3com 8807 사용자 가이드
16
MAC A
DDRESS
T
ABLE
M
ANAGEMENT
MAC Address Table
Management
Overview
Management
Overview
A 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 switch connected to
the device. The dynamic entries (not configured manually) are learned by the
switch. The 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 through 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.
includes the MAC address of a device and the port ID of the switch connected to
the device. The dynamic entries (not configured manually) are learned by the
switch. The 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 through 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 switch. The consequent packets destined the same MAC address can be
forwarded directly thereafter.
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 switch. The consequent packets destined the same MAC address can be
forwarded directly thereafter.
Figure 21 The switch forwards packets with MAC address table
The switch also provides the function of MAC address aging. If the switch receives
no packet for a period of time, it will delete the related entry from the MAC
address table. However, this function takes no effect on the static MAC addresses.
no packet for a period of time, it will delete the related entry from the MAC
address table. However, this function takes no effect on the static MAC addresses.
MAC Address
Port
MACA
1
MACB
1
MACC
2
MACD
2
MACD MACA
......
Port 1
MACD MACA
......
Port 2