diff --git a/neutron_lib/agent/l3_extension.py b/neutron_lib/agent/l3_extension.py
index eb6343595..ed831b0b1 100644
--- a/neutron_lib/agent/l3_extension.py
+++ b/neutron_lib/agent/l3_extension.py
@@ -58,3 +58,13 @@ class L3AgentExtension(extension.AgentExtension, metaclass=abc.ABCMeta):
         :param context: rpc context
         :param data: dict of router_id and new state
         """
+
+    @abc.abstractmethod
+    def update_network(self, context, data):
+        """Handle a network update event.
+
+        Called on network update.
+
+        :param context: RPC context.
+        :param data: dict of network data.
+        """
diff --git a/releasenotes/notes/l3-agent-extensions-update-network-e4887f7f258e40f0.yaml b/releasenotes/notes/l3-agent-extensions-update-network-e4887f7f258e40f0.yaml
new file mode 100644
index 000000000..6cfe64504
--- /dev/null
+++ b/releasenotes/notes/l3-agent-extensions-update-network-e4887f7f258e40f0.yaml
@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    A new method ``update_network`` has been added to ``L3AgentExtension``
+    to handle the network update events in the L3 agent extensions.