don't forget the header of the ping. the -s flag specifies the amount of data that the ping carries. By specifying a size of 500, you are creating a ping packet larger than the MTU.
On 24 June 2014 19:43, Andrea Venturoli <m...@netfence.it> wrote: > Hello. > > Today I experienced something weird (at least for me) on a 8.4 system: > > _ the system had vlan3 interface, with default MTU (1500 bytes); > _ "ping -D -s 1400 somehost" would work, but "ping -D -s 1500 somehost" > would yield "frag needed and DF set" (forgive me if the message is not > exact, I don't have it anymore); > > _ to make some tests I reduced MTU size with "ifconfig vlan3 mtu 500"; > _ now, of course, "ping -D -s 400 somehost" would work, but "ping -D -s > 500 somehost" would yield "frag needed and DF set"; > > _ then I raised MTU again with "ifconfig vlan3 mtu 1500" (notice ifconfig > would actually report this as "mtu 1500" was shown); > _ however the results were as before, i.e. "ping -D -s 400 somehost" would > work, but "ping -D -s 500 somehost" would yield "frag needed and DF set"; > > _ no way I could ping with a packet bigger than 500 bytes until I rebooted. > > Is this expected behaviour? Any way to get around this? > > bye & Thanks > av. > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org" > -- Carlos Miguel Ferreira Researcher at Telecommunications Institute Aveiro - Portugal Work E-mail - c...@av.it.pt Skype & GTalk -> carlosmf...@gmail.com LinkedIn -> http://www.linkedin.com/in/carlosmferreira _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
