diff --git a/udp.h b/udp.h
index fefee76..9624161 100644
--- a/udp.h
+++ b/udp.h
@@ -2,30 +2,25 @@
 #define COPPINO_UDP_H
 
 namespace udp {
-
-  const uint8_t LEN = 128;
-
   class UDPPacket {
     private:
-      char packet[LEN];
+      char packet[ipv6::LEN - 40];
     public:
-      UDPPacket();
-      UDPPacket(const char* packet, int len);
-      
       void setSrcPort(uint16_t port);
       uint16_t getSrcPort();
       void setDstPort(uint16_t port);
       uint16_t getDstPort();
       const char* UDPPacket::getPayload();
-      void setPayload(const char* payload, int len);
-      void computeChecksum(const ipv6::IPv6Addr* src_addr, const ipv6::IPv6Addr* dst_addr, int len);
+      void setPayload(const char* payload, int len);  /* also sets proper length */
+      void computeChecksum(const ipv6::IPv6Addr* src_addr, const ipv6::IPv6Addr* dst_addr, int len);  /* computes and updates checksum in the packet */
   };
 
+  /* UDP handler for lower layer protocol */
   int handleUDP(char* output_buffer, const char* input_buffer, int len);
 
+  /* pointer to server handler function */
   extern int(*server_handler) (char* output_buffer, const char* buffer, int size);
   extern uint16_t server_port;
-
   void set_handler(uint16_t port, int(* handler) (char* output_buffer, const char* input_buffer, int size));
 } 
 
diff --git a/udp.ino b/udp.ino
index 3e8c650..897468e 100644
--- a/udp.ino
+++ b/udp.ino
@@ -5,14 +5,6 @@ namespace udp {
 int(*server_handler) (char* output_buffer, const char* input_buffer, int size) = NULL;
 uint16_t server_port = 0;
 
-UDPPacket::UDPPacket() {
-  memset(packet, 0, LEN);
-}
-
-UDPPacket::UDPPacket(const char* buffer, int len) {
-  memcpy(packet, buffer, len);
-}
-
 void UDPPacket::setSrcPort(uint16_t port) {
   *(packet + 0) = port >> 8;
   *(packet + 1) = port & 0xff;
@@ -30,6 +22,7 @@ uint16_t UDPPacket::getDstPort() {
   return (*(packet + 2) << 8) + (uint8_t)*(packet + 3);
 }
 
+/* sets the payload and also updates the packet length field */
 void UDPPacket::setPayload(const char* payload, int len) {
   memcpy(packet + 8, payload, len);
   *(packet + 4) = (len + 8) >> 8;
@@ -39,17 +32,22 @@ const char* UDPPacket::getPayload() {
   return packet + 8;
 }
 
+/* computes the checksum and also updates it inside the UDP packet */
 void UDPPacket::computeChecksum(const ipv6::IPv6Addr* src_addr, const ipv6::IPv6Addr* dst_addr, int len) {
   memset(packet + 6, 0, 2);
   uint16_t checksum = ipv6::compute_checksum(src_addr, dst_addr, ipv6::NH_UDP, len, packet, len);
   memcpy(packet + 6, &checksum, 2);
 }
 
+/* sets an handler (a function) which will be called every time there is a packet for a certain given port */
 void set_handler(uint16_t port, int(* server_handler) (char* output_buffer, const char* input_buffer, int size)) {
   udp::server_port = port;
   udp::server_handler = server_handler;
 }
 
+/* handles an UDP packet, and (possibly) produces a reply UDP packet
+ * returns length of reply packet, which is written in output_buffer, or -1 if there is no reply packet
+*/
 int handleUDP(char* output_buffer, const char* input_buffer, int ilen) {
   UDPPacket* incoming_packet = (UDPPacket*)input_buffer;
   UDPPacket* outgoing_packet = (UDPPacket*)output_buffer;
@@ -62,11 +60,10 @@ int handleUDP(char* output_buffer, const char* input_buffer, int ilen) {
       outgoing_packet->setSrcPort(incoming_packet->getDstPort());
       outgoing_packet->setDstPort(incoming_packet->getSrcPort());
       outgoing_packet->setPayload(outgoing_packet->getPayload(), olen);
-      //outgoing_packet->setLen(olen);
       outgoing_packet->computeChecksum(ipv6::packetin.getDstAddress(), ipv6::packetin.getSrcAddress(), olen + 8);
       return olen + 8;
     }
-  } else {  /* echo default UDP application handler */
+  } else {  /* default UDP application handler: echoes back the packet content */
     outgoing_packet->setSrcPort(incoming_packet->getDstPort());
     outgoing_packet->setDstPort(incoming_packet->getSrcPort());
     outgoing_packet->setPayload(incoming_packet->getPayload(), ilen - 8);