Analyze network problems with the mmnetverify command

You can use the mmnetverify command to detect network problems and to identify nodes where a network problem exists.

The mmnetverify command is useful for detecting network problems and for identifying the type and node location of a network problem. The command can run 16 types of network checks in the areas of connectivity, ports, data, bandwidth, and flooding. For more information, see mmnetverify command.

The following examples illustrate some of the uses of this command:

Before you create a cluster, to verify that all your nodes are ready to be included in a cluster together, you can run the following command:
```
mmnetverify --configuration-file File connectivity -N all
```
This command runs several types of connectivity checks between each node and all the other nodes in the group and reports the results on the console. Because a cluster does not exist yet, you must include a configuration file File in which you list all the nodes that you want to test.
To check for network outages in a cluster, you can run the following command:
```
mmnetverify ping -N all
```
This command runs several types of ping checks between each node and all the other nodes in the cluster and reports the results on the console.
Before you make a node a quorum node, you can run the following check to verify that other nodes can communicate with the daemon:
```
mmnetverify connectivity port
```
To investigate a possible lag in large-data transfers between two nodes, you can run the following command:
```
mmnetverify data-large -N node2 --target-nodes node3 --verbose
min-bandwidth Bandwidth
```
This command establishes a TCP connection from node2 to node3 and causes the two nodes to exchange a series of large-sized data messages. If the bandwidth falls below the level that is specified, the command generates an error. The output of the command to the console indicates the results of the test.
To analyze a problem with connectivity between nodes, you can run the following command:
```
mmnetverify connectivity -N all --target-nodes all --verbose
--log-file File
```
This command runs connectivity checks between each node and all the other nodes in the cluster, one pair at a time, and writes the results of each test to the console and to the specified log file.