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Product Description
Ethernet Switching
Store-and-forward
Cut-through
Bridging
Bridge Address
Table
6
There are two popular methods to forward information: store-and-forward
and cut-through. Although your switch employs store-and-forward as the
default, you can also choose cut-through.
Store-and-forward means that your switch stores the entire packet and then
forwards it.
Store-and-forward switching, performed at the MAC layer, allows your
switch to temporarily store packets until network resources, typically a
congested port, are available. Frames which are incorrect, an invalid CRC for
example, are discarded. Store-and-forward switching, therefore, ensures data
integrity, thus preventing network error conditions from being generated
throughout the network.
Store-and-forward mode is implemented when packets are converted to cells
on each ATM transmission.
In a cut-through system, the device starts to forward the incoming packet
while the packet is still being received on the inbound link.
Cut-through switching requires software that can both look at the start of the
packet and determine which outbound link is to be used to forward the
packet. Cut-through does not check for errors before forwarding a packet.
Your switch operates as a transparent bridge to the Ethernet ports. As such,
it learns the source Media Access Control (MAC) addresses of all incoming
packets and ages out devices which have not been heard for a user or default
specified period of time.
The switch maintains a forwarding table with a maximum storage capacity of
2,048 MAC address. These Ethernet addresses are associated with all of the
devices that have been detected recently.
Your switch checks all incoming packets from each port for their destination
address against a Bridge Address Table. If a packet's destination address is
not on the same network segment as the originating packet, the switch
forwards the packet to the network segment associated with that destination
address. However, if the packet's source and destination address are on the
same network segment, known as local traffic, the packet is automatically
discarded (ignored) or filtered.
The switch creates and maintains a dynamic database of addresses which are
stored in a Bridge Address Table. Port information entries in the Bridge
Address Table are, in turn, used as a basis from which to compare and
examine every packet to determine its source address, segment origin and
port information.
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