Deploying Cisco traffic generator in GNS3

Goal: Deploy TRex, a realistic Cisco traffic generator, to test devices in GNS3.

TRex traffic generator is a tool designed to benchmark platforms using realistic traffic.
One of the tools through which TRex can be learned and tested is a virtual machine instance, fully simulating TRex without the need for any additional hardware.

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The TRex Virtual Machine is based on Oracle’s Virtual Box freeware.
It is designed to enable TRex newbies to explore this tool without any special resources.

Download the virtual appliance ova file: http://trex-tgn.cisco.com/trex/T_Rex_162_VM_Fedora_21.ova

Open the image in VMWare (I am using VMWare workstation)

From GNS3 import the VMWare device:

Edit the VM template and make sure to select “Allow GNS3 to use any configured VMware adapter”

Insert the a device to test, DUT (Device Under Test), in our case it is a Cisco IOU router and build the following topology, in which TRex will play the role of the client and the server for the generated traffic.

Topology

Because TRex doesn’t implement ARP, we have to manually indicate the router MAC addresses of the directly connected interfaces.
You can set TRex to match the DUT MACs or DUT to match the default MAC configured on TRex. We opt for the first solution:

Note the router interface MAC addresses:

Login to TRex through the console:

• Username: trex
• Password: trex

and edit Trex configuration file

/etc/trex_cfg.yaml

and change the DUT MACs

Make sure the list of interfaces ids match the ones defined by dpdk_nic_bind.py

cd v1.62

sudo ./dpdk_nic_bind.py –status

We also need to set our router under test with the MAC addersses used by TRex for the traffic.

On the IOU router:

IOU1(config-if)#int e0/0
IOU1(config-if)#ip address 192.168.10.2 255.255.255.0
IOU1(config-if)#du fu
IOU1(config-if)#no sh
IOU1(config-if)#int e0/1
IOU1(config-if)#ip address 192.168.20.2 255.255.255.0
IOU1(config-if)#du fu
IOU1(config-if)#no sh

IOU1(config)#arp 192.168.10.1  0800.2723.21dc ARPA
IOU1(config)#arp 192.168.20.1  0800.2723.21dd ARPA
IOU1(config)#do sh arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  192.168.10.1            –   0800.2723.21dc  ARPA
Internet  192.168.20.1            –   0800.2723.21dd  ARPA
IOU1(config)#

e0/1 and e0/2 IP addresses are configured with 192.168.10.2 and 192.168.20.2. In fact it doesn’t matter for TRex because we have routes to forward traffic out the appropriate interfaces to reach TRex interfaces.

On the router set routes to the emulated client and servers:

ip route 16.0.0.0 255.0.0.0 192.168.10.1
ip route 48.0.0.0 255.0.0.0 192.168.20.1

For this lab we will generate IMIX traffic (64byte UDP packets profile) from emulated clients and servers using virtual IP range configurable in 16.0.0.[1-255] and 48.0.[0.1-255.255]

Back to TRex:

cap2/imix_64.yaml

So let’s configure our router to route traffic destined to previous ranges out the appropriate interfaces.

IOU router:

IOU1(config)#ip route 16.0.0.0 255.0.0.0 192.168.10.1
IOU1(config)#ip route 48.0.0.0 255.0.0.0 192.168.20.1

Start the emulation on Trex:

sudo ./t-rex-64 -f cap2/imix_64.yaml  -d 60 -m 40000  -c 1

You can observe the generated traffic passing through the router with Wireshark

For more inf. please refer to

https://trex-tgn.cisco.com/trex/doc/trex_manual.html#_dns_basic_example

References:

• https://trex-tgn.cisco.com
• https://trex-tgn.cisco.com/trex/doc/trex_config_guide.html