Using Tracert to Test the Forwarding Path on an MPLS Network
A tracert operation tests the path over which a label distribution protocol (LDP) label switched path (LSP) or a TE tunnel that carries IPv4 packets is established or locate the failure point on the path.
Prerequisites
If the device interworks with a non-Huawei device, run the lspv echo-reply compitable fec enable command to enable the device to respond to MPLS Echo Request packets with MPLS Echo Reply packets that do not carry FEC information.
As NQA is deployed on the main control board of a device, both the initiator and responder of an LSP ping test need to send LSP ping test packets to the main control board for processing. If a large number of packets are sent to the main control board, the CPU usage of the main control board increases, which adversely affects device operation. To prevent this problem, run the lspv mpls-lsp-ping cpu-defend cpu-defend command to set an upper limit for the rate of sending MPLS Echo Request packets to the main control board.
Procedure
- To test the path over which an LDP LSP that carries IPv4 packets is established or locate the failure point on the path, run:
tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -r reply-mode | -t time-out | -s size | -g ] * ip destination-iphost mask-length [ ip-address ] [ nexthop nexthop-address ] [ detail ]
For example:
<HUAWEI> tracert lsp ip 1.1.1.1 32 LSP Trace Route FEC: IPV4 PREFIX 1.1.1.1/32 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.1/[3 ] 1 1.1.1.1 5 Egress - To test the path over which a TE tunnel (RSVP-TE tunnel, static TE tunnel, or dynamic TE tunnel) that carries IPv4 packets is established or locate the failure point on the path, run:
tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -r reply-mode | -t time-out | -s size | -g ] * te { tunnelName | ifType ifNum } [ hot-standby | primary ] [ compatible-mode ] | auto-tunnel auto-tunnelname [ detail ]
<HUAWEI> tracert lsp te Tunnel 1 LSP Trace Route FEC: TE TUNNEL IPV4 SESSION QUERY Tunnel1 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.1/[3 ] 1 1.1.1.1 4 Egress - Test the path over which an SR-MPLS TE IPv4 tunnel is established or locate the failure point on the path.
To test an SR-MPLS BE tunnel dynamically created, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -t time-out | -s size | -g ] * segment-routing auto-tunnel auto-tunnelname [ version { draft2 | draft4 | rfc8287 } ] [ hot-standby | primary ] [ detail ] command and specify auto-tunnelname on the ingress to initiate a tracert test to the egress.
<HUAWEI> tracert lsp segment-routing auto-tunnel Tunnel10 version draft4 LSP Trace Route FEC: AUTO TE TUNNEL IPV4 SESSION QUERY Tunnel10 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.2/[284688 ] 1 10.1.1.2 7 ms EgressTo test an SR-MPLS TE IPv4 tunnel manually configured, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -t time-out | -s size | -g ] * segment-routing te { tunnelName | ifType ifNum } [ draft2 | rfc8287 ] [ hot-standby | primary ] [ detail ] command and specify tunnelName or ifType ifNum on the ingress to initiate a tracert test to the egress.
<HUAWEI> tracert lsp segment-routing te Tunnel10 LSP Trace Route FEC: AUTO TE TUNNEL IPV4 SESSION QUERY Tunnel10 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.2/[284688 ] 1 10.1.1.2 7 ms Egress
- Test the path over which an SR-MPLS BE IPv4 tunnel is established or the failure point on the path.
To test the failure point on an SR-MPLS BE IPv4 tunnel, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -s size | -g ] * segment-routing ip ip-address mask-length [ flex-algo flex-algo-id ] [ version draft2 ] [ bypass ] [ remote remote-ip ] command.
<HUAWEI> tracert lsp segment-routing ip 2.2.2.2 32 version draft2 LSP Trace Route FEC: SEGMENT ROUTING IPV4 PREFIX 2.2.2.2/32 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 192.168.1.2/[1001 ] 1 192.168.1.2 6 ms Transit 192.168.2.2/[3 ] 2 192.168.2.2 6 ms Egress - Test the BGP LSP carrying IPv4 packets or locate the failure point on the path.
Run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -r reply-mode | -t time-out | -s size | -g ] * bgp destination-iphost mask-length [ ip-address ] [ detail ] [ nexthop nexthop-address ] command to test the BGP LSP carrying IPv4 packets or locate the failure point on the path.
<HUAWEI> tracert lsp -h 5 bgp 4.4.4.4 32 LSP Trace Route FEC: IPV4 PREFIX 4.4.4.4/32 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.2/[32967 3 ] 1 10.1.1.2 5 ms Transit 10.2.1.2/[32938 3 ] 2 10.2.1.2 6 ms Transit 10.3.1.2/[32989 3 ] 3 4.4.4.4 1 ms Egress - Locate a failure point on an LDP LSP connected with an SR-MPLS BE tunnel.
To locate a failure point on an LDP LSP connected with an SR-MPLS BE tunnel, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -r reply-mode | -t time-out | -s size | -g ] * ip destination-iphost mask-length [ ip-address ] [ nexthop nexthop-address ] [ detail ] [ ddmap ] command on the ingress to initiate a tracert test to the egress of the SR-MPLS BE tunnel.
<HUAWEI> tracert -h 10 ip 1.1.1.1 32 ddmap LSP Trace Route FEC: IPV4 PREFIX 5.5.5.9/32 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.1/[66010 ] 1 10.1.1.1 9 ms Transit 10.1.1.2/[33182 ] 2 10.1.1.2 7 ms Transit 10.1.1.3/[319836 ] 3 10.1.1.3 9 ms Transit 192.168.1.2/[3 ] 4 5.5.5.9 3 ms Egress - Locate a failure point on an SR-MPLS BE tunnel connected with an LDP LSP.
To locate a failure point on an SR-MPLS BE tunnel connected with an LDP LSP, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -s size | -g ] * segment-routing ip ip-address mask-length [ flex-algo flex-algo-id ] [ version draft2 ] [ bypass ] remote remote-ip command on the ingress to initiate a tracert test to the egress with the destination address being the LDP LSP.
When testing the connectivity of an SR-MPLS BE tunnel connected with an LDP LSP, specify a remote IP address using the remote remote-ip parameter.
<HUAWEI> tracert lsp -h 10 segment-routing ip 5.5.5.9 32 version draft2 remote 5.5.5.9 LSP Trace Route FEC: SEGMENT ROUTING IPV4 PREFIX 5.5.5.9/32 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.1/[319546 ] 1 10.1.1.1 7 ms Transit 10.1.1.2/[319546 ] 2 10.1.1.2 7 ms Transit 10.1.1.3/[33517 3 ] 3 10.1.1.3 11 ms Transit 192.168.1.2/[3 ] 4 5.5.5.9 2 ms Egress - Locate a failure point on an LDP LSP connected with an SR-MPLS BE tunnel (the LDP end does not support interworking).
To locate a failure point on an LDP LSP connected with an SR-MPLS BE tunnel, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -r reply-mode | -t time-out | -s size | -g ] * ip destination-iphost mask-length [ ip-address ] [ nexthop nexthop-address ] [ detail ] [ ddmap ] command on the ingress to initiate a tracert test to the egress of the SR-MPLS BE tunnel.
You must run the lspv echo-reply fec-validation ldp disable command on the SR-MPLS BE side to disable the LSPV response end from checking the LDP FEC.
<HUAWEI> tracert lsp ip 1.1.1.1 32 LSP Trace Route FEC: IPV4 PREFIX 1.1.1.1/32 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.1/[3 ] 1 1.1.1.1 5 Egress - Locate a failure point on an SR-MPLS BE tunnel connected with an LDP LSP (the LDP end does not support interworking).
To locate a failure point on an SR-MPLS BE tunnel connected with an LDP LSP, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -s packet-size | -g | -t time-out ] * segment-routing ip ip-address mask-length [ flex-algo flex-algo-id ] [ version draft2 ] [ bypass ] [ remote-fec ldp remoteipaddr remotemasklen ] command on the ingress to initiate a tracert test to the egress with the destination address being the LDP LSP.
<HUAWEI> tracert lsp -h 10 segment-routing ip 5.5.5.9 32 version draft2 remote-fec ldp 5.5.5.9 32 LSP Trace Route FEC: SEGMENT ROUTING IPV4 PREFIX 5.5.5.9/32 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.1/[319546 ] 1 10.1.1.1 7 ms Transit 10.1.1.2/[319546 ] 2 10.1.1.2 7 ms Transit 10.1.1.3/[33517 3 ] 3 10.1.1.3 11 ms Transit 192.168.1.2/[3 ] 4 5.5.5.9 2 ms Egress - Test the path over which an SR-MPLS TE policy tunnel carrying IPv4 packets is established or the failure point on the path.
To locate a failure point on an SR-MPLS TE policy tunnel, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -s packet-size | -t time-out | -g ] * sr-te policy { policy-name policyname | endpoint-ip endpoint-ip color colorid | binding-sid bsid } command.
<HUAWEI> tracert lsp sr-te policy policy-name test LSP Trace Route FEC: Nil FEC, press CTRL_C to break. sr-te policy's segment list: Preference : 300; Path Type: main; Protocol-Origin : local; Originator: 0, 0.0.0.0; Discriminator: 300; Segment-List ID : 1; Xcindex : 1 TTL Replier Time Type Downstream 0 Ingress 10.1.2.1/[13312 12] 1 10.1.2.1 63 ms Transit 10.1.2.2/[12 ] 2 6.6.6.6 93 ms Egress sr-te policy's segment list: Preference : 400; Path Type: backup; Protocol-Origin : local; Originator: 0, 0.0.0.0; Discriminator: 400; Segment-List ID : 1; Xcindex : 1 TTL Replier Time Type Downstream 0 Ingress 10.1.2.1/[13312 12] 1 10.1.2.1 63 ms Transit 10.1.2.2/[12 ] 2 6.6.6.6 93 ms Egress - Test the path over which an inter-AS E2E SR-MPLS TE tunnel is established or locate the failure point on the path.
To locate a failure point on an inter-AS E2E SR-MPLS TE tunnel, run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -t time-out | -s packet-size | -g | -r reply-mode ] * segment-routing { { auto-tunnel srAutoTunnelName version { draft2 | draft4 } } | te { tunnelName | ifType ifNum } [ draft2 ] } [ hot-standby ] [ detail ] command.
<HUAWEI> tracert lsp segment-routing te Tunnel 11 draft2 LSP Trace Route FEC: SEGMENT ROUTING TE TUNNEL IPV4 SESSION QUERY Tunnel11 , press CTRL_C to break. TTL Replier Time Type Downstream 0 Ingress 10.1.1.2/[48061 48120 2000 ] 1 10.1.1.2 393 ms Transit 10.2.1.2/[48120 2000 ] 2 10.2.1.2 18 ms Transit 10.3.1.2/[2000 ] 3 10.3.1.2 23 ms Transit 10.4.1.2/[3 ] 4 5.5.5.9 30 ms Egress - Check the path information or locate a fault in an MPLS LDP ECMP load balancing scenario.
Run the tracert lsp [ -a source-ip | -exp exp-value | -h ttl-value | -r reply-mode | -t time-out | -s packet-size | -g ] * ip destination-iphost mask-length multi-loopback-address [ begin-address to end-address ] [ nexthop nexthopAddr ] [ ddmap ] command to locate the failure point of an ECMP load balancing path.
<HUAWEI> tracert lsp ip 3.3.3.3 32 multi-loopback-address 127.0.0.0 to 127.0.0.3 LSP Trace Route FEC: IPV4 PREFIX 3.3.3.3/32 , press CTRL_C to break. destination-ip-address: 127.0.0.0 TTL Replier Time Type 1 10.1.1.2 7 ms Transit 2 3.3.3.3 6 ms Egress destination-ip-address: 127.0.0.1 TTL Replier Time Type 1 10.2.1.2 4 ms Transit 2 3.3.3.3 4 ms Egress destination-ip-address: 127.0.0.2 TTL Replier Time Type 1 10.1.1.2 2 ms Transit 2 3.3.3.3 3 ms Egress destination-ip-address: 127.0.0.3 TTL Replier Time Type 1 10.2.1.2 2 ms Transit 2 3.3.3.3 2 ms Egress --- summary of all paths --- path 1 found TTL Replier Time Type 1 10.1.1.2 2 ms Transit 2 3.3.3.3 3 ms Egress path 2 found TTL Replier Time Type 1 10.2.1.2 2 ms Transit 2 3.3.3.3 2 ms Egress - (Optional) Run the display lspv statistics command to check LSPV packet statistics.
If the test using the tracert lsp command fails, you can run this command to check whether the fault occurs on the LSP or the device.
- (Optional) Run the reset lspv statistics command to clear LSPV packet statistics.
Follow-up Procedure
After the test is completed, you are advised to run the undo lspv mpls-lsp-ping echo enable/undo lspv mpls-lsp-ping echo enable ipv6 command to disable the device from responding to MPLS Echo Request/MPLS Echo Request IPv6 packets to prevent system resource occupation.