Date: Wed, 19 Jun 2002 19:30:45 +0100 From: Brian Somers <brian@Awfulhak.org> To: Mike Tancsa <mike@sentex.net> Cc: freebsd-net@FreeBSD.ORG Subject: Re: tracking down strange MTU issues with PPPoE) Message-ID: <20020619193045.439046ce.brian@Awfulhak.org> In-Reply-To: <5.1.0.14.0.20020618203201.07212f30@192.168.0.12> References: <5.1.0.14.0.20020618163928.05018cf0@marble.sentex.ca> <5.1.0.14.0.20020618163928.05018cf0@marble.sentex.ca> <5.1.0.14.0.20020618203201.07212f30@192.168.0.12>
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Hi, The difference is that without the max bit, ppp treats the mtu as a suggestion rather than as a hard limit.... To see the difference, enable LCP logging and see what's being negotiated. On Tue, 18 Jun 2002 20:32:43 -0400, Mike Tancsa <mike@sentex.net> wrote: > > Yes, that did it! Thanks very much! What is different about that, and me > setting it on the other end as part of the virt-template ? > > ---Mike > > At 12:33 AM 6/19/2002 +0100, Brian Somers wrote: > >Perhaps adding > > > > set mtu max 1452 > > > >will help ? > > > >On Tue, 18 Jun 2002 16:54:49 -0400, Mike Tancsa <mike@sentex.net> wrote: > > > > > > The DSL whole supplier we use (Bell Canada) has been turfing their Redback > > > SMSes and moving to an ERX from unisphere networks. > > > > > > With the Redback, all was great... I had a FreeBSD box acting as a NAT > > > gateway for a number of Windows boxes and all was great. Then, the > > > customer got moved over to one of these ERXes and there is now some > > strange > > > MTU problem. Couple of things. Supposedly the default MTU on the ERX is > > > 1472 (or 1452) depending on who you talk to and not 1492. > > > > > > e.g. when doing a fetch to > > > >> lynx2.8.4rel.1.tar.bz2 doesn't seem to exist in /usr/ports/distfiles/. > > > >> Attempting to fetch from http://lynx.isc.org/current/. > > > Receiving lynx2.8.4rel.1.tar.bz2 (1940531 bytes): 0%^C > > > 16682 bytes transferred in 89.5 seconds (186.41 Bps) > > > fetch: transfer interrupted > > > > > > Notice the speed... Its totally brutal. yet, a transfer from just a few > > > hops away is fine. > > > > > > My question is, how can I track this problem down ? There seems to be > > some > > > strange interaction with FreeBSD because if I put a Windows box on the > > > other end, it does not suffer from this same problem. I can easily repeat > > > the problem, but the question is, how can I track down the issue and then > > > explain it to my telco. > > > > > > (Note, I have tried various MTU and MRU settings. > > > > > > Thanks for any pointers. > > > > > > 4.6-STABLE FreeBSD 4.6-STABLE #0: Tue Jun 18 > > > > > > > > > default: > > > set log Phase Chat LCP IPCP CCP tun command > > > ident user-ppp VERSION (built COMPILATIONDATE) > > > > > > # Ensure that "device" references the correct serial port > > > # for your modem. (cuaa0 = COM1, cuaa1 = COM2) > > > # > > > set device /dev/cuaa1 > > > > > > set speed 115200 > > > set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \ > > > \"\" AT OK-AT-OK ATE1Q0 OK \\dATDT\\T TIMEOUT 40 CONNECT" > > > set timeout 180 # 3 minute idle timer (the > > default) > > > enable dns # request DNS info (for > > resolv.conf) > > > > > > > > > pppoe: > > > set device PPPoE:fxp1 > > > #set mtu 1452 > > > #set mru 1452 > > > set speed sync > > > enable lqr > > > set lqrperiod 5 > > > set cd 5 > > > set dial > > > set login > > > set timeout 0 > > > disable deflate pred1 mppe > > > deny deflate pred1 mppe > > > set authname user@example.com > > > set authkey thepassword > > > set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.0 0.0.0.0 > > > add default HISADDR > > > > > > > > > > > > ---Mike > > > -------------------------------------------------------------------- > > > Mike Tancsa, tel +1 519 651 3400 > > > Sentex Communications, mike@sentex.net > > > Providing Internet since 1994 www.sentex.net > > > Cambridge, Ontario Canada www.sentex.net/mike > > > > > > > > >-- > >Brian <brian@Awfulhak.org> <brian.somers@sun.com> > > <http://www.Awfulhak.org>; <brian@[uk.]FreeBSD.org> > >Don't _EVER_ lose your sense of humour ! <brian@[uk.]OpenBSD.org> > > -------------------------------------------------------------------- > Mike Tancsa, tel +1 519 651 3400 > Sentex Communications, mike@sentex.net > Providing Internet since 1994 www.sentex.net > Cambridge, Ontario Canada www.sentex.net/mike > -- Brian <brian@Awfulhak.org> <brian.somers@sun.com> <http://www.Awfulhak.org>; <brian@[uk.]FreeBSD.org> Don't _EVER_ lose your sense of humour ! <brian@[uk.]OpenBSD.org> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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