Table of Contents

Erlang B Table

How to Use the Table

Calculating the Attendant Console Load

Traffic Engineering Tables

This appendix provides Erlang B and other tables for computing network traffic.

Erlang B Table

Table A-1 provides data for calculating the number of trunks you need, based on a target blockage level (in percent) and an Erlang value.

How to Use the Table

Complete the following steps to find the number of trunks required for a given Erlang value and a given blockage level:

Step 2   While staying in the same column, find the row with the desired Erlang value (round the Erlang value as necessary).

Step 3   Find the number of trunks in the selected row.

Note   For a description of Erlangs and other units of measurement used in traffic engineering, see "Traffic Engineering."

Table A-1: Erlang B Carried Traffic Capacity Table

Number of	Blockage Levels (%)
of Trunks	0.01	0.05	0.10	0.50	1.00	2.00	5.00	10.00	15.00	20.00
1	0.00	0.00	0.00	0.01	0.01	0.02	0.05	0.10	0.15	0.20
2	0.01	0.03	0.05	0.10	0.15	0.22	0.36	0.54	0.68	0.80
3	0.09	0.15	0.19	0.35	0.45	0.59	0.85	1.14	1.36	1.54
4	0.23	0.36	0.44	0.70	0.86	1.07	1.45	1.84	2.12	2.36
5	0.45	0.65	0.76	1.13	1.35	1.62	2.11	2.59	2.94	3.21
6	0.73	1.00	1.14	1.61	1.89	2.23	2.81	3.38	3.78	4.09
7	1.05	1.39	1.58	2.15	2.48	2.88	3.55	4.20	4.64	4.98
8	1.42	1.83	2.05	2.72	3.10	3.55	4.32	5.04	5.52	5.90
9	1.83	2.30	2.55	3.32	3.74	4.26	5.10	5.89	6.42	6.82
10	2.26	2.80	3.09	3.94	4.42	4.98	5.91	6.76	7.32	7.75
11	2.72	3.33	3.65	4.59	5.11	5.72	6.72	7.64	8.24	8.69
12	3.21	3.88	4.23	5.25	5.82	6.48	7.55	8.53	9.16	9.63
13	3.71	4.44	4.83	5.93	6.54	7.25	8.39	9.42	10.09	10.58
14	4.24	5.03	5.44	6.63	7.28	8.04	9.24	10.33	11.02	11.53
15	4.78	5.63	6.07	7.34	8.03	8.83	10.10	11.24	11.96	12.49
16	5.34	6.25	6.71	8.06	8.79	9.63	10.97	12.15	12.90	13.44
17	5.91	6.87	7.37	8.79	9.56	10.44	11.84	13.07	13.85	14.41
18	6.49	7.51	8.04	9.53	10.33	11.26	12.72	13.99	14.79	15.37
19	7.09	8.17	8.72	10.28	11.12	12.09	13.60	14.92	15.75	16.34
20	7.70	8.83	9.40	11.04	11.91	12.92	14.49	15.86	16.70	17.30
21	8.32	9.50	10.10	11.80	12.71	13.76	15.38	16.79	17.66	18.28
22	8.95	10.18	10.80	12.57	13.51	14.60	16.28	17.72	18.62	19.25
23	9.58	10.86	11.51	13.35	14.32	15.45	17.18	18.66	19.58	20.22
24	10.23	11.56	12.23	14.13	15.14	16.30	18.08	19.61	20.54	21.20
25	10.88	12.26	12.96	14.92	15.96	17.15	18.99	20.55	21.50	22.17
26	11.54	12.97	13.69	15.72	16.79	18.02	19.90	21.50	22.47	23.15
27	12.21	13.68	14.42	16.52	17.62	18.88	20.81	22.45	23.43	24.13
28	12.88	14.40	15.17	17.32	18.45	19.75	21.72	23.40	24.40	25.11
29	13.56	15.13	15.91	18.13	19.29	20.62	22.64	24.35	25.37	26.09
30	14.24	15.86	16.67	18.94	20.13	21.49	23.56	25.30	26.34	27.07
31	14.94	16.59	17.42	19.75	20.98	22.37	24.48	26.26	27.32	28.05
32	15.63	17.33	18.19	20.57	21.83	23.25	25.41	27.21	28.29	29.03
33	16.33	18.08	18.95	21.40	22.68	24.13	26.33	28.17	29.26	30.01
34	17.04	18.83	19.72	22.22	23.54	25.02	27.26	29.13	30.24	31.00
35	17.75	19.58	20.50	23.05	24.39	25.91	28.19	30.09	31.22	31.98
36	18.47	20.34	21.27	23.89	25.25	26.80	29.12	31.05	32.19	32.96
37	19.19	21.10	22.06	24.72	26.12	27.69	30.06	32.02	33.17	33.95
38	19.91	21.86	22.84	25.56	26.98	28.58	30.99	32.98	34.15	34.93
39	20.64	22.63	23.63	26.40	27.85	29.48	31.93	33.94	35.12	35.93
40	21.37	23.40	24.42	27.24	28.72	30.38	32.86	34.91	36.10	36.92

Calculating the Attendant Console Load

Table A-2 provides data for provisioning a set number of attendant consoles (phones used by operators or receptionists to answer and forward incoming calls) based on light, medium, or heavy traffic on a set number of lines.

Table A-2: Attendant Console Requirements

Number of Lines Supported	Average Number of Attendants for Required Traffic
	Light	Medium	Heavy
100	1	1	2
200	1	2	3
240	1	2	3
300	2	2	3
400	2	3	4
500	2	3	4

Posted: Mon Oct 2 13:20:41 PDT 2000
Copyright 1989-2000©Cisco Systems Inc.