+/**
+ * Push IPv6 header to buffer
+ *
+ * @param vm - vlib_main
+ * @param b - buffer to write the header to
+ * @param src - source IP
+ * @param dst - destination IP
+ * @param prot - payload proto
+ *
+ * @return - pointer to start of IP header
+ */
+always_inline void *
+vlib_buffer_push_ip6 (vlib_main_t * vm, vlib_buffer_t * b,
+ ip6_address_t * src, ip6_address_t * dst, int proto)
+{
+ ip6_header_t *ip6h;
+ u16 payload_length;
+
+ /* make some room */
+ ip6h = vlib_buffer_push_uninit (b, sizeof (ip6_header_t));
+
+ ip6h->ip_version_traffic_class_and_flow_label =
+ clib_host_to_net_u32 (0x6 << 28);
+
+ /* calculate ip6 payload length */
+ payload_length = vlib_buffer_length_in_chain (vm, b);
+ payload_length -= sizeof (*ip6h);
+
+ ip6h->payload_length = clib_host_to_net_u16 (payload_length);
+
+ ip6h->hop_limit = 0xff;
+ ip6h->protocol = proto;
+ clib_memcpy (ip6h->src_address.as_u8, src->as_u8,
+ sizeof (ip6h->src_address));
+ clib_memcpy (ip6h->dst_address.as_u8, dst->as_u8,
+ sizeof (ip6h->src_address));
+
+ return ip6h;
+}