Date: Sun, 9 Jun 2013 06:08:33 -0700 From: Jeremy Chadwick <jdc@koitsu.org> To: Alban Hertroys <haramrae@gmail.com> Cc: "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org> Subject: Re: fxp0 interface going up/down/up/down (dhclient related?) Message-ID: <20130609130833.GB36558@icarus.home.lan> In-Reply-To: <4459171F-E382-488D-81B1-978118665A86@gmail.com> References: <EBA9A2E3-3323-4069-9E58-ED4C431FDE4E@gmail.com> <20130609104401.GA33827@icarus.home.lan> <4459171F-E382-488D-81B1-978118665A86@gmail.com>
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On Sun, Jun 09, 2013 at 02:48:29PM +0200, Alban Hertroys wrote: > On Jun 9, 2013, at 12:44, Jeremy Chadwick <jdc@koitsu.org> wrote: >=20 > > On Sun, Jun 09, 2013 at 12:21:37PM +0200, Alban Hertroys wrote: > >> I'm having an issue where my fxp0 interface keeps looping between DO= WN/UP, with dhclient requesting a lease each time in between. I think it'= s caused by dhclient: > >>=20 > >> solfertje # dhclient -d fxp0 > >> DHCPREQUEST on fxp0 to 255.255.255.255 port 67 > >> send_packet: Network is down > >> DHCPREQUEST on fxp0 to 255.255.255.255 port 67 > >> DHCPACK from 109.72.40.1 > >> bound to 141.105.10.89 -- renewal in 7200 seconds. > >> fxp0 link state up -> down > >> fxp0 link state down -> up > >> DHCPREQUEST on fxp0 to 255.255.255.255 port 67 > >> DHCPACK from 109.72.40.1 > >> bound to 141.105.10.89 -- renewal in 7200 seconds. > >> fxp0 link state up -> down > >> fxp0 link state down -> up > >> DHCPREQUEST on fxp0 to 255.255.255.255 port 67 > >> DHCPACK from 109.72.40.1 > >> bound to 141.105.10.89 -- renewal in 7200 seconds. > >> fxp0 link state up -> down > >> fxp0 link state down -> up > >> DHCPREQUEST on fxp0 to 255.255.255.255 port 67 > >> DHCPACK from 109.72.40.1 > >> bound to 141.105.10.89 -- renewal in 7200 seconds. > >> fxp0 link state up -> down > >> fxp0 link state down -> up > >> DHCPREQUEST on fxp0 to 255.255.255.255 port 67 > >> DHCPACK from 109.72.40.1 > >> bound to 141.105.10.89 -- renewal in 7200 seconds. > >> fxp0 link state up -> down > >> ^C > >>=20 > >> In above test I turned off devd (/etc/rc.d/devd stop) and background= dhclient (/etc/rc.d/dhclient stop fxp0), and I still go the above result= . There's practically no time spent between up/down cycles, this just kee= ps going on and on. > >> fxp0 is the only interface that runs on DHCP. The others have static= IP's. > >>=20 > >> Initially I thought the issue might be caused by devd, because I hav= e both ethernet and 822.11 type NICs (2x ethernet, 1x wifi) in that syste= m. > >>=20 > >> This is 9-STABLE from yesterday. > >>=20 > >> Before, I had 9-RELEASE running on this system with the same config,= and that worked well. > >=20 > > And so what I predicted begins... > >=20 > > The issue is described in the 8.4-RELEASE Errata Notes; the driver is > > using the same driver version as in stable/9, hence you're experienci= ng > > the same problem. See Open Issues: > >=20 > > http://www.freebsd.org/releases/8.4R/errata.html > >=20 > > No fix for this has been committed. It is still under discussions by > > multiple kernel folks as to where the fix should be applied (dhclient= or > > the fxp(4) driver), because the changes made to dhclient (that tickle > > this bug) may actually affect more drivers than just fxp(4). > >=20 > > You can start by reading the (extremely long but very informative) > > thread here. I do urge you to read all the posts, not skim them: > >=20 > > http://lists.freebsd.org/pipermail/freebsd-stable/2013-May/073440.htm= l > > http://lists.freebsd.org/pipermail/freebsd-stable/2013-May/thread.htm= l#73440 >=20 > Goodness, and here I was hoping it was just a silly mistake I made=85 >=20 > IIUC, the issue is a combination of: > - dhclient now being aware of link state changes and > - the fxp driver reinitializes for certain mode changes, such as assign= ing an IP address >=20 > Which causes dhclient to think that the link state changed, fetch a "ne= w" IP address and assigns it to the fxp adapter again, causing the same l= ink state change over and over again. >=20 > Is that about correct? Someone else can answer this. > > The only known workarounds at this time are: > >=20 > > a) Cease use of DHCP; set a static IP in rc.conf, > >=20 > > b) Try some of the patches mentioned within the above thread, > > specifically this one: > > http://lists.freebsd.org/pipermail/freebsd-stable/2013-May/073581.htm= l >=20 > Or c) Use DHCP with a static media setting: > ifconfig_fxp0=3D"DHCP media 100baseTX mediaopt full-duplex" DO NOT DO THIS. People who do this do not understand what this does. This has bad effects on IEEE 802.3 and will not do/behave like you might think. The short version: The ONLY TIME you should be hard-setting speed and duplex in ifconfig is when you have a managed switch on the other end where you can set the speed/duplex for that port as well. Otherwise, if you have autoneg on one side, and forced speed/duplex on the other, there is ABSOLUTELY NO GUARANTEE it will work -- the behaviour at that point is "generally" undefined (and chaotic), and in my experience what happens is the switch ends up picking 100/half while the FreeBSD box thinks 100/full and you end up with an insane collision rate + hilariously slow network speeds (but usually only in one direction). The behaviour varies per brand (and revision) of switch, firmware, and other things. So bottom line: if you're going to use autoneg, use it consistently on both ends; if you're going to force speed/duplex, do so consistently on both ends. (If you don't own a managed switch, then autoneg is your only choice) > That worked for two out of three people apparently. > I'm not done reading this thread yet though and I noticed a patch by Yo= ngHyeon that I'll test first. The fact it didn't work for 1 person is enough, and furthers my point (re: the behaviour varies). The problem needs to get fixed properly by kernel folks, but as I said, "where" it's to be fixed is being discussed/debated. Kernel committers' time is very very sparse/limited right now, which is why the last post in that thread was from May 29th (a week and a half ago). As you can see in the thread, I tried to tell Glen Barber that demanding people just set a static IP in ifconfig / avoidance of DHCP was not going to fly, and this follow-up thread is proof. :-) --=20 | Jeremy Chadwick jdc@koitsu.org | | UNIX Systems Administrator http://jdc.koitsu.org/ | | Making life hard for others since 1977. PGP 4BD6C0CB |
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