Payload size

For DS3, E3, DS1, and E1 circuit emulation, the payload size can be configurable in number of octets. The default values for this parameter are shown in Table: Unstructured payload defaults. Unstructured payload sizes can be set to a multiple of 32 octets and minimally be 64 octets. TDM satellite supports only unstructured payloads.

Table: Unstructured payload defaults
TDM circuit Default payload size

DS1

192 octets

E1

256 octets

For N*64 kb/s circuits, the number of octets or DS1/E1 frames to be included in the TDM payload needs to be configurable in the range 4 to 128 DS1/E1 frames in increments of 1 or the payload size in octets. The default number of frames is shown in Table: Structured number of default frames with associated packet sizes. For the number of 64 kb/s channels included (N), the following number of default frames apply for no CAS: n=1, 64 frames; 2≤N≤ 4, 32 frames; 5≤N≤ 15, 16 frames; N≥16, 8 frames.

For CAS circuits, the number of frames can be 24 for DS1 and 16 for E1, which yields a payload size of N*24 octets for T1 and N*16 octets for E1. For CAS, the signaling portion is an additional ((N+1)/2) bytes, where N is the number of channels. The additional signaling bytes are not included in the TDM payload size, although they are included in the actual packet size shown in Table: Structured number of default frames.

The full ABCD signaling value can be derived before the packet is sent. This occurs for every 24 frames for DS1 ESF and every 16 frames for E1. For DS1 SF, ABAB signaling is actually sent because SF framing only supports AB signaling every 12 frames.

Table: Structured number of default frames
Num timeslots No CAS DS1 CAS E1 CAS
num-frames default Default payload Minimum payload Payload (24 frames) Packet size Payload (16 frames) Packet size

1

64

64

40

24

25

16

17

2

32

64

64

48

49

32

33

3

32

96

96

72

74

48

50

4

32

128

128

96

98

64

66

5

16

80

80

120

123

80

83

6

16

96

96

144

147

96

99

7

16

112

112

168

172

112

116

8

16

128

128

192

196

128

132

9

16

144

144

216

221

144

149

10

16

160

160

240

245

160

165

11

16

176

176

264

270

176

182

12

16

192

192

288

294

192

198

13

16

208

208

312

319

208

215

14

16

224

224

336

343

224

231

15

16

240

240

360

368

240

248

16

8

128

128

384

392

256

264

17

8

136

136

408

417

272

281

18

8

144

144

432

441

288

297

19

8

152

152

456

466

304

314

20

8

160

160

480

490

320

330

21

8

168

168

504

515

336

347

22

8

176

176

528

539

352

363

23

8

184

184

552

564

368

380

24

8

192

192

576

588

384

396

25

8

200

200

400

413

26

8

208

208

416

429

27

8

216

216

432

446

28

8

224

224

448

462

29

8

232

232

464

479

30

8

240

240

480

495

31

8

248

248

Note: The num-frames DS1 CAS are multiples of 24; num-frames E1 is a multiple of 16.