3.4 Switching Network
This section describes the functions of the switch fabric unit.
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.
3.4.1 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 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 use a shared-
memory model and are performed on LPUs; level-2 switching uses a Crossbar model and is
performed on SFUs.
shows the switching network of the CX600.
The level-1 switching chip on one LPU is fully connected to the level-2 switching chips on 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
on multiple switching planes. The entire switching network is unblocked. The following
describes how data packets are transmitted across the switching network.
1.
Data packets enter an 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 an LPU is fully connected to all of the level-2 switching chips. As a
result, the same number of cells can be distributed to each level-2 switching plane. This
implements load balancing on switching planes and facilitates fault tolerance.
2.
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.
3.
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, switching of the data packets is completed.
HUAWEI CX600-8/16/X3/X8/X16 Metro Service Platform
Hardware Description
3 CX600-X16
Issue 03 (2013-11-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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