diff --git a/ompi/mca/pml/base/pml_base_frame.c b/ompi/mca/pml/base/pml_base_frame.c
index 8468c5c4f17..2ab970b5324 100644
--- a/ompi/mca/pml/base/pml_base_frame.c
+++ b/ompi/mca/pml/base/pml_base_frame.c
@@ -192,6 +192,9 @@ static int mca_pml_base_close(void)
     OBJ_DESTRUCT(&mca_pml_base_send_requests);
     OBJ_DESTRUCT(&mca_pml_base_recv_requests);
 
+    OBJ_DESTRUCT(&mca_pml_ob1_send_requests);
+    OBJ_DESTRUCT(&mca_pml_ob1_recv_requests);
+
     mca_pml.pml_progress = mca_pml_base_progress;
 
     /* Free all the strings in the array */
@@ -223,6 +226,9 @@ static int mca_pml_base_open(mca_base_open_flag_t flags)
     OBJ_CONSTRUCT(&mca_pml_base_send_requests, opal_free_list_t);
     OBJ_CONSTRUCT(&mca_pml_base_recv_requests, opal_free_list_t);
 
+    OBJ_CONSTRUCT(&mca_pml_ob1_send_requests, opal_free_list_t);
+    OBJ_CONSTRUCT(&mca_pml_ob1_recv_requests, opal_free_list_t);
+
     OBJ_CONSTRUCT(&mca_pml_base_pml, opal_pointer_array_t);
 
     /* Open up all available components */
@@ -261,6 +267,7 @@ static int mca_pml_base_open(mca_base_open_flag_t flags)
             opal_pointer_array_add(&mca_pml_base_pml, strdup("ob1"));
             opal_pointer_array_add(&mca_pml_base_pml, strdup("ucx"));
             opal_pointer_array_add(&mca_pml_base_pml, strdup("cm"));
+            opal_pointer_array_add(&mca_pml_base_pml, strdup("topo"));
         } else {
 #if OPAL_ENABLE_DEBUG
             char **req_pml = opal_argv_split(default_pml[0], ',');
diff --git a/ompi/mca/pml/base/pml_base_request.c b/ompi/mca/pml/base/pml_base_request.c
index 791e6838ab5..7a25bfc952a 100644
--- a/ompi/mca/pml/base/pml_base_request.c
+++ b/ompi/mca/pml/base/pml_base_request.c
@@ -30,6 +30,9 @@
 opal_free_list_t mca_pml_base_send_requests = {{{0}}};
 opal_free_list_t mca_pml_base_recv_requests = {{{0}}};
 
+opal_free_list_t mca_pml_ob1_send_requests = {{{0}}};
+opal_free_list_t mca_pml_ob1_recv_requests = {{{0}}};
+
 static void mca_pml_base_request_construct(mca_pml_base_request_t* req)
 {
     req->req_ompi.req_type = OMPI_REQUEST_PML;
diff --git a/ompi/mca/pml/base/pml_base_request.h b/ompi/mca/pml/base/pml_base_request.h
index 90a86505e07..0e2619d99ed 100644
--- a/ompi/mca/pml/base/pml_base_request.h
+++ b/ompi/mca/pml/base/pml_base_request.h
@@ -44,6 +44,9 @@ BEGIN_C_DECLS
 OMPI_DECLSPEC extern opal_free_list_t mca_pml_base_send_requests;
 OMPI_DECLSPEC extern opal_free_list_t mca_pml_base_recv_requests;
 
+OMPI_DECLSPEC extern opal_free_list_t mca_pml_ob1_send_requests;
+OMPI_DECLSPEC extern opal_free_list_t mca_pml_ob1_recv_requests;
+
 /**
  * Type of request.
  */
diff --git a/ompi/mca/pml/base/pml_base_select.c b/ompi/mca/pml/base/pml_base_select.c
index e66ec02b5e4..ff1cb508d4b 100644
--- a/ompi/mca/pml/base/pml_base_select.c
+++ b/ompi/mca/pml/base/pml_base_select.c
@@ -189,7 +189,11 @@ int mca_pml_base_select(bool enable_progress_threads,
          item = opal_list_remove_first(&opened)) {
         om = (opened_component_t *) item;
 
-        if (om->om_component != best_component ) {
+        if (om->om_component != best_component
+            && strncmp(om->om_component->pmlm_version.mca_component_name, "ob1",
+                       strlen(om->om_component->pmlm_version.mca_component_name))
+            && strncmp(om->om_component->pmlm_version.mca_component_name, "cm",
+                       strlen(om->om_component->pmlm_version.mca_component_name))) {
             /* Finalize */
 
             if (NULL != om->om_component->pmlm_finalize) {
@@ -213,9 +217,20 @@ int mca_pml_base_select(bool enable_progress_threads,
        available list all unselected components.  The available list will
        contain only the selected component. */
 
-    mca_base_components_close(ompi_pml_base_framework.framework_output,
-                              &ompi_pml_base_framework.framework_components,
-                              (mca_base_component_t *) best_component);
+    // mca_base_components_close(ompi_pml_base_framework.framework_output,
+    //                           &ompi_pml_base_framework.framework_components,
+    //                           (mca_base_component_t *) best_component);
+
+    OPAL_LIST_FOREACH (cli, &ompi_pml_base_framework.framework_components, mca_base_component_list_item_t) {
+        component = (mca_pml_base_component_t *) cli->cli_component;
+        if (component != best_component
+            && strncmp(om->om_component->pmlm_version.mca_component_name, "ob1",
+                       strlen(om->om_component->pmlm_version.mca_component_name))
+            && strncmp(om->om_component->pmlm_version.mca_component_name, "cm",
+                       strlen(om->om_component->pmlm_version.mca_component_name))) {
+            mca_base_component_close(component, ompi_pml_base_framework.framework_output);
+        }
+    }
 
     /* register the winner's callback */
     if( NULL != mca_pml.pml_progress ) {
diff --git a/ompi/mca/pml/cm/pml_cm.c b/ompi/mca/pml/cm/pml_cm.c
index 51a63fdba4c..575e5e6fca0 100644
--- a/ompi/mca/pml/cm/pml_cm.c
+++ b/ompi/mca/pml/cm/pml_cm.c
@@ -127,11 +127,11 @@ mca_pml_cm_add_procs(struct ompi_proc_t** procs, size_t nprocs)
 #endif
 
     /* make sure remote procs are using the same PML as us */
-    if (OMPI_SUCCESS != (ret = mca_pml_base_pml_check_selected("cm",
-                                                              procs,
-                                                              nprocs))) {
-        return ret;
-    }
+    // if (OMPI_SUCCESS != (ret = mca_pml_base_pml_check_selected("cm",
+    //                                                           procs,
+    //                                                           nprocs))) {
+    //     return ret;
+    // }
 
     ret = OMPI_MTL_CALL(add_procs(ompi_mtl, nprocs, procs));
     return ret;
diff --git a/ompi/mca/pml/ob1/pml_ob1.c b/ompi/mca/pml/ob1/pml_ob1.c
index c8d0df3e24a..1995f51425d 100644
--- a/ompi/mca/pml/ob1/pml_ob1.c
+++ b/ompi/mca/pml/ob1/pml_ob1.c
@@ -175,7 +175,7 @@ int mca_pml_ob1_enable(bool enable)
      * should get ownership for the send and receive requests list, and
      * initialize them with the size of our own requests.
      */
-    opal_free_list_init ( &mca_pml_base_send_requests,
+    opal_free_list_init ( &mca_pml_ob1_send_requests,
                           sizeof(mca_pml_ob1_send_request_t) +
                           sizeof(mca_pml_ob1_com_btl_t[mca_pml_ob1.max_rdma_per_request]),
                           opal_cache_line_size,
@@ -186,7 +186,7 @@ int mca_pml_ob1_enable(bool enable)
                           mca_pml_ob1.free_list_inc,
                           NULL, 0, NULL, NULL, NULL);
 
-    opal_free_list_init ( &mca_pml_base_recv_requests,
+    opal_free_list_init ( &mca_pml_ob1_recv_requests,
                           sizeof(mca_pml_ob1_recv_request_t) +
                           sizeof(mca_pml_ob1_com_btl_t[mca_pml_ob1.max_rdma_per_request]),
                           opal_cache_line_size,
@@ -388,11 +388,11 @@ int mca_pml_ob1_add_procs(ompi_proc_t** procs, size_t nprocs)
         return rc;
 
     /* make sure remote procs are using the same PML as us */
-    if (OMPI_SUCCESS != (rc = mca_pml_base_pml_check_selected("ob1",
-                                                              procs,
-                                                              nprocs))) {
-        return rc;
-    }
+    // if (OMPI_SUCCESS != (rc = mca_pml_base_pml_check_selected("ob1",
+    //                                                           procs,
+    //                                                           nprocs))) {
+    //     return rc;
+    // }
 
     OBJ_CONSTRUCT(&reachable, opal_bitmap_t);
     rc = opal_bitmap_init(&reachable, (int)nprocs);
diff --git a/ompi/mca/pml/ob1/pml_ob1.h b/ompi/mca/pml/ob1/pml_ob1.h
index ddfd4693c13..7371d2ebb24 100644
--- a/ompi/mca/pml/ob1/pml_ob1.h
+++ b/ompi/mca/pml/ob1/pml_ob1.h
@@ -94,6 +94,8 @@ typedef struct mca_pml_ob1_t mca_pml_ob1_t;
 extern mca_pml_ob1_t mca_pml_ob1;
 extern int mca_pml_ob1_output;
 extern bool mca_pml_ob1_matching_protection;
+OMPI_DECLSPEC extern opal_free_list_t mca_pml_ob1_send_requests;
+OMPI_DECLSPEC extern opal_free_list_t mca_pml_ob1_recv_requests;
 /*
  * PML interface functions.
  */
diff --git a/ompi/mca/pml/ob1/pml_ob1_component.c b/ompi/mca/pml/ob1/pml_ob1_component.c
index a9a36413202..dc8fbea05a6 100644
--- a/ompi/mca/pml/ob1/pml_ob1_component.c
+++ b/ompi/mca/pml/ob1/pml_ob1_component.c
@@ -344,12 +344,12 @@ int mca_pml_ob1_component_fini(void)
     /* return the static receive/send requests to the respective free list and
      * let the free list handle destruction. */
     if( NULL != mca_pml_ob1_recvreq ) {
-        opal_free_list_return (&mca_pml_base_recv_requests, (opal_free_list_item_t *) mca_pml_ob1_recvreq);
+        opal_free_list_return (&mca_pml_ob1_recv_requests, (opal_free_list_item_t *) mca_pml_ob1_recvreq);
         mca_pml_ob1_recvreq = NULL;
     }
 
     if( NULL != mca_pml_ob1_sendreq ) {
-        opal_free_list_return (&mca_pml_base_send_requests, (opal_free_list_item_t *) mca_pml_ob1_sendreq);
+        opal_free_list_return (&mca_pml_ob1_send_requests, (opal_free_list_item_t *) mca_pml_ob1_sendreq);
         mca_pml_ob1_sendreq = NULL;
     }
 
@@ -375,17 +375,17 @@ int mca_pml_ob1_component_fini(void)
     }
 
 #if 0
-    if (mca_pml_base_send_requests.fl_num_allocated !=
-        mca_pml_base_send_requests.super.opal_list_length) {
+    if (mca_pml_ob1_send_requests.fl_num_allocated !=
+        mca_pml_ob1_send_requests.super.opal_list_length) {
         opal_output(0, "ob1 send requests: %d allocated %d returned\n",
-                    mca_pml_base_send_requests.fl_num_allocated,
-                    mca_pml_base_send_requests.super.opal_list_length);
+                    mca_pml_ob1_send_requests.fl_num_allocated,
+                    mca_pml_ob1_send_requests.super.opal_list_length);
     }
-    if (mca_pml_base_recv_requests.fl_num_allocated !=
-        mca_pml_base_recv_requests.super.opal_list_length) {
+    if (mca_pml_ob1_recv_requests.fl_num_allocated !=
+        mca_pml_ob1_recv_requests.super.opal_list_length) {
         opal_output(0, "ob1 recv requests: %d allocated %d returned\n",
-                    mca_pml_base_recv_requests.fl_num_allocated,
-                    mca_pml_base_recv_requests.super.opal_list_length);
+                    mca_pml_ob1_recv_requests.fl_num_allocated,
+                    mca_pml_ob1_recv_requests.super.opal_list_length);
     }
 #endif
 
diff --git a/ompi/mca/pml/ob1/pml_ob1_recvreq.h b/ompi/mca/pml/ob1/pml_ob1_recvreq.h
index 402d3f4dcec..b261b931ceb 100644
--- a/ompi/mca/pml/ob1/pml_ob1_recvreq.h
+++ b/ompi/mca/pml/ob1/pml_ob1_recvreq.h
@@ -82,7 +82,7 @@ static inline bool unlock_recv_request(mca_pml_ob1_recv_request_t *recvreq)
 #define MCA_PML_OB1_RECV_REQUEST_ALLOC(recvreq)                    \
 do {                                                               \
     recvreq = (mca_pml_ob1_recv_request_t *)                          \
-        opal_free_list_get (&mca_pml_base_recv_requests);             \
+        opal_free_list_get (&mca_pml_ob1_recv_requests);             \
 } while(0)
 
 
@@ -115,6 +115,9 @@ do {                                                                \
                                     tag,                            \
                                     comm,                           \
                                     persistent);                    \
+    (request)->req_rdma_cnt = 0;                                    \
+    (request)->rdma_bml = 0;                                        \
+    (request)->local_handle = NULL;                                 \
 } while(0)
 
 /**
@@ -144,7 +147,7 @@ static inline void mca_pml_ob1_recv_request_fini (mca_pml_ob1_recv_request_t *re
 #define MCA_PML_OB1_RECV_REQUEST_RETURN(recvreq)                        \
     {                                                                   \
         mca_pml_ob1_recv_request_fini (recvreq);                        \
-        opal_free_list_return (&mca_pml_base_recv_requests,             \
+        opal_free_list_return (&mca_pml_ob1_recv_requests,             \
                                (opal_free_list_item_t*)(recvreq));      \
     }
 
diff --git a/ompi/mca/pml/ob1/pml_ob1_sendreq.h b/ompi/mca/pml/ob1/pml_ob1_sendreq.h
index 1d50ecc033d..508ebd1b580 100644
--- a/ompi/mca/pml/ob1/pml_ob1_sendreq.h
+++ b/ompi/mca/pml/ob1/pml_ob1_sendreq.h
@@ -130,7 +130,7 @@ get_request_from_send_pending(mca_pml_ob1_send_pending_t *type)
                                                                         \
         if( OPAL_LIKELY(NULL != proc) ) {                               \
             sendreq = (mca_pml_ob1_send_request_t*)                     \
-                opal_free_list_wait (&mca_pml_base_send_requests);      \
+                opal_free_list_wait (&mca_pml_ob1_send_requests);      \
             sendreq->req_send.req_base.req_proc = proc;                 \
         }                                                               \
     }
@@ -159,6 +159,7 @@ get_request_from_send_pending(mca_pml_ob1_send_pending_t *type)
                                        0); /* convertor_flags */        \
         (sendreq)->req_recv.pval = NULL;                                \
         (sendreq)->ob1_proc = ob1_proc;                                 \
+        (sendreq)->req_rdma_cnt = 0;                                    \
     }
 
 #define MCA_PML_OB1_SEND_REQUEST_RESET(sendreq)                         \
@@ -241,7 +242,7 @@ static inline void mca_pml_ob1_send_request_fini (mca_pml_ob1_send_request_t *se
 #define MCA_PML_OB1_SEND_REQUEST_RETURN(sendreq)                        \
     do {                                                                \
         mca_pml_ob1_send_request_fini (sendreq);                        \
-        opal_free_list_return ( &mca_pml_base_send_requests,            \
+        opal_free_list_return ( &mca_pml_ob1_send_requests,            \
                                 (opal_free_list_item_t*)sendreq);       \
         sendreq = NULL;  /* for safety */                               \
     } while(0)
diff --git a/ompi/mca/pml/topo/Makefile.am b/ompi/mca/pml/topo/Makefile.am
new file mode 100644
index 00000000000..602da03b8fa
--- /dev/null
+++ b/ompi/mca/pml/topo/Makefile.am
@@ -0,0 +1,40 @@
+#
+# Copyright (c) Amazon.com, Inc. or its affiliates. All rights reserved.
+# $COPYRIGHT$
+#
+# Additional copyrights may follow
+#
+# $HEADER$
+#
+
+# Make the output library in this directory, and name it either
+# mca_<type>_<name>.la (for DSO builds) or libmca_<type>_<name>.la
+# (for static builds).
+
+EXTRA_DIST = post_configure.sh
+
+if MCA_BUILD_ompi_pml_topo_DSO
+component_noinst =
+component_install = mca_pml_topo.la
+else
+component_noinst = libmca_pml_topo.la
+component_install =
+endif
+
+local_sources = \
+	pml_topo.c \
+	pml_topo.h \
+	pml_topo_component.c \
+	pml_topo_component.h
+
+mcacomponentdir = $(ompilibdir)
+mcacomponent_LTLIBRARIES = $(component_install)
+mca_pml_topo_la_SOURCES = $(local_sources)
+mca_pml_topo_la_LIBADD = $(top_builddir)/ompi/lib@OMPI_LIBMPI_NAME@.la \
+	$(pml_topo_LIBS)
+mca_pml_topo_la_LDFLAGS = -module -avoid-version $(pml_topo_LDFLAGS)
+
+noinst_LTLIBRARIES = $(component_noinst)
+libmca_pml_topo_la_SOURCES = $(local_sources)
+libmca_pml_topo_la_LIBADD = $(pml_topo_LIBS)
+libmca_pml_topo_la_LDFLAGS = -module -avoid-version $(pml_topo_LDFLAGS)
diff --git a/ompi/mca/pml/topo/pml_topo.c b/ompi/mca/pml/topo/pml_topo.c
new file mode 100644
index 00000000000..600ec4f4220
--- /dev/null
+++ b/ompi/mca/pml/topo/pml_topo.c
@@ -0,0 +1,208 @@
+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) Amazon.com, Inc. or its affiliates. All rights reserved.
+ * $COPYRIGHT$
+ *
+ * Additional copyrights may follow
+ *
+ * $HEADER$
+ */
+
+#include "ompi_config.h"
+
+#include "ompi/communicator/communicator.h"
+#include "ompi/mca/pml/base/base.h"
+#include "ompi/mca/pml/base/pml_base_bsend.h"
+#include "ompi/mca/pml/base/pml_base_request.h"
+
+#include "ompi/mca/pml/cm/pml_cm.h"
+#include "ompi/mca/pml/ob1/pml_ob1.h"
+#include "pml_topo.h"
+#include "pml_topo_component.h"
+
+static int pml_topo_enable(bool enable)
+{
+    int ret;
+
+    ret = ompi_pml_cm.super.pml_enable(enable);
+    ret = mca_pml_ob1.super.pml_enable(enable);
+
+    return ret;
+}
+
+static int pml_topo_add_comm(ompi_communicator_t *comm)
+{
+    int ret;
+
+    ret = ompi_pml_cm.super.pml_add_comm(comm);
+    ret = mca_pml_ob1.super.pml_add_comm(comm);
+
+    return ret;
+}
+
+static int pml_topo_del_comm(ompi_communicator_t *comm)
+{
+    /* notify the MTL about the deleted communicator */
+    int ret;
+
+    ret = ompi_pml_cm.super.pml_del_comm(comm);
+    ret = mca_pml_ob1.super.pml_del_comm(comm);
+
+    return ret;
+}
+
+static int pml_topo_add_procs(struct ompi_proc_t **procs, size_t nprocs)
+{
+    int ret;
+
+    ret = ompi_pml_cm.super.pml_add_procs(procs, nprocs);
+    ret = mca_pml_ob1.super.pml_add_procs(procs, nprocs);
+
+    return ret;
+}
+
+static int pml_topo_del_procs(struct ompi_proc_t **procs, size_t nprocs)
+{
+    int ret;
+
+    ret = ompi_pml_cm.super.pml_del_procs(procs, nprocs);
+    ret = mca_pml_ob1.super.pml_del_procs(procs, nprocs);
+
+    return ret;
+}
+
+/* print any available useful information from this communicator */
+static int pml_topo_dump(struct ompi_communicator_t *comm, int verbose)
+{
+    return OMPI_ERR_NOT_IMPLEMENTED;
+}
+
+static inline bool is_local_peer(struct ompi_communicator_t *comm, int peer_id)
+{
+    ompi_proc_t *proc = ompi_comm_peer_lookup(comm, peer_id);
+    if (!proc) {
+        return false;
+    }
+
+    return OPAL_PROC_ON_LOCAL_NODE(proc->super.proc_flags);
+}
+
+static inline mca_pml_base_module_t *get_module(struct ompi_communicator_t *comm, int peer_id)
+{
+    if (is_local_peer(comm, peer_id)) {
+        return &mca_pml_ob1.super;
+    }
+
+    return &ompi_pml_cm.super;
+}
+
+static int pml_topo_irecv_init(void *addr, size_t count, ompi_datatype_t *datatype, int src,
+                               int tag, struct ompi_communicator_t *comm,
+                               struct ompi_request_t **request)
+{
+    return get_module(comm, src)->pml_irecv_init(addr, count, datatype, src, tag, comm, request);
+}
+
+static int pml_topo_irecv(void *addr, size_t count, ompi_datatype_t *datatype, int src, int tag,
+                          struct ompi_communicator_t *comm, struct ompi_request_t **request)
+{
+    return get_module(comm, src)->pml_irecv(addr, count, datatype, src, tag, comm, request);
+}
+
+static int pml_topo_imrecv(void *buf, size_t count, ompi_datatype_t *datatype,
+                           struct ompi_message_t **message, struct ompi_request_t **request)
+{
+    return get_module((*message)->comm, (*message)->peer)
+        ->pml_imrecv(buf, count, datatype, message, request);
+}
+
+static int pml_topo_mrecv(void *buf, size_t count, ompi_datatype_t *datatype,
+                          struct ompi_message_t **message, ompi_status_public_t *status)
+{
+    return get_module((*message)->comm, (*message)->peer)
+        ->pml_mrecv(buf, count, datatype, message, status);
+}
+
+static int pml_topo_recv(void *addr, size_t count, ompi_datatype_t *datatype, int src, int tag,
+                         struct ompi_communicator_t *comm, ompi_status_public_t *status)
+{
+    return get_module(comm, src)->pml_recv(addr, count, datatype, src, tag, comm, status);
+}
+
+static int pml_topo_isend_init(const void *buf, size_t count, ompi_datatype_t *datatype, int dst,
+                               int tag, mca_pml_base_send_mode_t sendmode,
+                               ompi_communicator_t *comm, ompi_request_t **request)
+{
+    return get_module(comm, dst)->pml_isend_init(buf, count, datatype, dst, tag, sendmode, comm,
+                                                 request);
+}
+
+static int pml_topo_isend(const void *buf, size_t count, ompi_datatype_t *datatype, int dst,
+                          int tag, mca_pml_base_send_mode_t sendmode, ompi_communicator_t *comm,
+                          ompi_request_t **request)
+{
+    return get_module(comm, dst)->pml_isend(buf, count, datatype, dst, tag, sendmode, comm,
+                                            request);
+}
+
+static int pml_topo_send(const void *buf, size_t count, ompi_datatype_t *datatype, int dst, int tag,
+                         mca_pml_base_send_mode_t sendmode, ompi_communicator_t *comm)
+{
+    return get_module(comm, dst)->pml_send(buf, count, datatype, dst, tag, sendmode, comm);
+}
+
+static int pml_topo_iprobe(int src, int tag, struct ompi_communicator_t *comm, int *matched,
+                           ompi_status_public_t *status)
+{
+    return get_module(comm, src)->pml_iprobe(src, tag, comm, matched, status);
+}
+
+static int pml_topo_probe(int src, int tag, struct ompi_communicator_t *comm,
+                          ompi_status_public_t *status)
+{
+    return get_module(comm, src)->pml_probe(src, tag, comm, status);
+}
+
+static int pml_topo_start(size_t count, ompi_request_t **requests)
+{
+    /* TODO */
+    return OMPI_ERR_NOT_IMPLEMENTED;
+}
+
+static int pml_topo_improbe(int src, int tag, struct ompi_communicator_t *comm, int *matched,
+                            struct ompi_message_t **message, ompi_status_public_t *status)
+{
+    return get_module(comm, src)->pml_improbe(src, tag, comm, matched, message, status);
+}
+
+static int pml_topo_mprobe(int src, int tag, struct ompi_communicator_t *comm,
+                           struct ompi_message_t **message, ompi_status_public_t *status)
+{
+    return get_module(comm, src)->pml_mprobe(src, tag, comm, message, status);
+}
+
+ompi_pml_topo_t ompi_pml_topo = {{
+    .pml_add_procs = pml_topo_add_procs,
+    .pml_del_procs = pml_topo_del_procs,
+    .pml_enable = pml_topo_enable,
+    .pml_progress = NULL, /* No progress function. The MTL register their own */
+    .pml_add_comm = pml_topo_add_comm,
+    .pml_del_comm = pml_topo_del_comm,
+    .pml_irecv_init = pml_topo_irecv_init,
+    .pml_irecv = pml_topo_irecv,
+    .pml_recv = pml_topo_recv,
+    .pml_isend_init = pml_topo_isend_init,
+    .pml_isend = pml_topo_isend,
+    .pml_send = pml_topo_send,
+    .pml_iprobe = pml_topo_iprobe,
+    .pml_probe = pml_topo_probe,
+    .pml_start = pml_topo_start,
+    .pml_improbe = pml_topo_improbe,
+    .pml_mprobe = pml_topo_mprobe,
+    .pml_imrecv = pml_topo_imrecv,
+    .pml_mrecv = pml_topo_mrecv,
+    .pml_dump = pml_topo_dump,
+    .pml_max_contextid = 65535,
+    .pml_max_tag = INT_MAX,
+    .pml_flags = 0 /* flags */
+}};
diff --git a/ompi/mca/pml/topo/pml_topo.h b/ompi/mca/pml/topo/pml_topo.h
new file mode 100644
index 00000000000..ba3d65d6bb5
--- /dev/null
+++ b/ompi/mca/pml/topo/pml_topo.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) Amazon.com, Inc. or its affiliates. All rights reserved.
+ * $COPYRIGHT$
+ *
+ * Additional copyrights may follow
+ *
+ * $HEADER$
+ */
+
+#ifndef PML_TOPO_H
+#define PML_TOPO_H
+
+#include "ompi_config.h"
+#include "ompi/communicator/communicator.h"
+#include "ompi/datatype/ompi_datatype.h"
+#include "ompi/mca/pml/base/base.h"
+#include "ompi/mca/pml/pml.h"
+#include "ompi/request/request.h"
+
+#include "ompi/mca/pml/base/pml_base_recvreq.h"
+#include "ompi/message/message.h"
+
+BEGIN_C_DECLS
+
+struct ompi_pml_topo_t {
+    mca_pml_base_module_t super;
+};
+typedef struct ompi_pml_topo_t ompi_pml_topo_t;
+extern ompi_pml_topo_t ompi_pml_topo;
+
+END_C_DECLS
+
+#endif /* PML_topo_H_HAS_BEEN_INCLUDED */
diff --git a/ompi/mca/pml/topo/pml_topo_component.c b/ompi/mca/pml/topo/pml_topo_component.c
new file mode 100644
index 00000000000..bcebb577873
--- /dev/null
+++ b/ompi/mca/pml/topo/pml_topo_component.c
@@ -0,0 +1,92 @@
+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) Amazon.com, Inc. or its affiliates. All rights reserved.
+ * $COPYRIGHT$
+ *
+ * Additional copyrights may follow
+ *
+ * $HEADER$
+ */
+
+#include "ompi_config.h"
+
+#include "opal/util/event.h"
+#include "pml_topo.h"
+
+#include "ompi/mca/pml/cm/pml_cm_component.h"
+#include "ompi/mca/pml/ob1/pml_ob1_component.h"
+#include "pml_topo_component.h"
+
+static int mca_pml_topo_component_register(void);
+static int mca_pml_topo_component_open(void);
+static int mca_pml_topo_component_close(void);
+static mca_pml_base_module_t* mca_pml_topo_component_init( int* priority,
+                            bool enable_progress_threads, bool enable_mpi_threads);
+static int mca_pml_topo_component_fini(void);
+
+mca_pml_base_component_2_1_0_t mca_pml_topo_component = {
+    /* First, the mca_base_component_t struct containing meta
+     * information about the component itself */
+
+    .pmlm_version = {
+        MCA_PML_BASE_VERSION_2_1_0,
+
+        .mca_component_name = "topo",
+        MCA_BASE_MAKE_VERSION(component, OMPI_MAJOR_VERSION, OMPI_MINOR_VERSION,
+                              OMPI_RELEASE_VERSION),
+        .mca_open_component = mca_pml_topo_component_open,
+        .mca_close_component = mca_pml_topo_component_close,
+        .mca_register_component_params = mca_pml_topo_component_register,
+    },
+    .pmlm_data = {
+        /* This component is not checkpoint ready */
+        MCA_BASE_METADATA_PARAM_NONE
+    },
+
+    .pmlm_init = mca_pml_topo_component_init,
+    .pmlm_finalize = mca_pml_topo_component_fini,
+};
+
+static int
+mca_pml_topo_component_register(void)
+{
+    return OMPI_SUCCESS;
+}
+
+static int
+mca_pml_topo_component_open(void)
+{
+    return OMPI_SUCCESS;
+}
+
+
+static int
+mca_pml_topo_component_close(void)
+{
+    int ret;
+
+    ret = mca_pml_cm_component.pmlm_version.mca_close_component();
+    ret = mca_pml_ob1_component.pmlm_version.mca_close_component();
+
+    return ret;
+}
+
+
+static mca_pml_base_module_t*
+mca_pml_topo_component_init(int* priority,
+                          bool enable_progress_threads,
+                          bool enable_mpi_threads)
+{
+    *priority = 100;
+
+    return &ompi_pml_topo.super;
+}
+
+
+static int
+mca_pml_topo_component_fini(void)
+{
+    mca_pml_cm_component.pmlm_finalize();
+    mca_pml_ob1_component.pmlm_finalize();
+    return OMPI_SUCCESS;
+}
diff --git a/ompi/mca/pml/topo/pml_topo_component.h b/ompi/mca/pml/topo/pml_topo_component.h
new file mode 100644
index 00000000000..7c11403beb3
--- /dev/null
+++ b/ompi/mca/pml/topo/pml_topo_component.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) Amazon.com, Inc. or its affiliates. All rights reserved.
+ * $COPYRIGHT$
+ *
+ * Additional copyrights may follow
+ *
+ * $HEADER$
+ */
+/**
+ *  @file
+ */
+
+#ifndef MCA_PML_TOPO_COMPONENT_H
+#define MCA_PML_TOPO_COMPONENT_H
+
+#include "ompi/mca/pml/pml.h"
+
+BEGIN_C_DECLS
+
+/*
+ * PML module functions.
+ */
+OMPI_DECLSPEC extern mca_pml_base_component_2_1_0_t mca_pml_topo_component;
+
+END_C_DECLS
+
+#endif
diff --git a/ompi/mca/pml/topo/post_configure.sh b/ompi/mca/pml/topo/post_configure.sh
new file mode 100644
index 00000000000..78ac62343ab
--- /dev/null
+++ b/ompi/mca/pml/topo/post_configure.sh
@@ -0,0 +1 @@
+DIRECT_CALL_HEADER="ompi/mca/pml/topo/pml_topo.h"