mpls bgp ttl-mode egress (MPLS-BGP-VPN instance view)

Function

The mpls bgp ttl-mode egress command sets a TTL processing mode for a BGP LSP egress.

The undo mpls bgp ttl-mode egress command restores the default TTL processing mode for a BGP LSP egress.

By default, the TTL processing mode of a BGP LSP egress is pipe.

Format

mpls bgp ttl-mode { uniform | pipe } egress

undo mpls bgp ttl-mode uniform egress

Parameters

Parameter	Description	Value
uniform	Sets the TTL processing mode to uniform for a BGP LSP egress.	-
pipe	Sets the TTL processing mode to pipe for a BGP LSP egress.	-

Parameter

Description

Value

uniform

Sets the TTL processing mode to uniform for a BGP LSP egress.

pipe

Sets the TTL processing mode to pipe for a BGP LSP egress.

Views

MPLS-BGP-VPN instance view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
bgp	write

Usage Guidelines

Usage Scenario

The BGP LSP egress processes the TTL of MPLS packets in either of the following mode:

Uniform mode
After an IP packet reaches the ingress of an LSP, its IP TTL decreases by 1 and is mapped to its MPLS TTL field. The MPLS TTL decreases by 1 at each hop along the LSP. After the packet reaches the egress, the egress reduces the MPLS TTL by 1 and maps the MPLS TTL value to the IP TTL field before forwarding the packet.
Pipe mode
On the ingress, the IP TTL in each packet decreases by 1, and the MPLS TTL is a fixed value. Then the MPLS TTL decreases by 1 at each hop along the LSP, and the IP TTL decreases by 1 only on the ingress and egress along the LSP.

Example

# Set the TTL processing mode to uniform for a BGP LSP egress.

<HUAWEI> system-view
[~HUAWEI] ip vpn-instance vpna
[*HUAWEI-vpn-instance-vpna] quit
[*HUAWEI] mpls
[*HUAWEI-mpls] quit
[*HUAWEI] bfd
[*HUAWEI-bfd] quit
[*HUAWEI] mpls bgp vpn-instance vpna
[*HUAWEI-mpls-bgp-vpn-instance-vpna] mpls bgp ttl-mode uniform egress