Troubleshooting MPLS

Troubleshooting MPLS L2VPN/VPLS

A PW failed to be pinged

Symptom

Execute the ping mpls pw command to test PW connectivity. However, the remote end cannot be pinged.

Common causes

The following are the common causes of this type of issue:

·     The PW being tested does not exist.

·     The PW template configuration is incorrect.

·     The PW has failed.

·     The PW does not have a valid forwarding path on the public network.

Analysis

To troubleshoot this type of issue, execute the ping mpls pw command, and then identify the cause of the issue depending on the received error message.

·     If you receive the Unknown PW error message, the issue occurs because the PW does not exist. You must modify the configuration to make sure the PW can be created correctly.

·     If the error message is No suitable control channel for the PW, check for VCCV control channel type misconfiguration. Then, execute the vccv cc command to specify the correct VCCV control channel type in the PW template.

·     If the error message is Please configure pseudowire control-word for control channel, execute the control-word enable command to enable the control word feature in the PW template.

·     If the error message is Request time out, identify whether the local PW is up, and then execute the tracert mpls pw command to locate the faulty node.

Figure 1 shows the troubleshooting flowchart.

Figure 1 Flowchart for troubleshooting ping failure

 

Solution

To resolve the issue:

If you receive the Unknown PW message, modify the configuration to ensure that the PW can be correctly created.

If you receive the No suitable control channel for the PW message, execute the vccv cc command to configure the same VCCV control channel type for both ends.

If you receive the Please configure pseudowire control-word for control channel message, execute the control-word enable command to enable the control word feature in the PW template.

If you receive the Request time out message, perform the following steps:

1.     Execute the display l2vpn pw command to verify that the PW is up.

<Sysname> display l2vpn pw

Flags: M - main, B - backup, E - ecmp, BY - bypass, H - hub link, S - spoke link

       N - no split horizon, A - administration, ABY - ac-bypass

       PBY - pw-bypass

Total number of PWs: 2

2 up, 0 blocked, 0 down, 0 defect, 0 idle, 0 duplicate

 

Xconnect-group Name: ldp

Peer            PWID/RmtSite/SrvID In/Out Label   Proto  Flag Link ID  State

192.3.3.3       500                1299/1299      LDP    M    0        Up

 

VSI Name: aaa

Peer            PWID/RmtSite/SrvID In/Out Label   Proto  Flag Link ID  State

2.2.2.9         2                  1420/1419      BGP    M    9        Up

¡     If the PW is in Down state, execute the display l2vpn pw verbose command to check for the failure reason and troubleshoot the issue.

<Sysname> display l2vpn pw verbose

VSI Name: aaa

  Peer: 2.2.2.9          Remote Site: 2

    Signaling Protocol  : BGP

    Link ID             : 9          PW State : Down

    In Label            : 1420       Out Label: 1419

    MTU                 : 1500

    PW Attributes       : Main

    VCCV CC             : -

    VCCV BFD            : -

    Flow Label          : Send

    Control Word        : Disabled

    Tunnel Group ID     : 0x800000960000000

    Tunnel NHLFE IDs    : 1038

    Admin PW            : -

    E-Tree Mode         : -

    E-Tree Role         : root

    Root VLAN           : -

    Leaf VLAN           : -

    Down Reasons        : Control word not match

The common causes of this type of issue are as follows:

-     BFD session for PW down—The BFD session for PW detection is down. To resolve this issue, execute the display bfd session command to display BFD session information. Check and edit BFD configuration or check the physical link for link failure or link quality issues.

-     BGP RD was deleted—The BGP RD has been deleted. To resolve this issue, execute the route-distinguisher route-distinguisher command in auto-discovery VSI view.

-     BGP RD was empty—No BGP RD is configured. To resolve this issue, execute the route-distinguisher route-distinguisher command in auto-discovery VSI view.

-     Control word not match—The control word configuration on the two ends of the PW is inconsistent. To resolve this issue, execute the control-word enable command to enable the control word feature on both ends.

-     Encapsulation not match—The encapsulation types on the two ends of the PW are inconsistent. Execute the pw-type command to configure the same encapsulation type for the two ends.

-     LDP interface parameter not match—The LDP negotiation parameters on the two ends of the PW are inconsistent. To resolve this issue, execute the vccv cc command to specify the same VCCV control channel (CC) type. Alternatively, specify the same CEM class for the CEM interfaces on both ends of the PW.

-     Non-existent remote LDP PW—The remote device has deleted the LDP PW. To resolve the issue, reconfigure the LDP PW on the remote device.

-     Local AC Down—The local AC is down. To resolve the issue, check and edit the configuration on the AC interface or troubleshoot the issue on the interface where the AC is located and make Assurance interface is in up state.

-     Local AC was non-existent—The local AC did not exist. To resolve this issue, configure a local AC and associate it with a VSI.

-     MTU not match—The MTU is not the same at the two ends of the PW. To resolve the issue, configure the same MTU at both ends of the PW or use the mtu-negotiate disable command to disable MTU negotiation.

-     Remote AC Down—The remote AC is down. Check and edit the configuration on the AC interface or troubleshoot the issue on the interface where the AC is located and make Assurance interface is in up state.

¡     If the PW is in up state, go to step 2.

2.     Execute the display l2vpn forwarding pw verbose command to verify that the In Label, Out Label, and Tunnel NHLFE IDs related to the tunnel that carries the PW are valid.

<Sysname> display l2vpn forwarding pw verbose

Xconnect-group Name: xcg1

 Connection Name: c1

  Link ID: 0

    PW Type           : VLAN                  PW State : Up

    In Label          : 110126                Out Label: 130126

    MTU               : 1500

    PW Attributes     : Main

    VCCV CC           : Router-Alert

    VCCV BFD          : Fault Detection with BFD

    Flow Label        : -

    Tunnel Group ID   : 0x800000130000001

    Tunnel NHLFE IDs  : 3

VSI Name: aaa

  Link ID: 8

    PW Type         : VLAN                  PW State : Up

    In Label        : 1272                  Out Label: 1275

    MTU             : 1500

    PW Attributes   : Main

    VCCV CC         : -

    VCCV BFD        : Fault Detection with BFD

    Flow Label      : -

    Tunnel Group ID : 0x960000000

    Tunnel NHLFE IDs: 1034

¡     If the values for the incoming and outgoing labels are empty or a hyphen (-), first execute the display l2vpn pw verbose command to check for the protocol that established the PW and then edit the configuration as follows:

-     If the protocol is BGP, check and edit BGP configuration.

-     If the protocol is LDP, check and edit LDP configuration.

-     If the protocol is Static, check and edit static PW configuration.

For more information about protocol that are used establish PWs, see MPLS L2VPN and VPLS in the MPLS Configuration Guide for your device.

¡     If no value is available for the Tunnel NHLFE IDs field, go to step 3.

¡     If the forwarding information for the PW is normal, go to step 4.

3.     Execute the display mpls lsp command to check for the tunnel that carries the PW. The tunnel is an LSP with the FEC as the PW peer IP address. If it does not exist, establish the tunnel that carries the PW.

<Sysname> display mpls lsp

FEC                         Proto    In/Out Label    Out Inter/NHLFE/LSINDEX

100.100.100.100/24          LDP      -/1049          GE2/0/1

4.     If the issue persists, collect the following information and contact Technical Support:

¡     Results of each step.

¡     The configuration file, log messages, and alarm messages.

¡     Use the display diagnostic-information command to collect diagnostic information.

Related alarm and log messages

Alarm messages

None.

Log messages

·     L2VPN/2/L2VPN_PWSTATE_CHANGE

·     L2VPN/4/L2VPN_BGPVC_CONFLICT_LOCAL

·     L2VPN/4/L2VPN_BGPVC_CONFLICT_REMOTE

·     L2VPN/4/L2VPN_HARD_RESOURCE_NOENOUGH

·     L2VPN/2/L2VPN_HARD_RESOURCE_RESTORE

·     L2VPN/4/L2VPN_LABEL_DUPLICATE