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Everything about Technology and Innovation

Everything about Technology and Innovation

This blog mainly constructed and built by an Asian passionate technical evangelist and system engineering person- Chris Hoo

Exploring Cisco DevNet TRex traffic generator

More often than none,network engineers will come across the situation whereby they being task on putting some works to perform testing on proving or simulating a networks environment using traffic generator or tester, mimicking the realistic mixes of traffic profiles scenarios with different network functions and features, traffic testing became vital and even mandatory to test and discover features or bottleneck face in a network

Traffic testing divided into stateless or stateful , throughout the years there's some stateless free open source traffics generator such as iperf, ostinato that contributed by communities however there's challenge finding a full fledged stateful traffics generator, and users always needed to opt for commercial traffic generator which brought them concerns and consideration such as CAPEX Cost, Scale, standardization and flexibility.

Until Cisco Devnet launched Cisco TRex- a fully open source software that can perform full stateful and stateless ( L1-L7) traffic generation using commodity x86 servers and NICs, providing end users and network administrators with option to have an open source full function traffic generator tools instead of just spending cash and money to purchase commercial test gear from  vendors . Very cool stuff! Hence in this post i wanted to share a little experimental labbing stuff that i did with Cisco TRex in my virtualbox environment. i am using TRex version v2.41 for this testing 

For more detailed information about Cisco TRex , please visit  https://trex-tgn.cisco.com/

Now lets move into my installation - I followed the guide from official website https://trex-tgn.cisco.com/trex/doc/trex_vm_manual.html#_trex_inside_virtual_box

I tried to setup everything in virtualbox laptop so that the entire test can be done using a single laptop. So the brief summary steps inclusive of below 

1. Download and setup TRex by importing the instance into virtualbox and  update TRex to version 2.41 from older version

Download and install the TRex image via http://trex-tgn.cisco.com/trex/ the ova build is on version 1.62 so once you  imported the ova file you need to update the TRex into the latest version with the steps below:

$mkdir trex
$cd trex
$wget --no-cache http://trex-tgn.cisco.com/release/latest
$tar -xzvf latest

p/s: Please make sure that the 'Reinitialize the MAC address of all network cards checkbox is not selected during the import of ova file into virtual box

2. Logging into TRex and check basic ports and platform configuration 

Once step (1) had completed and finished , turn on the vm by logging into trex for first time by using the credentials of : trex/trex

Some of the basic configuration and interfaces status that you can check once u logged in with commands below 

$cd /home/trex/v.241

$sudo ./dpdk_setup_ports.py -s 

the dpdk_setup_ports.py provide user with information about which NIC that's available for port binding , remember that the NIC with *Active* sign is the management ssh connection NIC, so please don use that to bind into TRex platform configuration file. Separately, the python script will also tell user what kind of NIC drivers that the NICs are using between DPDK and kernel driver

Next i will briefly walk you through the content of /etc/trex_cfg.yaml , this yaml file is the platform configuration file that TRex application will refer to during the initiation of the traffic gen application, by default the system came with a sample configuration file hence user can copy that file and amend the necessarily content from there.

first , copy the config file by issuing command below

$cp cfg/simple_cfg.yaml /etc/trex_cfg.yaml

next , amend trex_cfg.yaml according to your testing topology and setup, mine was a simple TRex to a DUT ubuntu VM that running as a layer 3 forwarding device

- port_limit refer to the number of ports that TRex server used in the application , default is 2

- version - MUST use 2 , a default value

- interfaces refer to the interfaces that being used for the application , get from the interfaces information that ran by dpdk setup script

- ip refer to ip  address refer to the physical interface ip that TRex server is using for port 0 and port 1 

-default_gw refer to the next hop device that routing the traffics from network A to network B

There are more configurable options , for full options please refer to TRex user guide 

3. Configuring Ubuntu VM as the DUT (Device Under Test)

The DUT in this example as mentioned above is a simple Ubuntu VM instance connected to TRex VM in a single virtualbox hypervisor. Topology will be 2 interfaces on the DUT connected to TRex client and server's interfaces respectively . Basic IP forwarding will be enabled to perform layer 3 forwarding between 2 different networks ( and, with a couple of static ARP and static routes to the client and server traffic generator's subnet

Trex client-MAC01----enps09----trex-client-----MAC03-Ubuntu-eth2
Trex server-MAC02----enps10----trex-server-----MAC04-Ubuntu-eth3

Configure the interfaces with an IP on separate subnets
Add the static routes for relevant pcap tests being run from Trex [eg; and]. Route to dummy IP towards Trex

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto enp0s3
iface enp0s3 inet dhcp

auto eth2
iface eth2 inet static
    up route add -net netmask gw

auto eth3
iface eth3 inet static
up route add -net netmask gw

$ sudo arp -i enp0s9 -s 08:00:27:4B:97:B5
$ sudo arp -i enp0s10 -s 08:00:27:DB:5D:0C

configured routing and arp information 

[root@chtrextest trex]#:/etc/network$ arp
Address                  HWtype  HWaddress           Flags Mask            Iface            ether   08:00:27:4B:97:B5   CM                    eth3            ether   08:00:27:DB:5D:0C   CM                    eth2

[root@chtrextest trex]#:/etc/network$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         UG    0      0        0 eth0        *        U     0      0        0 eth0       UG    0      0        0 eth2       UG    0      0        0 eth3     *      U     0      0        0 eth2     *      U     0      0        0 eth3       *      U     0      0        0 eth1
4. virtualbox network testing topology 

below with a very simple testing topology that I build in my personal laptop , basically both TRex and DUT contained 4 interfaces each connecting via 3 different networks adapter ( TRex traffic testing , host-only management , NAT interfaces for internet connectivity) 

5. Some basic traffics profile testing and results 

Once finished with the installation and configuration step 1-3 , next up I proceeded to run some traffics load test with pre-defined .pcap files and yaml configuration files. The files are all located under /trex/v2.41/cap2

[root@chtrextest cap2]# ls
190_packet.pcap                exchange.pcap           jumbo.yaml                rtsp_short.pcap
asa_exploit.pcap               http_browsing.pcap      lb_ex1.yaml               rtsp.yaml
asa_explot1.yaml               http_get.pcap           limit_multi_pkt.yaml      sfr2.yaml
christest.pcap                 http_plugin.yaml        limit_single_pkt.yaml     sfr3.yaml
citrix.pcap                    http_post.pcap          mail_pop.pcap             sfr4.yaml
cluster_example.yaml           http_short.yaml         many_client_example.yaml  sfr_agg_tcp14_udp11_http200msec_new_high_new_nir_profile_ipg_mix.yaml
cur_flow_single_tw_8.yaml      http_simple_ipv6.yaml   nat_test.yaml             sfr_agg_tcp14_udp11_http200msec_new_high_new_nir_profile.yaml
cur_flow_single.yaml           http_simple.yaml        Oracle.pcap               sfr.yaml
cur_flow.yaml                  https.pcap              per_template_gen1.yaml    short_tcp.yaml
delay_10_http_browsing_0.pcap  http_very_long.yaml     per_template_gen2.yaml    sip_short1.yaml
delay_10_rtp_250k_short.pcap   http.yaml               per_template_gen3.yaml    sip_short2.yaml
dns_no_delay.yaml              imix_1518.yaml          per_template_gen4.yaml    smtp.pcap
dns_one_server.yaml            imix_64_100k.yaml       per_template_gen5.yaml    test_pcap_mode1.yaml
dns.pcap                       imix_64_fast.yaml       rtp_160k.pcap             test_pcap_mode2.yaml
dns_single_server.yaml         imix_64.yaml            rtp_250k_rtp_only_1.pcap  tuple_gen.yaml
dns_test.yaml                  imix_9k_burst_10.yaml   rtp_250k_rtp_only_2.pcap  udp_10_pkts.pcap
dns_tw.yaml                    imix_9k.yaml            rtp_250k_rtp_only.pcap    udp_1518B.pcap
dns_wlen1.yaml                 imix_mimic.yaml         rtsp_full1.yaml           udp_594B.pcap
dns_wlen2.yaml                 ipv4_load_balance.yaml  rtsp_full2.yaml           udp_64B.pcap
dns_wlength.yaml               ipv6_load_balance.yaml  rtsp_short1_slow.yaml     Video_Calls.pcap
dns_wlen.yaml                  ipv6.pcap               rtsp_short1.yaml          Voice_calls_rtp_only.pcap
dns.yaml                       ipv6.yaml               rtsp_short2.yaml          wrong_ip.pcap
dyn_pyld1.yaml                 jumbo.pcap              rtsp_short3.yaml          wrong_ip.yam

The yaml file of TRex applcation contained pcap packet format that's going to use for streams and flows generation. By looking into the packet detail and format by using packet debugging function. Example debugging a SIP packet , command to execute as below 

./bp-sim-64-debug -f /cap2/sip_short1.yaml -0 my.erf -v 3

the debugging result explained the packets information that inclusive of transaction per second, connection per second,forwarding packets and bytes , duration , flows tuple information.

Next lets start proceed with traffics loading , I used simple http traffic profile to generate the stream.

The http traffic yaml file contained property information such as below 

-  Contain 255 clients start from - shown in clients_start and clients_end

-  Contain 255 servers start from -  shown in servers_start and servers_end

-  Contain 255 servers start from -  shown in servers_start and servers_end

- capping and measurement the inter packet gap information for traffics stream sending

- using delay_10_http_browsing_0.pcap as packets sample 

- 2.776 connection per seconds

- ipg of 10 msec

- rtt of 10 msec

- w representing to simultaneous flows that sent by a client ip , for this config it is only 1 time

Next we can begin to test and monitor the traffics on trex server by running simple command with few parameters below

$ sudo ./t-rex-64 -f cap2/http_simple.yaml -d 10 -m 1 --nc


-f is the source yaml file to be used for the test

-d Duration of the test in seconds (minimum is 30)

-m Factor for bandwidth (multiply the CPS of each template in the .yaml file by this number)

--nc If set, will terminate exacly at the end of the duration. This provides a faster, more accurate TRex termination. In default it wait for all the flow to terminate gracefully. In case of a very long flow the termination might be prolong.

-l Run the latency daemon in this Hz rate. Example: -l 1000 runs 1000 pkt/sec from each interface. A value of zero (0) disables the latency check.

-c Number of cores per dual interface. Use 4 for TRex 40Gb/sec. Monitor the CPU% of TRex - it should be ~50%. TRex uses 2 cores for inner needs, the rest of cores can be used divided by number of dual interfaces. For virtual NICs the limit is -c=1.

Once we begin the test we should see the following output

The results shown the true statistics of the test results inclusive of per port and global traffics statistics, number of client , CPS,PPS,drop rate,connections,windows , CPU  information on a granular level.

In the same time I did a simple tcpdump on both interfaces that's connected to TRex application server, below with the snapshot taken

Apart from that , TRex provided user with a TRex viewer app to monitor the statistics and latency or system information through zero mq port 4500 output , sample screenshot taken as below  (ignore the latency information as my ubuntu DUT vm were facing some issues during the point when screeshot was taken) 

6. Others useful stateful traffic generation features from TRex

Aside from what I had shared above , TRex did have more fancy configuration and options as well as features that available for a more complex and comprehensive testing such as below, this article that i wrote were merely just introduced the basic functions of this great tools, i definitely will continue explore this awesome tool for my upcoming POC and testing simulation

- VLAN dot1q support
- mixing different traffic type and templates
- measuring jitter and latency
- automation that ran through RPC and python API 
- client clustering 
- IPv6 support
- 200Gbps of scailing
- NAT support etc
- Scapy packets builder


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