Generic Routing Encapsulation Commands

This module describes the commands used to configure generic routing encapsulation (GRE).

For detailed information about GRE concepts, configuration tasks, and examples, refer to the L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers.

bandwidth

To set the tunnel interface bandwidth, use the bandwidth command in interface configuration mode. To undo the tunnel interface bandwidth that is set, use the no form of this command.

bandwidth kbps

no bandwidth kbps

Syntax Description

kbps

Interface bandwidth in kilobits per second (kbps). The range is from 0 to 4294967295. The default value is 100.

Command Default

None

Command Modes

interface configuration

Command History

Release Modification

Release 4.2.0

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID Operation

interface

read, write

Examples

This example shows how to set the bandwidth of the tunnel interface:


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 6677
RP/0/RSP0/CPU0:router(config-if)# bandwidth 56789

description (GRE)

To specify the description of any interface, use the description command in the interface configuration mode. To undo the specified description, use the no form of the command.

description description-name

no description

Syntax Description

description-name

Description of the Interface.

Command Default

None

Command Modes

Interface Configuration

Command History

Release Modification
Release 4.2.0

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID Operation

interface

read, write

Examples

The following output shows how to specify the description of an interface:

RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 789
RP/0/RSP0/CPU0:router(config-if)# description Interface

ipv4 address

To set the IPv4 address of the tunnel interface, use the ipv4 address command in interface configuration mode. To remove the IPv4 addresses, use the no form of this command.

ipv4 address prefix subnet mask [route-tag value | secondary [route-tag value]]

no ipv4 address prefix subnet mask [route-tag value | secondary [route-tag value]]

Syntax Description

prefix

IPv4 address of the interface.
subnet mask

Subnet mask of the interface.
route-tag

Specifies the tag associated with the IP address.
value

Tag value.
secondary

Specifies the secondary IPV4 address.

Command Default

None

Command Modes

Interface configuration

Command History

Release

Modification
Release 4.2.1

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

network

read, write

acl

read, write

Examples

This example shows how to set the IPV4 address with route-tag option:

RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)#interface tunnel-ip 67 ipv4 address 10.1.1.2 6.7.7.8 
route-tag 78
This example shows how to set the IPV4 address with secondary option:

RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)#interface tunnel-ip 67 ipv4 address 1.2.3.4 7.8.9.8 
secondary route-tag 89

ipv4 mtu (LxVPN)

To set the IPv4 MTU on the tunnel interface, use the ipv4 mtu command in interface configuration mode. To remove the IPv4 MTU, use the no form of this command.

ipv4 mtu size

no ipv4 mtu size

Syntax Description

size

Size of the MTU in bytes. The range is from 68 to 65535.

Command Default

None

Command Modes

Interface configuration

Command History

Release

Modification
Release 4.2.1

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

network

read, write

acl

read, write

Examples

This example shows how to set the IPv4 MTU:
RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)#interface tunnel-ip 78 ipv4 mtu 78

ipv6 address (LxVPN)

To set the IPv6 address of the tunnel interface, use the ipv6 address command in interface configuration mode. To remove the IPv6 addresses, use the no form of this command.

ipv6 {address zone {prefix length | link-local} [route-tag value] | zone/ length [route-tag value]}

no ipv6 {address zone {prefix length | link-local} [route-tag value] | zone/ length [route-tag value]}

Syntax Description

zone

Specifies the IPv6 address of the interface.
prefix length

Specifies the length of the IPv6 address prefix, in bits. The range is from 1 to 128.
link-local

Specifies the link-local address.
route-tag

Specifies the tag associated with the address.
value

Tag value. The range is from 1 to 4294967295.

Command Default

None

Command Modes

Interface configuration

Command History

Release

Modification
Release 4.2.1

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

network

read, write

interface

read, write

ipv6

read, write

Examples

This example shows how to set the ipv6 address for a tunnel interface:

RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)#interface tunnel-ip 67 ipv6 address 10:2::3 link-local 
route-tag 78

ipv6 mtu (LxVPN)

To set the IPv6 MTU on the tunnel interface, use the ipv6 mtu command in interface configuration mode. To remove the IPv6 MTU, use the no form of this command.

ipv6 mtu size

no ipv6 mtu size

Syntax Description

size

Size of the MTU in bytes. The range is from 1280 to 65535.

Command Default

None

Command Modes

Interface configuration

Command History

Release

Modification
Release 4.2.1

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

network

read, write

interface

read, write

ipv6

read, write

Examples

This example shows how to set the IPv4 MTU:
RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)#interface tunnel-ip 78 ipv6 mtu 3456

keepalive

To enable keepalive for a tunnel interface, use the keepalive command. To remove keepalive, use the no form of this command.

keepalive [time_in_seconds [retry_num] ]

no keepalive

Syntax Description

time_in_seconds

Specifies the frequency (in seconds) at which keepalive check is performed. The default is 10 seconds. The minimum value is 1 second.

retry_num

Specifies the number of keepalive retries before declaring that a tunnel destination is unreachable. The default is 3 retries. The minimum value is 1 retry.

Command Default

None

Command Modes

interface configuration

Command History

Release

Modification

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Use the keepalive command to enable keepalive for a tunnel interface.

Task ID

Task ID

Operations

interface

read, write

Examples

The following example shows how to configure interface tunnel:


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 400
RP/0/RSP0/CPU0:router(config-if)# keepalive 30

mtu (GRE)

To set the MTU size of the tunnel interface, use the mtu command in interface configuration mode. To undo the MTU size of the tunnel interface that is set, use the no form of this command.

This is a Generic Routing Encapsulation (GRE) command.

mtu size

no mtu size

Syntax Description

size

Size of MTU in bytes. The default value is 1500.

Command Default

None

Command Modes

Interface configuration

Command History

Release Modification

Release 4.2.0

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID Operation

interface

read, write

Examples

This example shows how to set the MTU size of the tunnel interface: 


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 456
RP/0/RSP0/CPU0:router(config-if)# mtu 334

shutdown (GRE)

To shut down any interface, use the shutdown command in interface configuration mode. To start the interface, use the no form of the command.

This is a Generic Routing Encapsulation (GRE) command.

shutdown

no shutdown

This command has no keywords or arguments.

Command Default

None

Command Modes

Interface configuration

Command History

Release Modification
Release 4.2.0

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID Operation

interface

read, write

Examples

This example shows how to shut down a given interface:


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 789
RP/0/RSP0/CPU0:router(config-if)# shutdown

tunnel destination

To specify a tunnel interface's destination address, use the tunnel destination command. To remove the destination address, use the no form of this command.


Note

The tunnel will not be operational until the tunnel destination is specified.

tunnel destination ip-address

no tunnel destination ip-address

Syntax Description

ip-address

Specifies the IPv4 address of the host destination.

Command Default

None

Command Modes

interface configuration

Command History

Release

Modification

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

interface

read, write

Examples

The following example shows how to configure interface tunnel: 


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 400
RP/0/RSP0/CPU0:router(config-if)# tunnel destination 10.10.10.1

Related Commands

Command Description
tunnel mode Configures the encapsulation mode of the tunnel interface.  
tunnel source Sets a tunnel interface's source address.  
tunnel tos Specifies the value of the TOS field in the tunnel encapsulating packets. 
tunnel ttl Configures the Time-To-Live (TTL) for packets entering the tunnel. 

tunnel key

To configure the key value for packets sent over a tunnel, use the tunnel key command. To delete the configured key value, use the no form of this command.

tunnel key key-value

no tunnel key key-value

Syntax Description

key-value

Specifies the tunnel key value. Range is from 0 to 4294967295.

Command Default

No value is configured.

Command Modes

interface configuration

Command History

Release Modification
Release 5.1.1

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

  • GRE tunnel key feature is supported only on Cisco ASR 9000 Enhanced Ethernet line cards. It is mandatory to have ingress and egress line cards as Enhanced Ethernet line cards.

  • GRE tunnel keepalive is not supported with tunnel key. If the configuration for the GRE keepalives and tunnel key are present at the same time, the tunnel is brought down and a warning message is displayed.

  • For a given router, either the same key or different keys can be configured under multiple GRE tunnels.

  • Different traffic streams passing through the same GRE tunnel contain the same GRE key configured for that tunnel.

Task ID

Task ID Operation
interface

read, write

tunnel

read, write

Examples

This example shows how to configure the tunnel key value at the GRE transmitter and receiver end: 

!Local GRE Interface
RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 10
RP/0/RSP0/CPU0:router(config-if)#ipv4 address 101.0.9.1 255.255.255.0
RP/0/RSP0/CPU0:router(config-if)# tunnel key 10
RP/0/RSP0/CPU0:router(config-if)# tunnel tos 96
RP/0/RSP0/CPU0:router(config-if)# tunnel source Loopback10
RP/0/RSP0/CPU0:router(config-if)# tunnel destination 33.0.9.33
!

!Remote GRE Interface

RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 10
RP/0/RSP0/CPU0:router(config-if)#ipv4 address 101.0.9.2 255.255.255.0
RP/0/RSP0/CPU0:router(config-if)# tunnel key 10
RP/0/RSP0/CPU0:router(config-if)# tunnel tos 96
RP/0/RSP0/CPU0:router(config-if)# tunnel source Loopback10
RP/0/RSP0/CPU0:router(config-if)# tunnel destination 11.0.9.11

!

tunnel key-ignore

To ensure that the decapsulation router skips GRE key validation before accepting the packet, use the tunnel key-ignore command. To remove the tunnel key ignore feature, use the no form of this command.

tunnel key-ignore

no tunnel key-ignore

Syntax Description

This command has no keywords or arguments.

Command Default

Tunnel key-ignore is disabled.

Command Modes

interface configuration

Command History

Release Modification
Release 5.1.1

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Do not configure any key value under GRE tunnel that has tunnel key-ignore feature enabled. This is because the configured tunnel key overrides the tunnel key-ignore feature. As a result, packets that arrive with configured key value are accepted and undergo further processing at the decapsulation router, while the remaining packets without the key value are dropped.

Task ID

Task ID Operation
interface

read, write

tunnel

read, write

Examples

This example shows how to configure the tunnel key-ignore feature at the GRE transmitter and receiver ends: 

!Local GRE Interface
RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 10
RP/0/RSP0/CPU0:router(config-if)#ipv4 address 101.0.9.1 255.255.255.0
RP/0/RSP0/CPU0:router(config-if)# tunnel key-ignore
RP/0/RSP0/CPU0:router(config-if)# tunnel tos 96
RP/0/RSP0/CPU0:router(config-if)# tunnel source Loopback10
RP/0/RSP0/CPU0:router(config-if)# tunnel destination 33.0.9.33
!

!Remote GRE Interface

RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router# interface tunnel-ip 10
RP/0/RSP0/CPU0:router#ipv4 address 101.0.9.2 255.255.255.0
RP/0/RSP0/CPU0:router# tunnel key-ignore
RP/0/RSP0/CPU0:router# tunnel tos 96
RP/0/RSP0/CPU0:router# tunnel source Loopback10
RP/0/RSP0/CPU0:router# tunnel destination 11.0.9.11

!

tunnel dfbit

To configure the DF bit setting in the tunnel transport header, use the tunnel dfbit command. To revert to the default DF bit setting value, use the no form of this command.

tunnel dfbit disable

no tunnel dfbit

Syntax Description

Syntax Description

disable

Disables the DF bit in the outer packet. This allows the outer packet to be fragmented, if required.

Command Default

The DF bit value in the outer packet is disabled. This allows outer packet fragmentation, if required.

Command Modes

interface configuration

Command History

Release

Modification

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

interface

read, write

Examples

The following example shows how to enable fragmentation over an interface tunnel. 


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 400
RP/0/RSP0/CPU0:router(config-if)# tunnel dfbit disable

Related Commands

Command Description
tunnel destination Specifies a tunnel interface's destination address.  
tunnel mode Configures the encapsulation mode of the tunnel interface.  
tunnel source Sets a tunnel interface's source address.  
tunnel tos Specifies the value of the TOS field in the tunnel encapsulating packets. 
tunnel ttl Configures the Time-To-Live (TTL) for packets entering the tunnel. 

tunnel mode

To configure the encapsulation mode of the tunnel interface, use the tunnel mode command. To revert the encapsulation to the default IPv4 GRE tunnel mode, use the no form of this command.

tunnel mode gre ipv4}

no tunnel mode

Syntax Description

Syntax Description

gre

ipv4

Specifies the tunnel as a GRE tunnel over an IPv4 transport network.

Command Default

The default tunnel mode is set as a GRE tunnel over an IPv4 transport network.

Command Modes

interface configuration

Command History

Release

Modification

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

interface

read, write

Examples

The following example shows how to configure interface tunnel: 


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 400
RP/0/RSP0/CPU0:router(config-if)#tunnel mode gre ipv4

Related Commands

Command Description

tunnel destination

Specifies a tunnel interface's destination address.  

tunnel source

Sets a tunnel interface's source address.  

tunnel tos

Specifies the value of the TOS field in the tunnel encapsulating packets. 

tunnel ttl

Configures the Time-To-Live (TTL) for packets entering the tunnel. 

tunnel source

To set a tunnel interface's source address, use the tunnel source command. To remove the source address, use the no form of this command.


Note

The tunnel will not be operational until the tunnel source is specified.

tunnel source {interface_name | ip-address}

no tunnel source {interface_name | ip-address}

Syntax Description

interface_name

Specifies the name of the interface whose IP address will be used as the source address of the tunnel. The interface name can be of a loopback interface or a physical interface.

ip-address

Specifies the IPv4 address to use as the source address for packets in the tunnel.

Command Default

None

Command Modes

interface configuration

Command History

Release

Modification

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

It is recommended that the tunnel source is identified using the interface ID and not the IP address. Using the interface ID enables the router to mark the tunnel as down when the interface is down and the routing protocol tries to find and use an alternate route to the tunnel route.

Task ID

Task ID

Operations

interface

read, write

Examples

The following example shows how to configure interface tunnel: 


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 400
RP/0/RSP0/CPU0:router(config-if)# tunnel source 10.10.10.1

Related Commands

Command Description

tunnel destination

Specifies a tunnel interface's destination address.  

tunnel mode

Configures the encapsulation mode of the tunnel interface.  

tunnel tos

Specifies the value of the TOS field in the tunnel encapsulating packets. 

tunnel ttl

Configures the Time-To-Live (TTL) for packets entering the tunnel. 

tunnel tos

To specify the value of the TOS field in the tunnel encapsulating packets, use the tunnel tos command. To return to the default TOS value, use the no form of this command.

tunnel tos tos_value

no tunnel tos tos_value

Syntax Description

tos_value

Specifies the value of the TOS field in the tunnel encapsulating packets. The TOS value ranges between 0 to 255.

Command Default

Copies the TOS/COS bits of the internal IP header to the GRE IP header. In case of labeled payload, EXP bits are copied to TOS bits of the GRE IP header.

Command Modes

interface configuration

Command History

Release

Modification

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID

Operations

interface

read, write

Examples

The following example shows how to configure interface tunnel:


RP/0/RSP0/CPU0:router# configure
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip 400
RP/0/RSP0/CPU0:router(config-if)# tunnel tos 100

Related Commands

Command Description

tunnel destination

Specifies a tunnel interface's destination address.  

tunnel mode

Configures the encapsulation mode of the tunnel interface.  

tunnel source

Sets a tunnel interface's source address.  

tunnel ttl

Configures the Time-To-Live (TTL) for packets entering the tunnel. 

tunnel ttl

To configure the Time-To-Live (TTL) for packets entering the tunnel, use the tunnel ttl command. To undo the configuration, use the no form of this command.

tunnel ttl ttl_value

no tunnel ttl ttl_value

Syntax Description

ttl_value

Specifies the value of TTL for packets entering the tunnel. The TTL value ranges between 1 to 255.

Command Default

The default TTL value is set to 255.

Command Modes

interface configuration

Command History

Release

Modification

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

This command specifies the Time-To-Live for packets entering the tunnel so that the packets are not dropped inside the carrier network before reaching the tunnel destination.

Task ID

Task ID

Operations

interface

read, write

Examples

The following example shows how to configure interface tunnel:


RP/0/RSP0/CPU0:router# configure 
RP/0/RSP0/CPU0:router(config)# interface tunnel-ip  400 
RP/0/RSP0/CPU0:router(config-if)#tunnel source 10.10.10.1

Related Commands

Command Description

tunnel destination

Specifies a tunnel interface's destination address.  

tunnel mode

Configures the encapsulation mode of the tunnel interface.  

tunnel tos

Specifies the value of the TOS field in the tunnel encapsulating packets. 

tunnel source

Sets a tunnel interface's source address.  

tunnel vrf

To specify the virtual routing and forwarding (VRF) instance of the interfaces of the tunnel endpoints, use the tunnel vrf command in tunnel interface configuration mode. To disassociate a VRF from the tunnel endpoints, use the no form of this command.

tunnel vrf vrf-name

Syntax Description

vrf-name

The name of the VRF instance.

Command Default

The tunnel addresses are looked up in the default VRF instance, that is, the global routing table.

Command Modes

Interface configuration

Command History

Release Modification

Release 5.2.0

This command was introduced.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

Task ID

Task ID Operation

tunnel

read, write

interface

read, write

Examples

The following example shows the tunnel "tunnel-ip1" endpoints associated with the VRF instance "blue". 


RP/0/RSP0/CPU0:router(config)# interface tunnel-ip1
RP/0/RSP0/CPU0:router(config-if)# ipv4 address 10.3.3.3 255.255.255.0
RP/0/RSP0/CPU0:router(config-if)# keepalive 5 3
RP/0/RSP0/CPU0:router(config-if)# tunnel mode gre ipv4
RP/0/RSP0/CPU0:router(config-if)# tunnel source Loopback0
RP/0/RSP0/CPU0:router(config-if)# tunnel destination 10.5.5.5
RP/0/RSP0/CPU0:router(config-if)# tunnel vrf blue