tracert ipv6-sid

Function

The tracert ipv6-sid command specifies SIDs and enables the system to trace gateways that packets pass through from the source to the destination on an SRv6 network.

Format

tracert ipv6-sid [ -f first-hop-limit | -m max-hop-limit | -p port-number | -q probes | -w timeout | -s packetsize | -a source-ipv6-address ] ^* [ overlay ] sid1 [ sid2 [ sid3 [ sid4 [ sid5 [ sid6 [ sid7 [ sid8 [ sid9 [ sid10 [ sid11 ] ] ] ] ] ] ] ] ] ] [ network-slice sliceid [ force-match-slice ] ]

Parameters

Parameter	Description	Value
-f first-hop-limit	Specifies the initial hop-limit. The hop-limit (TTL) field in the IPv6 packet header specifies the maximum number of hops that an IPv6 packet can pass through. This field is similar to the TTL field in IPv4. The value of the hop-limit field is set on the source host that sends the packet. The value of the hop-limit field decreases by 1 each time the packet passes through a router. When the value of the hop-limit field is 0, the packet is discarded. At the same time, an ICMPv6 timeout packet is sent to notify the source host. If first-hop-limit is set and the number of hops is smaller than the value of this parameter, the nodes that the packet passes through do not return ICMPv6 timeout packets to the source host because the value of the hop-limit field is greater than 0. If max-hop-limit is specified, the value of first-hop-limit must be smaller than that of max-hop-limit. This parameter cannot be specified for an overlay test.	The value is an integer ranging from 1 to 255. The default value is 1.
-m max-hop-limit	Specifies the maximum hop-limit. Generally, the value of max-hop-limit is set to the number of hops that packets pass through. When you need to modify the hop-limit value, use this parameter. If first-hop-limit is specified, the value of max-hop-limit must be greater than that of first-hop-limit. This parameter cannot be specified for an overlay test.	The value is an integer ranging from 1 to 255. The default value is 30.
-p port-number	Specifies the UDP port number of the destination host.	The value is an integer ranging from 1 to 65535. The default value is 33434.
-q probes	Specifies the number of probe packets to be sent each time. When the network quality is poor, you can increase the number of probe packets to ensure that the probe packets can reach the destination node.	The value is an integer that ranges from 1 to 65535. The default value is 3.
-w timeout	Specifies the timeout period for waiting for a response packet. When sending a data packet to a gateway times out, "*" is displayed. If the network quality is poor and the transmission speed is slow, you are advised to increase the timeout interval for sending data packets.	The value is an integer that ranges from 1 to 65535, in milliseconds. The default value is 5000 milliseconds.
-s packetsize	Specifies the packet size.	The value is an integer ranging from 20 to 9600, in bytes. The default value is 20.
-a source-ipv6-address	Specifies the source IPv6 address of packets configured using the tracert ipv6-sid command. If no source IPv6 address is specified, the address configured using the encapsulation source-address command is preferentially used in SRv6 BE scenarios. In other scenarios, the IPv6 address of the outbound interface is used as the source address for sending packets.	The value is a 32-digit hexadecimal number, in the format X:X:X:X:X:X:X:X.
overlay	Indicates overlay detection.	-
sid1	Specifies an SRv6 SID.	The value is a 32-digit hexadecimal number, in the format X:X:X:X:X:X:X:X. A maximum of 11 SRv6 SIDs can be specified, which are separated by spaces. The first specified SID is the outer SID.
network-slice sliceid	Specifies the ID of a network slice.	The value is an integer ranging from 1 to 4294967295.
force-match-slice	Forcibly matches network slices. This parameter takes effect only for the segment list with slice attributes.	-

Views

All views

Default Level

0: Visit level

Task Name and Operations

Task Name	Operations
sla	execute

Usage Guidelines

Usage Scenario

On an SRv6 network, if data forwarding fails over SRv6, the control plane for SRv6 establishment cannot detect this failure, making network maintenance difficult.

If a fault occurs on an SRv6 network, run the ping ipv6-sid command to check network connectivity and then run the tracert ipv6-sid command to locate fault points for diagnosis.

You can specify different parameters in the tracert ipv6-sid command in various test scenarios.

To check information about nodes between the source and destination on a network with poor quality, run the tracert ipv6-sid -q probes -w timeout sid & <1-11> command. If network reliability is poor, setting large values for the -q and -w parameters is recommended to obtain accurate test results.
To check the nodes along a specified segment of a path, run the tracert ipv6-sid -f first-hop-limit -m max-hop-limit sid & <1-11> command with the specified initial hop-limit and the maximum hop-limit.

Prerequisites

The UDP module of the initiator works properly.
The ICMPv6 module of the destination device works properly.

Implementation Procedure

The process of the

tracert ipv6-sid command is as follows:

The source sends a packet with the hop-limit of 1. After the hop-limit times out, the first hop sends an ICMPv6 Error message to the source, indicating that the packet cannot be forwarded.
The source sends a packet with the hop-limit of 2. After the hop-limit times out, the second hop sends an ICMPv6 Error message to the source, indicating that the packet cannot be forwarded.
The source sends a packet with the hop-limit of 3. After the hop-limit times out, the third hop sends an ICMPv6 Error message to the source, indicating that the packet cannot be forwarded.
The preceding process continues until the packet reaches the destination.
After receiving an IPv6 packet, the destination device sends an ICMPv6 Port Unreachable message to the source device because the packet is trying to access an invalid port at the destination device. This message indicates that the port is unreachable and the tracert ipv6-sid command execution is finished. The purpose behind this is to record the source of each ICMPv6 Time Exceeded message to provide a trace of the path the packet took to reach the destination.

Precautions

By default, the ICMPv6 module is automatically enabled after the IPv6 module is enabled.

Example

# Perform a tracert test on an SRv6 network.

<HUAWEI> tracert ipv6-sid 2001:DB8:10::1 2001:DB8:20::2 2001:DB8:30::3
  traceroute ipv6-sid 2001:DB8:10::1 2001:DB8:20::2 2001:DB8:30::3  30 hops max,60 bytes packet
1  2001:DB8:1:2::21(SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1, SL=2) 5 ms 3 ms 2 ms
2  2001:DB8:2:3::31(SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1, SL=1) 5 ms 2 ms 2 ms
3  2001:DB8:30::3(SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1, SL=1) 5 ms 10 ms 0.759 ms

# Initiate a tracert test on an SRv6 network and specify a network slice ID to forcibly match the network slice.

<HUAWEI> tracert ipv6-sid 2001:DB8:10::1 2001:DB8:20::2 2001:DB8:30::3 network-slice 100 force-match-slice
  traceroute ipv6-sid 2001:DB8:10::1 2001:DB8:20::2 2001:DB8:30::3  30 hops max,60 bytes packet
1  2001:DB8:1:2::21(SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1, SL=2, Slice-ID:100) 5 ms 3 ms 2 ms
2  2001:DB8:2:3::31(SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1, SL=1, Slice-ID:100) 5 ms 2 ms 2 ms
3  2001:DB8:30::3(SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1, SL=1, Slice-ID:100) 5 ms 10 ms 0.759 ms

**Table 1** Description of the **tracert ipv6-sid** command output
Item	Description
traceroute ipv6-sid HH:HH::HH:H x hops max,x bytes packet	traceroute ipv6-sid HH:HH::HH:H: SRv6 SIDs sent from a host to a destination device. x hops max: maximum hop limit (hop-limit) of tracert packets. x bytes packet: size of the packet to be sent.
1 2001:DB8:1:2::21(SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1, SL=2, Slice-ID:100) 5 ms 3 ms 2 ms	"1" indicates the first hop gateway. The sequence number increases by one each time a hop is added. "2001:DB8:1:2::21" indicates the response address of the packet. "SRH: 2001:DB8:30::3, 2001:DB8:20::2, 2001:DB8:10::1" indicates the SRH information of the path along which the tracert operation is performed. "SL=2" indicates the number of remaining SRv6 segments. "Slice-ID":100 indicates the network slice ID. "5 ms 3 ms 2 ms" indicates the round-trip time (RTT), in milliseconds.