route-tag

Function

The route-tag command sets a tag value for imported VPN routes.

The undo route-tag command restores the default setting.

By default, the tag value of a VPN route is calculated based on the AS number of BGP. If no BGP is configured, the default tag value is 0.

Product	Support
S5720-EI, S5720-HI, S5720I-SI, S5720S-SI, S5720-SI, S5735-S, S5735S-S, S5735-S-I, S5730-HI, S5730S-EI, S5730-SI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6720S-SI, S6720-SI, S6730-H, S6730S-H, S6730-S, and S6730S-S	Supported
S2720-EI, S5720-LI, S5735-L, S5735S-L, S5735S-L-M, S5720S-LI, S6720-LI, and S6720S-LI	Not supported

Format

route-tag { tag | disable }

undo route-tag

Parameters

Parameter	Description	Value
tag	Specifies the tag value of the imported VPN routes.	The value is an integer ranging from 0 to 4294967295.
disable	Disables a device from using a VPN route tag to detect loops.	-

Views

OSPF view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

The route-tag command can be used only in VPN scenarios to prevent loops on Type-5 and Type-7 LSAs when a CE is dual-homed to two PEs.

In a networking where a CE is dual-homed to two PEs, PE1 generates Type-5 and Type-7 LSAs based on the imported BGP routes and sends the LSAs to the CE, then to PE2. Because OSPF routes have higher priorities over BGP routes, OSPF routes will replace BGP routes on PE2, causing loops. After the route-tag command is run, if the tag value of the PE and an LSA are the same, the PE will neglect the LSA, and a loop is prevented.

By default, the first two bytes of the tag value are fixed as 0xD000, while the last two bytes are the AS number of the local BGP. If a BGP AS number is greater than 65535, the default tag 0 is used. You can use the command to change the tag in this case.

Precautions

Configuring the same VPN route tag on the PEs within the same area is recommended.
Different OSPF processes can be configured with the same VPN route tag.

The tags set by the route-tag command or other commands are different only in preference.

The preference of the tag configured using the import-route command is the highest.
The preference of the tag configured using the route-tag command is medium.
The preference of the tag configured using the default tag command is the lowest.

Example

# Set the route tag for OSPF process 100 to 100 in a VPN instance named huawei.

<HUAWEI> system-view

[HUAWEI] ip vpn-instance huawei

[HUAWEI-vpn-instance-huawei] route-distinguisher 100:1

[HUAWEI-vpn-instance-huawei-af-ipv4] quit

[HUAWEI-vpn-instance-huawei] quit

[HUAWEI] ospf 100 vpn-instance huawei

[HUAWEI-ospf-100] route-tag 100