Introduction
In this article, we will explore the concept of pings and received packets in the context of a LAN (Local Area Network) cable connection. We will answer the question of why pings still show received packets even when the LAN cable is disconnected. The article will cover the key concepts related to this topic and provide detailed explanations and examples.
What is a Ping?
A ping is a network utility used to test the connectivity between two devices on a network. It sends a small packet of data, known as an ICMP (Internet Control Message Protocol) echo request, to the target device and waits for a response, which is an ICMP echo reply. The time taken for the response to be received is measured and used to determine the network latency or the round-trip time (RTT) between the two devices.
How does a Ping work?
When a ping command is issued, the following steps occur:
- The operating system sends an ICMP echo request packet to the target device's IP address.
- The target device receives the packet and sends an ICMP echo reply packet back to the source device.
- The operating system measures the time taken for the reply packet to be received and displays the result in milliseconds.
What are Received Packets?
Received packets refer to the number of packets that have been successfully received by a device on a network. In the context of a ping, the number of received packets refers to the number of ICMP echo reply packets that have been received by the source device.
How are Received Packets measured?
The number of received packets is measured by counting the number of ICMP echo reply packets that are received by the source device in response to the ICMP echo request packets that were sent. This information is typically displayed in the output of the ping command.
Why do Pings still show Received Packets when the LAN Cable is Disconnected?
The reason why pings still show received packets even when the LAN cable is disconnected is due to the way that the ping command works. When a ping command is issued, the source device sends out the ICMP echo request packets and waits for a response. Even if the LAN cable is disconnected, the source device will still receive a response from its own local network interface, indicating that the packet was sent and received by the same device.
Example
For example, let's say that you have a laptop with an IP address of 192.168.1.100 and a subnet mask of 255.255.255.0. You issue a ping command to the IP address of another device on the network, but you accidentally disconnect the LAN cable while the ping is still in progress.
C:\>ping 192.168.1.101
Pinging 192.168.1.101 with 32 bytes of data:
Reply from 192.168.1.100: Destination host unreachable.
Reply from 192.168.1.100: Destination host unreachable.
Reply from 192.168.1.100: Destination host unreachable.
Reply from 192.168.1.100: Destination host unreachable.
Ping statistics for 192.168.1.101:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0msAs you can see from the output, the ping command still shows that 4 packets were received, even though the LAN cable was disconnected. This is because the source device received the ICMP echo reply packets from its own local network interface, indicating that the packets were sent and received by the same device.
In this article, we have explored the concept of pings and received packets in the context of a LAN cable connection. We have answered the question of why pings still show received packets even when the LAN cable is disconnected. By understanding how pings and received packets work, you can better troubleshoot network connectivity issues and improve your network knowledge.
References
- ICMP (Internet Control Message Protocol) RFC 792
- Ping Command Microsoft Docs
- IP Addressing Microsoft Docs