T-8110L AGERE [Agere Systems], T-8110L Datasheet - Page 140

• Manufacturer Part Number: T-8110L
• Manufacturer: AGERE [Agere Systems]

Ambassador T8110L H.100/H.110 Switch
Appendix A. Constant and Minimum Delay Connections
A.2 Delay Type Definitions
Minimum Delay—This is the most common type of switching, but has a shorter range than constant delay, and the
user must be aware of exceptions caused by interactions between the device's internal pipeline and the dual buff-
ering. The to time slot is at least 3 time slots after the from time slot, but no more than 128 time slots after the from
time slot. Exceptions exist at TS s of +1, +2, –126, and –127.
Example:
Simple summary:
Exceptions to Minimum Delay—Up until this point in the discussion, the STR s have not been discussed
because the to and from streams have been irrelevant in the switching process.
Note: The one universally disallowed connection on the device is a TS of 0 and a STR of 0. This is, of course, a
Rather than try to list the exceptions mathematically, a table is provided. The latencies in these cases may exceed
two frames due to the interaction of the intrinsic pipeline delays with the double buffering.
140
stream + time-slot switching to itself!
Using the same switching from the example above, TS(37) to TS(1), the delta is –36, so VFC is set
to 1 to effect the minimum delay (setting to 0 effects constant delay), and the resulting latency is
128 – 36 = 92 time slots. The relative positions of the end time slots are the same in both minimum and
constant delay, i.e., they both switch to TS(1)], but the actual data is delayed by an additional frame in
the constant delay case.
Forward connections, VFC = 0: L = TS (3
Reverse connections, VFC = 1: L = 128 + TS (–125
Use minimum delay for latencies of 3 to 128 time slots,
set VFC = 0 for forward connections,
set VFC = 1 for reverse connections.
–127
127
Figure 33. Constant Delay Connection Latency
0
(continued)
128
129
RESULTING LATENCY
(TIME SLOTS)
TS
127).
TS
(continued)
255
256
0).
Agere Systems Inc.
February 2004