Signal Flow On The Monitoring Plane - Huawei NE40E Hardware Description

NE40E
Hardware Description
cells using multiple switching planes, which improves the fault tolerance capability. The
switching unit sends data packets through outbound interfaces to a downlink board.
The processing of an outgoing signal flow is as follows:
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1.6.4 Signal Flow on the Monitoring Plane

The monitoring plane monitors the system environment. If a fault occurs on a unit, the
monitoring plane isolates the fault to prevent it from affecting other units on the device. The
Issue 01 (2018-05-03)
Switched network cell assembly on the downstream FIC: The downstream FIC
assembles switched network cells into packets after switched network cells flow from the
SFU to the downlink FIC.
Queuing and scheduling on the downlink TM: The downstream TM puts packets of the
signal flow in queues and schedules them based on the traffic shaping, policing,
congestion avoidance parameters. Then it sends the packets to the downstream NP.
The downlink TM also replicates multicast packets before sending them through several outbound
interfaces.
Forwarding table lookup and data layer link information query: The downlink NP
obtains data link layer encapsulation information, processes packets using a signal flow
processing module and outbound interface-specific processing modules. The processing
is as follows:
a. The downstream NP obtains data link layer encapsulation information and
encapsulates packets. The encapsulation process varies according to packet types.
For example:
 For Layer 2 802.1q-in-802.1q (QinQ) packets, the downlink NP adds a virtual
local area network (VLAN) tag to each packet.
 For MPLS packets, the downlink NP adds an MPLS label to each packet.
 For IP packets, the downlink NP searches for Address Resolution Protocol
(ARP) entries and adds MAC addresses mapped to ARP entries to the packets.
b. The flow processing module performs traffic classification and re-marks packets
based on priorities configured on outbound interfaces.
c. The downstream NP limits the rate limit at which outgoing packets are sent based
on CAR parameters configured on the outbound interface or those in the outgoing
traffic classification profile.
d. Host packets destined for the MPU are sent to an MPU, and packets to be
forwarded are sent to the outbound interface-specific processing modules.
Due to limited CPU processing capability on an MPU, the limit on packets destined for the CPU must be
configured. This prevents attack or defective packets from being sent to the MPU and causing high CPU
usage, which improves device security. The packets are verified, and only valid packets are sent to the
CPU at a specified rate, which defends against attacks on the CPU.
e. The outbound interface-specific processing module adds a Layer 2 header to each
packet and forwards the packets to the downlink PIC.
The downlink PIC converts data packets into optical and electrical signals and forwards
them through outbound interfaces connected to physical links.
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