[ovs-git] Open vSwitch: datapath: Consider tunnels to have no MTU, fixing jumbo frame support. (master)

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Fri Feb 4 17:55:32 UTC 2011


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- Log -----------------------------------------------------------------
commit f915f1a8ca180828983ef22cf2fd21b8f010b972
Diffs: http://openvswitch.org/cgi-bin/gitweb.cgi?p=openvswitch;a=commitdiff;h=f915f1a8ca180828983ef22cf2fd21b8f010b972
Author: Ben Pfaff <blp at nicira.com>
		
datapath: Consider tunnels to have no MTU, fixing jumbo frame support.
		
Until now, tunnel vports have had a specific MTU, in the same way that
ordinary network devices have an MTU, but treating them this way does not
always make sense.  For example, consider a datapath that has three ports:
the local port, a GRE tunnel to another host, and a physical port.  If
the physical port is configured with a jumbo MTU, it should be possible to
send jumbo packets across the tunnel: the tunnel can do fragmentation or
the physical port traversed by the tunnel might have a jumbo MTU.

However, until now, tunnels always had a 1500-byte MTU by default.  It
could be adjusted using ODP_VPORT_MTU_SET, but nothing actually did this.
One alternative would be to make ovs-vswitchd able to set the vport's MTU.
This commit, however, takes a different approach, of dropping the concept
of MTU entirely for tunnel vports.  This also solves the problem described
above, without making any additional work for anyone.

I tested that, without this change, I could not send 1600-byte "pings"
between two machines whose NICs had 2000-byte MTUs that were connected to
vswitches that were in turn connected over GRE tunnels with the default
1500-byte MTU.  With this change, it worked OK, regardless of the MTU of
the network traversed by the GRE tunnel.

This patch also makes "patch" ports MTU-less.

It might make sense to remove vport_set_mtu() and the associated callback
now, since ordinary network devices are the only vports that support it
now.

Signed-off-by: Ben Pfaff <blp at nicira.com>
Suggested-by: Jesse Gross <jesse at nicira.com>
Acked-by: Jesse Gross <jesse at nicira.com>
Bug #3728.


-----------------------------------------------------------------------

Summary of changes:
 datapath/datapath.c                     |    7 ++++++-
 datapath/tunnel.c                       |   25 -------------------------
 datapath/tunnel.h                       |    4 ----
 datapath/vport-capwap.c                 |    2 --
 datapath/vport-gre.c                    |    2 --
 datapath/vport-patch.c                  |   29 -----------------------------
 datapath/vport.c                        |   10 ++++++----
 datapath/vport.h                        |    3 ++-
 include/openvswitch/datapath-protocol.h |    3 ++-
 lib/dhcp-client.c                       |    6 ++----
 lib/dpif-linux.c                        |    4 +++-
 lib/dpif-netdev.c                       |    2 +-
 lib/netdev-linux.c                      |   13 ++++++++++++-
 lib/netdev-provider.h                   |    7 +++++--
 lib/netdev.c                            |    7 ++++---
 vswitchd/bridge.c                       |    2 +-
 vswitchd/vswitch.xml                    |    4 ++++
 17 files changed, 48 insertions(+), 82 deletions(-)


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