# Multicast Issue on Catalyst Devices

**URL:** <https://community.ouster.com/t/multicast-issue-on-catalyst-devices/424>\
**Category:** Software\
**Tags:** gemini\
**Created:** [November 25, 2025, 5:16pm UTC](https://community.ouster.com/t/multicast-issue-on-catalyst-devices/424 "2025-11-25T17:16:12Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![clark.dev](https://avatars.discourse-cdn.com/v4/letter/c/73ab20/32.png) [@clark.dev](https://community.ouster.com/u/clark.dev)\
**Post date:** [November 25, 2025, 5:16pm UTC](https://community.ouster.com/t/multicast-issue-on-catalyst-devices/424/1 "2025-11-25T17:16:12Z")

</div>

### The Issue

Adding a sensor in multicast mode **directly to a Catalyst DHCP-provisioned port** will fail and get the sensor stuck in the `INITIALIZING` state.

### Root Cause

The **Catalyst port’s DHCP configuration** lacked the required **gateway address** (`option routers`). Without a gateway, the sensor couldn’t correctly route its **multicast discovery packets**.

### The Fix

Modify the DHCP server configuration file (`/etc/dhcp/dhcpd.conf`) to include the gateway.

_ **Note:** All addresses (`subnet`, `range`, `option routers`) in this code snippet are examples and must be updated to reflect your actual network topology._

Bash

```auto
subnet 10.125.21.0 netmask 255.255.255.0 {
        range 10.125.21.2 10.125.21.22;
        option routers 10.125.21.1; 
}

```

Restart the DHCP service on the Linux host (Ubuntu/Debian):

Bash

```auto
sudo systemctl restart isc-dhcp-server

```