Hate to follow up, but realized a mistake... NIC's with TCP offload engines in hardware may put the TCP timestamp option in the header. I know from a co-worker that the Nvida TOE chipset does for example.
On 3/1/06, Aaron Turner <[EMAIL PROTECTED]> wrote: > No, NIC's don't put timestamps in packets. And depending on your > OS/NIC driver, the libpcap timestamp of the packet could be wrong or > at least non-sensical too (I've seen packets stamped with an earlier > timestamp then the previous read packet). > > IMHO, your best bet is to either use the TCP timestamp option on a > socket() or use libnet to generate raw packets and put your timestamp > in the payload. > > Btw, you do know that there are already tools which do this right??? > things like iperf and netperf. > > -- > Aaron Turner > http://synfin.net/ > > > On 3/1/06, J S <[EMAIL PROTECTED]> wrote: > > Hello > > I am setting up a framework for measuring one way delay between two Internet > > end points. > > For higher accuracy I am using libpcap time stamps (from the packet header) > > at the reciever. > > Does any one know if there is any method for improving accuracy at the > > sender side. > > Is it possible for sender's NIC to log the time stamp the packet was sent? > > or any other idea ? > -- Aaron Turner http://synfin.net/ - This is the tcpdump-workers list. Visit https://lists.sandelman.ca/ to unsubscribe.
