Archive | June, 2009
Bandwidth – a glossary post
Bandwidth constraints: Network capacity, or bandwidth, is the maximal number of bits a network connection or interface can carry at a given period of time. It is measured in bps (bits-per-second), Kbps, Mbps or Gbps. The greater the bandwidth, the greater the number of concurrent application sessions the link can serve (for a given transaction) and [...]
Continue reading...Jitter – a glossary post
25. June 2009
Jitter: Network jitter is the variation in the arrival rate of packets (more specifically, the inter packet gap of subsequent data packets as they arrive over a network). For most types of data applications large gap variations between arrival times (high jitter) are acceptable. For voice or video applications, relatively small jitter can cause perceptible [...]
Continue reading...Packet Loss – a glossary post
25. June 2009
Packet Loss: The term “packet loss” is used to describe the probability of dropping a packet at any point across the network link. The key reasons for packet loss across a network are: When networks get congested over a long period of time the router buffers get saturated which at some point leads to a situation [...]
Continue reading...Network Latency
25. June 2009
In the next couple of posts I will add some glossary definitions that I see repeat in reader’s questions. I will also use these as I describe some of the performance analysis insights we experience in the field. Network Latency/Network Delay One-way network latency is defined as the amount of time it takes for a [...]
Continue reading...Cisco place a bet on Video over IP
16. June 2009
By 2013, annual global IP traffic will reach two-thirds of a zettabyte, (a trillion GB), according to a new forecast of IP traffic (http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/white_paper_c11-481360_ns827_Networking_Solutions_White_Paper.html). What is driving this growth is video? Cisco forecasts that 90 percent of consumer IP traffic (which makes up the majority of total IP traffic) will be video in 2013. Cisco also predicts [...]
Continue reading...Monitoring Transactions by emulated location at runtime using VED and Vugen script – Part 1
10. June 2009
The Analysis application of LoadRunner 9.5 allows grouping transactions by emulated location. This enables users to see how each transaction performs in different locations. This is a very valuable feature but it is only available at analysis time, after the test stopped. In this post I’ll show how simple changes to the vugen scripts allow [...]
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25. June 2009