-p pattern: Sets the padding content for test packets, which is a hexadecimal number in the range of 0
to FFFFFFFF. For example, -p ff pads FF to all test packets. By default, 0x55 and 0xAA are padded
alternately.
ascending: Pads test packets with a hexadecimal number from 0x00 to 0xff in turn.
descending: Pads test packets with a hexadecimal number from 0xff to 0x00 in turn.
random: Pads test packets with a hexadecimal number from 0xff to 0x00 at random.
-s packetsize: Sets the size of test packets (excluding the 12-byte packet header), in the range of 0 to
1688 bytes. The default size is 52 bytes.
-t timeout: Sets the timeout time for receiving looped-back test packets, in the range of 0 to 65535
milliseconds. The default timeout time is 2000 milliseconds.
interface type number: Specifies an interface.
Usage guidelines
Use this command to detect loops on interfaces. The system returns the following line quality information:
Information about each test packet. If a test packet is looped back, the number of bytes, sequence
•
number, and delay are displayed for the test packet. If a test packet is not looped back before the
timeout timer expires, the system displays " Wait time out."
Statistics for all test packets, including the numbers of sent, received, lost, and error packets,
•
percentages for error and lost packets, and the conclusion.
If the line speed is slow, increase the timeout time.
Examples
# Perform a loop test on Serial 1/0/0.
<Sysname> looptest interface serial 1/0/0
LOOPTEST Serial1/0/0: 52 data bytes, press CTRL_C to break
Receive from Serial1/0/0: bytes=52 sequence=1 time=1 ms
Receive from Serial1/0/0: bytes=52 sequence=2 time=1 ms
Receive from Serial1/0/0: bytes=52 sequence=3 time=1 ms
Receive from Serial1/0/0: bytes=52 sequence=4 time=1 ms
Receive from Serial1/0/0: bytes=52 sequence=5 time=1 ms
--- Serial1/0/0 looptest statistics ---
5 packet(s) transmitted
5 packet(s) received
0 packet(s) lost
0 packet(s) error
0.00% packet lost
0.00% packet error
round-trip min/avg/max = 1/1/1 ms
conclusion: loopback
Related commands
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fe1 loopback
ft1 loopback
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loopback
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