[Bug 616064] Re: Broken networking in kvm guests

Tue Dec 20 17:50:25 UTC 2011

I've tested

# terminal 1
root at vs-master:~# brctl delif virbr1 veth0
root at vs-master:~# brctl addif br0 veth0
root at vs-master:~# ip link set veth1 netns 5039
root at vs-master:~# nc -4 -k -l 8080

# terminal 2
root at vs-master:~# /bin/ns_exec -cmn /bin/bash
about to clone with 40020000
clone: Invalid argument
root at vs-master:~# echo $$
5039
root at vs-master:~# ifconfig veth1 192.168.1.214
root at vs-master:~# ifconfig veth1
veth1     Link encap:Ethernet  HWaddr 1a:13:2e:39:53:2e
          inet adr:192.168.1.214  Bcast:192.168.1.255  Masque:255.255.255.0
          adr inet6: fe80::1813:2eff:fe39:532e/64 Scope:Lien
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Packets reçus:3202 erreurs:0 :0 overruns:0 frame:0
          TX packets:193 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:1000
          Octets reçus:123117 (123.1 KB) Octets transmis:39048 (39.0 KB)

>From my client :
user at host:~$ S=a; N=1; while [ 1 ]; do echo $N$S | nc 192.168.1.214 8080; ((N += 1)); S=${S}a; sleep 0.5s; done

The server (terminal 1) displays the strings without problems.

But I tried to stress it a bit more (with sleep 0.01s) and around 220 it
starts to lag a bit (but is not stuck anyway, still delivers the
content).

Moreover, I tried to use wireshark in order to show ARP packets, flushed
my local arp cache but without more results : the IP is resolved once
and then no more, and the TCP connection still sticks later.

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https://bugs.launchpad.net/bugs/616064

Title:
  Broken networking in kvm guests

Status in “bridge-utils” package in Ubuntu:
  Confirmed
Status in “linux” package in Ubuntu:
  Confirmed
Status in “qemu-kvm” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: qemu-kvm

  Some TCP operations receive unexpected reset (RST) packets when executed on the guest.  I can see these RST packets via
  Wireshark but can't explain their source.  This breaks certain (most) networking on the guest.

  I uncovered this when some 'git clone' operations failed with "Broken
  Pipe" in the guests.  I've been able to reproduce the same failures
  using scp and 'svn checkout'.  The failure occurs 80-90% of the time
  and 'svn checkout' seems to be the quickest to fail.  The same
  operations on the host are always successful.

  My setup is a Lucid amd64 host with two guests (Lucid and Hardy, both
  i386, using kvm).  Networking seems to mostly work.  I can maintain
  persistent ssh connections to the guest and some networking operations
  from the guest (ie. ping) never fail.  However, the git-clone/scp/svn-
  checkout operations fail almost all the time.  I've tried this with
  both virtio and e1000 drivers with no difference.

  This may be similar to some of the behavior reported in bug 584048 but
  not the final patch referenced in comment 27.  I built a custon deb
  including the upstream patch for testing and it had no effect.

  $ lsb_release -rd
  Description:	Ubuntu 10.04.1 LTS
  Release:	10.04

  $ apt-cache policy qemu-kvm
  qemu-kvm:
    Installed: 0.12.3+noroms-0ubuntu9.2
    Candidate: 0.12.3+noroms-0ubuntu9.2
    Version table:
   *** 0.12.3+noroms-0ubuntu9.2 0
          500 http://us.archive.ubuntu.com/ubuntu/ lucid-updates/main Packages
          100 /var/lib/dpkg/status
       0.12.3+noroms-0ubuntu9 0
          500 http://us.archive.ubuntu.com/ubuntu/ lucid/main Packages

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: kvm 1:84+dfsg-0ubuntu16+0.12.3+noroms+0ubuntu9.2
  ProcVersionSignature: Ubuntu 2.6.32-24.39-server 2.6.32.15+drm33.5
  Uname: Linux 2.6.32-24-server x86_64
  Architecture: amd64
  Date: Tue Aug 10 16:39:24 2010
  InstallationMedia: Ubuntu-Server 10.04 "Lucid Lynx" - Beta amd64 (20100406.1)
  KvmCmdLine:
   UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
   root     17641     1  1 2174883 1087144 1 15:42 ?      00:00:59 /usr/bin/kvm -S -M pc-0.12 -cpu qemu32 -enable-kvm -m 8192 -smp 8 -name hound-lucid -uuid 0e32438c-cb4d-1eb9-a560-f25c89c1dbf6 -chardev socket,id=monitor,path=/var/lib/libvirt/qemu/hound-lucid.monitor,server,nowait -monitor chardev:monitor -boot c -drive file=/opt/hound-lucid,if=virtio,index=0,boot=on -drive if=ide,media=cdrom,index=2 -net nic,macaddr=52:54:00:61:7e:c0,vlan=0,model=virtio,name=virtio.0 -net tap,fd=59,vlan=0,name=tap.0 -chardev pty,id=serial0 -serial chardev:serial0 -parallel none -usb -vnc 127.0.0.1:0 -k en-us -vga cirrus
  MachineType: IBM IBM System x3400 M2 Server -[7836AC1]-
  ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-24-server root=UUID=7d9adc6b-cfec-42fa-b469-bc09ccd24478 ro quiet
  ProcEnviron:
   PATH=(custom, user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: qemu-kvm
  dmi.bios.date: 11/20/2009
  dmi.bios.vendor: IBM Corp.
  dmi.bios.version: -[Y4E131BUS-1.02]-
  dmi.board.name: 49Y6715
  dmi.board.vendor: IBM
  dmi.board.version: GA
  dmi.chassis.type: 23
  dmi.chassis.vendor: IBM
  dmi.chassis.version: GA
  dmi.modalias: dmi:bvnIBMCorp.:bvr-[Y4E131BUS-1.02]-:bd11/20/2009:svnIBM:pnIBMSystemx3400M2Server-[7836AC1]-:pvr06:rvnIBM:rn49Y6715:rvrGA:cvnIBM:ct23:cvrGA:
  dmi.product.name: IBM System x3400 M2 Server -[7836AC1]-
  dmi.product.version: 06
  dmi.sys.vendor: IBM

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