tracert ipv6

Function

The tracert ipv6 command enables the system to trace gateways that packets pass through from the source to the destination with an IPv6 address.

Format

tracert ipv6 [ -f first-hop-limit | -m max-hop-limit | -p port-number | -q probes | -w timeout | vpn-instance vpn-instance-name | -s size | -name | -a source-ipv6-address | -v | -nexthop nextHopAddr | -passroute | { -tc tc | -dscp dscp } | -service-class classValue ] ^* host-name [ -i { ifName | ifType ifNum } ]

tracert ipv6 [ -f first-hop-limit | -m max-hop-limit | -p port-number | -q probes | -w timeout | { vpn-instance vpn-instance-name [ peer peerIpv6 ] } | -s size | -name | -a source-ipv6-address | -v | -nexthop nextHopAddr | -passroute | { -tc tc | -dscp dscp } ] ^* host-name [ -i { ifName | ifType ifNum } ]

Parameters

Parameter	Description	Value
-f first-hop-limit	Specifies the initial hop-limit. Carried in the IPv6 header, the hop-limit field indicates the lifetime of the IPv6 packet and specifies the maximum number of devices through which the packet can pass. The hop-limit field in IPv6 packets is similar to the TTL field in IPv4 packets. The hop-limit value is set on the source and reduced by 1 each time the packet passes through one device. When the hop-limit value is reduced to 0, the packet is discarded. At the same time, an ICMPv6 Timeout packet is sent to the source. If first-hop-limit is specified and the number of hops is less than the specified value, the hop-limit value will be greater than 0 after the packet passes through all the nodes. Therefore, no ICMPv6 Timeout packet is sent to the source. If max-hop-limit is specified, the value of first-hop-limit must be smaller than the value of max-hop-limit.	The value is an integer that ranges from 1 to 255. The default value is 1.
-m max-hop-limit	Specifies the maximum hop-limit. Usually, the maximum hop-limit is set to the number of hops through which packets passes. Use this parameter to change hop-limit. If first-hop-limit is specified, max-hop-limit must be greater than first-hop-limit.	The value is an integer that ranges from 1 to 255. The default value is 30.
-p port-number	Specifies the UDP port number of the destination. If no UDP port number is specified for the destination, when you run the tracert ipv6 command, a port with the port number greater than 32768 is randomly selected for the destination to receive trace packets. The UDP port number to be specified must not in use. If a used UDP number is specified, the trace test fails.	The value is an integer ranging from 1 to 65535. The default value is 33434.
-q probes	Specifies the number of test packets sent in a trace test instance. In the case of poor network qualities, increase value so that a test packet can reach the destination.	The value is an integer ranging from 1 to 65535. The default value is 3.
-w timeout	Specifies the period of time for waiting for a response. If a test packet reaches a gateway and times out, an asterisk (*) is displayed. In the case of poor network qualities and a low network transmission rate, increase the timeout period.	The value is an integer ranging from 1 to 65535, in milliseconds. The default value is 5000.
vpn-instance vpn-instance-name	Specifies the name of a VPN instance.	The value is a string of 1 to 31 case-sensitive characters.
-s size	Specifies the size of a packet.	The value is an integer that ranges from 20 to 9600.
-a source-ipv6-address	Specifies the source IPv6 address of an ICMPv6 echo request packet to be sent. If no source IPv6 address is specified, the IPv6 address of the outbound interface through which ICMPv6 echo request packets are sent is used as the source address.	The value is a 32-digit hexadecimal number, in the format of X:X:X:X:X:X:X:X.
-name	Displays the host name of the destination address.	-
-v	Displays packet details, including MPLS label information.	-
-nexthop nextHopAddr	Specifies an IPv6 address for the next hop. If you have specified this parameter, the device no longer searches the routing table before sending UDP packets.	The value is a 32-digit hexadecimal number, in the format of X:X:X:X:X:X:X:X. The specified next hop address must be the next hop address of a directly connected physical interface. When specifying the next hop address, you can configure -i interface-type interface-number to specify the outbound interface. The following conditions must be met to ensure a test success: The specified next hop address matches the outbound interface. The specified outbound interface cannot be a member interface of a logical interface. When you specify the next hop address, you cannot specify a VPN.
-passroute	Sends UDP packets without searching for the routing table.	-
-tc tc	Specifies the traffic class of ICMPv6 Echo Request messages. You can specify traffic-class-value to control ICMPv6 Echo Request messages.	The value is an integer that ranges from 0 to 255. The default value is <b>0</b>.
-dscp dscp	Specifies a DSCP value for ICMPv6 Echo Request packets to be sent.	The value is an integer in the range from 0 to 63. The default value is <b>0</b>.
host-name	Specifies the name or the IPv6 address of a destination host.	The value is a string of 1 to 255 characters. If the IPv6 address of a destination is specified, the value is in the format of X:X:X:X:X:X:X:X.
-i ifName	Sets the interface name for sending UDP messages.	The value is a string of 1 to 63 case-sensitive characters. It cannot contain spaces.
ifType	Sets the interface type for sending UDP messages.	-
ifNum	Sets the interface number for sending UDP messages.	The value is a string of 1 to 63 case-insensitive characters. It cannot contain spaces.
-service-class classValue	In an SRv6 TE Policy group scenario, you can specify this parameter to select a path.	Enumerated type. Range: {be,af1,af2,af3,af4,ef,cs6,cs7}.
peer peerIpv6	Specifies a peer SID, that is, the address of the last hop in the SRv6 domain, in EVPN L3VPN over SRv6 BE scenarios.	The value is a 32-digit hexadecimal number, in the format of X:X:X:X:X:X:X:X.

Views

All views

Default Level

0: Visit level

Task Name and Operations

Task Name	Operations
sla	execute

Usage Guidelines

Usage Scenario

You can run the ping ipv6 command to check the connectivity of the network and then run the tracert ipv6 command to locate the faulty node.

You can specify different parameters in the tracert ipv6 command in various test scenarios:

To check information about nodes between the source and destination IPv6 hosts, run the tracert ipv6 host command.
To check information about nodes between the source and destination IPv6 hosts on an L3VPN, run the tracert ipv6 -vpn-instance vpn-instance-name host command. On an L3VPN, devices may not have each other's routing information. In this case, the tracert ipv6 host command cannot be used to check the connectivity between the devices. The peer end can be reached only through the VPN. You can run the tracert ipv6 vpn-instance vpn-instance-name host command to view information about nodes between the source and destination in a specified VPN instance.
When the network environment is poor, you can run the tracert ipv6 -q probes -w timeout host command to check information about nodes between the source and destination IPv6 hosts. For a network with poor reliability, you are advised to set -q and -w to larger values to obtain more accurate detection information.
Run the tracert ipv6 -f first-hop-limit -m max-hop-limit host command and specify the start hop-limit (first-hop-limit) and the maximum hop-limit (max-hop-limit) to detect the nodes on a certain segment of a path.
You can run the tracert ipv6 -v command to display the label information of the tracert path.

Prerequisites

The UDP module of each node is working properly. If the UDP module is not working properly, the tracert ipv6 command fails to be run.
If vpn-instance is configured, the VPN module must work properly.
The ICMPv6 module of the node works properly. Otherwise, "* * *" is returned.

Implementation Procedure

The process of the tracert ipv6 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 repeats until the packet reaches the destination.
After the destination device of each hop receives the IPv6 packet, the destination device sends an ICMPv6 Port Unreachable message to the source device because the port specified in the packet is not applied to the destination device. This message indicates that the destination port is unreachable and the tracert ipv6 command is executed. In the command output of the source device, you can view the path that the packet passes through.

Precautions

By default, the ICMPv6 module is automatically enabled after the IPv6 module is enabled.
In an SRv6 TE flow group scenario where routes are recursed based on DSCP values, if the -service-class keyword is specified, the tracert ipv6 command fails to be run.

Example

# Perform a tracert test with the destination address being 2001:DB8:2::1.

<HUAWEI> tracert ipv6 -v 2001:DB8:2::1
traceroute to 2001:DB8:2::1 30 hops max,60 bytes packet
1 2001:DB8:1::2 81 ms 1 ms 1 ms 
2 2001:DB8:10::3[MPLS Label=32830/32829 Exp=0/0 S=0/1 TTL=1/1] 310 ms 1 ms 2 ms 
3 2001:DB8:20::4[MPLS Label=32830/32829 Exp=0/0 S=0/1 TTL=1/1] 118 ms 2 ms 1 ms 
4 2001:DB8:2::2 142 ms 1 ms 2 ms 
5 2001:DB8:2::1 95 ms 2 ms 2 ms

# Perform reverse domain name parsing to convert the IPv6 address into a domain name.

<HUAWEI> tracert ipv6 -name -f 1 -m 3 -p 65535 -q 2 2001:db8::1
 traceroute to 2001:DB8::1 (www.huawei.com) 3 hops max,60 bytes packet
 1 2001:DB8::1 67 ms  14

# Perform forward domain name parsing to convert the domain name into an IPv6 address.

<HUAWEI> tracert ipv6 -name -f 1 -m 3 -p 65535 -q 2 www.huawei.com
 Resolved Host ( www.huawei.com -> 2001:db8::1 )
 traceroute to www.huawei.com (2001:DB8::1)  3 hops max,60 bytes packet
 1 2001:DB8::1 66 ms  22 ms

# Trace the gateways along a specified segment of a path between the source host and the destination host at 2001:db8:100::3. Set the initial hop-limit and maximum hop-limit.

<HUAWEI> tracert ipv6 -f 2 -m 64 2001:db8:100::3
traceroute to vpn_out 2001:DB8:100::3 30 hops max,60 bytes packet
 1 2001:DB8:200::2 26 ms  23 ms  26 ms
 2 2001:DB8:300::1 47 ms 32 ms 33 ms
 3 2001:DB8:400::2 63 ms 46 ms 47 ms
 4 2001:DB8:100::3 78 ms 79 ms 62 ms

# Trace the gateways from the source to the destination at 2001:db8:100::3 on a specified L3VPN.

<HUAWEI> tracert ipv6 vpn-instance vsi6 2001:db8:100::3
traceroute to 2001:DB8:100::3  30 hops max,60 bytes packet
 1 2001:DB8:200::2 26 ms  23 ms  26 ms
 2 2001:DB8:100::2 3020 ms  !H 3024 ms  !H 4040 ms  !H

# Trace the gateways from the source to the destination at 2001:db8:100::3. Configure the test packets to be sent for 5 times and the timeout period to 8000 ms.

<HUAWEI> tracert ipv6 -q 5 -w 8000 2001:db8:100::3
traceroute to 2001:DB8:100::3 30 hops max,60 bytes packet
1 2001:DB8:200::2 26 ms 23 ms 26 ms 30 ms 29 ms 
2 2001:DB8:100::3 3020 ms 3024 ms 4040 ms 6820 ms 5584 ms

**Table 1** Description of the **tracert ipv6** command output
Item	Description
traceroute to HH:HH::HH:H	Destination IPv6 address.
1	Sequence number of the received ICMPv6 Echo Response packet.
x hops max	Maximum hop-limit.
x bytes packet	Size of a test packet.
HH:HH::HH:H	Address of a reply.
x ms x ms x ms	Round-Trip Time (RTT) value, in milliseconds.
MPLS Label	MPLS label value.
Exp	Traffic priority.
TTL	Time to live.