change of ip_pmtu_strategy value

[Alan Buenaventura]

Hi,

When changing ip_pmtu_strategy value from 1 to 0, is the change effected immediately?

Thanks.

[Ravi_8]

Hi,
yes, it should

[Alan Buenaventura]

hi,

how come the sniffer trace shows that it is still 1?

here's how i changed it:
ndd -set /dev/ip ip_pmtu_strategy 0

is this correct or have i missed something?

Thanks.

[U.SivaKumar_2]

Hi,

After changing PMTU strategy.

#route -f

Then

#/sbin/init.d/net start


Try again the sniffing

regards,

U.SivAKumar

[T G Manikandan]

You can use
ndd -get /dev/ip ip_pmtu_strategy

to check up the value.

These changes do not persist after reboot so make the appropriate changes in the /etc/rc.config.d/nddconf


Thanks

[Alan Buenaventura]

That's why the changes can't be seen bec. the sniffing was on the other side.
Switched to the proper sniffing location and saw the changes.
But the changes was not effected immediately, the routes have to be deleted and re-added for the changes to effect.

[rick jones]

Certainly, once you change ip_pmtu_strategy to zero from one, any _new_ connection will see the change. I'm not sure if it will affect the segment sizes of existing connections right away or not. It may not "take" for them until ip_ire_flush_interval or somesuch.

Of course, one might ask why the change to zero in the first place since it will cripple your TCP connections with a smaller MSS than they could otherwise use.