diff --git a/loxi_ir/ir_offset.py b/loxi_ir/ir_offset.py
index db55f24..5eff8e0 100644
--- a/loxi_ir/ir_offset.py
+++ b/loxi_ir/ir_offset.py
@@ -109,6 +109,7 @@
     of_octets_t = (0, False),
     of_bitmap_128_t = (16, True),
     of_checksum_128_t = (16, True),
+    of_bitmap_512_t = (64, True),
 )
 
 def type_dec_to_count_base(m_type):
diff --git a/openflow_input/bsn_in_ports b/openflow_input/bsn_in_ports
index 819bdde..bb4c030 100644
--- a/openflow_input/bsn_in_ports
+++ b/openflow_input/bsn_in_ports
@@ -60,3 +60,14 @@
     of_bitmap_128_t value;
     of_bitmap_128_t value_mask;
 };
+
+struct of_oxm_bsn_in_ports_512 : of_oxm {
+    uint32_t type_len == 0x00032640;
+    of_bitmap_512_t value;
+};
+
+struct of_oxm_bsn_in_ports_512_masked : of_oxm {
+    uint32_t type_len == 0x00032780;
+    of_bitmap_512_t value;
+    of_bitmap_512_t value_mask;
+};
diff --git a/test_data/of13/oxm_bsn_in_ports_masked_512.data b/test_data/of13/oxm_bsn_in_ports_masked_512.data
new file mode 100644
index 0000000..82cc45c
--- /dev/null
+++ b/test_data/of13/oxm_bsn_in_ports_masked_512.data
@@ -0,0 +1,36 @@
+-- binary
+00 03 # class
+27 # type/masked
+80 # length
+00 00 00 00 00 00 00 00 # value
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+7f ff ff ff ff ff ff ff # mask - Only ports 0, 17, 96, 511 are selected (and thus are zero)
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff fe ff ff ff ff # ...
+ff ff ff ff ff fd ff fe # ...
+-- python
+ofp.oxm.bsn_in_ports_512_masked(set(), set(range(0,512)) - set((0, 17, 96, 511)))
+-- c
+obj = of_oxm_bsn_in_ports_512_masked_new(OF_VERSION_1_3);
+{
+    of_bitmap_512_t bmap = { { 0, 0, 0, 0, 0, 0, 0, 0 } };
+    of_oxm_bsn_in_ports_512_masked_value_set(obj, bmap);
+}
+{
+    of_bitmap_512_t bmap = { { 0x7fffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xfffffffeffffffff, 0xfffffffffffdfffe } };
+    of_oxm_bsn_in_ports_512_masked_value_mask_set(obj, bmap);
+}
+-- java
+OFPortMap portmap = OFPortMap.ofPorts(OFPort.of(0), OFPort.of(17), OFPort.of(96));
+builder.setValue(portmap.getValue());
+builder.setMask(portmap.getMask());