Step-by-Step: Enable T3 Protocol

1. Log in to the WebLogic Admin Console

   Open a browser and navigate to:

   http://<admin-host>:<admin-port>/console   (default admin port: 7001)

   Log in with your WebLogic administrator credentials.

2. Click "Lock & Edit" in the Change Center

   In the top-left panel under Change Center, click Lock & Edit to enable editing.

3. Navigate to the Managed Server's Protocols page

   Domain Structure → Environment → Servers → [YourManagedServer] → Protocols → General
4. Enable T3 on the General tab

   On the General sub-tab, look for "Enable T3" and ensure the checkbox is checked (enabled).

   ℹ Default Behaviour By default, WebLogic 12c has T3 enabled on the default listen port. If this checkbox is unchecked, it means T3 was explicitly disabled — check it to re-enable.
5. Check the Channels tab (custom network channels)

   [YourManagedServer] → Protocols → Channels

   If custom channels exist, click each channel and verify that the Protocol column includes t3 or t3s.

   If no channels are listed (as shown with "There are no items to display"), the server uses the default channel — T3 is controlled by the General tab setting above.

6. Save and Activate Changes

   Click Save on the configuration page, then click Activate Changes in the Change Center.

7. Restart the Managed Server

   [YourManagedServer] → Control → Start/Stop

   Click Shutdown → Force Shutdown Now, wait for the server to stop, then click Start.

   ⚠ Restart Required Protocol changes on the default channel require a full server restart to take effect.

Verification

Option 1 — T3 Handshake via Telnet (from APM server)

# Step 1: Open telnet to the WebLogic port
telnet 172.18.23.15 7010

# Step 2: Once connected, type the T3 greeting
t3 12.2.1

# Expected response if T3 is enabled:
HELO:...

# If it hangs or disconnects — T3 is NOT active on this port