Changes between Version 31 and Version 32 of HowTo/ConfigureOVSWithLayer3Routing


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Timestamp:
08/28/14 10:16:04 (5 years ago)
Author:
sedwards@bbn.com
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  • HowTo/ConfigureOVSWithLayer3Routing

    v31 v32  
    22= Configure OVS With Layer 3 Routing =
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    4 Open vSwitch (OVS) acts as a Layer 2 device when it's not connected to its controller (and its `fail-safe-mode` is set to standalone [default]). If we want to do Layer 3 control, we need to write the control logic in its controller. However, sometimes we want to Layer 3 control while there is other Layer 3 control. For example, we want to do firewall or NAT while there is IP routing managed by XORP or Kernel Static Routing. A straightforward solution is to write your own IP forwarding logic in your controller (Yeah, practice of writing your own XORP is fun!). This is really violating the reusability principle of software engineering. Another solution is to cross your finger and hope there is someone has written it for the controller framework you use.
     4== What is the problem? == 
     5Sometimes it is desirable to have a box which provides a custom network function (e.g. firewall, NAT, etc) using a custom OpenFlow controller.  However we want the box to also provide default routing behaviour. 
     6
     7There are several approaches to solving this problem:
     8 * A straightforward solution is to write your own IP forwarding logic in your controller.  While implementing your own IP routing would be fun, it is time consuming and violates the reusability principle of software engineering.
     9 * Another solution is to hope someone has written an OpenFlow router as part of the controller framework you use.  But this limits your choices of controller frameworks.
     10 * Finally, you could combine OVS software switches with an existing routing implementation (provided by the kernel, XORP, etc) in the same box. 
     11
     12 
     13This page explains how to do the last of these options as shown in the figure. That is, it will allow us to make a custom firewall or NAT while IP routing is managed by XORP or Kernel Static Routing.
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    615[[Image(2boxes.png, 35%, nolink)]]
     16
     17== Approach ==
     18{{{
     19#!comment
     20Open vSwitch (OVS) acts as a Layer 2 device when it's not connected to its controller (and its `fail-safe-mode` is set to standalone [default]). If we want to do Layer 3 control, we need to write the control logic in its controller.
     21}}}
    722
    823In this page, we are going to show you how to configure OVS to work with Linux kernel static IP routing. The method is largely from the help of Ryan Izard, rizard@g.clemson.edu, from Clemson University.
     
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    1833In summary the idea is to create a single OVS bridge for each interface on your machine that you want to assign an IP; pass the packet between the interface and the network stack through the `LOCAL` port of OVS; and let Linux routing handle the rest.
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     35== Instructions ==
    1936This wiki page provides step-by-step instructions.
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