Troubleshooting MPLS

MPLS TE issues

MPLS TE tunnel down

Symptom

After an MPLS TE tunnel is created, the display interface tunnel command shows that the tunnel's current state is DOWN.

<Sysname> display interface tunnel 1

Tunnel1

Current state: DOWN

Line protocol state: DOWN

Description: Tunnel1 Interface

Bandwidth: 64kbps

Maximum transmission unit: 1496

Internet address: 7.1.1.1/24 (primary)

Tunnel source unknown, destination 4.4.4.9

Tunnel TTL 255

Tunnel protocol/transport CR_LSP

Last clearing of counters: Never

Last 300 seconds input rate: 0 bytes/sec, 0 bits/sec, 0 packets/sec

Last 300 seconds output rate: 6 bytes/sec, 48 bits/sec, 0 packets/sec

Input: 0 packets, 0 bytes, 0 drops

Output: 177 packets, 11428 bytes, 0 drops

Common causes

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

·     The link where the MPLS TE tunnel is located is down.

·     The configuration for the MPLS TE tunnel is incorrect.

·     The destination address of the MPLS TE tunnel is referenced by a static route.

Troubleshooting flow

Figure 1 shows the troubleshooting flowchart.

Figure 1 Flowchart for troubleshooting MPLS TE tunnel down

 

Solution

To resolve the issue:

1.     Verify that the MPLS TE tunnel’s output interface on the device is in up state.

Execute the display interface command to view the state of the output interface for the MPLS TE tunnel. Make sure the output interface is in up state.

2.     Verify that the MPLS TE configuration is correct.

Check the following settings in sequence:

a.     Make sure the mpls te enable command is configured in the OSPF/IS-IS area and on the interfaces that the MPLS TE tunnel passes through.

b.     Make sure the LSR ID and Router ID are the same Loopback interface address.

c.     If the MPLS TE tunnel is established using RSVP-TE, make sure the device and interfaces are configured with the rsvp and rsvp enable commands.

d.     If the mpls te bandwidth command is configured on the tunnel interface, make sure the device's output interface is configured with the mpls te max-link bandwidth and mpls te max-reservable bandwidth commands.

e.     If the mpls te affinity-attribute command is configured on the tunnel interface, make sure the mpls te link-attribute command is configured properly on the output interface. To ensure a link can be used by a tunnel, the following requirements must be met:

-     The link attribute bits corresponding to the 1 bits in the affinity mask are checked as follows: The link attribute bits corresponding to the 1 bits of the affinity attribute must have a minimum of one bit set to 1. The link attribute bits corresponding to the 0 bits of the affinity attribute must have no bit set to 1.

-     The link attribute bits corresponding to the 0 bits in the affinity mask are not checked.

f.     If the MPLS TE tunnel is established using Segment Routing, make sure segment routing related settings are configured in the IGP area of the device.

g.     If the MPLS TE tunnel is established by using an explicit path specified with the mpls te path command, verify that the explicit path configuration is appropriate: To use the strict mode, you must specify the IP address of the incoming interface hop by hop; to use the loose mode, you must specify the node address of the each device to be passed through.

3.     Verify that the destination address of the MPLS TE tunnel is not used by a static route.

4.     Execute the display current-configuration | include destination command to check whether the destination address of the MPLS TE tunnel is referenced by a static route. If it is referenced by a static route, modify the static route or change the destination address of the tunnel according to the actual network requirements.

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

¡     Results of each step.

¡     The configuration file of the device.

¡     Diagnostic information collected using the display diagnostic-information command.

Related alarm and log messages

Alarm messages

N/A

Log messages

N/A

MPLS TE tunnel state changing from up to down

Symptom

The state of an MPLS TE tunnel has changed from UP to Down.

Common causes

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

·     The link where the MPLS TE tunnel is located is down.

·     The configuration of the MPLS TE tunnel has been deleted or incorrectly configured.

·     RSVP message timeouts or errors have occurred.

·     The physical link does not meet the required bandwidth for the MPLS TE tunnel.

·     The BFD session is down on the MPLS TE tunnel interface or the physical interface where the tunnel is located.

Troubleshooting flow

Figure 2 shows the troubleshooting flowchart.

Figure 2 Flowchart for troubleshooting MPLS TE tunnel state changing from up to down

 

Solution

To resolve the issue:

1.     Verify that the MPLS TE tunnel's output interface is in up state.

Execute the display interface command to view the state of the output interface for the MPLS TE tunnel. Make sure the output interface is in up state.

2.     Verify that the MPLS TE configuration is correct.

Check the following settings in sequence:

a.     Verify that the mpls te enable command is configured in the OSPF/IS-IS area and on the interfaces that the MPLS TE tunnel passes through.

b.     Verify that the LSR ID and Router ID the same Loopback interface address.

c.     If the MPLS TE tunnel is established using RSVP-TE, make sure the device and interfaces are configured with the rsvp and rsvp enable commands.

d.     If the mpls te bandwidth command is configured on the tunnel interface, make sure the device's output interface is configured with the mpls te max-link bandwidth and mpls te max-reservable bandwidth commands.

e.     If the mpls te affinity-attribute command is configured on the tunnel interface, make sure the mpls te link-attribute command is configured properly on the output interface. To ensure a link can be used by a tunnel, the following requirements must be met:

-     The link attribute bits corresponding to the 1 bits in the affinity mask are checked as follows: The link attribute bits corresponding to the 1 bits of the affinity attribute must have a minimum of one bit set to 1. The link attribute bits corresponding to the 0 bits of the affinity attribute must have no bit set to 1.

-     The link attribute bits corresponding to the 0 bits in the affinity mask are not checked.

f.     If the MPLS TE tunnel is established using Segment Routing, make sure segment routing related settings are configured in the IGP area of the device.

g.     If the MPLS TE tunnel is established by using an explicit path specified with the mpls te path command, verify that the explicit path configuration is appropriate: To use the strict mode, you must specify the IP address of the incoming interface hop by hop; to use the loose mode, you must specify the node address of the each device to be passed through.

3.     Verify that no RSVP message timeouts or errors exist.

4.     Use the display rsvp statistics command to check if there are RSVP message timeouts (i.e., the number of Path messages sent and Resv messages received do not match, or the number of Path messages received and Resv messages sent do not match) or RSVP message errors (i.e., receiving PathError messages or ResvError messages). If RSVP message timeouts or errors are found, capture the error information carried in the PathError or ResvError packets, and then resolve the issue according to the error codes by referring to RFC 2205 and RFC 3209.

<Sysname> display rsvp statistics

P2P statistics:

Object                 Added            Deleted

  PSB                  3                1

  RSB                  3                1

  LSP                  3                1

P2MP statistics:

Object                 Added            Deleted

  PSB                  0                0

  RSB                  0                0

  LSP                  0                0

 

Packet                 Received         Sent

  Path                 5                5

  Resv                 5                5

  PathError            0                0

  ResvError            0                0

  PathTear             0                0

  ResvTear             0                0

  ResvConf             0                0

  Bundle               0                0

  Ack                  0                0

  Srefresh             0                0

  Hello                0                0

  Challenge            0                0

  Response             0                0

  Error                0                0

5.     Verify that the physical link meets the bandwidth required for the MPLS TE tunnel.

6.     When an MPLS TE tunnel with a higher priority is established on the device, it might preempt the bandwidth of an MPLS TE tunnel with lower priority, causing the state of the lower priority MPLS TE tunnel to become down. Check the remaining available bandwidth for each priority on the link by using the display mpls te link-management bandwidth-allocation command, and ensure that the remaining available bandwidth on the link is greater than the bandwidth required by the tunnel of that priority. If the remaining available bandwidth on the link cannot meet the requirements of the MPLS TE tunnel, modify the configuration, adjust the tunnel path, or provide more bandwidth for the link.

7.     Verify that the BFD session for the MPLS TE tunnel interface or the tunnel's physical interface is not down.

8.     Use the display mpls bfd te tunnel tunnel-number command to view the BFD state of the MPLS TE tunnel. If the BFD state of the MPLS TE tunnel is down, use the display bfd session command to identify the reason for the BFD session down state. Examine and modify the BFD configuration and clear link faults or quality issues of the physical links.

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

¡     Results of each step.

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

Related alarm and log messages

Alarm messages

Module Name: MPLS-TE-STD-MIB

·     mplsTunnelUp (1.3.6.1.2.1.10.166.3.0.1)

·     mplsTunnelDown (11.3.6.1.2.1.10.166.3.0.2)

Log messages

·     IFNET/5/LINK_UPDOWN

·     IFNET/3/PHY_UPDOWN

Loop in an MPLS TE tunnel

Symptom

A loop exists in the forwarding path of the MPLS TE tunnel, preventing traffic from being forwarded to the destination address through the MPLS TE tunnel.

Common causes

The same IP address exists on different devices that the MPLS TE tunnel passes through.

Solution

To resolve the issue:

1.     Check if the same IP address has been configured on different devices that the MPLS TE tunnel passes through. If yes, change the IP addresses to ensure that no identical IP addresses exist on the different devices that the MPLS TE tunnel travels through.

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

¡     Results of each step.

¡     The configuration file of the device.

¡     Diagnostic information collected using the display diagnostic-information command.

Related alarm and log messages

Alarm messages

N/A

Log messages

N/A

Tunnel path computation failure

Symptom

The computation of the MPLS TE tunnel path failed, causing the tunnel to be down.

Common causes

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

·     No IGP neighbors have been established.

·     No MPLS TEDB information exists.

·     The configuration for the MPLS TE tunnel is incorrect.

Troubleshooting flow

Figure 3 shows the troubleshooting flowchart.

Figure 3 Flowchart for troubleshooting tunnel path computation failure

 

Solution

To resolve the issue:

1.     Verify that an IGP neighbor has been established.

Execute the display ospf peer or display isis peer command to check if an IGP neighbor has been established.

¡     If an IGP neighbor has been established, proceed to step 2.

¡     If no IGP neighbor has been established, complete the OSPF or IS-IS configuration to establish an IGP neighbor. For more information about OSPF and IS-IS, see OSPF configuration and IS-IS configuration respectively in the Layer 3—IP Routing Configuration Guide of the device.

2.     Execute the display mpls te tedb command to view the information of MPLS TEDB.

If MPLS TEDB information exists, proceed to step 3.

If MPLS TEDB information does not exist, check the following configurations in order:

a.     Verify that the mpls enable and mpls te enable commands are configured in the OSPF/IS-IS area and on the interfaces that the MPLS TE tunnel passes through.

b.     Verify that the LSR ID and Router ID the same Loopback interface address.

3.     Verify that the MPLS TE configuration is correct.

a.     If the MPLS TE tunnel is established using RSVP-TE, make sure the device and interfaces are configured with the rsvp and rsvp enable commands.

b.     If the MPLS TE tunnel is established using Segment Routing, make sure the segment-routing mpls command is configured in the IGP area of the device.

c.     If the mpls te bandwidth command is configured on the tunnel interface, make sure the device's output interface is configured with the mpls te max-link bandwidth and mpls te max-reservable bandwidth commands.

d.     If the mpls te affinity-attribute command is configured on the tunnel interface, make sure the mpls te link-attribute command is configured properly on the output interface. To ensure a link can be used by a tunnel, the following requirements must be met:

-     The link attribute bits corresponding to the 1 bits in the affinity mask are checked as follows: The link attribute bits corresponding to the 1 bits of the affinity attribute must have a minimum of one bit set to 1. The link attribute bits corresponding to the 0 bits of the affinity attribute must have no bit set to 1.

-     The link attribute bits corresponding to the 0 bits in the affinity mask are not checked.

e.     If the MPLS TE tunnel is established by using an explicit path specified with the mpls te path command, verify that the explicit path configuration is appropriate: To use the strict mode, you must specify the IP address of the incoming interface hop by hop; to use the loose mode, you must specify the node address of the each device to be passed through.

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

¡     Results of each step.

¡     The configuration file of the device.

¡     Diagnostic information collected using the display diagnostic-information command.

Related alarm and log messages

Alarm messages

N/A

Log messages

N/A

Hot-standby CRLSP establishment failure

Symptom

After the mpls te backup hot-standby command is configured for an MPLS TE tunnel, no hot-standby backup CRLSP is established as expected.

Common causes

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

·     The device has only one interface that is adjacent to the neighbor.

·     The configuration for the MPLS TE tunnel is incorrect.

Troubleshooting flow

Figure 4 shows the troubleshooting flowchart.

Figure 4 Flowchart for troubleshooting hot-standby CRLSP establishment failure.

 

 

Solution

To resolve the issue:

1.     According to the configured IGP protocol, execute the display ospf peer or display isis peer command to view information about the interfaces connected with the same neighbor (to the same System ID or Router ID).

# Display the summary information of IS-IS neighbors.

<Sysname> display isis peer

 

                         Peer information for IS-IS(1)

                         -----------------------------

 

 System ID: 0000.0000.0001

Interface: GE2/0/1                 Circuit Id:  0000.0000.0001.01

 State: Up     HoldTime:  27s       Type: L1(L1L2)     PRI: 64

 

 System ID: 0000.0000.0001

Interface: GE2/0/2                 Circuit Id:  0000.0000.0001.01

 State: Up     HoldTime:  27s       Type: L2(L1L2)     PRI: 64

# Display OSPF neighbor summary information.

<Sysname> display ospf peer

 

          OSPF Process 1 with Router ID 1.1.1.1

               Neighbor Brief Information

 

 Area: 0.0.0.0

 Router ID       Address         Pri Dead-Time  State             Interface

1.1.1.2         1.1.1.2         1   40         Full/DR           GE2/0/1

¡     If the number of interfaces connected to the neighbor is greater than or equal to 2, proceed to step 2.

¡     If the number of interfaces connected to the neighbor is less than 2, increase the physical links between the device and the neighbor to ensure a path is available for establishing the backup CRLSP.

2.     Verify that the MPLS TE configuration is correct.

Check the following settings in sequence:

a.     Verify that the mpls te enable command is configured in the OSPF/IS-IS area and on the interfaces that the MPLS TE tunnel passes through.

b.     Verify that the LSR ID and Router ID the same Loopback interface address.

c.     If the MPLS TE tunnel is established using RSVP-TE, make sure the device and interfaces are configured with the rsvp and rsvp enable commands.

d.     If the mpls te bandwidth command is configured on the tunnel interface, make sure the device's output interface is configured with the mpls te max-link bandwidth and mpls te max-reservable bandwidth commands.

e.     If the mpls te affinity-attribute command is configured on the tunnel interface, make sure the mpls te link-attribute command is configured properly on the output interface. To ensure a link can be used by a tunnel, the following requirements must be met:

-     The link attribute bits corresponding to the 1 bits in the affinity mask are checked as follows: The link attribute bits corresponding to the 1 bits of the affinity attribute must have a minimum of one bit set to 1. The link attribute bits corresponding to the 0 bits of the affinity attribute must have no bit set to 1.

-     The link attribute bits corresponding to the 0 bits in the affinity mask are not checked.

f.     If the MPLS TE tunnel is established using Segment Routing, make sure the segment-routing mpls command is configured in the IGP area of the device.

g.     If the MPLS TE tunnel is established by using an explicit path specified with the mpls te path command, verify that the explicit path configuration is appropriate: To use the strict mode, you must specify the IP address of the incoming interface hop by hop; to use the loose mode, you must specify the node address of the each device to be passed through.

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

¡     Results of each step.

¡     The configuration file of the device.

¡     Diagnostic information collected using the display diagnostic-information command.

Related alarm and log messages

Alarm messages

N/A

Log messages

TE/5/TE_BACKUP_SWITCH