S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
Figure 17 Snapshot of DCB Buffers after addition of Link with smaller transport delay
DCB
DCB
DCB
DCB
Link 0
Link 1
Link 2
Link3
Write
Pointer 3
36
32
28
24
20
16
12
8
Write
Pointer 0
25
21
17
13
9
Write
Pointer 1
14
10
6
Write
Pointer 2
5
7
3
Group
Read
Pointer
1
2
4
Adding a link with a larger transport delay requires the DCB buffer depth to be smaller than the
DCB for the link with the largest delay. If the desired DCB depth for the new link is less than 0,
this means that the data for the other links has been played out prior to the arrival of data for the
new link. This is shown in Figure 18. For the new link to be accepted, delay must be added to
all other links in the group. When delay is added to the other links in the group, the playout of
ATM cells is halted until enough delay is built up. This causes CDV for the group. Once the
delay has been added, the DCB for the new link can be aligned with the existing links and
added to the round robin for playout. Figure 19 shows the case after delay was added to the
existing links within the group. The adding of delay to a group may be disabled. In this case, the
new link would be rejected due to a LODS defect meaning that the DCB could not be aligned
with the group.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
63
PMC [ PMC-SIERRA, INC ]
