PM8610-BIAP PMC [PMC-Sierra, Inc], PM8610-BIAP Datasheet - Page 67

• Manufacturer Part Number: PM8610-BIAP
• Description: SBS Telecom Standard Product Data Sheet Preliminary
• Manufacturer: PMC [PMC-Sierra, Inc]

10.1.9
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000168, Issue 3
Because the E3 tributary rate is less than the rate of the grey region, padding octets are
interleaved with the E3 tributary to make up the difference in rate. Interleaved with every E3
frame is an alternating pattern of 81 and 82 stuff octets, one of which is the V5 octet. These 81 or
82 stuff octets are spread evenly across the E3 frame. Each E3 subframe is 48 octet which is
further broken into 4 equal blocks of 12 octets each. Table 16 shows the alternating E3 frame
stuffing format that is packed into the grey region of Table 15. Note that there are 6 stuff octets
after the V5 octet in one frame and 5 stuff octets after the V5 octet in the next frame. In this table
V5 indicates the V5 octet which is also a stuff octet, R indicates a stuff octet, D indicates an E3
data octet, FAS indicates the first byte of the 10 bit E3 Frame Alignment Signal.
Table 16 E3 Frame Stuffing Format
E3 asynchronous timing is compensated via the H3 octet as described in Section 10.1.2. E3 link
rate adjustments are optionally passed across the SBI via the Linkrate octet as described in
section 10.1.3. E3 alarm conditions are optionally passed across the SBI bus via the Linkrate octet
as described in section 10.1.3 and 10.1.4.
VT1.5 and TU11 virtual tributaries, TVT1.5s, are transported across the SBI bus in a similar
manner to the T1 tributary mapping. Table 17 shows the transparent structure where “I” is used to
indicate information bytes. There are two options when carrying virtual tributaries on the SBI
bus, the primary difference being how the floating V5 payload is located.
The first option is locked TVT mode which carries the entire VT1.5/TU11 virtual tributary
indicated by the shaded region in Table 17. Locked is used to indicate that the location of the
V1,V2 pointer is locked. The virtual tributary must have a valid V1,V2 pointer to locate the V5
payload. In this mode the V5 indicator and payload signals, IV5, OV5, IPL and OPL, may be
generated but must be ignored by the receiving device. In locked mode timing is always sourced
by the transmitting side, therefore justification requests are not used and the JUST_REQ signal is
ignored. Other than the V1 and V2 octets which must carry valid pointers, all octets can carry
data in any format. The location of the V1,V2,V3 and V4 octets is fixed to the locations shown in
Table 17.
V5
V5
Transparent VT1.5/TU11 Mapping
6*R
5*R
5*R
5*R
5*R
5*R
5*R
5*R
FAS
FAS
FAS
FAS
FAS
FAS
FAS
FAS
11*D
11*D
11*D
11*D
11*D
11*D
11*D
11*D
5*R
5*R
5*R
5*R
5*R
5*R
5*R
5*R
12*D
12*D
12*D
12*D
12*D
12*D
12*D
12*D
5*R
5*R
5*R
5*R
5*R
5*R
5*R
5*R
12*D
12*D
12*D
12*D
12*D
12*D
12*D
12*D
SBS Telecom Standard Product Data Sheet
5*R
5*R
5*R
5*R
5*R
5*R
5*R
5*R
12*D
12*D
12*D
12*D
12*D
12*D
12*D
12*D
Preliminary
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