From owner-freebsd-hackers Wed Jun 28 14:49:15 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id OAA24613 for hackers-outgoing; Wed, 28 Jun 1995 14:49:15 -0700 Received: from rah.star-gate.com (rah.star-gate.com [204.188.121.18]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id OAA24604 for ; Wed, 28 Jun 1995 14:49:12 -0700 Received: from localhost.v-site.net (localhost.v-site.net [127.0.0.1]) by rah.star-gate.com (8.6.11/8.6.9) with SMTP id OAA01416; Wed, 28 Jun 1995 14:49:05 -0700 Message-Id: <199506282149.OAA01416@rah.star-gate.com> X-Authentication-Warning: rah.star-gate.com: Host localhost.v-site.net didn't use HELO protocol To: Scott Mace Cc: hackers@freebsd.org Subject: Re: Space Shuttle Mission is being broadcasted In-reply-to: Your message of "Wed, 28 Jun 1995 15:33:08 CDT." <199506282033.PAA07529@crash.ops.neosoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1413.804376142.1@rah.star-gate.com> Date: Wed, 28 Jun 1995 14:49:02 -0700 From: Amancio Hasty Sender: hackers-owner@freebsd.org Precedence: bulk >>> Scott Mace said: > > > > > > Howdy, > > > > > > If you have an mbone connection the Space Shuttle Mission is being > > broadcasted. > > > > Yes!, I'm getting good video right now... audio is choppy but thats because of my internal config... > > getting between 1-5fps at 130kbps > > Scott Well, there has been some slight problems on the MBONE. BTW: Does anyone if we can generate the bogus ICMP messages mentioned in the enclosed mail. Enjoy, Amancio Return-Path: geoffw@nexsys.net Received: from nexsys.nexsys.net (nexsys.nexsys.net [192.188.198.1]) by rah.star-gate.com (8.6.11/8.6.9) with ESMTP id KAA00942 for ; Wed, 28 Jun 1995 10:59:28 -0700 Received: by nexsys.nexsys.net (8.6.10/SM-8.6.4) id LAA29248; Wed, 28 Jun 1995 11:01:47 -0700 Date: Wed, 28 Jun 1995 11:01:47 -0700 From: geoffw@nexsys.net (Geoff White) Message-Id: <199506281801.LAA29248@nexsys.nexsys.net> To: hasty@star-gate.com Subject: Re: host viviane.usl.edu still trashing shuttle video stream Cc: ramsey@netcom.com Hmmm... ----- Begin Included Message ----- >From list-mgr@ISI.EDU Wed Jun 28 09:57:24 1995 Return-Path: To: Van Jacobson Cc: mbone@ISI.EDU, mahler@usl.edu Subject: Re: host viviane.usl.edu still trashing shuttle video stream Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Id: <26459.804354074.1@msf.psi.net> Date: Wed, 28 Jun 1995 11:41:14 -0400 From: "Mark S. Fedor" Content-Length: 2981 X-Lines: 57 Status: RO FYI... I've been running RTP traces on the shuttle video at mae-bone.psi.net (on mae-east) all morning and I have an average loss rate of 30%. At this time, the loss rate continues at 30%. Mark ------- > As Bill Fenner pointed out yesterday, host viviane.usl.edu > (130.70.40.162) appears to be causing the >50% packet loss that > most people are seeing on the Shuttle video session. It is > causing the loss by sending an ICMP unreachable packet in > reponse to every multicast packet put on the 130.70.40 subnet at > USL. For a few hours yesterday evening, it appears that > alpha.noc.usl.edu (the mbone tunnel endpoint at USL) was off the > mbone and the NASA video reception here was perfect (0% loss). > At around 12:50am, I started to see ICMP unreachables from > viviane again (sent in response to my session msgs in the > shuttle audio session) and the NASA video loss rate immediately > went up to 50%. > > There are already ~400 people tuned into the Shuttle mission > and there will probably be a couple thousand trying to watch > the MIR docking. It would be a shame if this one broken host > screwed up the video for people all over the world. It would be > best if viviane.usl.edu could be moved to a subnet that didn't > get any multicast traffic or just powered off (the machines that > normally generate these bogus ICMPs are IBM RTs & Unisys machines -- > often these are just as useful with the power off as on). If > it can't be powered off or moved, perhaps a filter can be installed > on the local gateway to discard all ICMPs from viviane. If USL > can't do anything, perhaps Georgia Tech could temporarily disconnect > the tunnel from houdini-fddi.gatech.edu to alpha.noc.usl.edu until > USL has time to fix the problem. > > For the curious, the reason that viviane's ICMPs are trashing > the video stream is that the kernel interprets ICMP unreachables > as an error (they probably would be an error if the traffic were > unicast) which causes the next send that nv does to be aborted > with an ENETUNREACH error. Nv effectively ignores the error but > it does cause the packet that it was trying to send to be > discarded. If the nv packets are well spaced, the result is > that every other packet gets discarded (50% loss). (The reason > that vat audio is working is because vat looks for EUNREACH > errors and resends the packet if it gets one.) Viviane is > probably not running the multicast apps or a multicast kernel -- > it is probably just some host with a broken IP stack that is > mis-handling any multicast traffic that happens to appear on the > local wire. The reason it's cobbering the Shuttle session is > because Steve Mahler is tuned into the Shuttle sessions on host > alpha.noc.usl.edu (which is not misbehaving) and that causes the > shuttle multicast traffic to get put on the 130.70.40 subnet > where viviane lives. Until viviane gets fixed, any video > session that Steve tunes into will get trashed. > > - Van ----- End Included Message -----