Mitel SX-200 DIGITAL Pabx Engineering Information Manual
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Engineering Information 13. TRAFFIC CONSIDERATIONS a General 13.01 This Part specifies the SX-ZOO@ DIGITAL PABX traffic char- acteristics. Information includes: l Busy Hour Call Attempt (BHCA) l System Traffic Capacity e Grade of Service l Receiver Provisioning l Trunk Distribution. Traffic specifications shown here assume a typical fully configured system as shown in Table 13-1, unless otherwise stated. Page 13-1
Engineering information Page 13-2 TABLE 13-1 TYPICAL CONFIGURED SYSTEM QUANTITIES Category 480-Port Configuration Lines 350 Trunks 54 Cabinets 2 Peripheral Bays: Digital - 2 Analog - 3 Busy Hour Call Attempt (BHCA) 13.02 The BHCA should not exceed the limits specified in Table 13-2. TABLE 13-2 BUSY HOUR CALL ATTEMPTS Traffic Capacity 13.03 The .SX-200m DIGITAL PABX traffic capacity is outlined in Table 13-3. TABLE 13-3 SX-200@ DIGITAL PABX TRAFFIC CAPACITY (Both Way Traffic) System/Port Calls/Hour Erlang CC% per Port 5.59 0.19 6.83 System 1956.50 66.50 2390.5
Engineering information Grade of Service 13.04 The SX-200@ DIGITAL PABX Grade of Service (GOS) (in terms of blocking) is outlined in Table 13-4. TABLE 13-4 SX-200@ DIGITAL PABX GRADE OF SERVICE (GOS) I Link/Resource Blocking Blocking Probability Link Blocking: Peripheral to Network Network to Network Resource Blocking Software DTMF Receivers, Trunks < 0.1% 0.0% < 0.01% provisioning dependent Receiver Provisioning . 13.05 The number of receivers required to be installed in the PABX is dependent on various factors, such as the number of lines and trunks installed, the amount of traffic flow estimated for the system and the desired grade of service. In order to arrive at the quantity of receivers required the following assumptions were made: l Average receiver holding time for intercomcall is 6 seconds 0 Average receiver holding time for a trunk call is 17.4 seconds 0 Holding time for receivers is exponential 0 Call originations are Poisson l Call holding times are exponential e Receivers are provisioned in multiples of 4. 13.06 For a given load (heavy, medium and light traffic), the minimum number of required receivers was determined for the following grades of service (ABSBH): 9 ABSBH = 98.5 - 98.5 % of all receiver requests serviced within 3 seconds. a ABSBH = 99.5 - 99.5 % of all receiver requests serviced within 3 seconds. 13.07 The following calculations are used to generate Tables 13-5 through 13-7: Receiver Holding Time ( h ) = 6 x (% intercom traffic) + 17.4 x (% trunk traffic) Seconds Page 13-3
Engineering Information Receiver Traffic (A) = (Originating Calls per hour) x (Receiver holding time (set)) Erlangs 3600 Multiple of holding time (t) = 3 h (~1 Probability of of delay greater than t (P(X)) = 1 - ABSBH/lOO Using Erlang C formula delay curves, knowing t, A, P(X), the minimum number of receivers can be obtained. Trunk Distribution 13.03 Since the digital bays are non-blocking, while the analog bays are blocking, as many trunks as possible should be distributed in the digital bays. Analog type trunks should be evenly distributed throughout the analog bays. For example, a fully configured system in a heavy traffic environment might have four to five trunk cards in each of the anlog bays. Page 13-4
Engineering Information TABLE 13-5 HEAVY TRAFFIC - out CCS 140 176 216 254 292 329 365 402 439 476 511 547 563 619 655 691 - OUt ccs 76 97 118 138 159 179 199 220 240 259 279 298 318 337 357 377 395 415 - ntre :ei1s 77 106 136 187 188 229 281 292 324 356 388 420 542 483 516 547 - Drig falls xiii 238 296 356 414 473 533 591 651 717 770 829 888 946 1007 1065 In rrks 11 12 14 16 17 19 20 21 23 24 25 27 28 29 a? 32 - Out wsy Trks rrks -ii- 16 11 19 13 228 14 25 15 28 17 30 18 33 20 36 21 38 22 41 23 43 25 46 26 48 27 51 28 53 30 55 lo. hoe 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 zcs/ Line 5.94 5.77 5.67 5.60 5.55 5.51 5.48 5.46 5.44 5.43 5.41 5.40 5.39 6.38 5.38 5.37 - lntra ccs - 67 93 120 149 177 207 237 267 298 330 362 394 428 459 493 526 I In L3lls -iT 108 131 153 174 196 217 238 258 279 299 319 338 357 376 395 - :ak OUt MIS 103 132 160 189 216 244 272 299 327 355 382 409 436 463 491 518 TDtel ccs - 356 462 567 672 777‘ 882 986 1092 1197 1303 1407 1512 1617 1722 1829 1933 dc”S - 150 190 230 269 306 346 364 422 460 497 534 570 607 643 680 716 - Receivers Required for ABSSH = 98.5% Receivers Required for ABSSH = 99.5% 4 4 4 8 8 8 8 8 8 8 ii 8 8 8 8 8 8 8 8 8 8 8 8 R 8 12 8 12 12 12 12 12 TABLE 13-6 MEDIUM TRAFFIC Orig MIS 98 130 161 194 126 258 290 323 355 387 220 452 464 512 548 581 612 644 In Trks 7 8 9 10 11 12 13 14 15 16 16 17 18 19 19 20 21 22 - Out !Wey Frks Trks 6 11 8 13 8 14 9 16 10 18 11 19 12 21 13 22 13 24 14 25 15 27 16 26 16 30 17 31 18 32 19 34 19 35 20 36 ccs/ rotal Line ccs 3.23 i&i 3.14 251 3.09 309 3.05 366 3.02 423 3.00 480 2.99 536 2.98 596 2.87 653 2.96 710 2.95 767 2.94 623 2.94 882 2.93 938 2.93 996 2.93 1055 2.92 1110 2.92 1166 Out 3alls - 56 72 87 103 118 133 148 163 178 193 206 223 238 252 267 263 297 312 - ntra hIIS 42 58 74 91 108 125 142 160 177 194 212 229 246 263 281 298 315 332 - IO. of snes - 60 80 100 120 140 160 180 200 220 240 260 260 300 320 340 360 360 400 d& ntra CCS 37 51 66 81 96 113 129 146 163 180 197 214 233 250 269 287 305 324 Receivers Required Receivers Required for ASSSH = 98.5% for ASSBH = 99.5% 81 103 125 147 168 188 210 230 251 271 291 311 331 350 371 391 409 429 46 59 71 83 95 109 118 130 141 152 163 174 185 195 205 215 225 235 4 4 4 4 4 4 4 4 4 4 4 8 4 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 B 8 8 8 8 8 8 Page 13L5
Engineering information TABLE 13-7 LIGHT TRAFFIC IO. of ccw IO. of ccw Total Total .ines .ines LhW LhW cc5 cc5 2s d& out out lntra lntra ccs cek cs: ccs cek cs: lntre lntre Orig In Orig In out out PWay PWay CCS ccs CdlS Calls Cells Cells Receivers Required Receivers Required Trks Trks Trks Trks Trks Trks Receivers Required Receivers Required for A6SBH = 98.5% for A6SBH = 98.5% for ABSBH = 99.5% for ABSBH = 99.5% 60 60 1.41 1.41 a5 65 36 36 33 33 16 16 20 20 24 24 16 16 42 42 5 5 4 4 7 7 4 4 4 4 a0 80 1.41 1.41 113 113 46 46 44 44 23 23 26 26 32 32 26 26 58 59 6 6 5 5 8 8 4 4 4 4 100 100 1.41 1.41 141 141 57 57 54 54 30. 30. 33 33 40 40 34 34 74 74 6 6 5 5 9 9 4 4 4 4 120 120 1.41 1.41 169 169 69 69 64 64 37 37 38 38 47 47 42 42 69 69 7 7 6 6 .lO .lO . . 4 4 4 4 140 140 1.41 1.41 197 197 78 78 74 74 45 45 44 44 55 55 Xl 50 105 105 7 7 6 6 11 11 4 4 4 4 Page % 3-6/6
Engineering Information APPENDIX A CALL PROCESSING INFORMATION Al.01 1. - Digital Bay to Digital Bay (within bays 1 and 2) The Main Control Card (MCC) scans for on-hook/off-hook change of state. 2. 3. 4. An extension goes off-hook in Bay 1. The MCC detects the off-hook during its line card scan. MCC checks for the COS of the extension to determine if the call is allowed. 5. 6. The MCC checks for and idle receiver. The MCC connects the DTMF receiver to the line circuit through the DX matrix on a PCM channel. 7. The MCC connects the same channel to the Digital Signal Pro- cessor (DSP) to provide dial tone. 8. 9. The MCC monitors the circuit for rotary pulses. The DTMF receiver detects any DTMF tones and sends a mes- sage to the MCC indicating the value of the dialed digits. 10. On receipt of the first digit, the MCC removes the DSP from the assigned channel. 11. The MCC monitors the digits dialed and checks the idle/busy condition of the destination. 12. If the destination is idle, the MCC connects the DSP to the originator and- ringback is supplied. 13. The MCC sends the originator a cadence message to provide interruption of the ringback tone. 14. The MCC sends ringing to the Bay Power Supply from the DSP via a DX link. 15. The Bay Power Supply amplifies and routes the ringing to the destination. ‘16. The MCC sends a message to the destination to turn ringing on. 17. When the destination answers, the MCC detects the off-hook change of state. Page A-7
Engineering Infqrmation P 18. 19. 20. 2-i. 22. Al .02 1. 2. 3. 4. 5. 8. 7. 8. 9. 10. 4 1. 12. 13. 14. 15. Ringing is removed from the destination. Ringback is removed from the originator. A channel is connected between the originator and the destina- tion. The MCC scans for on-h=Woff-hook changes of state. When an on-hook is detected, the MCC removes the channel, and the call is terminated. - Analog Bay (Rotary) to Analog Bay The Scanner card scans the line circuits for on-hook/off-hook changes of state. An extension goes off-hook in Bay 3. The Scanner detects an off-hook during the line card scan. The Scanner sends an IRQ to the Peripheral Control Card (PCC). The PCC determines the originator, generates a message and passes it to the Digital Interface Card (DIC). . The DIC formats and sends a message to the MCC. The MCC checks the originator’s COS to determine if the call is allowed. The MCC checks for an idle DTMF receiver. The MCC sends a message to the PC6 to connect a junctor to the originator. The MCC assigns a channel of the link to the junctor, and conects the DTMF receiver to the channel through the DX ma- trix. The MCC connects the same channel to the DSP to provide dial tone. The PCC monitors the circuit for rotary pulses. The DTMF receiver detects any DTMF tones and sends a mes- sage to the MCC indicating the value of the tones. On receipt of the first digit, the MCC removes the DSP from the assigned channel. The MCC monitors the digits dialed and checks the idle/busy condition of the destination. Page A-2
. Engineering Information 16. If the destination is idle, the MCC connects the DSP to the originator and ringback tone is supplied. 17. The MCC sends a cadence message to the PCC of the origina- tor to provide interruption of the ringback tone. 18. 19. The MCC sends a message to the PCC to ring the destination. When the destination answers, the Scanner detects the off- hook. 20. 21. The Scanner sends an IRQ to the PCC. The PCC stops ringing and sends a message to the MCC in- dicating that the destination is off-hook. 22. 23. Ringback is removed from the originator. Since both parties are in Bay 3, the MCC sends a message to the PCC to provide a connection between the originator and the destination using a speech path. (There are no PCM channels used in this connection). 24. The Scanner scans for on-hook/off-hook changes of state. 25. When an on-hook is detected, the PCC sends a message to th.e MCC indicating that the extension(s) have gone on-hook; the call is terminated. Page A-3/3
MITEL STANDARD PRACTICE - SECTION MITL9108-093-350-NA Issue 2, September 1986 SX-200” DIGITAL PRIVATE AUTOMATIC BRANCH EXCHANGE (PABX) TROUBLESHOOTING Copyright of MiTEL Corporation 1986 TM - Trademark of MITEL Corporation @‘Registered Trademark of MiTEL Corporation i