Hi. I've noticed that when sending more than one pbuf in low_level_output() that each pbuf gets sent individually over the network and is being treated as individual packets. I 'fixed' this problem by copying the different pbufs into one buffer and sending this buffer in one go (basically as a test to verify the issue). I guess the problem has to do with how l4ankh_send() calls l4shmc_rb_sender_commit_packet() after each pbuf instead of waiting until all pbufs of the packet in question are passed on with l4shmc_rb_sender_next_copy_in(). Best regards, Johan