Huawei CX600-8 Hardware Description page 111

HUAWEI CX600-8/16/X3/X8/X16 Metro Service Platform
Hardware Description
4.4.1 Introduction to the Switching Network
This section describes the principle of the SFU.
The switching network responsible for switching data between LPUs is a key component of the
CX600. The CX600 uses the switching chips developed by Huawei and Memory-Crossbar-
Memory (M-C-M) to provide a three-level switching mode. Level-1 and level-3 switching adopts
the shared-memory model and is performed on LPUs; level-2 switching adopts the Crossbar
model and is performed on an SFU.
The level-1 switching chip on one LPU is fully connected to all the level-2 switching chips on
the SFUs. The level-2 switching chips on the SFUs are also fully connected to the level-3
switching chip on another LPU. In addition, the level-2 crossbar switching chips work in load
balancing mode across multiple switching planes. The entire switching network is unblocked.
The following describes how data packets are transmitted across the switching network.
1.
2.
3.
Issue 03 (2013-11-30)
NOTE
The 200G switch fabric unit cannot be used together with 40G switch fabric unit for long-term working,
and can be used together only for short-term operation during upgrade.
Data packets enter the LPU through physical interfaces and are fragmented into cells of a
fixed length. These cells are then sent to the level-1 switching chips. After being buffered
and scheduled, the cells enter the crossbar switching chips on the SFU. The level-1
switching chip on the LPU is fully connected to all of the level-2 switching chips on SFUs.
As a result, the same number of cells can be distributed to each level-2 switching plane.
This implements load balancing across switching planes and facilitates fault tolerance.
After the cells reach the crossbar switching chips, the crossbar switching chips schedule
the cells to the corresponding outbound interfaces according to the destination interfaces
of the data packets. The cells are then sent to the level-3 switching chips on another LPU.
At this point, the switching of the cells by the level-2 switching chips is completed.
After the cells reach the level-3 switching chips on another LPU, the system searches for
the destination interfaces. Once found, the cells are reassembled and sent out through
physical interfaces. At this point, the switching of the data packets is completed.
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Figure 4-15 shows the switching network of the CX600.
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