diff --git a/CHANGELOG.md b/CHANGELOG.md
index dc84398d..0264def0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@
 - Fixed assertion error on closing or invalidating a link with messages forwarded from a virtual link.
 - Fixed host hanging if stopped while an instance is in the process of creating a save during startup.
 - Fixed `instance.auto_start` option.
+- Fixed host log spammed with errors when plugins broadcast messages to instances with the plugin disabled.
 
 
 ## Version 2.0.0-alpha.14
diff --git a/packages/controller/index.ts b/packages/controller/index.ts
index 5218034f..caebb912 100644
--- a/packages/controller/index.ts
+++ b/packages/controller/index.ts
@@ -1,7 +1,9 @@
 import { bootstrap } from "./controller";
 export { default as Controller } from "./src/Controller";
 export { default as ControllerUser } from "./src/ControllerUser";
+export { default as ControllerRouter } from "./src/ControllerRouter";
 export { default as ControlConnection } from "./src/ControlConnection";
+export { default as HostConnection } from "./src/HostConnection";
 export { default as InstanceInfo } from "./src/InstanceInfo";
 export { default as BaseControllerPlugin } from "./src/BaseControllerPlugin";
 export { default as UserManager } from "./src/UserManager";
diff --git a/packages/controller/src/BaseConnection.ts b/packages/controller/src/BaseConnection.ts
index 493ebbde..3ebac51e 100644
--- a/packages/controller/src/BaseConnection.ts
+++ b/packages/controller/src/BaseConnection.ts
@@ -6,7 +6,6 @@ import type WsServerConnector from "./WsServerConnector";
 
 import * as lib from "@clusterio/lib";
 const { logger } = lib;
-import ControllerRouter from "./ControllerRouter";
 import * as routes from "./routes";
 
 
@@ -24,7 +23,7 @@ export default class BaseConnection extends lib.Link {
 		public _controller: Controller
 	) {
 		super(connector);
-		this.router = new ControllerRouter(this._controller);
+		this.router = _controller.router;
 		for (let [Request, handler] of this._controller._registeredRequests) { this.handle(Request, handler); }
 		for (let [Request, handler] of this._controller._fallbackedRequests) { this.fallbackRequest(Request, handler); }
 		for (let [Event, handler] of this._controller._registeredEvents) { this.handle(Event, handler); }
diff --git a/packages/controller/src/Controller.ts b/packages/controller/src/Controller.ts
index 8930f854..3e81c0c1 100644
--- a/packages/controller/src/Controller.ts
+++ b/packages/controller/src/Controller.ts
@@ -26,6 +26,7 @@ import WsServer from "./WsServer";
 import HostConnection from "./HostConnection";
 import HostInfo from "./HostInfo";
 import BaseControllerPlugin from "./BaseControllerPlugin";
+import ControllerRouter from "./ControllerRouter";
 
 const endpointDurationSummary = new Summary(
 	"clusterio_controller_http_endpoint_duration_seconds",
@@ -74,6 +75,7 @@ export default class Controller {
 
 	/** WebSocket server */
 	wsServer: WsServer;
+	router = new ControllerRouter(this);
 	trustedProxies: BlockList;
 	debugEvents: events.EventEmitter = new events.EventEmitter();
 	private _events: events.EventEmitter = new events.EventEmitter();
@@ -1374,7 +1376,11 @@ export default class Controller {
 				}
 
 			} else if (dst.id === lib.Address.instance || dst.id === lib.Address.host) {
+				const plugin = event.constructor.plugin;
 				for (let hostConnection of this.wsServer.hostConnections.values()) {
+					if (plugin && !hostConnection.plugins.has(plugin)) {
+						continue;
+					}
 					hostConnection.sendEvent(event, dst);
 				}
 
diff --git a/packages/controller/src/ControllerRouter.ts b/packages/controller/src/ControllerRouter.ts
index 84420595..4679312d 100644
--- a/packages/controller/src/ControllerRouter.ts
+++ b/packages/controller/src/ControllerRouter.ts
@@ -7,8 +7,6 @@ import ControlConnection from "./ControlConnection";
 const { logger } = lib;
 
 export default class ControllerRouter {
-	pendingRequests: Map<any, any> = new Map();
-
 	constructor(
 		public controller: Controller
 	) {}
@@ -16,12 +14,14 @@ export default class ControllerRouter {
 	/**
 	 * @param origin - Source link of the message.
 	 * @param message - Link the message originated from.
+	 * @param entry - message entry if message is a request or an event.
 	 * @param hasFallback - true if fallback handling is available.
 	 * @returns true if the message was handled
 	 */
 	forwardMessage(
 		origin: ControlConnection | HostConnection,
 		message: lib.MessageRoutable,
+		entry: lib.RequestEntry | lib.EventEntry | undefined,
 		hasFallback: boolean
 	): boolean {
 		if (!["request", "response", "responseError", "event"].includes(message.type)) {
@@ -32,7 +32,7 @@ export default class ControllerRouter {
 		let nextHop: ControlConnection | HostConnection | undefined;
 		let msg: string = "";
 		if (dst.type === lib.Address.broadcast) {
-			this.broadcastMessage(origin, message);
+			this.broadcastMessage(origin, message, entry as lib.EventEntry);
 			return true;
 		} else if (dst.type === lib.Address.host) {
 			nextHop = this.controller.wsServer.hostConnections.get(dst.id);
@@ -96,13 +96,17 @@ export default class ControllerRouter {
 	broadcastMessage(
 		origin: lib.Link,
 		message: lib.MessageRoutable,
+		entry: lib.EventEntry,
 	) {
 		let dst = message.dst;
 		if (message.type !== "event") {
 			this.warnUnrouted(message, `Unexpected broadcast of ${message.type}`);
-		} else if (dst.id === lib.Address.host || dst.id === lib.Address.instance) {
+			return;
+		}
+		const plugin = entry.Event.plugin;
+		if (dst.id === lib.Address.host || dst.id === lib.Address.instance) {
 			for (let hostConnection of this.controller.wsServer.hostConnections.values()) {
-				if (hostConnection !== origin) {
+				if (hostConnection !== origin && (!plugin || hostConnection.plugins.has(plugin))) {
 					hostConnection.connector.send(message);
 				}
 			}
@@ -126,5 +130,3 @@ export default class ControllerRouter {
 		logger.warn(msg ? `${baseMsg}: ${msg}.` : `${baseMsg}.`);
 	}
 }
-
-module.exports = ControllerRouter;
diff --git a/packages/host/index.ts b/packages/host/index.ts
index 2b01bc21..f39ce536 100644
--- a/packages/host/index.ts
+++ b/packages/host/index.ts
@@ -1,6 +1,9 @@
 import { bootstrap } from "./host";
 export { default as BaseHostPlugin } from "./src/BaseHostPlugin";
 export { default as BaseInstancePlugin } from "./src/BaseInstancePlugin";
+export { default as Host, HostRouter } from "./src/Host";
+export { default as Instance } from "./src/Instance";
+export { default as InstanceConnection } from "./src/InstanceConnection";
 
 if (module === require.main) {
 	bootstrap();
diff --git a/packages/host/src/Host.ts b/packages/host/src/Host.ts
index 06a23809..b1b9dd41 100644
--- a/packages/host/src/Host.ts
+++ b/packages/host/src/Host.ts
@@ -82,7 +82,7 @@ const instanceStartingMessages = new Set([
 	lib.InstanceExportDataRequest.name,
 ]);
 
-class HostRouter {
+export class HostRouter {
 	constructor(
 		public host: Host
 	) { }
@@ -93,16 +93,22 @@ class HostRouter {
 	 * @param origin -
 	 *    Link the message originated from.
 	 * @param message - Message to process.
+	 * @param entry - message entry if message is a request or an event.
 	 * @param hasFallback - is fallback available
 	 * @returns true if the message was handled, false if fallback
 	 *     is requested
 	 */
-	forwardMessage(origin: lib.Link, message: lib.MessageRoutable, hasFallback: boolean) {
+	forwardMessage(
+		origin: lib.Link,
+		message: lib.MessageRoutable,
+		entry: lib.RequestEntry | lib.EventEntry | undefined,
+		hasFallback: boolean,
+	) {
 		let dst = message.dst;
 		let nextHop: lib.Link | undefined;
 		let msg: string | undefined;
 		if (dst.type === lib.Address.broadcast) {
-			this.broadcastMessage(origin, message);
+			this.broadcastMessage(origin, message, entry as lib.EventEntry);
 			return true;
 		} else if (
 			dst.type === lib.Address.controller
@@ -153,27 +159,36 @@ class HostRouter {
 		return true;
 	}
 
-	broadcastMessage(origin: lib.Link, message: lib.MessageRoutable) {
+	broadcastMessage(
+		origin: lib.Link,
+		message: lib.MessageRoutable,
+		entry: lib.EventEntry,
+	) {
 		let dst = message.dst;
 		if (message.type !== "event") {
 			this.warnUnrouted(message, `Unexpected broadcast of ${message.type}`);
-		} else if (dst.id === lib.Address.host || dst.id === lib.Address.instance) {
+			return;
+		}
+		const plugin = entry.Event.plugin;
+		if (dst.id === lib.Address.instance) {
 			for (let instanceConnection of this.host.instanceConnections.values()) {
-				if (instanceConnection !== origin) {
+				if (instanceConnection !== origin && (!plugin || instanceConnection.plugins.has(plugin))) {
 					instanceConnection.connector.send(message);
 				}
 			}
-			if (this.host !== origin) {
+			if (this.host !== origin && (!plugin || this.host.serverPlugins.has(plugin))) {
 				this.host.connector.send(message);
 			}
 		} else if (dst.id === lib.Address.control) {
 			if (this.host !== origin) {
-				this.host.connector.send(message);
+				if (!plugin || this.host.serverPlugins.has(plugin)) {
+					this.host.connector.send(message);
+				}
 			} else {
-				logger.warn(`Received control broadcast of ${(message as lib.MessageEvent).name} from master.`);
+				logger.warn(`Received control broadcast of ${(message as lib.MessageEvent).name} from controller.`);
 			}
 		} else {
-			this.warnUnrouted(message, `Unexpected broacdast target ${dst.id}`);
+			this.warnUnrouted(message, `Unexpected broadcast target ${dst.id}`);
 		}
 	}
 
diff --git a/packages/lib/src/link/link.ts b/packages/lib/src/link/link.ts
index 14b7d1ec..520e5fe4 100644
--- a/packages/lib/src/link/link.ts
+++ b/packages/lib/src/link/link.ts
@@ -72,7 +72,12 @@ export type RequestHandler<Req, Res> = (request: Req, src: libData.Address, dst:
 export type EventHandler<T> = (event: T, src: libData.Address, dst: libData.Address) => Promise<void>;
 
 interface Router {
-	forwardMessage(origin: Link, message: MessageRoutable, fallback: boolean): boolean,
+	forwardMessage(
+		origin: Link,
+		message: MessageRoutable,
+		entry: RequestEntry | EventEntry | undefined,
+		fallback: boolean,
+	): boolean,
 }
 
 // Some definitions for the terminology used here:
@@ -343,7 +348,7 @@ export class Link {
 		let fallback =
 			message.type === "request" ? this._requestFallbacks.get((entry as RequestEntry).Request) : undefined
 		;
-		if (this.router.forwardMessage(this, message, Boolean(fallback))) {
+		if (this.router.forwardMessage(this, message, entry, Boolean(fallback))) {
 			return;
 		}
 		if (!fallback) {
diff --git a/test/integration/routing.js b/test/integration/routing.js
new file mode 100644
index 00000000..6881f079
--- /dev/null
+++ b/test/integration/routing.js
@@ -0,0 +1,422 @@
+"use strict";
+const assert = require("assert").strict;
+
+const lib = require("@clusterio/lib");
+const { Host, Instance, InstanceConnection } = require("@clusterio/host");
+const { ControlConnection, Controller, HostConnection, InstanceInfo } = require("@clusterio/controller");
+
+const addr = lib.Address.fromShorthand;
+
+class Control extends lib.Link { }
+
+/**
+ * @param {Controller} controller
+ * @param {number} hostId
+ */
+function connectHost(controller, hostId, plugins) {
+	const [controllerSide, hostSide] = lib.VirtualConnector.makePair(addr("controller"), addr({ hostId }));
+	const registerData = new lib.RegisterHostData("", "0.0.0", hostId, plugins);
+	const hostConnection = new HostConnection(registerData, controllerSide, controller, "host-a.test");
+	controller.wsServer.hostConnections.set(hostId, hostConnection);
+	const hostConfig = new lib.HostConfig("host");
+	hostConfig.set("host.id", hostId);
+	return new Host(hostSide, "invalid", hostConfig, undefined, []);
+}
+
+/**
+ * @param {Controller} controller
+ * @param {Host} host
+ * @param {number} instanceId
+ */
+function connectInstance(controller, host, instanceId) {
+	const hostAddress = addr({ hostId: host.config.get("host.id")});
+	const instanceAddress = addr({ instanceId });
+	const [instanceSide, hostSide] = lib.VirtualConnector.makePair(instanceAddress, hostAddress);
+	const instanceConfig = new lib.InstanceConfig("host");
+	instanceConfig.set("instance.id", instanceId);
+	instanceConfig.set("instance.assigned_host", host.config.get("host.id"));
+	host.instanceInfos.set(instanceId, { path: "invalid", config: instanceConfig });
+	controller.instances.set(instanceId, new InstanceInfo(instanceConfig, "stopped"));
+	const instance = new Instance(host, instanceSide, "invalid", "invalid", instanceConfig);
+	const instanceConnection = new InstanceConnection(hostSide, host, instance);
+	host.instanceConnections.set(instanceId, instanceConnection);
+	return instance;
+}
+
+/**
+ * @param {Controller} controller
+ * @param {number} hostId
+ */
+function connectControl(controller, controlId) {
+	const [controllerSide, controlSide] = lib.VirtualConnector.makePair(addr("controller"), addr({ controlId }));
+	const registerData = new lib.RegisterControlData("", "0.0.0");
+	let user = controller.userManager.users.get("test");
+	if (!user) {
+		user = controller.userManager.createUser("test");
+	}
+	const controlConnection = new ControlConnection(registerData, controllerSide, controller, user, controlId);
+	controller.wsServer.controlConnections.set(controlId, controlConnection);
+	return new Control(controlSide);
+}
+
+class TestRequest {
+	static type = "request";
+	static src = ["controller", "host", "instance", "control"];
+	static dst = ["controller", "host", "instance", "control"];
+	static permission = null;
+}
+
+class TestEvent {
+	static type = "event";
+	static src = ["controller", "host", "instance", "control"];
+	static dst = ["controller", "host", "instance", "control"];
+	static permission = null;
+}
+
+class PluginEvent {
+	static type = "event";
+	static src = ["controller", "host", "instance", "control"];
+	static dst = ["controller", "host", "instance", "control"];
+	static permission = null;
+	static plugin = "test";
+}
+
+lib.Link.register(TestRequest);
+lib.Link.register(TestEvent);
+lib.Link.register(PluginEvent);
+
+describe("Integration of link routing", function() {
+	/** @type {Controller} */
+	let controller;
+	/** @type {Host} */
+	let hostA;
+	/** @type {Host} */
+	let hostB;
+	/** @type {Instance} */
+	let instanceA1;
+	/** @type {Instance} */
+	let instanceA2;
+	/** @type {Instance} */
+	let instanceB1;
+	/** @type {Control} */
+	let controlA;
+	/** @type {Control} */
+	let controlB;
+
+	beforeEach(function() {
+		controller = new Controller(
+			{},
+			[],
+			"invalid",
+			new lib.ControllerConfig("controller")
+		);
+		hostA = connectHost(controller, 10, []);
+		hostB = connectHost(controller, 20, []);
+		instanceA1 = connectInstance(controller, hostA, 11);
+		instanceA2 = connectInstance(controller, hostA, 12);
+		instanceB1 = connectInstance(controller, hostB, 21);
+		controlA = connectControl(controller, 100);
+		controlB = connectControl(controller, 101);
+	});
+
+	/** @returns {Controller | Host | Instance} */
+	function get(name) {
+		return {
+			controller,
+			hostA,
+			hostB,
+			instanceA1,
+			instanceA2,
+			instanceB1,
+			controlA,
+			controlB,
+		}[name];
+	}
+
+	// Combinations to try. Equivalent paths have been removed.
+	const parties = [
+		["controller", ["hostA", "instanceA1", "controlA"]],
+		["hostA", ["controller", "hostB", "instanceA1", "instanceB1", "controlA"]],
+		["instanceA1", ["controller", "hostA", "hostB", "instanceA2", "instanceB1", "controlA"]],
+		["controlA", ["controller", "hostA", "instanceA1", "controlB"]],
+	];
+
+	function handle(dst, Message, handler) {
+		if (dst instanceof Controller) {
+			for (const host of dst.wsServer.hostConnections.values()) {
+				host.handle(Message, handler);
+			}
+			for (const control of dst.wsServer.controlConnections.values()) {
+				control.handle(Message, handler);
+			}
+		} else if (dst instanceof Host) {
+			for (const instance of dst.instanceConnections.values()) {
+				instance.handle(Message, handler);
+			}
+			dst.handle(Message, handler);
+		} else {
+			dst.handle(Message, handler);
+		}
+	}
+
+	/**
+	 * @param {Controller | Host | Instance} link
+	 * @param {Address} dst
+	 */
+	function send(link, dst, message) {
+		// This logic exists becasue .sendTo doesn't forward all kinds of
+		// messages to the correct location from all places.  Idealy this
+		// would not be neccessary and .sendTo would do the right thing.
+		if (link instanceof Host) {
+			const instance = link.instanceConnections.get(dst.id);
+			if (instance) {
+				return instance.sendTo(dst, message);
+			}
+		}
+		return link.sendTo(dst, message);
+	}
+
+	describe("request routing", function() {
+		for (const [srcName, dstNames] of parties) {
+			it(`should route from ${srcName}`, async function() {
+				for (const dstName of dstNames) {
+					let called;
+					const dst = get(dstName);
+					handle(dst, TestRequest, async () => { called = true; });
+					const dstAddr = dst instanceof Controller ? addr("controller") : dst.connector.src;
+					await send(get(srcName), dstAddr, new TestRequest());
+					assert(called, `${dstName} handler was not called`);
+				}
+			});
+		}
+	});
+
+	describe("event routing", function() {
+		for (const [srcName, dstNames] of parties) {
+			it(`should route from ${srcName}`, async function() {
+				for (const dstName of dstNames) {
+					let called;
+					const dst = get(dstName);
+					handle(dst, TestEvent, async () => { called = true; });
+					const dstAddr = dst instanceof Controller ? addr("controller") : dst.connector.src;
+					send(get(srcName), dstAddr, new TestEvent());
+					assert(called, `${dstName} handler was not called`);
+				}
+			});
+		}
+	});
+
+	/**
+	 * @param {Controller | Host | Instance | Control} link
+	 * @param {"allHosts" | "allInstances" | "allControls"} dst
+	 */
+	function bcast(link, dst, message) {
+		// This logic exists becasue .sendTo doesn't forward all kinds of
+		// messages to the correct location from all places.  Idealy this
+		// would not be neccessary and .sendTo would do the right thing.
+		if (link instanceof Host) {
+			const plugin = message.constructor.plugin;
+			if (dst === "allInstances") {
+				for (const instance of link.instanceConnections.values()) {
+					if (plugin && !instance.plugins.has(plugin)) {
+						continue;
+					}
+					instance.sendTo(dst, message);
+				}
+			}
+			if (plugin && !link.serverPlugins.has(plugin)) {
+				return;
+			}
+		}
+		link.sendTo(dst, message);
+	}
+
+	function bhandle(srcName, dst, Event, canReach = (dstB) => true) {
+		const asserts = [];
+		const dsts = {
+			allHosts: ["hostA", "hostB"],
+			allInstances: ["instanceA1", "instanceA2", "instanceB1"],
+			allControls: ["controlA", "controlB"],
+		};
+		for (const dstName of dsts[dst]) {
+			if (srcName === dstName) { continue; }
+			// TODO remove when broadcasting from instance to hosts is fixed, see #575
+			if (srcName === "instanceA1" && dstName === "hostB") { continue; }
+			let called;
+			handle(get(dstName), Event, async () => { called = true; });
+			const should = canReach(dstName);
+			asserts.push(() => assert(
+				!should ^ called,
+				`${dstName} handler was ${should ? "not " : ""}called from ${srcName}`,
+			));
+		}
+		return asserts;
+	}
+
+	describe("event broadcast", function() {
+		for (const srcName of ["controller", "hostA", "instanceA1", "controlA"]) {
+			it(`should broadcast from ${srcName}`, async function() {
+				for (const dstName of ["allHosts", "allInstances", "allControls"]) {
+					const dstAsserts = bhandle(srcName, dstName, TestEvent);
+					bcast(get(srcName), dstName, new TestEvent());
+					for (const dstAssert of dstAsserts) {
+						dstAssert();
+					}
+				}
+			});
+		}
+	});
+
+	const graph = {
+		controller: ["hostA", "hostB", "controlA", "controlB"],
+		hostA: ["controller", "instanceA1", "instanceA2"],
+		hostB: ["controller", "instanceB1"],
+		instanceA1: ["hostA"],
+		instanceA2: ["hostA"],
+		instanceB1: ["hostB"],
+		controlA: ["controller"],
+		controlB: ["controller"],
+	};
+
+	// Returns true if the path from src to dst goes through via
+	function goesVia(src, dst, via) {
+		// Places we've been to
+		const checked = new Set();
+		// Places left to check
+		const paths = new Set([src]);
+		while (paths.size) {
+			const [candidate] = paths;
+			paths.delete(candidate);
+			if (candidate === via) {
+				continue;
+			}
+			if (checked.has(candidate)) {
+				continue;
+			}
+			if (candidate === dst) {
+				return false;
+			}
+			checked.add(candidate);
+			for (const newCandidate of graph[candidate]) {
+				paths.add(newCandidate);
+			}
+		}
+		return true;
+	}
+	assert(goesVia("instanceA1", "instanceB1", "controller"));
+	assert(!goesVia("instanceA1", "instanceA2", "controller"));
+	assert(goesVia("instanceA1", "hostB", "hostA"));
+	assert(!goesVia("instanceA1", "hostB", "controlA"));
+	assert(goesVia("controlA", "controlB", "controller"));
+	assert(goesVia("controlA", "hostA", "controller"));
+
+	function addPluginExceptFor(exName) {
+		const ex = get(exName);
+		const exAddr = ex instanceof Controller ? addr("controller") : ex.connector.src;
+		for (const name of [
+			"controller", "hostA", "hostB", "instanceA1", "instanceA2", "instanceB1", "controlA", "controlB",
+		]) {
+			const party = get(name);
+			if (party instanceof Controller) {
+				for (const host of party.wsServer.hostConnections.values()) {
+					if (!host.connector.dst.equals(exAddr)) {
+						host.plugins.set("test", "0.0.0");
+					}
+				}
+				for (const control of party.wsServer.controlConnections.values()) {
+					if (!control.connector.dst.equals(exAddr)) {
+						// No way to set plugins
+					}
+				}
+			} else if (party instanceof Host) {
+				for (const instance of party.instanceConnections.values()) {
+					if (!instance.connector.dst.equals(exAddr)) {
+						instance.plugins.set("test", "0.0.0");
+					}
+				}
+				if (!party.connector.dst.equals(exAddr)) {
+					party.serverPlugins.set("test", "0.0.0");
+				}
+			} else if (party instanceof Instance) {
+				// Currently does not handle plugins
+			} else if (party instanceof Control) {
+				// Currently does not handle plugins
+			}
+		}
+	}
+
+	// When plugin events are broadcast the party sending the event should
+	// filter it out if the next hop it is forwarded to does not have plugin
+	// the event was defined in loaded.
+	describe("event broadcast with controller missing plugin", function() {
+		for (const srcName of ["hostA", "instanceA1", "controlA"]) {
+			it(`should broadcast from ${srcName}`, async function() {
+				if (srcName === "controlA") {
+					this.skip(); // Not implemented
+				}
+				addPluginExceptFor("controller");
+				for (const dstName of ["allHosts", "allInstances", "allControls"]) {
+					const dstAsserts = bhandle(
+						srcName, dstName, PluginEvent, dstB => !goesVia(srcName, dstB, "controller"),
+					);
+					bcast(get(srcName), dstName, new PluginEvent());
+					for (const dstAssert of dstAsserts) {
+						dstAssert();
+					}
+				}
+			});
+		}
+	});
+
+	describe("event broadcast with host missing plugin", function() {
+		for (const srcName of ["controller", "hostA", "instanceA1", "controlA"]) {
+			it(`should broadcast from ${srcName}`, async function() {
+				addPluginExceptFor("hostB");
+				for (const dstName of ["allHosts", "allInstances", "allControls"]) {
+					const dstAsserts = bhandle(
+						srcName, dstName, PluginEvent, dstB => !goesVia(srcName, dstB, "hostB"),
+					);
+					bcast(get(srcName), dstName, new PluginEvent());
+					for (const dstAssert of dstAsserts) {
+						dstAssert();
+					}
+				}
+			});
+		}
+	});
+
+	describe("event broadcast with instance missing plugin", function() {
+		for (const srcName of ["controller", "hostA", "instanceA1", "controlA"]) {
+			it(`should broadcast from ${srcName}`, async function() {
+				addPluginExceptFor("instanceA2");
+				for (const dstName of ["allHosts", "allInstances", "allControls"]) {
+					const dstAsserts = bhandle(
+						srcName, dstName, PluginEvent, dstB => !goesVia(srcName, dstB, "instanceA2"),
+					);
+					bcast(get(srcName), dstName, new PluginEvent());
+					for (const dstAssert of dstAsserts) {
+						dstAssert();
+					}
+				}
+			});
+		}
+	});
+
+	describe("event broadcast with control missing plugin", function() {
+		for (const srcName of ["controller", "hostA", "instanceA1", "controlA"]) {
+			it(`should broadcast from ${srcName}`, async function() {
+				this.skip(); // Currently not implemented.
+				addPluginExceptFor("controlB");
+				for (const dstName of ["allHosts", "allInstances", "allControls"]) {
+					const dstAsserts = bhandle(
+						srcName, dstName, PluginEvent, dstB => !goesVia(srcName, dstB, "controlB"),
+					);
+					bcast(get(srcName), dstName, new PluginEvent());
+					for (const dstAssert of dstAsserts) {
+						dstAssert();
+					}
+				}
+			});
+		}
+	});
+});