Hello,
On Thu, 17 Nov 2016, Rick Jones wrote:
> raj@tardy:~/netperf2_trunk$ strace -v -o /tmp/netperf.strace src/netperf -F
> src/nettest_omni.c -t UDP_STREAM -l 1 -- -m 1472
>
> ...
>
> socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP) = 4
> getsockopt(4, SOL_SOCKET, SO_SNDBUF, [212992], [4]) = 0
> getsockopt(4, SOL_SOCKET, SO_RCVBUF, [212992], [4]) = 0
> setsockopt(4, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
> bind(4, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("0.0.0.0")},
> 16) = 0
> setsockopt(4, SOL_SOCKET, SO_DONTROUTE, [1], 4) = 0
connected socket can benefit from dst cached in socket
but not if SO_DONTROUTE is set. If we do not want to send packets
via gateway this -l 1 should help but I don't see IP_TTL setsockopt
in your first example with connect() to 127.0.0.1.
Also, may be there can be another default, if -l is used to
specify TTL then SO_DONTROUTE should not be set. I.e. we should
avoid SO_DONTROUTE, if possible.
Regards
--
Julian Anastasov <j...@ssi.bg>
