
146
Agere Systems Inc.
Data Sheet
May 2001
and Packet Payload Engine
Ambassador T8110 PCI-Based H.100/H.110 Switch
14
Connection Control—Standard and Virtual Channel
(continued)
5-9637 (F)
Figure 48. Microprocessor Programming
—Read Virtual Channel Scratchpad Command
14.2 Switching Operation
T8110 provides two main switching operations, standard (telephony) switching and virtual channel (packet pay-
load) switching. The basic building block of switching is one-half simplex connections loaded into the connection
memory. Each connection memory location controls data flow, either from a serial stream input to a location in data
memory, or from data memory to a serial stream output. A typical telephony simplex switch connection would use
one
from
and one
to
connection, each using the same data memory location. A virtual channel switch connection
would only use one half simplex connection (
to
or
from
), plus control provided in virtual channel memory to initiate
transfers between the data memory and an external buffer in the PCI space.
14.2.1 Memory Architecture and Configuration
14.2.1.1 Connection Memory
The T8110 connection memory consists of 8192 locations, one location for each of the possible stream/time-slot
combinations, to provide a full nonblocking switch for up to 128 time slots on 32 H1x0 streams (CT_D[31:0]) and 32
local streams (L_D[31:0]). Connection memory is physically addressed by time slot (7 bits), H1x0/local select
(1 bit), and stream (5 bits).
The 8192 locations are divided into four pages of 2048, with each page dedicated to a set of 16 serial streams as
follows:
n
H1x0 even streams (CT_D[30, 28, . . . 0])
n
H1x0 odd streams (CT_D[31, 29, . . . 1])
n
Local high streams (L_D[31:16])
n
Local low streams (L_D[15:0])
A[19:0]
19:16
0001
15:8
VC IDENTIFIER ADDRESS
7
6:4
000
7:0
DATA
BYTE 0
VC PAGE ADDRESS
0 = VC EVEN PAGE
1 = VC ODD PAGE
VCPA
00000000
DATA
BYTE 2
7:0
DATA
BYTE 1
DATA
BYTE 3
7:0
SCRATCHPAD CURRENT OFFSET (SPCO)
SCRATCHPAD CURRENT DEPTH (SPCD)
3
1
2:0
000
STATIC/SCRATCHPAD SELECT
0 = STATIC ENTRIES
1 = SCRATCHPAD
SSS
7:0
00000000
VALUE OF THE COUNTER WHICH
TRACKS THE NUMBER OF BYTES
USED IN THE BUFFER
MEMORY POINTER, CURRENT
OFFSET WITHIN CHANNEL BUFFER