Intel NETWORK PROCESSOR IXP2800 - Manual (Page 246)

246 Hardware Reference Manual
Intel
®
IXP2800 Network Processor
Media and Switch Fabric Interface
8.1.2 CSIX
CSIX_L1 (Common Switch Interface) defines an interface between a Traffic Manager (TM) and a
Switch Fabric (SF) for ATM, IP, MPLS, Ethernet, and similar data communications applications.
The Network Processor Forum (NPF) www.npforum.org, controls the CSIX_L1 specification.
The basic unit of information transferred between TMs and SFs is called a CFrame. There are a
number of CFrame types defined as shown in Table 85 .
For transmission from the IXP2800 Network Processor, CFrames are constructed for transmission
under Microengine software control, and written into the Transmit Buffer (TBUF).
On receive to the IXP2800 Network Processor, CFrames are either discarded, placed into Receive
Buffer (RBUF), or placed into Flow Control Egress FIFO (FCEFIFO), according to mapping
defined in the CSIX_Type_Map CSR. CFrames put into RBUF are passed to a Microengine to be
parsed by software. CFrames put into FCEFIFO are sent to the Ingress IXP2800 Network
Processor over the Flow Control bus. Link-level Flow Control information (CSIX Ready field) in
the Base Header of all CFrames (including Idle) is handled by hardware.
8.1.3 CSIX/SPI-4 Interleave Mode
SPI-4 packets and CSIX CFrames are interleaved when the RBUF and TBUF are configured in
3-partition mode. When the protocol signal RPROT or TPROT is high, the data bus is transferring
CSIX CFRAMES or IDLE cycles. When protocol is low, the data bus is transferring SPI-4 packets
or idle cycles. When operating in interleave mode, RPROT must be driven high (logic 1) for the
entire CSIX CFRAME or low (logic 0) for the entire SPI-4 burst. When in 3-partition mode, the
SPI-4 interval should be padded using SPI-4 idle cycles so that it ends on a 32-bit boundary or a
complete RCLK or TCLK clock cycle. The actual SPI-4 data length can be any size. However, the
SPI-4 interval, which includes the SPI-4 control words and payload data, must end on a 32-bit
boundary.
Table 85. CFrame Types
Type Encoding CFrame Type
0 Idle
1 Unicast
2 Multicast Mask
3 Multicast ID
4 Multicast Binary Copy
5 Broadcast
6 Flow Control
7 Command and Status
8-F CSIX Reserved