touch-packages team mailing list archive

[Mark Shuttleworth <1355813@xxxxxxxxxxxxxxxxxx>]

Do we need to take into account any overhead being added by the protocol
stack along the way?

For example, if the underlying MAAS machine can be told to use 9000 byte
MTUs and jumbo frames, then each layer up could adopt that, but might
need to chop off some of that for protocol / tunnel / encapsulation
overhead. I've seen cases where your "internal" interface needs to have,
say 20 byte smaller MTUs than the host. Perhaps THAT's the bit that we
should focus on specifying. So MAAS gets told "just jumbo frames here"
and then everything else focuses on understanding and allowing for
overhead, but maximising MTU subject to that overhead.

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https://bugs.launchpad.net/bugs/1355813

Title:
  Interface MTU management across MAAS/juju

Status in juju-core:
  Fix Released
Status in MAAS:
  Triaged
Status in juju-core package in Ubuntu:
  Triaged
Status in lxc package in Ubuntu:
  Invalid

Bug description:
  Context:

  juju + MAAS deployed OpenStack environment, misc services deployed
  under LXC on the bootstrap node, interfaces configured for jumbo
  frames - note that I had to manually set the LXC container interfaces
  to mtu 9000 before the bridge would do the same.

  Action:

  Reboot one of the containers; MTU on br0 resets from 9000 -> 1500.

  This feels like more of a 'we need a better way to orchestrate MTU
  configuration across different services' so raising tasks for MAAS and
  Juju as well.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: lxc 1.0.5-0ubuntu0.1
  ProcVersionSignature: User Name 3.13.0-24.47-generic 3.13.9
  Uname: Linux 3.13.0-24-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3.3
  Architecture: amd64
  Date: Tue Aug 12 13:26:00 2014
  KernLog:

  SourcePackage: lxc
  UpgradeStatus: No upgrade log present (probably fresh install)
  defaults.conf:
   lxc.network.type = veth
   lxc.network.link = lxcbr0
   lxc.network.flags = up
   lxc.network.hwaddr = 00:16:3e:xx:xx:xx
  lxcsyslog:

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