Chapter 2 Mac Address Table Management; Mac Address Table Management Overview - Huawei Quidway S3000-EI Series Operation Manual

Operation Manual - System Management
Quidway S3000-EI Series Ethernet Switches

Chapter 2 MAC Address Table Management

2.1 MAC Address Table Management Overview

An Ethernet Switch maintains a MAC address table for fast forwarding packets. A table
entry includes the MAC address of a device and the port ID of the Ethernet switch
connected to it. The dynamic entries (not configured manually) are learned by the
Ethernet switch. The Ethernet switch learns a MAC address in the following way: after
receiving a data frame from a port (assumed as port A), the switch analyzes its source
MAC address (assumed as MAC_SOURCE) and considers that the packets destined
at MAC_SOURCE can be forwarded via the port A. If the MAC address table contains
the MAC_SOURCE, the switch will update the corresponding entry, otherwise, it will
add the new MAC address (and the corresponding forwarding port) as a new entry to
the table.
The system forwards the packets whose destination addresses can be found in the
MAC address table directly through the hardware and broadcasts those packets whose
addresses are not contained in the table. The network device will respond after
receiving a broadcast packet and the response contains the MAC address of the device,
which will then be learned and added into the MAC address table by the Ethernet
switch. The consequent packets destined the same MAC address can be forwarded
directly thereafter. If the MAC address cannot be found even after broadcasting the
packet, the switch will drop it and notify the transmitter that the packet can not arrive at
the destination.
MACD MACA
Figure 2-1 The Ethernet switch forwards packets with MAC address table
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Huawei Technologies Proprietary
Chapter 2 MAC Address Table Management
MAC Address Port
MACA
MACB
MACC
MACD
MACD MACA ......
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