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Hardware Reference Manual 303
Intel
®
IXP2800 Network Processor
Media and Switch Fabric Interface
8.9.4 CSIX-L1 Protocol Support
8.9.4.1 CSIX-L1 Interface Reference Model: Traffic Manager and Fabric
Interface Chip
The CSIX-L1 protocol operates between a Traffic Manger and a Fabric Interface Chip(s) across a
full-duplex interface. It supports mechanisms to interface to a fabric that avoid congestion using
virtual output queue (VOQ) flow control and enables a fabric that offers lossless, non-blocking
transfer of data from ingress port to egress ports. Both data and control information pass over the
receiver and transmitter interfaces.
The Traffic Manger on fabric ingress is responsible for segmentation of packet data and scheduling
the transmission of data segments into the fabric. The fabric on ingress is responsible for
influencing the scheduling of data transmission through link-level flow control and Virtual Output
Queue (VOQ) flow control so that the fabric does not experience blocking or data loss due to
congestion. The fabric on egress is responsible for scheduling the transfer of data to the Traffic
Manager according to the flow control indications from the Traffic Manager.
The CSIX-L1 protocol supports addressing up to 4096 fabric ports and identifies up to 256 classes
of unicast traffic. It optionally supports multicast and broadcast traffic, supporting identification of
up to 256 queues of such traffic. Virtual output queue flow control is supported at the ingress to the
fabric and the egress from the fabric.
The standard CSIX-L1 interface supports interface widths of 32, 64, 94, and 128 bits. A single
clocked transfer of information across the interface is called a CWord. The CWord size is the width
of the interface.
Figure 113. CSIX-L1 Interface Reference Model with Receiver and Transmitter Labels
Corresponding to Fabric Interface Chip Functions
B2751-01
Fabric
Interface
Chip(s)
Traffic
Manager
Receiver
Signals
CSIX-L1
Interface
Transmitter
Signals
Ingress
Network
Processor
Egress
Network
Processor
Printed Circuit Card