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Method to Set Source IP in SDN Router Generated ICMP Error Messages

IP.com Disclosure Number: IPCOM000245166D
Publication Date: 2016-Feb-16
Document File: 5 page(s) / 108K

Publishing Venue

The IP.com Prior Art Database

Abstract

SDN supported switches can implement L2 forwarding and L3 forwarding functionality. When a SDN switch supports L3 forwarding or IP routing functionality, it should support generation of ICMP error messages. Some examples where ICMP error message generation is required include: Route-not-found, Host-not-found, TTL is 0, not all fragments received, fragmentation needed but DF bit set, etc. The SDN switch can communicate to the controller and IP routing application to generate ICMP error messages. To reduce the overhead of the communicating application for generation of ICMP error messages, a switch can support generating ICMP error messages. With current Openflow 1.5.1 standards, SDN IP routing functionality may not able to set the router's IP address in its generated ICMP error messages. This paper provides a method to enhance Openflow standards to set the router's IP address.

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Method to Set Source IP in SDN Router Generated ICMP Error Messages

Abstract

SDN supported switches can implement L2 forwarding and L3 forwarding functionality. When a SDN switch supports L3 forwarding or IP routing functionality, it should support generation of ICMP error messages. Some examples where ICMP error message generation is required include: Route-not-found, Host-not-found, TTL is 0, not all fragments received, fragmentation needed but DF bit set, etc.  The SDN switch can communicate to the controller and IP routing application to generate ICMP error messages. To reduce the overhead of the communicating application for generation of ICMP error messages, a switch can support generating ICMP error messages. With current Openflow 1.5.1 standards, SDN IP routing functionality may not able to set the router’s IP address in its generated ICMP error messages. This paper provides a method to enhance Openflow standards to set the router’s IP address.

Introduction

SDN (Software Defined Networking) architectures are used to decouple the functionalities of the control and data planes.  Some advantages of SDN architecture are that it can be centrally managed, directly programmable to one or more device, agile, provides open standards, etc.  SDN can be implemented using Openflow Switch specifications. These specifications are defined by Open Networking Foundation (ONF). 

Openflow switch defines datapath, flow tables, match fields, instructions and actions.  RFC 792 defines the ICMP messages. RFC 1812 defines the required ICMP error messages to be supported for IP routing functionality.  SDN IP routing functionality can be implemented using Openflow defined instructions and actions.  SDN IP router should support generation of ICMP error messages.

Problem

RFC 792 specifies that Source IP address in IP header of ICMP error message should contain the IP address of the IP router.  IP router can be configured with one or more IP addresses.  SDN IP router functionality can be implemented using flow entries, table-miss entries, standard instructions and actions like output, TTL decrement, set Ethernet source MAC, set Ethernet destination MAC addresses, etc.

Suppose while executing TTL decrement action, a packet arrives with TTL 0/ TTL 1.  In this case, SDN IP router should generate an ICMP error message and output to the received port number.  SDN IP router can generate ICMP error message, but cannot find its corresponding IP address, instead it may set a wrong IP address. This may give wrong results in executing traceroute functionality.

Solution

Solution includes the following steps:

  • Define a gateway IP addresses flow table (GIT)
  • Reserve a flow table Identifer for gateway IP addresses flow table.
  • Enhance Openflow switch set_config message to communicate Gateway IP addresses flow table Identifier.
  • IP router switch can process set_config message and save the gateway IP addresses flow table Identifier globally.
  • When a router constructing I...