Deploying MPLS LDP

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Configuration Roadmap

Figure 1-21  MPLS LDP topology 
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Configuration Roadmap

The configuration roadmap is as follows:

  1. Configure an LSR ID and enable MPLS LDP globally and on each interface.
  2. Configure synchronization between LDP and OSPF to prevent traffic loss caused by switchovers of the primary and backup LSPs.
  3. Configure LDP GR so that traffic forwarding is not interrupted upon primary/backup switchovers and protocol restarts.
  4. Configure BFD for LSP to quickly detect LDP LSP faults on the core ring.

Data Plan

imgDownload?uuid=7b2929a95a544ba68576cc7 NOTE:

The data provided in this section is used as an example, which may vary depending on the network scale and topology.

Plan data before configuring MPLS LDP.

Table 1-19  MPLS parameters

Parameter

Value

Remarks

mpls lsr-id

IP address of LSR loopback interface 1

Configure LSR IDs before running MPLS commands.

label advertise

non-null

Disable penultimate hop popping (PHP) because it affects switchover performance.

bfd bind ldp-lsp

discriminator local

discriminator remote

detect-multiplier

min-tx-interval

min-rx-interval

process-pst

Configure static BFD for LDP LSPs.

Set the local discriminator of the local system to be the same as the remote discriminator of the remote system, and adjust the local detection multiplier of BFD.

Set the minimum interval at which BFD packets are sent and received to 3.3 ms.

Allow BFD sessions to change the port status table (PST) to speed up switchovers.

Enabling MPLS LDP

Procedure

  • Configure SPEs.

    The following uses the configuration of Core_SPE1 on the core ring as an example. The configurations of Core_SPE2 and Core_SPE3 are similar to the configuration of Core_SPE1, and are not mentioned here.

    mpls lsr-id 172.16.0.5    //Configure an MPLS LSR ID. The IP address of a loopback interface is recommended. mpls    //Enable MPLS globally.  label advertise non-null    //Disable PHP so that the egress node assigns labels to the penultimate hop properly. # mpls ldp    //Enable MPLS LDP globally. # interface Eth-Trunk4  mpls  mpls ldp    //Enable MPLS LDP on an interface. # interface Eth-Trunk5  mpls  mpls ldp    //Enable MPLS LDP on an interface. # interface Eth-Trunk17  mpls  mpls ldp    //Enable MPLS LDP on an interface. # interface XGigabitEthernet6/0/4  mpls  mpls ldp    //Enable MPLS LDP on an interface. #

  • Configure UPEs.

    The following uses the configuration of Site1_UPE1 as an example. The configurations of Site1_UPE2, Site2_UPE3, Site2_UPE4, Site3_UPE5, and Site3_UPE6 are similar to the configuration of Site1_UPE1, and are not mentioned here.

    mpls lsr-id 172.16.2.51    //Configure an MPLS LSR ID. The IP address of a loopback interface is recommended. mpls    //Enable MPLS globally.  label advertise non-null     //Disable PHP so that the egress node assigns labels to the penultimate hop properly. # mpls ldp    //Enable MPLS LDP globally. # interface Eth-Trunk7  mpls  mpls ldp    //Enable MPLS LDP on an interface. # interface Eth-Trunk17  mpls  mpls ldp    //Enable MPLS LDP on an interface. #

Checking the Configuration
  • Run the display mpls ldp session all command to view the MPLS LDP session status. Using Core_SPE1 as an example, if the value of Status is Operational, an MPLS LDP session has been set up successfully.

    [Core_SPE1]display mpls ldp session all  LDP Session(s) in Public Network  Codes: LAM(Label Advertisement Mode), SsnAge Unit(DDDD:HH:MM)  A '*' before a session means the session is being deleted.  ------------------------------------------------------------------------------  PeerID             Status      LAM  SsnRole  SsnAge      KASent/Rcv  ------------------------------------------------------------------------------  172.16.0.3:0       Operational DU   Passive  0000:00:56  226/226  172.16.0.4:0       Operational DU   Active   0000:00:56  226/226  172.16.2.51:0      Operational DU   Passive  0000:00:55  223/223  172.16.2.86:0      Operational DU   Passive  0000:00:55  223/223  ------------------------------------------------------------------------------  TOTAL: 4 session(s) Found.

Configuring Synchronization Between LDP and OSPF

Context

LDP LSRs set up LSPs using OSPF. When an LDP session fault (non-link fault) occurs on the primary LSP or the primary LSP recovers from a fault, synchronization between LDP and OSPF can prevent traffic loss caused by switchovers of the primary and backup LSPs.

Procedure

  • Configure SPEs.

    The following uses the configuration of Core_SPE1 on the core ring as an example. The configurations of Core_SPE2 and Core_SPE3 are similar to the configuration of Core_SPE1, and are not mentioned here.

    interface Eth-Trunk4  ospf ldp-sync    //Enable synchronization between LDP and OSPF on the protected interface.  ospf timer ldp-sync hold-down 20    //Set a Hold-down time that an interface uses to delay setting up an OSPF neighbor relationship until an LDP session is set up. # interface Eth-Trunk5  ospf ldp-sync  ospf timer ldp-sync hold-down 20 # interface Eth-Trunk17  ospf ldp-sync  ospf timer ldp-sync hold-down 20 # interface XGigabitEthernet6/0/4  ospf ldp-sync  ospf timer ldp-sync hold-down 20 #

  • Configure UPEs.

    The following uses the configuration of Site1_UPE1 as an example. The configurations of Site1_UPE2, Site2_UPE3, Site2_UPE4, Site3_UPE5, and Site3_UPE6 are similar to the configuration of Site1_UPE1, and are not mentioned here.

    interface Eth-Trunk7  ospf ldp-sync  ospf timer ldp-sync hold-down 20 # interface Eth-Trunk17  ospf ldp-sync  ospf timer ldp-sync hold-down 20 #

Configuring LDP GR

Context

LDP GR can be configured so that traffic forwarding is not interrupted upon primary/backup switchovers and protocol restarts.

Procedure

  • Configure SPEs.

    The following uses the configuration of Core_SPE1 on the core ring as an example. The configurations of Core_SPE2 and Core_SPE3 are similar to the configuration of Core_SPE1, and are not mentioned here.

    mpls ldp  graceful-restart    //Enable LDP GR. #

  • Configure UPEs.

    The following uses the configuration of Site1_UPE1 as an example. The configurations of Site1_UPE2, Site2_UPE3, Site2_UPE4, Site3_UPE5, and Site3_UPE6 are similar to the configuration of Site1_UPE1, and are not mentioned here.

    mpls ldp  graceful-restart #

Configuring BFD for LSP

Context

To ensure reliability of LDP LSPs between SPEs on the core ring, configure BFD to detect LDP LSPs quickly.

Procedure

  • Configure SPEs.

    The following uses the configuration of Core_SPE1 on the core ring as an example. The configurations of Core_SPE2 and Core_SPE3 are similar to the configuration of Core_SPE1, and are not mentioned here.

    bfd SPE1toSPE2 bind ldp-lsp peer-ip 172.16.0.3 nexthop 172.17.4.9 interface Eth-Trunk4    //Enable static BFD to detect the LDP LSP between SPE1 and SPE2.  discriminator local 317    //Set the local discriminator. The local discriminator of the local system must be the same as the remote discriminator of the remote system.  discriminator remote 137    //Set the remote discriminator.  detect-multiplier 8    //Set the local detection multiplier of BFD.  min-tx-interval 3    //Set the minimum interval at which the local device sends BFD packets to 3.3 ms.  min-rx-interval 3    //Set the minimum interval at which the local device receives BFD packets to 3.3 ms.  process-pst    //Allow BFD sessions to change the PST to speed up switchovers.  commit    //Commit the BFD session configuration. # bfd SPE1toSPE3 bind ldp-lsp peer-ip 172.16.0.4 nexthop 172.17.4.3 interface Eth-Trunk5    //Enable static BFD to detect the LDP LSP between SPE1 and SPE3.  discriminator local 32  discriminator remote 23  detect-multiplier 8  min-tx-interval 3  min-rx-interval 3  process-pst  commit #

Checking the Configuration
  • Run the display bfd session all for-lsp command to check the BFD for LSP session status. Using Core_SPE1 as an example, if BFD sessions with the tunnel type being S_LDP_LSP are all in Up state, BFD for LSP sessions have been set up successfully.

    [Core_SPE1]display bfd session all for-lsp -------------------------------------------------------------------------------- Local Remote     PeerIpAddr      State     Type         InterfaceName            -------------------------------------------------------------------------------- 32    23         172.16.0.4      Up        S_LDP_LSP    Eth-Trunk4                317   137        172.16.0.3      Up        S_LDP_LSP    Eth-Trunk5               --------------------------------------------------------------------------------      Total UP/DOWN Session Number : 2/0

See more please click 

https://support.huawei.com/enterprise/en/doc/EDOC1000069520/9aadccc0/comprehensive-configuration-examples


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