Huawei NE40E Hardware Description page 81

NE40E
Hardware Description
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The signal flow on the control plane is bidirectional.
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Issue 01 (2018-05-03)
Singling signal flow and operation and maintenance signal flow: processed by the system
management and control unit.
Clock signal flow: processed by the system clock unit.
Signal flow contains host packets carrying signals, for example, routing protocols.
− Board-to-MPU signal flow: calculates data. Therefore, a board sends these packets
to the MPU, and the management and control unit on the MPU parses these packets.
Then the MPU delivers signaling to the data plane so that they can be identified by
the data plane.
− MPU-to-board signal flow: used to update entries in forwarding tables. After the
MPU delivers parsed data to a board, the board uses the data to forward packets on
the data plane.
In the following example, routing calculation is used. A packet arrives at an interface of a
board. The network processor (NP) on the board identifies the packet that needs to be
sent to the MPU. The NP sends the packet to the MPU. The MPU calculates the packet
and delivers the destination IP address and the next-hop IP address to the routing table on
the NP. The data plane forwards the packet to the next-hop address over a route to the
destination IP address.
Operation and maintenance signal flow: Operation data includes configuration,
debugging, and query data. Maintenance data includes system-generating data, such as
logs and alarms.
− Board-to-MPU signal flow: contains maintenance signals. The system management
and control unit uses the system buses to collect maintenance information, such as
logs and alarms that are generated by modules and saves the information in an
information center. The maintenance data helps query and maintain the device.
For example, when a user wants to query active alarms, the user runs the display
alarm active command. The control plane parses this command and instructs the
information center to display all collected active alarms.
− MPU-to-board signal flow: contains operation signals. The control plane provides
software interfaces to communicate with other devices, communication interfaces to
communicate with host software, and LAN switch interfaces to communicate with
other boards and modules. These interfaces form a logical network. Operation
commands are configured on the control plane. The control plane then sorts
information based on types and priorities and sends the information through
interfaces along various channels to various modules.
For example, a user runs the power off slot 1 command to power off a board in slot
1. The control plane parses the command and delivers the command through an
outband interface to the board in slot 1.
Clock signal flow: contains synchronization Ethernet or 1588v2 (also called IEEE
Standard for a Precision Clock Synchronization Protocol for Networked Measurement
and Control Systems) signals.
− Board-to-MPU signal flow: used to obtain clock signals. An uplink board obtains
clock frequency signals from packets and sends them to the system clock unit on an
MPU. The system clock unit then selects a clock source.
− MPU-to-board signal flow: used to restore the system clock frequency and time.
After the MPU selects a clock source, it restores the synchronous system clock and
delivers it to all boards so that a device forwards packets all carrying the
synchronous signals to downstream devices through outbound interfaces.
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