From 81f9a039828efe593434c089a5c767ab1e55e1fd Mon Sep 17 00:00:00 2001 From: Justin Pettit Date: Tue, 20 Mar 2012 23:23:00 -0700 Subject: [PATCH] WHY-OVS: Update to reflect OVS's inclusion in Linux 3.3. Signed-off-by: Justin Pettit Suggested-by: Martin Casado --- WHY-OVS | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/WHY-OVS b/WHY-OVS index ac9a3815..e8c6f752 100644 --- a/WHY-OVS +++ b/WHY-OVS @@ -1,13 +1,13 @@ 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 -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 @@ -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 - 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 @@ -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 -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 -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. -- 2.30.2