diff --git a/sys/net/sixlowpan/sixlownd.c b/sys/net/sixlowpan/sixlownd.c
index fd3f38c442..5b291e025d 100644
--- a/sys/net/sixlowpan/sixlownd.c
+++ b/sys/net/sixlowpan/sixlownd.c
@@ -2,37 +2,111 @@
 
 #include "sixlowip.h"
 #include "sixlownd.h"
+#include "sixlowmac.h"
 #include <stdio.h>
 
-#define (struct *ipv6_hdr)&buffer[LL_HEADER_LENGTH]  
+#define PRINTF(...) printf(__VA_ARGS__) 
+#define PRINT6ADDR(addr) PRINTF("%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x\n", ((uint8_t *)addr)[0], ((uint8_t *)addr)[1], ((uint8_t *)addr)[2], ((uint8_t *)addr)[3], ((uint8_t *)addr)[4], ((uint8_t *)addr)[5], ((uint8_t *)addr)[6], ((uint8_t *)addr)[7], ((uint8_t *)addr)[8], ((uint8_t *)addr)[9], ((uint8_t *)addr)[10], ((uint8_t *)addr)[11], ((uint8_t *)addr)[12], ((uint8_t *)addr)[13], ((uint8_t *)addr)[14], ((uint8_t *)addr)[15])
+
+static uint8_t option_field_length;
+
+#define IP_BUFFER ((struct ipv6_hdr*)&buffer[LL_HEADER_LENGTH])  
+#define ICMP_BUFFER ((struct icmpv6_hdr*)&buffer[LLHDR_IPV6HDR_LENGTH])
+#define IPH_LLH_BUFFER &buffer[LL_HEADER_LENGTH + IPV6_HEADER_LENGTH]
+#define OPT_FIELD_BUFFER ((struct option_hdr*)&buffer[LLHDR_IPV6HDR_LENGTH + option_field_length])
+
+uint8_t rs_count;
 
 /* send router solicitation message - RFC4861 section 4.1 */
-void send_rs(icmpv6_hdr *icmphdr, ipv6_hdr *iphdr){
-    create_all_routers_multicast_addr(iphdr->destaddr);
+void send_rs(void){
+      uint8_t ipv6_ext_hdr_len = 0;
+    if(rs_count < MAX_RTR_SOLICITATIONS){
+        ICMP_BUFFER->type = ICMP_ROUTER_SOLICITATION;
+        ICMP_BUFFER->code = 0;
 
-    icmphdr->type = ICMP_ROUTER_SOLICITATION;
-    icmphdr->code = 0;
-    icmphdr->checksum = calc_icmpv6_checksum();
+        IP_BUFFER->version_trafficclass = IPV6_VERSION;
+        IP_BUFFER->trafficclass_flowlabel = 0;
+        IP_BUFFER->flowlabel = 0;
+        IP_BUFFER->nextheader = ICMP_NEXTHEADER;
+        IP_BUFFER->hoplimit = NEIGHBOR_DISCOVERY_HOPLIMIT;
 
-    iphdr->version_trafficclass = IPV6_VERSION;
-    iphdr->trafficclass_flowlabel = 0;
-    iphdr->flowlabel = 0;
-    iphdr->nextheader = ICMP_NEXTHEADER;
-    iphdr->hoplimit = NEIGHBOR_DISCOVERY_HOPLIMIT;
+        create_all_routers_mcast_addr(&IP_BUFFER->destaddr);
+        PRINT6ADDR(&IP_BUFFER->destaddr);
+        /* set payload length */
+        IP_BUFFER->length = ICMP_HEADER_LENGTH + RS_LENGTH + SLLAO_OPT_LENGTH; 
+        set_llao(&buffer[LLHDR_ICMPV6HDR_LENGTH + RS_LENGTH], SLLAO_OPT_LENGTH);
+        ICMP_BUFFER->checksum = 0;
+        ICMP_BUFFER->checksum = ~chksum_calc(ICMP_NEXTHEADER);
+        printf("%x\n",ICMP_BUFFER->checksum);
 
-    /* icmp header len + rs header len + slla option len*/
-    iphdr->length = ICMP_HEADER_LEN + RS_LEN + LLOA_OPT_LEN; 
-    set_llao(); 
-}
-
-void set_llao(void){
-    
+        rs_count++;
+        // sleep 4 sec
+        swtimer_usleep(ROUTER_SOLICITATION_INTERVAL * 1000000);
+    } 
 }
 
 void recv_rs(void){
+    option_field_length = RS_LENGTH;
+    /* get link layer address option from buf */
+    if(OPT_FIELD_BUFFER->type == SLLAO_OPT_LENGTH){
+        uint8_t *llao = OPT_FIELD_BUFFER;
+    }
 
+    if(llao != NULL){
+        // TODO: Neighbor lookup        
+    }
+
+    send_ra();        
 }
 
-void calc_icmpv6_checksum(void){
-
+void send_ra(void){
+    
+}
+
+/* link-layer address option - RFC4861 section 4.6.1/ RFC4944 8. */
+void set_llao(uint8_t *llao, uint8_t type){
+    llao[ND_OPT_TYPE] = type;
+    if(SLLAO_OPT_LENGTH == 16){
+        // 802.15.4 long address
+        llao[ND_OPT_LENGTH] = 2;
+    } else
+        // 16-bit short address
+        llao[ND_OPT_LENGTH] = 1;
+    // get link layer address
+    link_layer_addr mac;
+    get_link_layer_addr_from_ipaddr(&IP_BUFFER->srcaddr,&mac);    
+
+    memcpy(&llao[ND_OPT_DATA], &mac, SIXLOWPAN_IPV6_LL_ADDR_LEN);
+    // padding (all zeros) - 48bit 
+    memset(&llao[ND_OPT_DATA + SIXLOWPAN_IPV6_LL_ADDR_LEN], 0, 
+            SLLAO_OPT_LENGTH - SIXLOWPAN_IPV6_LL_ADDR_LEN - 2); 
+}
+
+/* pseudo-header checksum calculation - RFC4443 Section 2.3*/
+uint16_t chksum_calc(uint8_t type){
+    uint16_t length = IP_BUFFER->length;
+    uint16_t sum = length + type;
+    
+    uint8_t *addrptr = (uint8_t)&IP_BUFFER->srcaddr;
+    uint16_t addr_fields_length = (2 * sizeof(ipv6_addr));
+    while(addr_fields_length > 1){
+        sum += (addrptr[0] << 8) + addrptr[1];
+        addrptr += 2;
+        addr_fields_length -= 2;
+    }    
+    if(addr_fields_length > 1){
+        sum += (addrptr[0] << 8) + 0;
+    }
+
+    uint8_t *bufptr = IPH_LLH_BUFFER;
+    while(length > 1){
+        sum += (bufptr[0] << 8) + bufptr[1];
+        bufptr += 2;
+        length -= 2;
+    } 
+    if(length){
+        sum += (bufptr[0] << 8) + 0;
+    }
+
+    return sum; 
 }