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Using Level 3 Networking and Linux Quality of Service to create a low-cost network simulation environment

IP.com Disclosure Number: IPCOM000124289D
Publication Date: 2005-Apr-14
Document File: 3 page(s) / 188K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a technique for building a large network simulation environment using a minimum amount of hardware and freely available software. Level 3 networking allows the creation of a large network of up to 254 subnets within a single router. Linux Quality of Service allows for the routing and shaping of all network paths between these subnets. Furthermore, Linux routing rules can be employed to create any network topology required for the application.

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Using Level 3 Networking and Linux[i] Quality of Service to create a low-cost network simulation environment

© 2005 Lockheed Martin Corporation.  All Rights Reserved.

Disclosed is a technique for building a large network simulation environment using a minimum amount of hardware and freely available software.  Level 3 networking allows the creation of a large network of up to 254 subnets within a single router.  Linux Quality of Service allows for the routing and shaping of all network paths between these subnets.  Furthermore, Linux routing rules can be employed to create any network topology required for the application.

This technique requires using three technologies to save on required hardware.  It uses Level 3 Networking to create a collection of subnets or VLANs.  (VLAN is a virtual local area network.)  It uses Linux Routing to tie each VLAN together into the required network topology.  Finally, it uses Linux Quality of Service in order to degrade and restrict bandwidth between each of the VLANs.

Level 3 Networking is a standard feature on many of the larger switches on the market today.  This feature allows you to partition a switch into multiple independent networks which are unable to communicate directly with each other.  This creates the illusion of multiple unconnected switches in a single piece of hardware.  It is possible to allocate one or more ports in Level 3 networking as an 802.1Q[ii] trunk.  A computer attached to this port would then be able to route between any of the VLANs for which the trunk is configured.

Linux is capable of connecting to an 802.1Q trunk and routing between the available VLANs exposed on the trunk.  To build and enforce a network topology, the Linux server must be attached to the switch using multiple 802.1Q trunks.  The Linux server must have multiple 802.1Q connections enabled for a subnet if a packet will ever need to traverse that subnet.  (A packet traversing the subnet must enter the subnet on a different trunk than it leaves, otherwise the path would short-circuit eliminating this subnet from its path.)

Linux Quality of Service classifies and shapes traffic as it traverses the router.  The traffic in the network should be classified based on the next link in its journey to its destination.  This link should be shaped using either the Token Bucket Filter (TBF) or Heirarchical Token Bucket Filter (HTB) shapers.  (These shapers are also called Queuing Disciplines, or qdisc in the Linux QoS documentation.)

Figure 1 shows an example of a network topology that can be simulated.  The blue ellipses represent each of the VLANs created in the network topology.  The purple circles represent each route...