diff --git a/test/175_stop_start_test.sh b/test/175_stop_start_test.sh
new file mode 100755
index 00000000..791d7a8c
--- /dev/null
+++ b/test/175_stop_start_test.sh
@@ -0,0 +1,30 @@
+#! /bin/bash
+
+. ./config.sh
+
+start_suite "Check restart re-uses same container when possible"
+
+ID=$(weave_on $HOST1 launch-router)
+weave_on $HOST1 stop-router
+assert "weave_on $HOST1 launch-router" "$ID"
+# Can't start if already running with different args
+assert_raises "weave_on $HOST1 launch-router --log-level=debug" 1
+# Stop then start with different arg
+weave_on $HOST1 stop-router
+ID2=$(weave_on $HOST1 launch-router --log-level=debug)
+assert "[ $ID != $ID2 ]"
+
+# Stop then start with different password
+weave_on $HOST1 stop-router
+ID3=$(weave_on $HOST1 launch-router --password=xyzzy)
+assert "[ $ID2 != $ID3 ]"
+# Stop then start with same password
+weave_on $HOST1 stop-router
+assert "weave_on $HOST1 launch-router --password=xyzzy" "$ID3"
+
+# Fails on bad argument
+assert_raises "weave_on $HOST1 launch-plugin --foo" 1
+# Fails again on bad argument, although there is a dead container
+assert_raises "weave_on $HOST1 launch-plugin --foo" 1
+
+end_suite
diff --git a/weave b/weave
index b16131db..f899d5fc 100755
--- a/weave
+++ b/weave
@@ -936,28 +936,58 @@ detach() {
 # functions for interacting with containers
 ######################################################################
 
-# Check that a container for component $1 named $2 with image $3 is not running
-check_not_running() {
-    RUN_STATUS=$(docker inspect --format='{{.State.Running}} {{.State.Status}} {{.Config.Image}}' $2 2>/dev/null) || true
+args_match() {
+    prev_args="$(docker inspect -f '{{.Args}} {{.Config.Env}}' $1)"
+    shift
+    dummy_container=$(docker create "$@" 2>/dev/null) || return 1
+    dummy_args="$(docker inspect -f '{{.Args}} {{.Config.Env}}' $dummy_container)"
+    docker rm $dummy_container >/dev/null
+    [ "$prev_args"  = "$dummy_args" ]
+}
+
+# Check if a container for component $1 named $2 with image $3 and args $4... is running,
+# and start it if necessary
+start_if_necessary() {
+    component=$1
+    name=$2
+    image=$3
+    shift 3
+    image_base=${image%:*}
+    IMAGE_ID=$(docker inspect --format='{{.Id}}' $image)
+    RUN_STATUS=$(docker inspect --format='{{.State.Running}} {{.Image}} {{.Config.Image}} {{.Id}}' $name 2>/dev/null) || true
+    CONTAINER_ID=${RUN_STATUS##* }
     case ${RUN_STATUS%:*} in
-        "true restarting $3")
-            echo "$2 is restarting; you can stop it with 'weave stop-$1'." >&2
-            return 3
+        "true $IMAGE_ID "*)
+            if args_match $CONTAINER_ID "$@" ; then
+                ALREADY_RUNNING_CONTAINER=$CONTAINER_ID
+                echo $CONTAINER_ID
+            else
+                echo "$name is already running with different arguments; you can stop it with 'weave stop-$component'." >&2
+                return 1
+            fi
             ;;
-        "true "*" $3")
-            echo "$2 is already running; you can stop it with 'weave stop-$1'." >&2
-            return 1
+        "false $IMAGE_ID "*)
+            if args_match $CONTAINER_ID "$@" ; then
+                docker start $CONTAINER_ID
+            else
+                docker rm $name >/dev/null
+                docker run -d --name=$name "$@"
+            fi
             ;;
-        "false "*" $3")
-            docker rm $2 >/dev/null
+        true*$image_base)
+            echo "Found another version of $name running. Aborting." >&2
+            return 2
             ;;
         true*)
-            echo "Found another running container named '$2'. Aborting." >&2
+            echo "Found another running container named '$name'. Aborting." >&2
             return 2
             ;;
         false*)
-            echo "Found another container named '$2'. Aborting." >&2
-            return 2
+            docker rm $name >/dev/null
+            docker run -d --name=$name "$@"
+            ;;
+        "")
+            docker run -d --name=$name "$@"
             ;;
     esac
 }
@@ -1177,6 +1207,7 @@ check_running() {
         echo  "$1 container is not present. Have you launched it?" >&2
         return 1
     elif [ "$STATUS" = "true true" ] ; then
+        [ -n "$ALREADY_RUNNING_CONTAINER" ] && return 0
         echo "$1 container is restarting." >&2
         return 2
     elif [ "$STATUS" != "true false" ] ; then
@@ -1590,8 +1621,8 @@ launch_router() {
     # Set WEAVE_DOCKER_ARGS in the environment in order to supply
     # additional parameters, such as resource limits, to docker
     # when launching the weave container.
-    ROUTER_CONTAINER=$(docker run --name=$CONTAINER_NAME \
-        -d --privileged --net=host $(docker_sock_options) \
+    start_if_necessary router $CONTAINER_NAME $IMAGE \
+        --privileged --net=host $(docker_sock_options) \
         -e WEAVE_PASSWORD \
         -e CHECKPOINT_DISABLE \
         $WEAVE_DOCKER_ARGS $IMAGE $COVERAGE_ARGS \
@@ -1601,9 +1632,10 @@ launch_router() {
         --dns-effective-listen-address $DOCKER_BRIDGE_IP \
         $DNS_ROUTER_OPTS $NO_DNS_OPT \
         --http-addr $HTTP_ADDR \
-        "$@")
+        "$@"
     setup_router_iface_$BRIDGE_TYPE
-    attach_router
+    wait_for_status $CONTAINER_NAME http_call $HTTP_ADDR
+    [ -n "$ALREADY_RUNNING_CONTAINER" ] || attach_router
 }
 
 # Recreate the parameter values that are set when the router is first launched
@@ -1614,7 +1646,6 @@ fetch_router_args() {
 }
 
 attach_router() {
-    wait_for_status $CONTAINER_NAME http_call $HTTP_ADDR
     if [ -n "$IPRANGE" ] ; then
         # Tell the newly-started weave IP allocator about existing weave IPs
         with_container_addresses ipam_reclaim weave:expose $(docker ps -q --no-trunc)
@@ -1646,8 +1677,8 @@ launch_proxy() {
        docker create -v /w -v /w-noop -v /w-nomcast --name=$VOLUMES_CONTAINER_NAME \
            --label=weavevolumes --entrypoint=/bin/false $EXEC_IMAGE >/dev/null
     fi
-    PROXY_CONTAINER=$(docker run --name=$PROXY_CONTAINER_NAME \
-        -d --privileged --net=host $(docker_sock_options) \
+    start_if_necessary proxy $PROXY_CONTAINER_NAME $EXEC_IMAGE \
+        --privileged --net=host $(docker_sock_options) \
         $PROXY_VOLUMES \
         --volumes-from $VOLUMES_CONTAINER_NAME \
         -v /var/run/weave:/var/run/weave \
@@ -1659,7 +1690,7 @@ launch_proxy() {
         -e WEAVE_HTTP_ADDR \
         -e EXEC_IMAGE=$EXEC_IMAGE \
         --entrypoint=/home/weave/weaveproxy \
-        $WEAVEPROXY_DOCKER_ARGS $EXEC_IMAGE $COVERAGE_ARGS $PROXY_ARGS)
+        $WEAVEPROXY_DOCKER_ARGS $EXEC_IMAGE $COVERAGE_ARGS $PROXY_ARGS
     wait_for_status $PROXY_CONTAINER_NAME http_call_unix $PROXY_CONTAINER_NAME status.sock
 }
 
@@ -1669,21 +1700,12 @@ stop_proxy() {
 }
 
 launch_plugin_if_not_running() {
-    retval=0
-    check_not_running plugin $PLUGIN_CONTAINER_NAME $BASE_PLUGIN_IMAGE || retval=$?
-    # If an existing plugin is running (we start it with restart=always), return its ID
-    [ $retval = 1 ] && PLUGIN_CONTAINER=$(container_id $PLUGIN_CONTAINER_NAME) && return 0
-    # Any other kind of error code from check_not_running is a failure.
-    [ $retval -gt 0 ] && return $retval
-
-    if ! PLUGIN_CONTAINER=$(docker run --name=$PLUGIN_CONTAINER_NAME \
-        -d --privileged --net=host $(docker_sock_options) \
+    start_if_necessary plugin $PLUGIN_CONTAINER_NAME $PLUGIN_IMAGE \
+        --privileged --net=host $(docker_sock_options) \
         --restart=always \
         -v /run/docker/plugins:/run/docker/plugins \
         -e WEAVE_HTTP_ADDR \
-        $PLUGIN_IMAGE "$@") ; then
-        return 1
-    fi
+        $PLUGIN_IMAGE "$@"
     wait_for_status $PLUGIN_CONTAINER_NAME http_call_unix $PLUGIN_CONTAINER_NAME status.sock
     util_op create-plugin-network weave weavemesh
 }
@@ -1848,19 +1870,14 @@ EOF
         ;;
     launch)
         deprecation_warnings "$@"
-        check_not_running router $CONTAINER_NAME        $BASE_IMAGE
-        check_not_running proxy  $PROXY_CONTAINER_NAME  $BASE_EXEC_IMAGE
-        # Don't check the plugin here, since we start it with `--restart=always`
         COMMON_ARGS=$(common_launch_args "$@")
-        launch_router "$@"
-        launch_proxy  $COMMON_ARGS
-        plugin_disabled || launch_plugin_if_not_running $COMMON_ARGS
+        launch_router "$@" >/dev/null
+        launch_proxy  $COMMON_ARGS >/dev/null
+        plugin_disabled || launch_plugin_if_not_running $COMMON_ARGS >/dev/null
         ;;
     launch-router)
         deprecation_warnings "$@"
-        check_not_running router $CONTAINER_NAME $BASE_IMAGE
         launch_router "$@"
-        echo $ROUTER_CONTAINER
         ;;
     attach-router)
         check_running $CONTAINER_NAME
@@ -1868,17 +1885,15 @@ EOF
         create_bridge
         fetch_router_args
         with_container_netns $CONTAINER_NAME setup_router_iface_$BRIDGE_TYPE
+        wait_for_status $CONTAINER_NAME http_call $HTTP_ADDR
         attach_router
         ;;
     launch-proxy)
         deprecation_warnings "$@"
-        check_not_running proxy $PROXY_CONTAINER_NAME $BASE_EXEC_IMAGE
         launch_proxy "$@"
-        echo $PROXY_CONTAINER
         ;;
     launch-plugin)
         launch_plugin_if_not_running "$@"
-        echo $PLUGIN_CONTAINER
         ;;
     env|proxy-env)
         [ "$COMMAND" = "env" ] || deprecation_warning "$COMMAND" "'weave env'"