---
title: "Queuing characteristics; M/D/6/10/FIFO"
subject: "Simulation and Modeling"
chapter: 4
key: "semester_8/simulation_and_modeling:queuing-characteristics-mdfifo-6"
source: https://www.bctengineer.com/q/semester_8/simulation_and_modeling/queuing-characteristics-mdfifo-6
site: BCT Engineering
---

# Queuing characteristics; M/D/6/10/FIFO

Simulation and Modeling · Chapter 4: Queuing system

- Asked in: 2070 Bhadra, 2.5+5+2.5 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/simulation_and_modeling/queuing-characteristics-mdfifo-6
- Whole chapter: https://www.bctengineer.com/md/semester_8/simulation_and_modeling/chapter-4

## Question

Mention the characteristics of a queuing system. Explain the Kendall's notation in queuing systems. What is the meaning of M/D/6/10/FIFO in queuing system?

## Short answer

Key characteristics: calling population, arrival process, service mechanism, queue discipline, system capacity, customer behavior. Kendall's notation A/B/c/K/N/Z: A=inter-arrival distribution, B=service distribution, c=servers, K=capacity, N=population, Z=discipline; defaults are infinite capacity/population and FIFO. M/D/6/10/FIFO: Poisson arrivals, constant service time, 6 servers, capacity 10, FIFO.

## Answer

#### Characteristics of a queuing system

- **Calling population**: finite or infinite source of customers.
- **Arrival process**: distribution of inter-arrival times; single or batch arrivals.
- **Service mechanism**: distribution of service times; number of servers.
- **Queue discipline**: FIFO, LIFO, SIRO or priority.
- **System capacity**: limit on the number in the system.
- **Customer behaviour**: balking, reneging, jockeying.

#### Kendall's notation

Kendall's notation writes a queue as **A/B/c/K/N/Z**, so that any queue can be named in one line.

| Symbol | Position | Meaning | Common codes |
|---|---|---|---|
| A | 1st | Inter-arrival time distribution | M (exponential), D (deterministic), Ek (Erlang), G (general) |
| B | 2nd | Service time distribution | M, D, Ek, G |
| c | 3rd | Number of parallel servers | 1, 2, 3, ... |
| K | 4th | System capacity (queue + service) | finite number or infinity |
| N | 5th | Size of calling population | finite number or infinity |
| Z | 6th | Queue discipline | FIFO, LIFO, SIRO, PRI |

Omitted fields mean infinite capacity, infinite population and FIFO. Examples:

- **M/M/1**: Poisson arrivals, exponential service, one server (single-counter shop).
- **M/M/c**: same with c parallel servers (bank with several tellers).
- **M/G/1**: Poisson arrivals, general service time, one server (CPU).
- **M/D/1**: constant service time (automatic car wash).

#### Meaning of M/D/6/10/FIFO

| Field | Meaning |
|---|---|
| M | Poisson arrivals |
| D | Constant service time |
| 6 | Six servers in parallel |
| 10 | System capacity of 10 customers (6 in service, at most 4 waiting) |
| FIFO | Customers are served in order of arrival |

Calling population is infinite since it is not stated. Example: a six-lane toll plaza where every vehicle takes a fixed time to pay, with room for only 10 vehicles in the plaza; vehicles beyond that are turned away.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which list correctly names queue characteristics?
   A. Calling population, arrival process, service mechanism, discipline, capacity, customer behaviour
   B. Voltage, current, resistance, power
   C. Compiler, linker, loader, debugger
   D. Mean, median, mode, variance only
   Answer: A. These are the standard characteristics of a queuing system. (Key point: Characteristics)

2. In A/B/c/K/N/Z, which symbol is the system capacity?
   A. A
   B. K
   C. N
   D. Z
   Answer: B. K is the 4th field, the maximum number in the system including those in service. (Key point: Kendall symbols)

3. What does D mean as a distribution code?
   A. Discrete random
   B. Delayed exponential
   C. Deterministic (constant time)
   D. Disciplined arrival
   Answer: C. D = deterministic; M = exponential; Ek = Erlang; G = general. (Key point: Distribution codes)

4. In M/D/6/10/FIFO, how many customers can be waiting at most?
   A. 10
   B. 6
   C. 16
   D. 4
   Answer: D. Capacity 10 includes 6 in service, so at most 4 wait. (Key point: M/D/6/10/FIFO)

## Related in Simulation and Modeling

- [Queuing system, characteristics, Kendall notation](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Aqueuing-characteristics-role-kendall) — Simulation and Modeling, chapter 4, asked 2×
- [Queuing model; M/D/2/60/150/FIFO meaning](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Aqueuing-model-mdpq-kendall) — Simulation and Modeling, chapter 4
- [Queuing model, Kendall, M/D/8/15/LIFO](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Aqueuing-model-mdlifo-8) — Simulation and Modeling, chapter 4
- [Queuing notation, default values, elements](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Aqueuing-notation-defaults-elements) — Simulation and Modeling, chapter 4
- [Queuing characteristics; D/M/1/LIFO/20/510](https://www.bctengineer.com/question.md?key=semester_8%2Fsimulation_and_modeling%3Aqueuing-dmlifo-application) — Simulation and Modeling, chapter 4

## Related in other subjects

- [Kendall-Lee notation for queuing systems](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Akendall-lee-notation) — Telecommunications, chapter 6, asked 2×
- [Queuing system and Kendall's notation](https://www.bctengineer.com/question.md?key=semester_8%2Ftelecommunications%3Aqueuing-system-kendall) — Telecommunications, chapter 6, asked 4×