Re: ip_no_pmtu_disc and UDP

 I think the no_pmtu_disc could be renamed to pmtu_disc to be less
confusion to users.

pmtu_disc: IP_PMTUDISC_DONT, clear DF bit
pmtu_disc: IP_PMTUDISC_WANT, set DF bit

 just my .2 cents

On Fri, Oct 23, 2015 at 9:45 AM, Vincent Li [off-list ref] wrote:

Hi,

It looks ip_no_pmtu_disc setting does not affect UDP IP packet DF bit
setting, is that intended behavior? echo 0, 1, 2, 3 respectively to
ip_no_pmtu_disc, UDP IP packet always have DF bit cleared, unless use
IP_PMTUDISC_DO on IP_MTU_DISCOVER as ip man page says.

in inet_create, seems to prove that.

       if (net->ipv4.sysctl_ip_no_pmtu_disc)
                inet->pmtudisc = IP_PMTUDISC_DONT;
        else
                inet->pmtudisc = IP_PMTUDISC_WANT;

so I am wondering why UDP is excluded by ip_no_pmtu_disc, why in
inet_create, not assign each individual ip_no_pmtu_disc setting to
inet->pmtudisc but only check true and assign IP_PMTUDISC_DONT or
IP_PMTUDISC_WANT only.

Thanks

Vincent