Intel IXP2800 and IXP2850 Network Processors
Functional Units
14
Datasheet
Each channel can be expanded by depth, according to the number of port enables available. If
external decoding is used, then the number of SRAMs used is not limited by the number of port
enables generated by the SRAM controller.
Note:
External decoding may require external pipeline registers to account for the decode time,
depending on the desired frequency.
Table 2 lists the QDR Address/RPE/WPE Mapping.
Maximum SRAM system sizes are shown in
Table 3. Shaded entries require external decoding,
because they use more port enables than the SRAM controller can supply directly.
2.7
Media and Switch Fabric Interface
The Media and Switch Fabric (MSF) Interface connects the network processor to a physical layer
device (PHY) and/or a Switch Fabric Interface. The MSF consists of the following external
interfaces:
Receive and transmit interfaces, each of which can be individually configured for either the
SPI-4 Phase 2 (System Packet Interface) to a PHY or the CSIX–L1 protocol to a switch fabric.
A Flow Control Interface, which provides a point-to-point connection used primarily to pass
CSIX-L1 flow control C-Frames either between two network processors or between a network
processor and a switch fabric.
Table 2.
QDR Address/RPE/WPE Mapping
SRAM
Configuration/Size
SRAM_CONTROL
[SRAM_SIZE][9:7]
SRAM_CONTROL
[PORT_CTL][5:4]
RPE[2]/WPE[2]
RPE[3]/WPE[3]
512K x 18 - 1MB
000
11
QDR_ADDR[23:22]
QDR_ADDR[21:20]
1Mb x 18 - 2MB
001
11
QDR_ADDR[23:22]
QDR_ADDR[21:20]
2Mb x 18 - 4MB
010
11
QDR_ADDR[23:22]
QDR_ADDR[21:20]
4Mb x 18 - 8MB
011
10
QDR_ADDR[23:22]
N/A
8Mb x 18 - 16MB
100
10
QDR_ADDR[23:22]
N/A
16Mb x 18 - 32MB
101
00
N/A
32Mb x 18 - 64MB
110
00
N/A
Table 3.
Total Memory per Channel
SRAM Size
Number of SRAMs on Channel
12
345
67
8
512K x 18
1 MB
2 MB
3 MB
4 MB
5 MB
6 MB
7 MB
8 MB
1M x 18
2 MB
4 MB
6 MB
8 MB
10 MB
12 MB
14 MB
16 MB
2M x 18
4 MB
8 MB
12 MB
16 MB
20 MB
24 MB
28 MB
32 MB
4M x 18
8 MB
16 MB
24 MB
32 MB
64 MB
NA
8M x 18
16 MB
32 MB
48 MB
64 MB
NA
16M x 18
32 MB
64 MB
NA
32M x 18
64 MB
NA