Alcatel Carrier Internetworking Solutions 6648 - Manual (Page 340)

The Fabric Architecture
page -16 OmniSwitch Troubleshooting Guide September 2005
The Fabric Architecture
ASIC provides the switching fabric functionality for the OmniSwitch Series. The switching fabric does no
frame processing and does not distinguish between L2 switching and L3 routing. The fabric provides only
a limited amount of FIFO buffering for each port, flood and the multicast queue. Most of the system buff-
ering is in the Ingress Coronado’s Queue Manager. The backplane fabric is a bit-sliced ASIC. Each chip
contains a control element and data buffering and queuing logic. All fabrics in the primary fabric operate
in a lock step under control of the “master” fabric. The fabric provides one unicast queue for each physi-
cal port on the OmniSwitch Series plus broadcast and multicast queues and, inter-processor communica-
tion queues. Switching Fabric monitors the depth of its on-chip queues and provides flow control feedback
to the Coronado ASICs. Switching fabric also generates control messages for each of four priorities to
drive the Coronado bandwidth control. The backplane is wired like a wagon wheel where the fabric card is
the “hub” and the point-to-point backplane connections are the spokes. Each network interface card (NI) is
at the end of a spoke. Each NI is connected to the redundant fabric by an identical but separate set of
connections. For redundancy, each NI slot is wired to both fabric cards by separate traces.
OS7XXX and OS8800 use different Fabric ASICs for the backplane connectivity between all the slots:
• OS-7XXX uses Nantucket ASIC
• OS-8800 uses ROMA ASIC