diff --git a/ibv-conduit/gasnet_core.c b/ibv-conduit/gasnet_core.c
index e91c97c85..eb46310db 100644
--- a/ibv-conduit/gasnet_core.c
+++ b/ibv-conduit/gasnet_core.c
@@ -2063,8 +2063,8 @@ static int gasnetc_init( gex_Client_t            *client_p,
   // Ensure work-arounds like MLX5_SCATTER_TO_CQE are propogated
   gasneti_propagate_env("MLX5_", GASNETI_PROPAGATE_ENV_PREFIX);
 
-  /* bootstrapInit may set gasneti_nodes==0 if would overflow 16-bit field */
-  if (!gasneti_nodes || (gasneti_nodes > GASNET_MAXNODES)) {
+  // Node count from bootstrapInit might exceed GASNET_MAXNODES
+  if (gasneti_nodes > GASNET_MAXNODES) {
     GASNETI_RETURN_ERRR(RESOURCE, "job size exceeds ibv-conduit capabilities");
   }
 
diff --git a/ibv-conduit/gasnet_core_connect.c b/ibv-conduit/gasnet_core_connect.c
index 2b8f2b023..a0d9f3877 100644
--- a/ibv-conduit/gasnet_core_connect.c
+++ b/ibv-conduit/gasnet_core_connect.c
@@ -192,11 +192,7 @@ typedef struct gasnetc_xrc_snd_qp_s {
 } gasnetc_xrc_snd_qp_t;
 
 static gasnetc_xrc_snd_qp_t *gasnetc_xrc_snd_qp = NULL;
-#if GASNET_MAXNODES <= 65535
-static uint16_t *gasnetc_xrcd_map = NULL;
-#else
 static uint32_t *gasnetc_xrcd_map = NULL;
-#endif
 static int gasnetc_xrcd_simple;
 
 static gasnetc_xrc_snd_qp_t *
@@ -379,7 +375,6 @@ static int _gasnetc_xrc_compare_keys(gex_Rank_t a_r, gex_Rank_t b_r) {
                 sizeof(uint16_t) * gasnetc_num_ports);
 }
 static int _gasnetc_xrc_compare_fn(const void *a_p, const void *b_p) {
-  gasneti_static_assert(GASNET_MAXNODES < INT_MAX);
   gex_Rank_t a_r = *(gex_Rank_t *)a_p;
   gex_Rank_t b_r = *(gex_Rank_t *)b_p;
 
@@ -388,7 +383,7 @@ static int _gasnetc_xrc_compare_fn(const void *a_p, const void *b_p) {
   if (result) return result;
 
   // tie-break using the rank itself
-  return (int)a_r - (int)b_r;
+  return (a_r == b_r) ? 0 : (a_r < b_r ? -1 : 1);
 }
 
 // Compute XRC domain mebership
@@ -1221,8 +1216,8 @@ typedef enum {
   GASNETC_CONN_CMD_ACK
 } gasnetc_conn_cmd_t;
 
-#define GASNETC_CONN_CMD_MASK  0x0f
-#define GASNETC_CONN_IS_ORIG   0x10
+#define GASNETC_CONN_CMD_MASK  0x7
+#define GASNETC_CONN_IS_ORIG   0x8
 
 static gasnetc_ud_snd_desc_t *
 conn_get_snd_desc(uint32_t flags)
@@ -1230,7 +1225,9 @@ conn_get_snd_desc(uint32_t flags)
   gasnetc_ud_snd_desc_t *desc;
   GASNETI_SPIN_UNTIL_TRACE((desc = gasneti_lifo_pop(&conn_snd_freelist)),
                            C, CONN_STALL_DESC, conn_snd_poll());
-  desc->wr.imm_data = flags | (gasneti_mynode << 16);
+  gasneti_assert_uint((flags >> 4) ,==, 0);
+  gasneti_assert_uint(gasneti_mynode ,<, (1 << 28));
+  desc->wr.imm_data = flags | (gasneti_mynode << 4);
   return desc;
 }
 
@@ -1934,7 +1931,7 @@ gasnetc_conn_rcv_wc(struct ibv_wc *comp)
   gasnetc_ud_rcv_desc_t *desc = (gasnetc_ud_rcv_desc_t *)(1 ^ (uintptr_t)comp->wr_id);
   gasnetc_conn_cmd_t cmd = (gasnetc_conn_cmd_t)(comp->imm_data & GASNETC_CONN_CMD_MASK);
   uint32_t is_orig = comp->imm_data & GASNETC_CONN_IS_ORIG;
-  gex_Rank_t node = (comp->imm_data >> 16) & 0xffff;
+  gex_Rank_t node = (comp->imm_data >> 4) & 0x0fffffff;
   gasneti_tick_t now = gasneti_ticks_now();
 
 #if GASNET_DEBUG /* Drop 1 in N to aid debugging */
diff --git a/ibv-conduit/gasnet_core_internal.h b/ibv-conduit/gasnet_core_internal.h
index 9d8d90fa8..cdc7cfaea 100644
--- a/ibv-conduit/gasnet_core_internal.h
+++ b/ibv-conduit/gasnet_core_internal.h
@@ -529,17 +529,17 @@ typedef struct {
  * gasnetc_epid_d is node and qp encoded together
  * passing just a node (the default) means any qp to that node
  */
-typedef uint32_t gasnetc_epid_t;
+typedef uint64_t gasnetc_epid_t;
 
-/* The 'epid' type holds 'node' in the low 16 bits.
- * The upper 16 bits holds a qp index (qpi).
+/* The 'epid' type holds 'node' in the low 32 bits.
+ * The upper 32 bits holds a qp index (qpi).
  * A qpi of zero is a wildcard (an 'unbound' epid).
  * Therefore, setting epid=node means "use any qp for that node".
  * Non-zero qpi is 1 + the array index of the desired queue pair.
  */
-#define gasnetc_epid2node(E)	((E)&0xffff)
-#define gasnetc_epid2qpi(E)	((E)>>16)
-#define gasnetc_epid(N,Q)	((N)|(((Q)+1)<<16))
+#define gasnetc_epid2node(E)	GASNETI_LOWORD(E)
+#define gasnetc_epid2qpi(E)	GASNETI_HIWORD(E)
+#define gasnetc_epid(N,Q)	GASNETI_MAKEWORD((Q)+1,(N))
 
 /* Forward decl */
 struct gasnetc_cep_t_;
@@ -638,7 +638,7 @@ struct gasnetc_cep_t_ {
   // This is total size of R/W fields, with possible trailing padding prior to R/O fields,
   // correct independent of GASNETI_THREADS
   #define _GASNETC_CEP_RW_BYTES GASNETI_ALIGNUP_NOASSERT(_GASNETC_CEP_RW_EARLY+sizeof(gasnetc_sema_t),\
-                                                         sizeof(void *))
+                                                         sizeof(uint64_t))
 
   //
   // Read-only fields
@@ -647,8 +647,8 @@ struct gasnetc_cep_t_ {
   // These are sorted by size to get dense packing
 
   // 64-bit fields
-  // None currently
-  // Change _GASNETC_CEP_RW_BYTES's alignment to 8 if any are added
+  gasnetc_epid_t        epid;           // == uint64_t
+  #define _GASNETC_CEP_64_0 8
 
   // Pointer-width fields
   gasnetc_hca_t         *hca;
@@ -673,8 +673,7 @@ struct gasnetc_cep_t_ {
 #endif
 
   // 32-bit fields
-  gasnetc_epid_t        epid;           // == uint32_t
-  #define _GASNETC_CEP_32_0 4
+  #define _GASNETC_CEP_32_0 0           // Placeholder for unconditional fields above
 #if GASNETC_PIN_SEGMENT
   uint32_t              rkey;           // Copy of hca->rkeys[gasnetc_epid2node(epid)]
   #define _GASNETC_CEP_32_1 1*4
@@ -704,6 +703,7 @@ struct gasnetc_cep_t_ {
 
 #define _GASNETC_CEP_TO_PAD (\
     _GASNETC_CEP_RW_BYTES + \
+    _GASNETC_CEP_64_0 + \
     _GASNETC_CEP_PTR_0+_GASNETC_CEP_PTR_1+_GASNETC_CEP_PTR_2 + \
     _GASNETC_CEP_32_0+_GASNETC_CEP_32_1+_GASNETC_CEP_32_2+_GASNETC_CEP_32_3+_GASNETC_CEP_32_4)
 #if GASNETI_THREADS