set-df

Function

The set-df command disables packet fragmentation based on the Don't Fragment(DF) bit. After that, the packet will not be fragmented.

The undo set-df command enables packet fragmentation.

By default, fragmentation is allowed.

Format

set-df

undo set-df

Parameters

None

Views

NQA view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
sla	write

Usage Guidelines

Usage Scenario

In path MTU detection, to prevent packet fragmentation, run the set-df command. By increasing the packet size, the path MTU is obtained.

You can check the path MTU by using a trace test instance as follows:

Run the set-df command to disable packet fragmentation. Then, run the datasize command to set the size of the packet data area. After that, start the test instance. If the test is successful, the size of the sent packet's data area is smaller than the path MTU. Then, keep increasing the packet data area size using the datasize command until the test fails. If the test fails, the size of the sent packet's data area is greater than the path MTU.

Example

# Prevent packets sent in the test instance named user test from being fragmented.

<HUAWEI> system-view
[~HUAWEI] nqa test-instance user test
[*HUAWEI-nqa-user-test] test-type trace
[*HUAWEI-nqa-user-test] set-df