Learn how to create Consul network segments to enable services in the LAN gossip pool to communicate across communication boundaries.
---
# Create Network Segments
This topic describes how to create Consul network segments so that services can connect to other services in the LAN gossip pool that have been placed into separate communication boundaries. Refer to [Network Segments Overview](/consul/docs/enterprise/network-segments/network-segments-overview) for additional information.
## Requirements
- Consul Enterprise 0.9.3+
## Define segments in the server configuration
1. Add the `segments` block to your server configuration. Refer to the [`segments`](/consul/docs/agent/config/config-files#segments) documentation for details about how to define the configuration.
In the following example, an `alpha` segment is configured to listen for traffic on port `8303` and a `beta` segment is configured to listen to traffic on port `8304`:
<CodeTabs heading="Example network segments configuration for server agents">
```hcl
segments = [
{
name = "alpha"
bind = "10.0.0.1"
advertise = "10.0.0.1"
port = 8303
},
{
name = "beta"
bind = "10.0.0.1"
advertise = "10.0.0.1"
port = 8304
}
]
```
```json
{
"segments": [
{
"name": "alpha",
"bind": "10.0.0.1",
"advertise": "10.0.0.1",
"port": 8303
},
{
"name": "beta",
"bind": "10.0.0.1",
"advertise": "10.0.0.1",
"port": 8304
}
]
}
```
</CodeTabs>
1. Start the server using the `consul agent` command. Copy the address for each segment listener so that you can [direct clients to join the segment](#configure-clients-to-join-segments) when you start them:
[INFO] consul: Started listener for LAN segment "alpha" on 10.20.10.11:8303
[INFO] serf: EventMemberJoin: server1 10.20.10.11
[INFO] consul: Started listener for LAN segment "beta" on 10.20.10.11:8304
[INFO] serf: EventMemberJoin: server1 10.20.10.11
```
1. Verfiy that the server is a member of all segments:
```shell-session
$ consul members
Node Address Status Type Build Protocol DC Segment
server1 10.20.10.11:8301 alive server 1.14+ent 2 dc1 <all>
```
## Configure clients to join segments
Client agents can only be members of one segment at a time. You can direct clients to join a segment by specifying the address and name of the segment with the [`-join`](/consul/docs/agent/config/cli-flags#_join) and [`-segment`](/consul/docs/agent/config/cli-flags#_segment) command line flags when starting the agent.
```shell-session
$ consul agent -config-file client.hcl -join 10.20.10.11:8303 -segment alpha
```
Alternatively, you can add the [`retry_join`](/consul/docs/agent/config/config-files#retry_join) and [`segment`](/consul/docs/agent/config/config-files#segment-1) parameters to your client agent configuration file:
```hcl
node_name = "consul-client"
server = false
datacenter = "dc1"
data_dir = "consul/client-data"
log_level = "INFO"
retry_join = ["10.20.10.11:8303"]
segment = "alpha"
```
## Verify segments
You can use the CLI, API, or GUI to verify which segments your agents have joined.
<Tabs>
<Tab heading="CLI">
Run the `consul members` command to verify that the client agents are joined to the correct segments:
<CodeBlockConfig>
```shell-session
$ consul members
Node Address Status Type Build Protocol DC Partition Segment
server 192.168.4.159:8301 alive server 1.14+ent 2 dc1 default <all>
You can also pass the name of a segment in the `-segment` flag to view agents in a specific segment. Note that server agents display their LAN listener port for the specified segment the segment filter applied. In the following example, the command returns port `8303` for alpha, rather than for the `<default>` segment port:
<CodeBlockConfig>
```shell-session
$ consul members -segment alpha
Node Address Status Type Build Protocol DC Segment
server1 10.20.10.11:8301 alive server 1.14+ent 2 dc1 alpha
If the UI is enabled in your agent configuration, the segment name appears in the node’s Metadata tab.
1. Open the URL for the UI. By default, the UI is `localhost:8500`.
1. Click **Node** in the sidebar and click on the name of the client agent you want to check.
1. Click the **Metadata** tab. The network segment appears as a key-value pair.
</Tab>
</Tabs>
## Related resources
You can also create and run a prepared query to query for additional information about the services registered to client nodes. Prepared queries are HTTP API endpoint features that enable you to run complex queries of Consul nodes. Refer [Prepared Query HTTP Endpoint](/consul/api-docs/query) for usage.
