Configuring LDP Sessions

Context

The MPLS LDP session is classified into local LDP sessions and remote LDP sessions. You can choose one of the following configurations according to your requirements:

Configuring a local LDP session

In most cases, you need to configure a local LDP session when deploying MPLS LDP services.
Configuring a remote LDP session

The remote LDP session is set up between two indirectly connected LSRs, and is applied in the L2VPN and LDP over TE scenarios.
- Allocate inner L2VPN labels.
  
  If a Martini VLL or VPLS connection is to be established between two LSRs, the remote LDP session must be established between the LSRs to allocate inner labels.
- Configure LDP over TE.
  
  If the core devices on an MPLS network support TE while edge devices use LDP, you need to configure a remote LDP session between the two edge LSRs on the TE network. After LDP over TE is configured, the TE tunnel is regarded as a hop of the entire LDP LSP.

A local LDP session and a remote LDP session can coexist. That is, two LSRs can establish a local LDP session and a remote LDP session simultaneously. In this case, configurations of the local and remote LDP sessions at both ends must be the same.

Procedure

Configuring a local LDP session
Perform the following steps on two directly connected LSRs.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The view of the interface on which the LDP session is to be set up is displayed.
3. (Optional) On an Ethernet interface, run undo portswitch
  The interface is switched to Layer 3 mode.
  
  By default, an Ethernet interface works in Layer 2 mode.
  
  Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
4. Run mpls
  MPLS is enabled on the interface.
  
  By default, no interface is enabled with MPLS.
5. Run mpls ldp
  MPLS LDP is enabled on the interface.
  
  By default, no interface is enabled with LDP.
Configuring a remote MPLS LDP session
Perform the following steps on the LSRs on both ends of a remote LDP session.
1. Run system-view
  The system view is displayed.
2. Run mpls ldp remote-peer remote-peer-name
  The remote peer is created and the remote peer view is displayed.
3. Run remote-ip ip-address
  The IP address of the remote MPLS LDP peer is configured.
  
  By default, the IP address of the remote LDP peer is not configured.
  
  This IP address must be the LSR ID of the remote MPLS LDP peer. If the LSR IDs of the LDP instance and the local node are different, use the LSR ID of the LDP instance.
  - Modifying or deleting the IP address of a remote peer leads to deletion of the remote LDP session and MPLS service interruption.
  - After the IP address of the remote peer is configured using the remote-ip ip-address command, the value of ip-address cannot be used as the IP address of the local interface. Otherwise, the remote session will be interrupted, causing MPLS service interruption.