In one my previous posts, I shown you how to test a connection using a hidden Cisco IOS tool called TTCP. A few days ago I run into an issue. I had to test a TCP connection to a remote Cisco router, but I had not other router on which to initiate the TTCP connection. As explained in Testing TCP Connection post, to use TTCP you need 2 Cisco routers.
Now, I found 2 new ways to do the testing without the need of having 2 routers, but just one. Maybe you already know this methods, but for those who don’t please keep on reading.
First, there is a Windows tool called TTCPW (download here) (actually you can download also the code, and I think it’s possible to compile and run it under Linux as well). This TTCW tool have the same option like Cisco TTCP and can work together without any issue.
On Cisco router, issue the ttcp command, and keep the regular parameters (we are not interested for now in fine tuning). Below I set the Cisco router to be the receiver:
On PC side, you download TTCPW and use the same settings. Basically to transmit you only need to input ttcpw.exe -t or -r “ip.address” and that’s it Of course you can tune the settings to meet your needs. Just type ttcpw.exe to see all the settings.
The second tool that you can use with Cisco TTCP is IPerf (text mode) or JPerf (Java graphical mode). Just fill in the IP address and the port (5001 if default) and you’re ready to go:
Of course there are some limitations on JPerf to TTCP compared to JPerf to JPerf testing. One of then is that you cannot use parallel streams, if you want to stress the connection. To overcome this limitation, I do the following.
Open 2 or 3 connection to the Cisco router where TTCP will run. Start one each connection one TTCP daemon with different ports (e.g. assuming 3 connection than ports 5001, 5002 and 5003). Then on the client start 3 JPerf (Iperf) with the same IP address but different ports (you can take the one below). In this way you can stress the connection a little bit.
An undersea cable plugging east Africa into high speed Internet access went live Thursday, providing an alternative to expensive satellite connections.
The cable links southern Africa to Europe and Asia.
SEACOM, the cable provider company, opened its 17,000 kilometer submarine cable, capable of 1.28 terabytes per second, allowing the region true connectivity.
Most Africans rely on expensive and slow satellite connections, which make the use of applications such as YouTube and Facebook extremely trying.
“This is going to reduce the cost of doing business in Africa, within Africa and with international parties” said Suveer Ramdhani, SEACOM spokesman in South Africa.
In this article I want to show you how to extend your posibilities to test a network in GNS3. Sure, it’s simple sometime to use a Loobpack interface on one of your edge routers to simulate an external network, but sometime is useful to have something connected to the router port. Take as an example QoS marking and classification. If you want to mark something inbound, then you need a connection to the router port where you want to mark the packets.
Even most of you are familiar with GNS3 and maybe Virtual PC Simulator, let me begin with some short description about this 2 software.
GNS3 is a Graphical Network Simulator that allows emulation of complex networks. It allows you to run a Cisco IOS in a virtual environment on your computer (running Linux, MacOS X or Linux). GNS3 is a graphical front end to a product called Dynagen. Dynamips is the core program that allows IOS emulation.
The Virtual PC Simulator (VPCS) allow you to simulate up to 9 PCs. You can ping/traceroute them, or ping/traceroute the other hosts/routers from the virtual PCs when you study the Cisco routers in the Dynamips. VPCS is not the traditional PC, it is just a program running on the Linux or Windows, and only few network commands can be used in it. But VPCS can give you a big hand when you study the Cisco devices in the Dynamips. VPCS can replace the routers or VMware boxes which are used as PCs in the Dynamips network.
Before we start, I assume that you already have these tools installed. If not, please download and install GNS3 and VPCS.
On the following example I will show you how to configure a network topology including 2 Virtual PCs and one router and how to interconnect them in GNS3. This presentation is simulate a basic network, but after you learn how to do it, you can configure more complex one. You can have a look to the topology to understand better what I’m talking about.
Please see the video presentation below:
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