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TRex with Realtime Network Emulation

Cisco Employee

What is Network Emulation?

Network emulation is one of the key elements of effective network testing, helping you find problems in-house instead of customer environments. To create such test environments, it would require either physical hardware or virtual simulation matching the target network environment. Virtual simulators should have the capability of sending control plane traffic (like MPLS/BGP etc) and data plane traffic (like VxLAN/TCP/UDP), along with the capability to address necessary realism by adding network impairments to the network being tested like burst mode traffic, delays in traffic, route flaps etc. to closely simulate a real network.


Does TRex support Network Emulation?

TRex now supports Realtime Network Emulation with integration of IOL (IOS version of Linux) and Routem.

This is for Cisco Employees only.

It brings in most of the control plane features supported by IOS within TRex as our own IOS will be acting as a feature validating component. Additionally, Routem a tool that generates routes is modified to communicate with IOL interfaces in increasing the routes scale, or routem can be used independently on each trex port to send millions of routes.




What value-add does this bring?

Control plane protocols along with 100gig nic support on a low cost hardware(UCS), which can be used by multiple users simultaneously, can help address many asks. Instead of using multiple Physical routers, multiple IOL instances can be used to simulate scenarios ,like testing BGP/OSPF etc seen in customer network.

No Licensing fees are needed for testing any protocol. IOL Release Software V16_11_01PRD12_FC1 is used as a part of TRex package. It can be replaced with any version of IOL or upgrades.

What has been tested?
Realtime Routing emulation with IPv4/v6 + traffic, with support from Switching team, L3VPN feature with MPLS/LDP/VRF/BGP (topology below) are few features that have been successfully tested. We have also verified IS-IS, OSPFv2, OSPFv3, static IPv6 routes with traffic.

What can be tested?
Most of the control plane protocols/features supported by IOS can be tested.


What are the different ways to configure TRex and build a Topology?
From CLI, NETMAP file can be modified to create a topology as per user’s test requirement. For ex, if NETMAP contains 100:1 102:2, it means 100th  IOL instance port 1(eth1/0) is connected to 102nd IOL instance port 2 (eth2/0). Users can also telnet to each IOL instances to configure the protocols/interfaces etc using IOS commands.
Aastha is the new GUI with capability of traditional TRex GUI features, with topology creation,realtime network emulation, packet editor with detailed configuration options for many protocols etc. It is provided as a desktop app for MAC/Win/Linux or an option to install TRex GUI as a web service.
HLTApi for realtime protocol emulation is addressed for regression suites.


Please visit and for more help, Next article on aastha will help you more on GUI front.

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