How to control the network latency

latencynetworking

My company is developing a network software and its network stability is very important. So my supervisor want me to set up the testing environment for our QA team.

I can take care of almost everything to set it up except the network latency test. I need to find a tool that can control the network latency but I couldn't able to find one. My supervisor have mentioned that there is a tool which create a virtual NIC to control network latency or something.

Please let me know if you've seen any of network latency control tool or something helpful information.

Thank you..

Best Answer

If it has to be windows.. its not going to be easy and free i think. If you got some budget for this, go Shunra. No budget, go linux and use Qdisc.

Ive tried some free linux WAN simulators to emulate 4 hostingsites with delays and bandwidthlimits.. all just crashed with my config so i ended up setting up Qdisc manually.

If you decide to go with the linux option i could assisst in the Qdisc config.

For more opinions youve got a link from Zoredache in you questionpost.

Related Solutions

How Geography Affects Network Latency

There is a distance delay and all other things being equal (routing efficiency, processing overhead, congestion, etc.) a site on the west coast accessed by a host on the east coast is going to take longer than if that site is on the east coast but we're talking milliseconds here.

Networking – Typical Network Latency for East to West Coast USA

Speed of Light:
You are not going beat the speed of light as an interesting academic point. This link works out Stanford to Boston at ~40ms best possible time. When this person did the calculation he decided the internet operates at about "within a factor of two of the speed of light", so there is about ~85ms transfer time.

TCP Window Size:
If you are having transfer speed issues you may need to increase the receiving window tcp size. You might also need to enable window scaling if this is a high bandwidth connection with high latency (Called a "Long Fat Pipe"). So if you are transferring a large file, you need to have a big enough receiving window to fill the pipe without having to wait for window updates. I went into some detail on how to calculate that in my answer Tuning an Elephant.

Geography and Latency:
A failing point of some CDNs (Content Distribtuion Networks) is that they equate latency and geography. Google did a lot of research with their network and found flaws in this, they published the results in the white paper Moving Beyond End-to-End Path Information to Optimize CDN Performance:

First, even though most clients are served by a geographically nearby CDN node, a sizeable fraction of clients experience latencies several tens of milliseconds higher than other clients in the same region. Second, we find that queueing delays often override the benefits of a client interacting with a nearby server.

BGP Peerings:
Also if you start to study BGP (core internet routing protocol) and how ISPs choose peerings, you will find it is often more about finances and politics, so you might not always get the 'best' route to certain geographic locations depending on your ISP. You can look at how your IP is connected to other ISPs (Autonomous Systems) using a looking glass router. You can also use a special whois service:

whois -h v4-peer.whois.cymru.com "69.59.196.212"
PEER_AS | IP               | AS Name
25899   | 69.59.196.212    | LSNET - LS Networks
32869   | 69.59.196.212    | SILVERSTAR-NET - Silver Star Telecom, LLC

It also fun to explore these as peerings with a gui tool like linkrank, it gives you a picture of the internet around you.

Best Answer

Related Solutions

How Geography Affects Network Latency

Networking – Typical Network Latency for East to West Coast USA

Related Topic