csum = ip_csum_sub_even (*checksum, dport);
csum = ip_csum_add_even (csum, udp->dst_port);
*checksum = ip_csum_fold (csum);
vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;
csum = ip_csum_sub_even (*checksum, dport);
csum = ip_csum_add_even (csum, udp->dst_port);
*checksum = ip_csum_fold (csum);
vnet_buffer (ctx->b)->sw_if_index[VLIB_TX] = bibe->fib_index;