Docker Containers - Connectivity Test

When Docker starts, it creates a virtual interface called “Ethernet bridge” on the Docker server. The Ethernet bridge automatically forwards packets to/from the Docker to the external network interfaces. Every time, Docker creates the containers, it creates a pair of “peer” interfaces that are like opposite ends of a pipe. The packets sent through one of the peer interfaces will be received by the other peer interface. By binding the peer interfaces to the Ethernet bridge, Docker creates a virtual subnet shared between the Docker server and every Docker container so as to ensure uninterrupted communication between the Docker server and the Docker containers. For a connection to be uninterrupted, it is essential to keep track of the network delay as well as the packet loss. The Docker Containers – Connectivity test helps administrators to keep track of such delays and loss.

This test monitors the network connectivity to the Docker containers from an external location.

Target of the test : A Docker server

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each container available in the target Docker server being monitored.

Configurable parameters for the test

Parameter	Description
Test Period	How often should the test be executed.
Host	The IP address of the host for which this test is to be configured.
Port	The port number at which the specified HOST listens. The default is 2375.
UseSUDO	By default, this flag is set to Yes. You are advised not to change the default setting of this flag.
PacketSize	Here, specify the size of the packets used for the test.
PacketCount	Here, specify the number of packets to be transmitted during the test.
Timeout	Specify the maximum time (in seconds) that the test should wait for the response to a transmitted packet. A response received after the TIMEOUT period is ignored by the test. The default timeout period is 100 seconds.
PacketInterval	Represents the interval (in milliseconds) between successive packet transmissions during the execution of the test for a specific target.

Measurements made by the test

Measurement	Description	Measurement Unit	Interpretation
Network availability of container	Indicates whether/not the network connection to this container is available.	Percent	A value of 100 indicates that this container is accessible over the network. The value 0 indicates that the container is inaccessible. Typically, the value 100 corresponds to a Packet loss of 0.
Avg network delay	Indicates the average delay between transmission of packets to this container and receipt of the response to the packet at the source.	Secs	Ideally, the value of this measure should be low.
Min network delay	The minimum time between transmission of a packet and receipt of the response back.	Secs	A significant increase in the minimum round-trip time is often a sure sign of network congestion.
Packet loss	Indicates the percentage of packets lost during transmission from source to target and back.	Percent	Packet loss is often caused by network buffer overflows at a network router or by packet corruptions over the network. The detailed diagnosis for this measure provides a listing of routers that are on the path from the external agent to target server, and the delays on each hop. This information can be used to diagnose the hop(s) that could be causing excessive packet loss/delays.