lowpan_cb
if (ipv6_addr_any(&lowpan_cb(skb)->gw)) {
nexthop = &lowpan_cb(skb)->gw;
memcpy(&lowpan_cb(skb)->gw, nexthop, sizeof(struct in6_addr));
lowpan_cb(skb)->chan = NULL;
lowpan_cb(skb)->chan = peer->chan;
if (lowpan_cb(skb)->chan) {
&lowpan_cb(skb)->addr, lowpan_cb(skb)->chan);
err = send_pkt(lowpan_cb(skb)->chan, skb, netdev);