92
C
HAPTER
4: P
ATH
B
UILDER
S600 M
ODULE
AND
A
PPLICATION
O
VERVIEW
Figure 55
DS1 Unstructured Tunneling
Use unstructured services when DS0 midspan access is not required and end to
end DS1 service is required, for example to provide CSU or DSU end to end
connectivity. The encapsulation of unstructured DS1 occupies DS1 bandwidth on
the VCC and uses AAL 1 SAR, as shown in Figure 56.
Figure 56
AAL1 Structured DS1
ATM Network
Data
Service
Unit
Channel
Service
Unit
Data
Service
Unit
Channel
Service
Unit
T1
Unstructured
DS1 Signal Tunneled Through a PVC
PathBuilder S600
PathBuilder S600
FEC for SN/CSI
Lost Cell
Detection
Clock Recovery
A/D Converter
AAL Layer
ATM Layer
47 Bytes
1 Bit
3 Bits 4 Bits
CSI
SN
SNP
SAR-SDU
ATM Header
AAL 1 Data
5 Bytes
48 Bytes
CSI - Convergence Sublayer Indicator
FEC - Forward Error Correction
SNP - Sequence Number Protection
SN - Sequence Number
SAR - SDU - Segmentation and Reassembly Service Data Unit
VCC - V irtual Channel Connection
DS0
DS0 BLANK A & B
Signaling
Structured DS1
DS1 Frame
Unstructured DS1
SAR
AAL 1
VCC
Summary of Contents for 3C63100-AC-C - PathBuilder S600...
Page 8: ...INDEX 3COM CORPORATION LIMITED WARRANTY ...
Page 14: ...xiv CHAPTER SUPPLEMENTARY REGULATORY INFORMATION ...
Page 18: ...18 ABOUT THIS GUIDE ...
Page 28: ...28 CHAPTER 1 SYSTEM DESCRIPTION ...
Page 74: ...74 CHAPTER 3 GETTING STARTED ...
Page 230: ...230 INDEX ...