tracert vc -vpn-instance

Function

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

Format

tracert vc -vpn-instance vpn-instance-name local-ce-id remote-ce-id [ -exp exp-value | -f firstTtl | -m maxTtl | -r reply-mode | -t timeout | -g ] ^* { control-word | label-alert [ no-control-word ] } [ full-lsp-path ] [ detail ] [ bypass -si { sourceIfName | sourceIfType sourceIfNum } ]

Parameters

Parameter	Description	Value
local-ce-id	Specifies the ID of the local CE.	It is a decimal integer ranging from 0 to 65534.
remote-ce-id	Specifies the ID of the remote CE.	It is a decimal integer ranging from 0 to 65534.
-exp exp-value	Specifies the 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 firstTtl	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 maxTtl	Specifies the value of the maximum TTL.	It is a decimal integer ranging from 1 to 255 and must be larger 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.	It is a decimal integer ranging from 1 to 4.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.
-t timeout	Specifies the timeout period for waiting for MPLS echo reply packets.	The value is a decimal integer ranging from 0 to 65535 ms. By default, the value is 5.
-g	Performs the test using MPLS fragments.	-
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.	-
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.	-
detail	Displays details carried in MPLS Echo Reply packets.	-
bypass	Forwards packets through a specified public bypass LSP of a PW.	-
-si sourceIfName	Specifies the name of an inbound interface. Sets the inbound interface of MPLS ECHO-REQUEST packets to simulate a remote device to send packets. It can be used to detect the fault of the packet forwarding path that enters through a specific interface.	-
sourceIfType	Specifies the name of an inbound type.	-
sourceIfNum	Specifies the name of an inbound number.	-
-vpn-instance vpn-instance-name	Specifies the VPN instance name.	It is a string of 1 to 31 case-sensitive characters without spaces.

Views

All views

Default Level

0: Visit level

Task Name and Operations

Task Name	Operations
sla	execute

Usage Guidelines

Usage Scenario

After an echo reply packet is received, packet information is displayed.

After the control word is encapsulated, in the case of a multi-segment PW, on the switch node, if the TTL value of the label does not time out, the echo request packet is not sent to the CPU. In control word mode, the source obtains less PW information, but the performance of the node is seldom affected and meanwhile the source is unaware of the downstream information about this switch 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-segment PW, on the switch node, the echo request packet is sent to the CPU. In router alert mode, the source obtains more PW information, but in the case of a great number of packets, the performance of the node is affected severely. In the case of a small number of packets, the router alert mode is recommended.

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   10.2.2.2/[21505 1026 ]
  1     10.2.2.2           60 ms   Transit   10.3.3.3/[1026 ]
  2     10.3.3.3           50 ms   Transit   10.4.4.4/[3 ]
  3     10.1.1.1           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.