ZXR10 2600 Product Description
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protocol process and data driving. The data forwarding is automatically completed. The
management plane processes data configuration and notifies the current operation
status. The configuration is basically completed under an interactive environment.
ZX10R 2600 series provide the layer 2 switching function, VLAN management function,
IGMP Snooping function, and QoS policy. The system has reserved interfaces for the
convenience of future development.
4.3.2
Data Processing Procedure
4.3.2.1
Data Exchange Process
For a switch, data exchange actually means forwarding data from port to port. After
receiving a data frame, the switch sends it to the proper port according to the destination
MAC address in the frame header.
The switch completely depends on an important internal data structure CAM table
(namely, the MAC address table) to select ports according to the destination MAC
address. The CAM table contains information of MAC address and port identification
(such as port ID) at least. When a packet reaches a port, the switch will check the
destination MAC address in the address table and display the destination address of the
port. If the destination address is an inbound port, the packet will be discarded or filtered
because it is addressed to the local lot. If the destination address is another port, the
packet will be forwarded to the port and queued until it is output. If the destination
address is not in the address table, the data frame will be sent to all ports other than the
source port. If the source address of the packet is not found in the address table, the
source address and the inbound port ID will be recorded to determine the subsequent
forwarding.
A layer 2 Ethernet switch exchanges data in the following three steps:
•
Address learning: The switch receives a data frame at one port and checks the
CAM table according to the source MAC address of the data frame. If the MAC
does not exist in the CAM table, the switch will add related information (including
the source port ID) of the MAC to the CAM table. In this way, address learning is
completed.
•
Forwarding decision: After address learning, the switch will search the CAM table
according to the destination MAC address of the data frame. If the MAC is found,
the switch will send the data frame to the send queue of the corresponding port
according to the search result (including the source port identification). If the MAC is
not in the address table, the switch will send the data frame to all ports other than
the source port. This process is called flooding.
•
Data forwarding: After making the forwarding decision, the switch will forward the
data frame by means of the hardware.
