tracert vc vpn-instance

Function

The tracert vc vpn-instance command detects the hop-by-hop connectivity of the LSP between PEs in the Kompella networking.

Format

tracert vc -vpn-instance vpn-name local-ce-id remote-ce-id [ -exp exp-value | -f first-ttl | -m max-ttl | -r reply-mode | -t timeout-value ] ^* { control-word | label-alert [ no-control-word ] | draft6 } [ full-lsp-path ]

Parameters

Parameter	Description	Value
-vpn-instance vpn-name	Specifies the VPN instance name.	The value is an existing VPN instance name.
local-ce-id	Specifies the ID of the local CE.	It is a decimal integer ranging from 0 to 249.
remote-ce-id	Specifies the ID of the remote CE.	It is a decimal integer ranging from 0 to 249.
-exp exp-value	specifies value of the EXP field in an outer label in an Echo Request packet.	It is a decimal integer ranging from 0 to 7.
-f first-ttl	Specifies the value of the first TTL.	It is a decimal integer ranging from 1 to 255 and must be smaller than max-ttl. By default, the value is 1.
-m max-ttl	Specifies the value of the maximum TTL.	It is a decimal integer ranging from 1 to 255 and must be greater than the value of first-ttl. By default, the value is 30.
-r reply-mode	Specifies the mode in which the peer responds to the Echo Reply packet. The meaning of each value is as follows: 1: indicates no reply. 2: indicates a reply with an IPv4 or IPv6 UDP datagram. 3: indicates a reply with an IPv4 or IPv6 datagram carrying an MPLS router alert label. 4: indicates a reply through the control channel of the application plane.	It is a decimal integer ranging from 1 to 4.
-t timeout-value	Specifies the timeout period for waiting for MPLS Echo Reply packets.	The value is a decimal integer ranging from 0 ms to 65535 ms. By default, the value is 5.
control-word	Indicates the control word encapsulated in packets.	-
label-alert	Indicates the router alert label encapsulated in packets.	-
no-control-word	Disables the control word mode.	-
draft6	Indicates the version of the command. If the parameter is specified, the command is implemented according to draft-ietf-mpls-lsp-ping-06. By default, the command is implemented according to RFC 4379.	-
full-lsp-path	Displays information about responses of all nodes along the LSP that an Echo Request packet passes. If this parameter is not specified, only the response of each PW node along the LSP is displayed.	-

Views

All views

Default Level

0: Visit level

Usage Guidelines

Usage Scenario

In a Kompella networking, if any node on the backbone network fails, use this command to identify the faulty node.

The tracert vc vpn-instance command applies to the following networking scenarios:

Kompella VLL PW tracert

In Kompella VLL networking, you can start a VLL PW tracert to check PW connectivity.

A VLL PW tracert can help you obtain information about PEs and Ps along the path that the message travels from the source to the destination, check the connectivity of the Layer 2 forwarding link, and locate faults of the PW.

Different from the PWE3 VLL PW tracert, the Kompella VLL tracert does not need the PW template and can be performed in control word mode or label alert mode. The default mode is label alert. Like PWE3 VLL PW tracert, Kompella VLL tracert can be enabled using a command.

Precautions

If the control word is encapsulated in MPLS echo request packets on a multi-hop PW, the packets on the switch node are not sent to the CPU for processing until the TTL times out. In control word mode, the source obtains less PW information, but the performance of the node is seldom affected and the source is unaware of the downstream information about this transit node. When there are a large number of packets, the control word mode is recommended.

After the router alert is encapsulated, in the case of a multi-hop PW, on the transit node, the Echo Request packet is sent to the CPU. In Label Alert mode, the source obtains more PW information. However, when a large number of packets are transmitted, the performance of the node degrades severely. The Label Alert mode is recommended when a small number of packets are transmitted on the network.

Example

# Perform the Tracert test on the VPN instance named vpn1 in label-alert mode.

<HUAWEI> tracert vc -vpn-instance vpn1 1 2 label-alert full-lsp-path

  TTL   Replier            Time    Type      Downstream
  0                                Ingress   20.1.1.1/[21505 1026 ]
  1     20.1.1.1           60 ms   Transit   30.1.1.1/[1026 ]
  2     30.1.1.1           50 ms   Transit   40.1.1.1/[3 ]
  3     4.4.4.4            70 ms   Egress

**Table 1** Description of the **tracert vc vpn-instance** command output
Item	Description
TTL	TTL of MPLS Echo Request packets, indicating the number of hops along the tunnel that the packets pass.
Replier	Source IP address in an Echo Reply packet.
Time	How long a packet is processed
Type	Type of a node: Ingress Transit Egress
Downstream	Address and label of the downstream node