T-8110L AGERE [Agere Systems], T-8110L Datasheet - Page 117

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

February 2004
Agere Systems Inc.
12 Connection Control
12.2 Switching Operation
12.2.2 Standard Switching
Standard telephony switching is achieved by loading control fields into the connection memory for one-half simplex
connections (refer to Figure 22 on page 114, and Section 12.2.1.1 on page 115).
12.2.2.1 Constant Delay and Minimum Delay Connections
The VFC control bit in connection memory determines which of two data pages is accessed, when the data mem-
ory is configured to double-buffering for telephony connections (refer to Figure 23). This bit always affects to con-
nections (read the data memory, send it out to a serial stream output) in a double-buffer configuration. This bit can
control a from connection in a double-buffer configuration, only if it is a subrate connection; otherwise, the VFC bit
has no bearing on from connections.
The double-buffering configuration creates two data pages. During a particular frame (125 s time boundary, parti-
tioned into time slots), one page is the active page, the other is the inactive page. The active/inactive page status
toggles at every frame boundary. For all from connections (except for subrate connections), incoming serial data is
always written to the active page. For all to connections, the VFC control bit indicates whether to read from the
active or inactive page. Manipulation of this bit affects the latency between the incoming from data and the outgo-
ing to data. This latency defines whether or not a connection is constant delay or minimum delay.
Please see Appendix A on page 139 for more details on constant and minimum delay connections.
12.2.2.2 Pattern Mode
The PME control bit in connection memory affects only to connections. Instead of reading a value out of the data
memory for subsequent output to a serial stream, the lower 8 bits of the TAG field provide a byte pattern for the
serial output.
12.2.2.3 Subrate
The subrate control bit field in connection memory is used only by from connections and controls how individual
bits or groups of bits of an incoming serial byte are shuffled prior to writing them to the data memory, in order to
achieve subrate switching.
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Ambassador T8110L H.100/H.110 Switch
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