ofp-util: Work on decoding OF1.1 flow_mods.

[openvswitch] / WHY-OVS

diff --git a/WHY-OVS b/WHY-OVS
index ac9a3815a1a00ca3ad024bfb7d6652a040de8899..e8c6f752b1e287ea3c8b0bd2ec17db5374ae0063 100644 (file)
--- a/WHY-OVS
+++ b/WHY-OVS
@@ -1,13 +1,13 @@
                           Why Open vSwitch?
                           =================
 
                           Why Open vSwitch?
                           =================
 

-We love the existing network stack in Linux.  It is robust, flexible,
-and feature rich.  Linux already contains an in-kernel L2 switch (the
-Linux bridge) which can be used by VMs for inter-VM communication.  So,
-it is reasonable to ask why there is a need for a new network switch.
+Hypervisors need the ability to bridge traffic between VMs and with the
+outside world.  On Linux-based hypervisors, this used to mean using the
+built-in L2 switch (the Linux bridge), which is fast and reliable.  So,
+it is reasonable to ask why Open vSwitch is used.

 
 The answer is that Open vSwitch is targeted at multi-server
 
 The answer is that Open vSwitch is targeted at multi-server

-virtualization deployments, a landscape for which the existing stack is
+virtualization deployments, a landscape for which the previous stack is

 not well suited.  These environments are often characterized by highly
 dynamic end-points, the maintenance of logical abstractions, and
 (sometimes) integration with or offloading to special purpose switching
 not well suited.  These environments are often characterized by highly
 dynamic end-points, the maintenance of logical abstractions, and
 (sometimes) integration with or offloading to special purpose switching


@@ -83,7 +83,8 @@ vSwitch cope with the above requirements.
 
   There are many ongoing efforts to port Open vSwitch to hardware
   chipsets.  These include multiple merchant silicon chipsets (Broadcom
 
   There are many ongoing efforts to port Open vSwitch to hardware
   chipsets.  These include multiple merchant silicon chipsets (Broadcom

-  and Marvell), as well as a number of vendor-specific platforms.
+  and Marvell), as well as a number of vendor-specific platforms.  (The
+  PORTING file discusses how one would go about making such a port.)

 
   The advantage of hardware integration is not only performance within
   virtualized environments.  If physical switches also expose the Open
 
   The advantage of hardware integration is not only performance within
   virtualized environments.  If physical switches also expose the Open


@@ -92,13 +93,13 @@ vSwitch cope with the above requirements.
   network control.
 
 In many ways, Open vSwitch targets a different point in the design space
   network control.
 
 In many ways, Open vSwitch targets a different point in the design space

-than the existing Linux networking stack, focusing on the need for
+than previous hypervisor networking stacks, focusing on the need for

 automated and dynamic network control in large-scale Linux-based
 virtualization environments.
 
 The goal with Open vSwitch is to keep the in-kernel code as small as
 possible (as is necessary for performance) and to re-use existing
 subsystems when applicable (for example Open vSwitch uses the existing
 automated and dynamic network control in large-scale Linux-based
 virtualization environments.
 
 The goal with Open vSwitch is to keep the in-kernel code as small as
 possible (as is necessary for performance) and to re-use existing
 subsystems when applicable (for example Open vSwitch uses the existing

-QoS stack).  Open vSwitch limits disruption by using existing hooks into
-the kernel, so Open vSwitch can be deployed as a module without
-requiring any modification to the kernel.
+QoS stack).  As of Linux 3.3, Open vSwitch is included as a part of the
+kernel and packaging for the userspace utilities are available on most
+popular distributions.