l2tp-class l2tpclass2
Specifies the L2TP class name and enters L2TP class configuration mode.
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Step 4
exit
Example:Router(config-l2tp-class)# exit
Exits L2TP class configuration mode.
Step 5
pseudowire-class [pw-class-name]
Example:Router(config)# pseudowire-class pwclass2
Enters pseudowire class configuration mode and optionally specifies the name of the L2TP pseudowire class.
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Step 6
exit
Example:Router(config-pw)# exit
Exits pseudowire class configuration mode.
Step 7
interface virtual-ppp number
Example:Router(config)# interface virtual-ppp 2
Enters interface configuration mode and assigns a virtual-PPP interface number.
Step 8
ppp authentication {protocol1 [protocol2...]} [if-needed] [list-name | default] [callin] [one-time]
Example:Router(config-if)# ppp authentication chap
Enables CHAP or PAP or both and specifies the order in which CHAP and PAP authentication is selected on the interface.
Step 9
ppp chap hostname [hostname]
Example:Router(config-if)# ppp chap hostname peer2
Creates a pool of dialup routers that all appear to be the same host when authenticating with CHAP.
Step 10
pseudowire peer-ip-address vcid pw-class pw-class-name [sequencing {transmit | receive | both}]
Example:Router(config-if)# pseudowire 172.16.32.24 10 pw-class pwclass2
Specifies the IP address of the peer provider edge (PE) router and the 32-bit virtual circuit identifier shared between the PE at each end of the control channel.
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Step 11
exit
Example:Router(config-if)# exit
Exits interface configuration mode.
Step 12
ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]
Example:Router(config)# ip route 10.20.20.0 255.255.255.0 Virtual-PPP1
Establishes static routes.
Configuring L2TP Control Channel Parameters
The L2TP class configuration procedure creates a template of L2TP control channel parameters that can be inherited by different pseudowire classes. L2TP control channel parameters are used in control channel authentication, keepalive messages, and control channel negotiation. In an L2TPv3 session, the same L2TP class must be specified in the pseudowire configured on the PE router at each end of the control channel. Configuring L2TP control channel parameters is optional. However, the L2TP class must be configured before it is associated with a pseudowire class (see the section "Configuring the L2TPv3 Pseudowire").
The three main groups of L2TP control channel parameters that you can configure in an L2TP class are described in the following sections:
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After the router enters L2TP class configuration mode, you can configure L2TP control channel parameters in any order. If you have multiple authentication requirements you can configure multiple sets of L2TP class control channel parameters with different L2TP class names. However, only one set of L2TP class control channel parameters can be applied to a connection between any pair of IP addresses.
Configuring L2TP Control Channel Timing Parameters
The following L2TP control channel timing parameters can be configured in L2TP class configuration mode:
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This task configures a set of timing control channel parameters in an L2TP class. All of the timing control channel parameter configurations are optional and may be configured in any order. If these parameters are not configured, the default values are applied.
SUMMARY STEPS
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DETAILED STEPS
Configuring L2TP Control Channel Authentication Parameters
The following L2TP control channel authentication parameters can be configured in L2TP class configuration mode:
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This task configures a set of authentication control channel parameters in an L2TP class. All of the authentication control channel parameter configurations are optional and may be configured in any order. If these parameters are not configured, the default values will be applied.
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Configuring L2TP Control Channel Maintenance Parameters
The L2TP hello packet keepalive interval control channel maintenance parameter can be configured in L2TP class configuration mode.
This task configures the interval used for hello messages in an L2TP class. This control channel parameter configuration is optional. If this parameter is not configured, the default value will be applied.
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DETAILED STEPS
Configuring the L2TPv3 Pseudowire
The pseudowire class configuration procedure creates a configuration template for the pseudowire. You use this template, or class, to configure session-level parameters for L2TPv3 sessions that will be used to transport attachment circuit traffic over the pseudowire.
The pseudowire configuration specifies the characteristics of the L2TPv3 signaling mechanism, including the data encapsulation type, the control protocol, sequencing, fragmentation, payload-specific options, and IP properties. The setting that determines if signaling is used to set up the pseudowire is also included.
For simple L2TPv3 signaling configurations on most platforms, pseudowire class configuration is optional. However, specifying a source IP address to configure a loopback interface is highly recommended. If you do not configure a loopback interface, the router will choose the best available local address, which could be any IP address configured on a core-facing interface. This configuration could prevent a control channel from being established. If you do not configure other pseudowire class configuration commands, the default values are used.
SUMMARY STEPS
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DETAILED STEPS
Step 1
enable
Example:Router> enable
Enables privileged EXEC mode.
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Step 2
configure terminal
Example:Router# configure terminal
Enters global configuration mode.
Step 3
pseudowire-class [pw-class-name]
Example:Router(config)# pseudowire-class etherpw
Enters pseudowire class configuration mode and optionally specifies the name of the L2TP pseudowire class.
Step 4
encapsulation {l2tpv2 | l2tpv3 [manual]| mpls}
Example:Router(config-pw)# encapsulation l2tpv3
Specifies the data encapsulation method used to tunnel IP traffic.
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protocol {l2tpv2 | l2tpv3 | none} [l2tp-class-name]
Example:Router(config-pw)# protocol l2tpv3 class1
(Optional) Specifies the L2 signaling protocol to be used to manage the pseudowires created with the control channel parameters in the specified L2TP class (see the section "Configuring L2TP Control Channel Parameters").
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ip local interface interface-name
Example:Router(config-pw)# ip local interface e0/0
Specifies the PE router interface whose IP address is to be used as the source IP address for sending tunneled packets.
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ip pmtu
Example:Router(config-pw)# ip pmtu
(Optional) Enables the discovery of the path maximum transmission unit (PMTU) for tunneled traffic.
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ip tos {value value | reflect}
Example:Router(config-pw)# ip tos reflect
(Optional) Configures the value of the type of service (ToS) byte in IP headers of tunneled packets, or reflects the ToS byte value from the inner IP header.
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ip dfbit set
Example:Router(config-pw)# ip dfbit set
(Optional) Configures the value of the DF bit in the outer headers of tunneled packets.
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ip ttl value
Example:Router(config-pw)# ip ttl 100
(Optional) Configures the value of the time to live (TTL) byte in the IP headers of tunneled packets.
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ip protocol {l2tp | uti | protocol-number}
Example:Router(config-pw)# ip protocol uti
(Optional) Configures the IP protocol to be used for tunneling packets.
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sequencing {transmit | receive | both}
Example:Router(config-pw)# sequencing both
(Optional) Specifies the direction in which sequencing of data packets in a pseudowire is enabled.
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Configuration Examples for L2TP Client-Initiated Tunneling
This section contains the following configuration examples:
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Configuring L2TP Client-Initiated Tunneling on the Local Peer for L2TP Tunnels: Example
The following example configures the L2TP Client-Initiated Tunneling feature on the local peer. This configuration is for L2TP tunnels.
l2tp-class l2tpclass1!pseudowire-class pwclass1encapsulation l2tpv2protocol l2tpv2 pw-class1ip local interface ethernet0/0!interface virtual-ppp 1ip unnumbered loopback1ppp authentication chapppp chap hostname peer1pseudowire 172.24.13.196 10 pw-class pwclass1!ip route 10.10.10.0 255.255.255.0 virtual-PPP1Configuring L2TP Client-Initiated Tunneling on the Local Peer for L2TPv3 Tunnels: Example
The following example configures the L2TP Client-Initiated Tunneling feature on the local peer. This configuration is for L2TPv3 tunnels.
l2tp-class l2tpclass1!pseudowire-class pwclass1encapsulation l2tpv3protocol l2tpv3 pw-class1ip local interface ethernet0/0!interface virtual-ppp 1ip unnumbered loopback1ppp authentication chapppp chap hostname peer1pseudowire 172.24.13.196 10 pw-class pwclass1!ip route 10.10.10.0 255.255.255.0 virtual-PPP1Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TP Tunnels: Example
The following example configures the L2TP Client-Initiated Tunneling feature on the remote peer using a VPDN group. This configuration is for L2TP tunnels.
vpdn-group vpdngroup1accept-dialinprotocol l2tpvirtual-template 1terminate-from host peer1!interface virtual-template 1ip unnumbered loopback1ppp authentication chapppp chap hostname peer2Configuring L2TP Client-Initiated Tunneling on the Remote Peer for L2TPv3 Tunnels: Example
The following example configures the L2TP Client-Initiated Tunneling feature on the remote peer using an L2TP class and a pseudowire class. This configuration is for L2TPv3 tunnels.
l2tp-class l2tpclass2!pseudowire-class pwclass2encapsulation l2tpv3protocol l2tpv3 pw-class1ip local interface ethernet0/1!interface virtual-ppp 2ip unnumbered loopback1ppp authentication chapppp chap hostname peer2pseudowire 172.16.32.24 10 pw-class pwclass2!ip route 10.20.20.0 255.255.255.0 virtual-PPP1Additional References
The following sections contain additional information related to the L2TP Client-Initiated Tunneling feature.
Related Documents
Standards
MIBs
None
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
RFCs
Technical Assistance
Command Reference
This section documents new and modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.3T command reference publications.
authentication (L2TP)
To enable Layer 2 Tunnel Protocol (L2TP) or L2TP Version 3 (L2TPv3) authentication, use the authentication (L2TP) command in L2TP class configuration mode. To disable Layer 2 (L2) authentication, use the no form of this command.
authentication
no authentication
Syntax Description
This command has no arguments or keywords.
Defaults
L2 authentication is enabled.
Command Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use the authentication command to enable L2 authentication only if authentication was previously disabled.
Examples
The following example enables authentication in L2 pseudowires configured using the L2TP class configuration named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# authenticationRelated Commands
l2tp-class
Creates a template of L2TP control plane configuration settings that can be inherited by different pseudowire classes and enters L2TP class configuration mode.
encapsulation (L2TP)
To specify the Layer 2 (L2) data encapsulation method to be used for tunneling IP traffic over a pseudowire, use the encapsulation (L2TP) command in pseudowire class configuration mode. To remove the specified L2 encapsulation method, use the no form of this command.
encapsulation {l2tpv2 | l2tpv3 [manual] | mpls}
no encapsulation {l2tpv2 | l2tpv3 [manual] | mpls}
Syntax Description
Defaults
No encapsulation method is specified.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
The l2tpv2 keyword was added and this command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
This command must be configured if the pseudowire class will be referenced from an xconnect or pseudowire configured to forward L2 traffic.
Examples
The following example shows how to configure L2TPv3 as the data encapsulation method for the pseudowire class named ether-pw:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# encapsulation l2tpv3Related Commands
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
hello
To configure the interval used to exchange hello keepalive packets in a Layer 2 (L2) control channel, use the hello command in L2TP class configuration mode. To disable the sending of hello keepalive packets, use the no form of this command.
hello interval
no hello interval
Syntax Description
Defaults
60 seconds
Command Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
You can configure different values with the hello command on the router at each end of an L2 control channel.
Examples
The following example sets an interval of 120 seconds between the sending of hello keepalive messages in pseudowires configured using the L2TP class configuration named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# hello 120Related Commands
l2tp-class
Creates a template of L2TP control plane configuration settings that can be inherited by different pseudowire classes and enters L2TP class configuration mode.
hidden
To hide the attribute-value pair (AVP) values in Layer 2 Tunneling Protocol (L2TP) control messages, use the hidden command in L2TP class configuration mode. To unhide AVPs, use the no form of this command.
hidden
no hidden
Syntax Description
This command has no arguments or keywords.
Defaults
L2TP AVP hiding is disabled.
Command Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use the hidden command to provide additional security for the exchange of control messages between provider edge routers in a Layer 2 Tunnel Protocol Version 3 (L2TPv3) control channel. Because username and password information is exchanged between devices in clear text, it is useful to encrypt L2TP AVP values with the hidden command.
Examples
The following example enables AVP hiding and encrypts AVPs in control messages in L2TPv3 pseudowires configured using the L2TP class configuration named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# hiddenRelated Commands
l2tp-class
Creates a template of L2TP control plane configuration settings that can be inherited by different pseudowire classes and enters L2TP class configuration mode.
hostname (L2TP)
To configure the host name that the router will use to identify itself during Layer 2 Tunnel Protocol Version 3 (L2TPv3) authentication, use the hostname (L2TP) command in L2TP class configuration mode. To remove the host name, use the no form of this command.
hostname name
no hostname name
Syntax Description
Defaults
No host name is specified for L2TPv3 authentication.
Command Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
If you do not use the hostname command, the host name of the router is used for L2TPv3 authentication.
Examples
The following example configures the host name yb2 for a provider edge router used at one end of an L2TPv3 control channel in an L2TPv3 pseudowire configured using the L2TP class configuration named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# hostname yb2Related Commands
interface virtual-ppp
To enter interface configuration mode and assign a virtual-PPP interface number, use the interface virtual-ppp command in global configuration mode. To disable a virtual-PPP interface, use the no form of this command.
interface virtual-ppp number
no interface virtual-ppp number
Syntax Description
Defaults
No default behavior or values
Command Modes
Global configuration mode
Command History
Usage Guidelines
Use the interface virtual-ppp command to create a virtual interface with PPP encapsulation.
Issuing the interface virtual-ppp command enters interface configuration mode.
Examples
The following example configures a virtual-PPP interface with the number 503 and enters virtual-PPP interface configuration mode:
interface virtual-ppp 503Related Commands
ip dfbit set
To enable the Don't Fragment (DF) bit in the outer Layer 2 (L2) header, use the ip dfbit set command in pseudowire class configuration mode. To disable the DF bit setting, use the no form of this command.
ip dfbit set
no ip dfbit set
Syntax Description
This command has no arguments or keywords.
Defaults
The default value is DF bit off, except for Cisco 12000 series Internet routers, which have this command enabled by default.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use this command to set the DF bit on if, for performance reasons, you do not want tunneled packet reassembly to be performed on the router.
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Examples
The following example shows how to enable the DF bit in the outer L2 header in pseudowires created from the pseudowire class named ether-pw:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# ip dfbit setRelated Commands
ip pmtu (L2TP)
Enables the discovery of a PMTU for L2 traffic.
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
ip local interface
To configure the IP address of the provider edge (PE) router interface to be used as the source IP address for sending tunneled packets, use the ip local interface command in pseudowire class configuration mode. To remove the IP address, use the no form of this command.
ip local interface interface-name
no ip local interface interface-name
Syntax Description
interface-name
Name of the PE interface whose IP address is used as the source IP address for sending tunneled packets over a Layer 2 (L2) pseudowire.
Defaults
NoIP address is configured.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use the same local interface name for all pseudowire classes configured between a pair of PE routers. It is highly recommended that a loopback interface is configured with this command. If you do not configure a loopback interface, the router will choose the "best available local address," which could be any IP address configured on a core-facing interface. This configuration could prevent a control channel from being established.
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Examples
The following example shows how to configure the IP address of the local Ethernet interface named e0/0 as the source IP address for sending Ethernet packets through an L2TPv3 session:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# ip local interface e0/0Related Commands
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
ip pmtu
To enable the discovery of a path maximum transmission unit (PMTU) for Layer 2 (L2) traffic, use the ip pmtu command in pseudowire class configuration mode. To disable PMTU discovery, use the no form of this command.
ip pmtu
no pmtu
Syntax Description
This command has no arguments or keywords.
Defaults
Path MTU discovery is disabled.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
The ip pmtu command enables the processing of Internet Control Message Protocol (ICMP) unreachable messages that indicate fragmentation errors in the IP backbone network carrying the tunneled traffic. The MTU of the L2TPv3 session is updated according to the MTU information contained in the ICMP unreachable message.
The ip pmtu command also enables MTU checking for IP packets that are sent into an L2TPv3 session with the Don't Fragment (DF) bit set. If an IP packet is larger than the MTU of the tunnel, the packet is dropped and an ICMP unreachable message is sent. If an IP packet is smaller than the MTU of the tunnel, the DF bit in the packet header is reflected from the inner IP header to the tunnel header.
Examples
The following example shows how to enable the discovery of the path MTU for pseudowires created from the pseudowire class named ether-pw:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# ip pmtuRelated Commands
ip dfbit set
Enables the DF bit in the outer L2TPv3 tunnel header.
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
ip protocol
To configure the Layer 2 Tunnel Protocol (L2TP) or Universal Tunnel Interface (UTI) as the IP protocol used for tunneling packets in a Layer 2 (L2) pseudowire, use the ip protocol command in pseudowire class configuration mode. To remove the IP protocol configuration, use the no form of this command.
ip protocol {l2tp | uti | protocol-number}
no ip protocol {l2tp | uti | protocol-number}
Syntax Description
Defaults
The default IP protocol is L2TP.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use the ip protocol command to ensure backward compatibility with routers running UTI. This command allows you to configure an L2TPv3 pseudowire between a router running L2TPv3 and a peer router running UTI.
Note
To configure L2TP as the IP protocol used to tunnel packets in an L2TPv3 pseudowire, you may enter 115, the IP protocol number assigned to L2TPv3, instead of l2tp in the ip protocol command.
To configure UTI as the IP protocol used to tunnel packets in an L2TPv3 pseudowire, you may enter 120, the IP protocol number assigned to UTI, instead of uti in the ip protocol command.
Note
Examples
The following example shows how to configure UTI as the IP protocol used to tunnel packets in an L2TPv3 pseudowire created from the pseudowire class named ether-pw:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# encapsulation l2tpv3Router(config-pw)# ip protocol utiRelated Commands
ip tos (L2TP)
To configure the Type of Service (ToS) byte in the header of Layer 2 (L2) tunneled packets, use the ip tos (L2TP) command in pseudowire class configuration mode. To disable a configured ToS value or IP ToS reflection, use the no form of this command.
ip tos {value value | reflect}
no tos {value value | reflect}
Syntax Description
Defaults
The default ToS value is 0.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
The ip tos command allows you to manually configure the value of the ToS byte used in the headers of L2 tunneled packets or to have the ToS value reflected from the IP header of the encapsulated packet.
Note
Note
In addition, you can configure both IP ToS reflection and a ToS priority level (from 0 to 255) for a pseudowire class. In this case, the ToS value in the tunnel header defaults to the value you specify with the ip tos value value command. IP packets received on the Layer 2 interface and encapsulated into the L2TPv3 session have their ToS byte reflected into the outer IP session, overriding the default value configured with the ip tos value value command.
Examples
The following example shows how to configure the ToS byte in the headers of tunneled packets in L2 tunnels created from the pseudowire class named ether-pw to be reflected from the ToS value in the header of each encapsulated IP packet:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# ip tos reflectRelated Commands
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
ip ttl
To configure the time-to-live (TTL) byte in the IP headers of Layer 2 (L2) tunneled packets, use the ip ttl command in pseudowire class configuration mode. To remove the configured TTL value, use the no form of this command.
ip ttl value
no ip ttl value
Syntax Description
value
Value of the TTL byte in the IP headers of L2TPv3 tunneled packets. The valid values range from 1 to 255. The default value is 255.
Defaults
The default value of the TTL byte is 255.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use this command to set the Don't Fragment (DF) bit on if, for performance reasons, you do not want tunneled packet reassembly to be performed on the router.
Examples
The following example shows how to set the TTL byte to 100 in the IP header of L2 tunneled packets in pseudowires created from the pseudowire class named ether-pw:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# ip ttl 100Related Commands
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
l2tp-class
To create a template of Layer 2 Tunneling Protocol control plane configuration settings that can be inherited by different pseudowire classes and to enter L2TP class configuration mode, use the l2tp-class command in global configuration mode.
l2tp-class [l2tp-class-name]
Syntax Description
l2tp-class-name
(Optional) Name of the L2TP class. The l2tp-class-name argument must be specified if you want to configure multiple sets of L2TP control parameters.
Defaults
No default behavior or values.
Command Modes
Global configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
The l2tp-class l2tp-class-name command allows you to configure an L2TP class template that consists of configuration settings used by different pseudowire classes. An L2TP class includes the following configuration settings:
•
•
•
•
•
•
•
The l2tp-class command enters L2TP class configuration mode, where L2TP control plane parameters are configured.
You must use the same L2TP class in the pseudowire configuration at both ends of an L2TPv3 control channel.
Examples
The following example shows how to switch to L2TP class configuration mode to create an L2TP class configuration template for the class named ether-pw:
Router(config)# l2tp-class ether-pwRouter(config-l2tp-class)#Related Commands
password (L2TP)
To configure the password used by a provider edge (PE) router for Layer 2 (L2) authentication, use the password (L2TP) command in L2TP class configuration mode. To disable a configured password, use the no form of this command.
password [encryption-type] password
no password [encryption-type] password
Syntax Description
Defaults
If a password is not configured for the L2TP class with the password command, the password configured with the username password command in global configuration mode is used.
Command Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
The password that you define with the password command is also used for attribute-value pair (AVP) hiding.
The password hierarchy sequence used for a local and remote peer PE for L2TPv3 authentication is as follows:
•
•
Examples
The following example sets the password named tunnel2 to be used to authenticate an L2TPv3 session between the local and remote peers in L2TPv3 pseudowires configured with the L2TP class configuration named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# password tunnel2Related Commands
l2tp-class
Creates a template of L2TP control plane configuration settings that can be inherited by different pseudowire classes and enters L2TP class configuration mode.
protocol (L2TP)
To specify the signaling protocol to be used to manage the pseudowires created from a pseudowire class for a Layer 2 (L2) session, and that control plane configuration settings are to be taken from a specified L2TP class, use the protocol (L2TP) command in pseudowire class configuration mode. To remove the signaling protocol (and the control plane configuration to be used) from a pseudowire class, use the no form of this command.
protocol {l2tpv2 | l2tpv3 | none} [l2tp-class-name]
no protocol {l2tpv2 | l2tpv3 | none} [l2tp-class-name]
Syntax Description
Defaults
The default protocol option is l2tpv3.
If you do not enter a value for the l2tp-class-name argument, the default control plane configuration settings in the L2TP signaling protocol are used.Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use the protocol (L2TP) command to configure the signaling protocol to use in sessions created from the specified pseudowire class. In addition, you can use this command to specify the L2TP class from which the control plane configuration settings are to be taken.
Use the protocol none command to specify that no signaling will be used in L2TPv3 sessions created from the specified pseudowire class. This configuration is required for interoperability with a remote peer running the Universal Tunnel Interface (UTI).
Do not use the command if you want to configure a pseudowire class used to create manual L2TPv3 sessions.
Examples
The following example shows how to enter pseudowire class configuration mode, and how to configure L2TPv3 as the signaling protocol. The control plane configuration used in the L2TP class named class1 will be used to create dynamic L2TPv3 sessions for a VLAN Xconnect interface:
Router(config)# pseudowire-class vlan-xconnectRouter(config-pw)# protocol l2tpv3 class1Related Commands
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
pseudowire
To bind an attachment circuit to a Layer 2 (L2) pseudowire for xconnect service, use the pseudowire command in interface configuration mode.
pseudowire peer-ip-address vcid pw-class pw-class-name [sequencing {transmit | receive | both}]
Syntax Description
Defaults
No default behavior or values
Command Modes
Interface configuration
Command History
Usage Guidelines
The combination of the peer-ip-address and vcid must be unique on the router. Each pseudowire configuration must have a unique combination of peer-ip-address and vcid configuration.
The same vcid value that identifies the attachment circuit must be configured using the pseudowire command on the local and remote router at each end of an L2 session. The virtual circuit identifier creates the binding between a pseudowire and an attachment circuit.
The pw-class pw-class-name value binds the pseudowire configuration of an attachment circuit to a specific pseudowire class. In this way, the pseudowire class configuration serves as a template that contains settings used by all attachment circuits bound to it with the pseudowire command.
Examples
The following example creates a virtual-PPP interface with the number 1, configures PPP on the virtual-PPP interface, and binds the attachment circuit to an L2TPv3 pseudowire for Xconnect service for the pseudowire class named pwclass1:
interface virtual-ppp 1ppp authentication chapppp chap hostname peer1pseudowire 172.24.13.196 10 pw-class pwclass1Related Commands
pseudowire-class
To specify the name of a Layer 2 (L2) pseudowire class and enter pseudowire class configuration mode, use the pseudowire-class command in global configuration mode.
pseudowire-class [pw-class-name]
Syntax Description
pw-class-name
(Optional) The name of a L2 pseudowire class. If you want to configure more than one pseudowire class, you must enter a value for the pw-class-name argument.
Defaults
No pseudowire class is defined.
Command Modes
Global configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
The pseudowire-class command allows you to configure a pseudowire class template that consists of configuration settings used by all attachment circuits bound to the class. A pseudowire class includes the following configuration settings:
•
•
•
•
•
After you enter the pseudowire-class command, you switch to pseudowire class configuration mode, where pseudowire settings may be configured.
Examples
The following example shows how to enter pseudowire class configuration mode to configure a pseudowire configuration template named ether-pw:
Router(config)# pseudowire-class ether-pwRouter(config-pw)#Related Commands
receive-window
To configure the packet size of the receive window on the remote provider edge router at the other end of a Layer 2 (L2) control channel, use the receive-window command in L2TP class configuration mode. To disable the configured value, use the no form of this command.
receive-window size
no receive-window size
Syntax Description
Defaults
The default value is the upper limit the remote peer has for receiving packets.
Command Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
To determine the upper limit for the size argument, refer to the platform-specific documentation for the peer router.
Examples
The following example sets a receive window of 30 packets to the remote peer in L2 pseudowires configured with the L2TP class named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# receive-window 30Related Commands
l2tp-class
Creates a template of L2TP control plane configuration settings that can be inherited by different pseudowire classes and enters L2TP class configuration mode.
retransmit
To configure the retransmission settings of control packets, use the retransmit command in L2TP class configuration mode. To disable the configured values, use the no form of this command.
retransmit {initial retries initial-retries | retries retries | timeout {max | min} timeout}
no retransmit {initial retries initial-retries | retries retries | timeout {max | min} timeout}
Syntax Description
Defaults
Initial retries: 2
Retries: 15
Maximum timeout interval: 8 seconds
Minimum timeout interval: 1 secondCommand Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use this command to configure the amount of time spent trying to establish or maintain a control channel.
Examples
The following example configures ten retries for sending tunneled packets to a remote peer in L2 pseudowires configured with the L2TP class named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# retransmit retries 10Related Commands
l2tp-class
Creates a template of L2TP control plane configuration settings that can be inherited by different pseudowire classes and enters L2TP class configuration mode.
sequencing
To configure the direction in which sequencing is enabled for data packets in an a Layer 2 (L2) pseudowire, use the sequencing command in pseudowire class configuration mode. To remove the sequencing configuration from the pseudowire class, use the no form of this command.
sequencing {transmit | receive | both}
no sequencing {transmit | receive | both}
Syntax Description
Defaults
Sequencing is off.
Command Modes
Pseudowire class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
When you enable sequencing using any of the available options, the sending of sequence numbers is automatically enabled and the remote provider edge (PE) peer is requested to send sequence numbers. Out-of-order packets received on the pseudowire are dropped only if you use the sequencing receive or sequencing both command.
If sequencing is enabled for L2 pseudowires on the Cisco 7500 series, all traffic on the pseudowires is switched through the Route Switch Processor (RSP) regardless of the setting configured with the ip cef distributed command.
Examples
The following example shows how to enable sequencing in data packets in L2 pseudowires created from the pseudowire class named ether-pw so that Sequence Number field is updated in tunneled packet headers for data packets both sent and received over the pseudowire:
Router(config)# pseudowire-class ether-pwRouter(config-pw)# sequencing bothRelated Commands
pseudowire-class
Specifies the name of an L2TP pseudowire class and enters pseudowire class configuration mode.
timeout setup
To configure the amount of time allowed to set up a control channel with a remote provider edge (PE) router at the other end of a Layer 2 (L2) pseudowire, use the timeout setup command in L2TP class configuration mode. To disable the configured value, use the no form of this command.
timeout setup seconds
no timeout setup seconds
Syntax Description
seconds
The number of seconds allowed to set up an L2 control channel. The valid values range from 60 to 6000. The default value is 300 seconds.
Defaults
300 seconds
Command Modes
L2TP class configuration
Command History
12.0(23)S
This command was introduced.
12.3(2)T
This command was integrated into Cisco IOS Release 12.3(2)T.
Usage Guidelines
Use this command to configure the amount of time spent attempting to establish a control channel.
Examples
The following example sets a timeout period of 200 seconds to establish a control channel with a remote peer in L2 pseudowires configured with the L2TP class named l2tp class1:
Router(config)# l2tp-class l2tp-class1Router(config-l2tp-class)# timeout setup 200Related Commands
l2tp-class
Creates a template of L2TP control plane configuration settings that can be inherited by different pseudowire classes and enters L2TP class configuration mode.
Copyright © 2003 Cisco Systems, Inc. All rights reserved.
