I seemed to have solved the problem, mostly. If a really long burst (200+) of UDP packets hits a UML host with 200 UML instances, there are still a few packets lost. My comp has only .75 GB of memory so maybe it's a buffer issue. I will try it on a 4GB machine to see how that goes.
The problem: When adding interfaces (created with 'tunctl -u user -t umlif..') to the bridge, the bridge takes the mac address of the 1st interface added. In my configuration the 1st interface, and mac address, will be assigned to the first uml instance created. I think there is a conflict for inbound packets routed from eth0 to the bridge when two interfaces (bridge and 1st uml interface) have the same mac address. I created an unused interface that I added to the bridge at start up (so the bridge has it's own unshared mac address) and also set the bridge to promiscuous. This seemed to do the trick. > -----Original Message----- > From: Blaisorblade [mailto:[EMAIL PROTECTED] > Sent: Tuesday, June 07, 2005 5:29 PM > To: user-mode-linux-user@lists.sourceforge.net > Cc: Johnson, Don > Subject: Re: [uml-user] Losing packets between eth0 and uml-bridge > > > On Wednesday 08 June 2005 02:20, Johnson, Don wrote: > > Configuration: > > > > 20 UML instances on a P4 2.8 Ghz w/ .75 GB memory > How old are they? On <= 2.6.9 there was a UDP checksum > problem with fragmented > packets... (guess on 2.4 this hasn't happened but I'm not too sure). > > a bridge (uml-bridge) set up with 20 interfaces, one for > each of the UML > > instances uml-bridge has ip address of 10.3.82.4 > > UML instances have addresses 10.3.82.5-24 > > UML instances have a default route of 10.3.82.4 > > eth0 has address of 10.3.0.82 > > zebra+rip advertise the 10.3.82.x route as 10.3.0.82 > > ip_forwarding is enabled > > > > Problem: > > > > When a burst of UDP packets is sent to a number of UML > hosts (i.e. several > > packets to each host), packets are lost between eth0 and uml-bridge. > > tcpdump on eth0 shows all incoming packets. tcpdump on > uml-bridge shows > > missing packets. Running ifconfig for uml-bridge shows lost > TX packets at > > about the same rate as is shown between the two tcpdump sessions. > > > > This computer is one of 30-50 units (some with up to 250 > UML instances) > > that we use to simulate thousands of computers. Originally > I used bridging > > to connect uml-bridge to eth0 but with hundreds of ip > addresses bridging > > onto a single network segment (with proxy arp enabled), arp > caching became > > a problem. My solution was to route between the uml-bridge and eth0 > > (instead of adding eth0 to the bridge) and use zebra+rip > for the route > > advertising. Functionally it works really well but inbound > UDP packets in > > bursts are lost. TCP works just fine. Anyone have any ideas > about those > > lost packets? > > > > > > ------------------------------------------------------- > > This SF.Net email is sponsored by: NEC IT Guy Games. How > far can you > > shotput a projector? How fast can you ride your desk chair > down the office > > luge track? If you want to score the big prize, get to know > the little guy. > > Play to win an NEC 61" plasma display: http://www.necitguy.com/?r > > _______________________________________________ > > User-mode-linux-user mailing list > > User-mode-linux-user@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user > > -- > Inform me of my mistakes, so I can keep imitating Homer > Simpson's "Doh!". > Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", > ICQ 215621894) > http://www.user-mode-linux.org/~blaisorblade > > > ___________________________________ > Yahoo! Messenger: chiamate gratuite in tutto il mondo > http://it.beta.messenger.yahoo.com > > ------------------------------------------------------- This SF.Net email is sponsored by: NEC IT Guy Games. How far can you shotput a projector? How fast can you ride your desk chair down the office luge track? If you want to score the big prize, get to know the little guy. Play to win an NEC 61" plasma display: http://www.necitguy.com/?r _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
