Traffic Analysis

Publisher

Cisco Systems

URL

https://www.cisco.com/c/en/us/td/docs/ios/solutions_docs/voip_solutions/TA_ISD.html

Published

2001-07-02

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

Cisco copyright; all rights reserved; no-redistribution; short excerpts and locators only

Source notes citing this source

• In Cisco's traffic model comparison, Engset assumes a smooth arrival pattern; EART/EARC and Neal-Wilkerson assume peaked arrivals; Poisson, Erlang B, Extended Erlang B and Erlang C assume random arrivals. in context
• Cisco's 2001 Traffic Analysis document states that in a standard business environment the busy hour carries about 15 to 20 percent of the day's traffic, and that 17 percent of daily traffic is generally used to represent the peak hour. in context
• One CCS (centum call second) is 100 seconds of calls on the same circuit, and 1 erlang equals 36 CCS; voice switches generally measure traffic in CCS. in context
• Cisco's Traffic Analysis document lists the Erlang B assumptions as an infinite number of sources, a random traffic arrival pattern, blocked calls cleared, and exponentially distributed hold times. in context
• Cisco's Traffic Analysis document says the Erlang C model is more commonly used for conservative automatic call distributor (ACD) design, to find the number of agents needed. in context
• Cisco's Traffic Analysis document lists the Erlang C assumptions as an infinite number of sources, a random traffic arrival pattern, blocked calls delayed, and exponentially distributed hold times. in context
• Worked example: an outbound trunk group offered 17 erlangs in the busy hour and designed for under 1% blockage needs 27 circuits, which gives a grade of service of 0.64 percent. in context
• Cisco's Extended Erlang B example assumes that 50 percent of blocked users retry immediately. Extended Erlang B is Erlang B with blocked calls retried instead of lost. in context
• In Cisco's traffic model comparison, all of Poisson, Erlang B, Extended Erlang B, Erlang C, EART/EARC and Neal-Wilkerson assume infinite sources and Engset assumes finite sources. Blocked calls are held (Poisson), cleared (Erlang B, Engset, EART/EARC), retried (Extended Erlang B) or delayed (Erlang C). in context
• For peaked call arrival patterns, Cisco suggests rollover trunk groups in some cases but says that in general enough resources must be allocated to handle the peak traffic. in context

Cite this source record

APA

WarmTransfer. (2001, July 2). Traffic Analysis. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-ios-voip-traffic-analysis

BibTeX

@misc{warmtransfer-cisco-ios-voip-traffic-analysis,
  title  = {Traffic Analysis},
  author = {{WarmTransfer}},
  year   = {2001},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-ios-voip-traffic-analysis},
  note   = {Cisco Systems, accessed 2026-09-25}
}