diff --git a/doc/plan.org b/doc/plan.org
index dc256c3..43c35d8 100644
--- a/doc/plan.org
+++ b/doc/plan.org
@@ -188,13 +188,16 @@
 |            | Need to setup hardware addresses -> in theor resolution -> hardcoded atm   |       |
 |            |                                                                            |       |
 |            |                                                                            |       |
-| 2019-04-04 | PLAN: NAT64 1:1 table ICMP, ICMPv6 working                                 | x     |
+| 2019-04-04 | NAT64 1:1 table ICMP, ICMPv6 working                                       | x     |
 |            | Will need some switch local ip addresses                                   | x     |
 |            |                                                                            |       |
+| 2019-04-11 | PLAN: NAT64 1:1 table UDP working                                          |       |
+|            | checksums in both directions                                               |       |
 |            |                                                                            |       |
 | 2019-04-18 | PLAN: NAT64 1:1 table TCP/UDP working                                      |       |
 |            |                                                                            |       |
 |            |                                                                            |       |
+|            |                                                                            |       |
 | 2019-05-02 | Jool SIIT / range / offset support https://www.jool.mx/en/run-vanilla.html |       |
 |            | Jool EAMT support https://www.jool.mx/en/run-eam.html                      |       |
 |            | Bidirectional support                                                      |       |
diff --git a/p4src/bug1-bool.p4 b/p4src/bug1-bool.p4
index 4a2a4a7..e54e588 100644
--- a/p4src/bug1-bool.p4
+++ b/p4src/bug1-bool.p4
@@ -131,7 +131,7 @@ struct headers {
 }
 
 struct metadata {
-    bit<16> tcp_length;
+    bit<16> length_without_ip_header;
     bool do_cksum;
 }
 
@@ -151,7 +151,7 @@ parser MyParser(packet_in packet,
 
     state ipv4 {
         packet.extract(hdr.ipv4);
-		meta.tcp_length = hdr.ipv4.totalLen - 16w20;
+		meta.length_without_ip_header = hdr.ipv4.totalLen - 16w20;
 
         transition select(hdr.ipv4.protocol){
             PROTO_TCP: tcp;
@@ -164,7 +164,7 @@ parser MyParser(packet_in packet,
 
     state ipv6 {
         packet.extract(hdr.ipv6);
-		meta.tcp_length = hdr.ipv6.payload_length;
+		meta.length_without_ip_header = hdr.ipv6.payload_length;
 
         transition select(hdr.ipv6.next_header){
             PROTO_TCP: tcp;
diff --git a/p4src/checksums.p4 b/p4src/checksums.p4
index 5b52f06..189cdc5 100644
--- a/p4src/checksums.p4
+++ b/p4src/checksums.p4
@@ -87,6 +87,103 @@ control MyComputeChecksum(inout headers  hdr, inout metadata meta) {
             },
             hdr.ipv4.hdrChecksum,
             HashAlgorithm.csum16);
+
+	    update_checksum_with_payload(meta.chk_udp_v4 == 1,
+            {
+                hdr.ipv4.src_addr,
+                hdr.ipv4.dst_addr,
+                8w0,
+                hdr.ipv4.protocol,
+			    meta.length_without_ip_header,
+
+				// UDP header
+                hdr.udp.src_port,
+                hdr.udp.dst_port,
+                hdr.udp.payload_length,
+            },
+            hdr.udp.checksum,
+            HashAlgorithm.csum16
+        );
+
+	    update_checksum_with_payload(meta.chk_udp_v6 == 1,
+            {
+                hdr.ipv6.src_addr,               /* 128 */
+                hdr.ipv6.dst_addr,               /* 128 */
+			    meta.length_without_ip_header,   /* 32 */
+                24w0,                            /* 24 */
+				hdr.ipv6.next_header,            /* 8 */
+                                                 /* total: 324 */
+
+				// UDP header
+                hdr.udp.src_port,                /* 16 */
+                hdr.udp.dst_port,                /* 16 */
+                hdr.udp.payload_length,          /* 16 */
+                                                 /* all: 372 */
+
+            },
+            hdr.udp.checksum,
+            HashAlgorithm.csum16
+        );
+
+		update_checksum_with_payload(meta.chk_tcp_v4 == 1,
+			{
+                hdr.ipv4.src_addr,
+				hdr.ipv4.dst_addr,
+				8w0,
+				hdr.ipv4.protocol,
+                meta.length_without_ip_header,
+
+				// TCP header
+				hdr.tcp.src_port,
+				hdr.tcp.dst_port,
+				hdr.tcp.seqNo,
+				hdr.tcp.ackNo,
+				hdr.tcp.data_offset,
+				hdr.tcp.res,
+				hdr.tcp.cwr,
+				hdr.tcp.ece,
+				hdr.tcp.urg,
+				hdr.tcp.ack,
+				hdr.tcp.psh,
+				hdr.tcp.rst,
+				hdr.tcp.syn,
+				hdr.tcp.fin,
+				hdr.tcp.window,
+				hdr.tcp.urgentPtr
+			},
+			hdr.tcp.checksum,
+			HashAlgorithm.csum16
+        );
+
+		update_checksum_with_payload(meta.chk_tcp_v6 == 1,
+			{
+                hdr.ipv6.src_addr,
+				hdr.ipv6.dst_addr,
+			    meta.length_without_ip_header,
+				24w0,
+				hdr.ipv6.next_header,
+
+				// TCP header
+				hdr.tcp.src_port,
+				hdr.tcp.dst_port,
+				hdr.tcp.seqNo,
+				hdr.tcp.ackNo,
+				hdr.tcp.data_offset,
+				hdr.tcp.res,
+				hdr.tcp.cwr,
+				hdr.tcp.ece,
+				hdr.tcp.urg,
+				hdr.tcp.ack,
+				hdr.tcp.psh,
+				hdr.tcp.rst,
+				hdr.tcp.syn,
+				hdr.tcp.fin,
+				hdr.tcp.window,
+				hdr.tcp.urgentPtr
+			},
+			hdr.tcp.checksum,
+			HashAlgorithm.csum16);
+
     }
 }
 
diff --git a/p4src/headers.p4 b/p4src/headers.p4
index 8c48927..24dea27 100644
--- a/p4src/headers.p4
+++ b/p4src/headers.p4
@@ -212,8 +212,12 @@ struct metadata {
     bit<1> chk_icmp6;
     bit<1> chk_icmp;
     bit<1> chk_ipv4;
+    bit<1> chk_udp_v4;
+    bit<1> chk_udp_v6;
+    bit<1> chk_tcp_v4;
+    bit<1> chk_tcp_v6;
 
-    bit<16> tcp_length;
+    bit<16> length_without_ip_header;
     bit<32> cast_length;
     table_t table_id;
 }
diff --git a/p4src/parsers.p4 b/p4src/parsers.p4
index 2d4ec34..c55bb47 100644
--- a/p4src/parsers.p4
+++ b/p4src/parsers.p4
@@ -17,6 +17,10 @@ parser MyParser(packet_in packet,
         meta.chk_icmp        = 0;
         meta.chk_icmp6       = 0;
         meta.chk_icmp6_na_ns = 0;
+        meta.chk_ipv4        = 0;
+        meta.chk_udp_v4      = 0;
+        meta.chk_udp_v6      = 0;
+        meta.chk_tcp         = 0;
 
         packet.extract(hdr.ethernet);
         transition select(hdr.ethernet.ethertype){
@@ -30,7 +34,7 @@ parser MyParser(packet_in packet,
 
     state ipv4 {
         packet.extract(hdr.ipv4);
-		meta.tcp_length = hdr.ipv4.totalLen - 16w20;
+		meta.length_without_ip_header = hdr.ipv4.totalLen - 16w20;
 
         transition select(hdr.ipv4.protocol){
             PROTO_TCP: tcp;
@@ -43,7 +47,7 @@ parser MyParser(packet_in packet,
 
     state ipv6 {
         packet.extract(hdr.ipv6);
-		meta.tcp_length = hdr.ipv6.payload_length;
+		meta.length_without_ip_header = hdr.ipv6.payload_length;
 
         transition select(hdr.ipv6.next_header){
             PROTO_TCP: tcp;
diff --git a/p4src/static-mapping.p4 b/p4src/static-mapping.p4
index 4116dfc..d79d75d 100644
--- a/p4src/static-mapping.p4
+++ b/p4src/static-mapping.p4
@@ -446,6 +446,9 @@ Echo or Echo Reply Message
                         hdr.icmp.code = 0;
                     }
                 }
+                if(hdr.udp.isValid()) {
+                    meta.chk_udp = 1;
+                }
 
                 v4_networks.apply();       /* apply egress for IPv4 */
                 exit;                      /* no further v6 processing */