ping multicast

Function

The ping multicast command enables a device to detect the reserved members in the network segment, simulates the common group traffic, triggers the establishment of a distribution tree, and checks whether the network can normally bear multicast services.

Format

Parameters

Parameter	Description	Value
-c count	Specifies the number of times for sending ICMP Echo Request messages.	The value is an integer that ranges from 1 to 65535. The default value is 5.
-h ttl-value	Sets the TTL value of an ICMP Echo Request message.	The value is an integer that ranges from 1 to 255. The default value is 255.
-i interface-type interface-number	Sets the outgoing interface that sends ICMP Echo Request messages. When the MPing destination group address is a reserved multicast group address, -i must be specified. When the MPing destination group address is a common multicast group address, -i cannot be specified.	-
-m time	Specifies the time to wait before sending the next ICMP Echo Request message. Each time the source sends an ICMP Echo Request message using the ping multicast command, the source waits a period of time (2000 ms by default) before sending the next ICMP Echo Request message. You can set the time to wait before sending the next ICMP Echo Request message using the parameter time. In the case of poor network condition, the value should be equal to or larger than 2000, in milliseconds.	The value is an integer that ranges from 1 to 10000, in milliseconds. The default value is 2000.
-p pattern	Specifies the padding byte of ICMP Echo Request messages. After the padding byte of the ICMP Echo Request message is set, the destination host can identify a certain ICMP Echo Reply message.	The value ranges from 0 to FFFFFFFF, in the hexadecimal format. By default, the padding starts from 0x01, and continues in ascending order.
-q	Indicates that only statistics are displayed. When -q is specified in the ping multicast command, only the number of sent and received packets, packet loss rate, and the minimum, average, and maximum RTTs are displayed.	By default, all information is displayed.
-s packetsize	Sets the length of an ICMP Echo Request message, excluding the IP or ICMP header.	The value is an integer that ranges from 20 to 8100, in bytes. The default value is 56.
-t timeout	Specifies the timeout period to wait for an ICMP Echo Reply message after an ICMP Echo Request message is sent. After the ping multicast command is run, the source sends an ICMP Echo Request message to a destination and waits for an ICMP Echo Reply message. If the destination, after receiving the ICMP Echo Request message, returns an ICMP Echo Reply message to the source within the period specified by the parameter timeout, the destination is reachable. If the destination does not return an ICMP Echo Reply message within the specified period, the source displays a message indicating that the message times out. Normally, the source receives an ICMP Echo Reply message within 1 to 10 seconds after sending an ICMP Echo Request message. If the transmission speed is low, properly prolong the timeout period.	The value is an integer that ranges from 0 to 65535, in milliseconds. The default value is 2000.
-tos tos-value	Specifies the ToS value of the sent ICMP Echo Request messages.	The value is an integer that ranges from 0 to 255. The default value is 196.
-v	Displays all received ICMP Echo Reply messages. If -v is not specified, the system displays the received ICMP Echo Reply messages of the user. If -v is specified, the system displays all received ICMP Echo Reply messages.	By default, only ICMP Echo Reply messages of the user are displayed.
host	Specifies the destination address of an ICMP Echo Request message, also called the MPing destination group address.	It includes reserved group addresses and common group addresses.

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Usage Guidelines

Usage Scenario

The ping multicast command is used to check a multicast network in the following scenarios:

Scenario 1: When configuring the destination group address host as a reserved group address, you can run the ping multicast command to check which reserved multicast members reside on the network segment of the outbound interface. In this scenario, the TTL of an ICMP Echo Request message cannot be set.

The reserved multicast group identifies a group of network devices (reserved multicast members) that match certain conditions. When the reserved multicast members receive ICMP Echo Request messages with the destination addresses as the reserved group addresses, they return ICMP Echo Reply messages. Common reserved group addresses are as follows:

224.0.0.1: indicates all systems in the subnet.
224.0.0.2: indicates all routers in the subnet.
224.0.0.5: indicates OSPF IGP routers.
224.0.0.13: indicates PIM routers.

In this scenario, -i must be specified in the ping multicast command.

Scenario 2: When setting the destination group address host as a common group address, you can run the ping multicast command to implement the following functions:

Simulates the multicast traffic and triggers a series of protocol processes. By viewing the multicast routing information on the switch, check whether the protocol running status is normal and whether the multicast distribution tree is correctly established.
Check multicast members in the network and calculate the TTL value and the RTT from the MPing initiator to multicast members. This function requires that the host support MPing and is implemented by calculating the number of ICMP Echo Reply messages sent by the destination host. MPing is performed continuously at a certain interval to calculate the network delay and route jitter.

In this scenario, -i cannot be specified in the ping multicast command.

You can specify different parameters in ping multicast command for different scenarios:

On an unstable network, you can run the ping multicast -c count -t timeout host command to check the quality of the multicast network. By analyzing the packet loss rate and average delay in the command output, you can evaluate the network quality. If the network is unreliable, set the packet transmission count (-c) and timeout (-t) to the upper limits. This makes the test result accurate.
You can run the ping multicast -s packetsize host to set the size of a multicast probe packet. In this way, you can check the quality of the multicast network by simulating real service datagrams. The path MTU is then obtained through multiple probes.

Prerequisites

Before running the ping multicast command, ensure that the ICMP module is working properly.

Configuration Impact

If an intermediate device is disabled from responding to ICMP messages, detection on this node fails.

Precautions

If a fault occurs in the MPing process, you can press Ctrl+C to terminate the MPing operation.

Example

# Perform MPing, specify the reserved multicast group address as 224.0.0.5 and the outbound interface as VLANIF 100, and detect the OSPF IGP router in the network segment.

<HUAWEI> ping multicast -i vlanif 100 224.0.0.5

MULTICAST PING 224.0.0.5 : 56 data bytes, press Ctrl+C to break
Reply from 10.1.1.5 : bytes=56 Sequence=1 TTL =255 time=30ms
Reply from 10.1.1.5 : bytes=56 Sequence=2 TTL =255 time=10ms
Reply from 10.1.1.5 : bytes=56 Sequence=3 TTL =255 time=10ms
Reply from 10.1.1.5 : bytes=56 Sequence=4 TTL =255 time=20ms
Reply from 10.1.1.5 : bytes=56 Sequence=5 TTL =255 time=10ms
Destination multicast address 224.0.0.5
--- Multicast ping statistics ---
5 Request packet(s) transmitted
5 Reply packet(s) received
0.00% packet loss
Round-trip min/avg/max = 10/16/40 ms

# Specify the padding field of -p.

<HUAWEI> ping multicast -i vlanif 100 -p 12345678 224.0.0.5

MULTICAST PING 224.0.0.5 : 56 data bytes, press Ctrl+C to break
The padding string: 12345678
Reply from 10.1.1.5 : bytes=56 Sequence=1 TTL =255 time=30ms
Reply from 10.1.1.5 : bytes=56 Sequence=2 TTL =255 time=10ms
Reply from 10.1.1.5 : bytes=56 Sequence=3 TTL =255 time=10ms
Reply from 10.1.1.5 : bytes=56 Sequence=4 TTL =255 time=20ms
Reply from 10.1.1.5 : bytes=56 Sequence=5 TTL =255 time=10ms
Destination multicast address 224.0.0.5
--- Multicast ping statistics ---
5 Request packet(s) transmitted
5 Reply packet(s) received
0.00% packet loss
Round-trip min/avg/max = 10/16/40 ms

**Table 1** Description of the ping multicast command output
Item	Description
MULTICAST PING 224.0.0.5	The destination group address of MPing is 224.0.0.5.
56 data bytes	The length of the sent ICMP Echo Request message is 56 bytes.
press Ctrl+C to break	The ongoing MPing test can be terminated by pressing Ctrl+C.
The padding string: 12345678	The padding string is 12345678. If -p is not specified, the padding character string is not displayed.
Reply from 10.1.1.5: bytes=56 Sequence=1 TTL=255 time=30ms	The ICMP Echo Reply message sent from 10.1.1.5 is received. The message carries the following information: bytes=56: indicates the length of the ICMP Echo Reply message. Sequence=1: indicates the sequence number of the ICMP Echo Reply message. TTL=255: indicates the TTL value of the ICMP Echo Reply message. time=30ms: indicates the RTT, in milliseconds. If no ICMP Echo Reply message is received after the timeout period, "Request time out" is displayed.
Destination multicast address 224.0.0.5	The destination group address is 224.0.0.5.
--- Multicast ping statistics --- 5 Request packet(s) transmitted 5 Reply packet(s) received 0.00% packet loss Round-trip min/avg/max = 10/16/40 ms	Statistics collected after the Ping test on the destination host. The statistics are as follows: Number of sent ICMP Echo Request messages: 5 Number of received ICMP Echo Reply messages: 5 Percentage of non-Reply messages against total sent messages: 0.00% The minimum RTT is 10 ms, the average RTT is 16 ms, and the maximum RTT is 40 ms.