diff --git a/orte/mca/ras/simulator/ras_sim.h b/orte/mca/ras/simulator/ras_sim.h
index ee48391af9..9987aa42fb 100644
--- a/orte/mca/ras/simulator/ras_sim.h
+++ b/orte/mca/ras/simulator/ras_sim.h
@@ -18,10 +18,12 @@ BEGIN_C_DECLS
 
 struct orte_ras_sim_component_t {
     orte_ras_base_component_t super;
-    int num_nodes;
+    char *num_nodes;
     int slots;
     int slots_max;
-    char *topofile;
+    char *topofiles;
+    bool have_cpubind;
+    bool have_membind;
 };
 typedef struct orte_ras_sim_component_t orte_ras_sim_component_t;
 
diff --git a/orte/mca/ras/simulator/ras_sim_component.c b/orte/mca/ras/simulator/ras_sim_component.c
index b4768c81f3..ea73a1498f 100644
--- a/orte/mca/ras/simulator/ras_sim_component.c
+++ b/orte/mca/ras/simulator/ras_sim_component.c
@@ -65,10 +65,8 @@ orte_ras_sim_component_t mca_ras_simulator_component = {
 
 static int ras_sim_open(void)
 {
-    mca_base_param_reg_int(&mca_ras_simulator_component.super.base_version,
-                           "num_nodes",
-                           "Number of nodes to simulate",
-                           false, false, 0, &mca_ras_simulator_component.num_nodes);
+    int tmp;
+
     mca_base_param_reg_int(&mca_ras_simulator_component.super.base_version,
                            "slots",
                            "Number of slots on each node to simulate",
@@ -79,18 +77,37 @@ static int ras_sim_open(void)
                            false, false, 0, &mca_ras_simulator_component.slots_max);
 #if OPAL_HAVE_HWLOC
     mca_base_param_reg_string(&mca_ras_simulator_component.super.base_version,
-                              "topo_file",
-                              "File containing xml topology description for simulated nodes",
-                              false, false, NULL, &mca_ras_simulator_component.topofile);
+                              "num_nodes",
+                              "Comma-separated list of number of nodes to simulate for each topology",
+                              false, false, NULL, &mca_ras_simulator_component.num_nodes);
+    mca_base_param_reg_string(&mca_ras_simulator_component.super.base_version,
+                              "topo_files",
+                              "Comma-separated list of files containing xml topology descriptions for simulated nodes",
+                              false, false, NULL, &mca_ras_simulator_component.topofiles);
+    mca_base_param_reg_int(&mca_ras_simulator_component.super.base_version,
+                           "have_cpubind",
+                           "Topology supports binding to cpus",
+                           false, false, (int)true, &tmp);
+    mca_ras_simulator_component.have_cpubind = OPAL_INT_TO_BOOL(tmp);
+    mca_base_param_reg_int(&mca_ras_simulator_component.super.base_version,
+                           "have_membind",
+                           "Topology supports binding to memory",
+                           false, false, (int)true, &tmp);
+    mca_ras_simulator_component.have_membind = OPAL_INT_TO_BOOL(tmp);
+#else
+    mca_base_param_reg_string(&mca_ras_simulator_component.super.base_version,
+                              "num_nodes",
+                              "Number of nodes to simulate",
+                              false, false, NULL, &mca_ras_simulator_component.num_nodes);
 #endif
-
+        
     return ORTE_SUCCESS;
 }
 
 
 static int ras_sim_component_query(mca_base_module_t **module, int *priority)
 {
-    if (0 < mca_ras_simulator_component.num_nodes) {
+    if (NULL != mca_ras_simulator_component.num_nodes) {
         *module = (mca_base_module_t *) &orte_ras_sim_module;
         *priority = 1000;
         /* cannot launch simulated nodes or resolve their names to addresses */
diff --git a/orte/mca/ras/simulator/ras_sim_module.c b/orte/mca/ras/simulator/ras_sim_module.c
index 06c48b18aa..60d06bcb22 100644
--- a/orte/mca/ras/simulator/ras_sim_module.c
+++ b/orte/mca/ras/simulator/ras_sim_module.c
@@ -17,6 +17,7 @@
 #include "opal/class/opal_list.h"
 #include "opal/mca/hwloc/hwloc.h"
 
+#include "orte/util/show_help.h"
 #include "orte/runtime/orte_globals.h"
 
 #include "ras_sim.h"
@@ -39,83 +40,125 @@ orte_ras_base_module_t orte_ras_sim_module = {
 
 static int allocate(opal_list_t *nodes)
 {
-    int i, val, dig;
+    int i, n, val, dig, num_nodes;
     orte_node_t *node;
 #if OPAL_HAVE_HWLOC
     hwloc_topology_t topo;
     hwloc_obj_t obj;
     unsigned j, k;
+    struct hwloc_topology_support *support;
+    char **files=NULL;
+    bool use_local_topology = false;
+#endif
+    char **node_cnt=NULL;
+
+    node_cnt = opal_argv_split(mca_ras_simulator_component.num_nodes, ',');
+
+#if OPAL_HAVE_HWLOC
+    if (NULL == mca_ras_simulator_component.topofiles) {
+        /* use our topology */
+        use_local_topology = true;
+        if (1 != opal_argv_count(node_cnt)) {
+            orte_show_help("help-ras-base.txt", "ras-sim:mismatch", true);
+            return ORTE_ERR_SILENT;
+        }
+    } else {
+        files = opal_argv_split(mca_ras_simulator_component.topofiles, ',');
+        if (opal_argv_count(files) != opal_argv_count(node_cnt)) {
+            orte_show_help("help-ras-base.txt", "ras-sim:mismatch", true);
+            return ORTE_ERR_SILENT;
+        }
+    }
+
 #endif
 
+    /* count the total number of nodes */
+    val = 0;
+    for (n=0; NULL != node_cnt[n]; n++) {
+        val += strtol(node_cnt[n], NULL, 10);
+    }
     /* get number of digits */
-    val = mca_ras_simulator_component.num_nodes;
     for (dig=0; 0 != val; dig++) {
         val /= 10;
     }
 
-    /* check for topology */
+    /* process the request */
+    val = 0;
+    for (n=0; NULL != node_cnt[n]; n++) {
+        num_nodes = strtol(node_cnt[n], NULL, 10);
+
+        /* check for topology */
 #if OPAL_HAVE_HWLOC
-    if (NULL == mca_ras_simulator_component.topofile) {
-        /* use our topology */
-        topo = opal_hwloc_topology;
-    } else {
-        if (0 != hwloc_topology_init(&topo)) {
-            return ORTE_ERROR;
-        }
-        if (0 != hwloc_topology_set_xml(topo, mca_ras_simulator_component.topofile)) {
-            hwloc_topology_destroy(topo);
-            return ORTE_ERROR;
-        }
-        /* since we are loading this from an external source, we have to
-         * explicitly set a flag so hwloc sets things up correctly
-         */
-        if (0 != hwloc_topology_set_flags(topo, HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM)) {
-            hwloc_topology_destroy(topo);
-            return ORTE_ERROR;
-        }
-        if (0 != hwloc_topology_load(topo)) {
-            hwloc_topology_destroy(topo);
-            return ORTE_ERROR;
-        }
-        /* remove the hostname from the topology. Unfortunately, hwloc
-         * decided to add the source hostname to the "topology", thus
-         * rendering it unusable as a pure topological description. So
-         * we remove that information here.
-         */
-        obj = hwloc_get_root_obj(topo);
-        for (k=0; k < obj->infos_count; k++) {
-            if (NULL == obj->infos[k].name ||
-                NULL == obj->infos[k].value) {
-                continue;
+        if (use_local_topology) {
+            /* use our topology */
+            topo = opal_hwloc_topology;
+        } else {
+            if (0 != hwloc_topology_init(&topo)) {
+                return ORTE_ERROR;
             }
-            if (0 == strncmp(obj->infos[k].name, "HostName", strlen("HostName"))) {
-                free(obj->infos[k].name);
-                free(obj->infos[k].value);
-                /* left justify the array */
-                for (j=k; j < obj->infos_count-1; j++) {
-                    obj->infos[j] = obj->infos[j+1];
+            if (0 != hwloc_topology_set_xml(topo, files[n])) {
+                hwloc_topology_destroy(topo);
+                return ORTE_ERROR;
+            }
+            /* since we are loading this from an external source, we have to
+             * explicitly set a flag so hwloc sets things up correctly
+             */
+            if (0 != hwloc_topology_set_flags(topo, HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM)) {
+                hwloc_topology_destroy(topo);
+                return ORTE_ERROR;
+            }
+            if (0 != hwloc_topology_load(topo)) {
+                hwloc_topology_destroy(topo);
+                return ORTE_ERROR;
+            }
+            /* remove the hostname from the topology. Unfortunately, hwloc
+             * decided to add the source hostname to the "topology", thus
+             * rendering it unusable as a pure topological description. So
+             * we remove that information here.
+             */
+            obj = hwloc_get_root_obj(topo);
+            for (k=0; k < obj->infos_count; k++) {
+                if (NULL == obj->infos[k].name ||
+                    NULL == obj->infos[k].value) {
+                    continue;
+                }
+                if (0 == strncmp(obj->infos[k].name, "HostName", strlen("HostName"))) {
+                    free(obj->infos[k].name);
+                    free(obj->infos[k].value);
+                    /* left justify the array */
+                    for (j=k; j < obj->infos_count-1; j++) {
+                        obj->infos[j] = obj->infos[j+1];
+                    }
+                    obj->infos[obj->infos_count-1].name = NULL;
+                    obj->infos[obj->infos_count-1].value = NULL;
+                    obj->infos_count--;
+                    break;
                 }
-                obj->infos[obj->infos_count-1].name = NULL;
-                obj->infos[obj->infos_count-1].value = NULL;
-                obj->infos_count--;
-                break;
             }
+            /* unfortunately, hwloc does not include support info in its
+             * xml output :-(( To aid in debugging, we set it here
+             */
+            support = (struct hwloc_topology_support*)hwloc_topology_get_support(topo);
+            support->cpubind->set_thisproc_cpubind = mca_ras_simulator_component.have_cpubind;
+            support->membind->set_thisproc_membind = mca_ras_simulator_component.have_membind;
+            /* add it to our array */
+            opal_pointer_array_add(orte_node_topologies, topo);
         }
-    }
 #endif
 
-    for (i=0; i < mca_ras_simulator_component.num_nodes; i++) {
-        node = OBJ_NEW(orte_node_t);
-        asprintf(&node->name, "node%0*d", dig, i);
-        node->state = ORTE_NODE_STATE_UP;
-        node->slots_inuse = 0;
-        node->slots_max = mca_ras_simulator_component.slots_max;
-        node->slots = mca_ras_simulator_component.slots;
+        for (i=0; i < num_nodes; i++) {
+            node = OBJ_NEW(orte_node_t);
+            asprintf(&node->name, "node%0*d", dig, val++);
+            node->state = ORTE_NODE_STATE_UP;
+            node->slots_inuse = 0;
+            node->slots_max = mca_ras_simulator_component.slots_max;
+            node->slots = mca_ras_simulator_component.slots;
 #if OPAL_HAVE_HWLOC
-        node->topology = topo;
+            node->topology = topo;
 #endif
-        opal_list_append(nodes, &node->super);
-     }
+            opal_list_append(nodes, &node->super);
+        }
+    }
 
     /* record the number of allocated nodes */
     orte_num_allocated_nodes = opal_list_get_size(nodes);