Date: Tue, 24 Jun 2014 17:01:08 -0700 From: Charles Swiger <cswiger@mac.com> To: Andrea Venturoli <ml@netfence.it> Cc: freebsd-net@freebsd.org Subject: Re: MTU not regrowing? Message-ID: <2CA56230-440A-4D77-83BD-222FBC704F70@mac.com> In-Reply-To: <53A9C6D0.3090900@netfence.it> References: <53A9C6D0.3090900@netfence.it>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi-- On Jun 24, 2014, at 11:43 AM, Andrea Venturoli <ml@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? Does "ifconfig vlan3 down; ifconfig vlan3 up" do any good? Or that run against the physical NIC? What is the ethernet HW; and are you using VLAN_HWTAGGING capability? Regards, -- -Chuck
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?2CA56230-440A-4D77-83BD-222FBC704F70>