Amer Networks SS3GR24i - Manual (Page 39)

SS3GR24i/SS3GR48i Layer3 Stackable Gigabit Switch User’s Guide
tagged VLAN. If it is not, the packet will be dropped. If the ingress
port is a member of the 802.1Q VLAN, the Switch then determines
if the destination port is a member of the 802.1Q VLAN. If it is not,
the packet is dropped. If the destination port is a member of the
802.1Q VLAN, the packet is forwarded and the destination port
transmits it to its attached network segment.
If the packet is not tagged with VLAN information, the ingress
port will tag the packet with its own PVID as a VID (if the port is a
tagging port). The Switch then determines if the destination port is
a member of the same VLAN (has the same VID) as the ingress
port. If it does not, the packet is dropped. If it has the same VID,
the packet is forwarded and the destination port transmits it on its
attached network segment.
This process is referred to as ingress filtering and is used to
conserve bandwidth within the Switch by dropping packets that
are not on the same VLAN as the ingress port at the point of
reception . This eliminates the subsequent processing of packets
that will just be dropped by the destination port.
TCP/IP
The TCP/IP protocol suite is a set of protocols that allow computers
to share resources across a network. TCP and IP are only two of
the Internet suite of protocols, but they are the best known and it
has become common to refer the entire family of Internet protocols
as TCP/IP.
TCP/IP is a layered set of protocols. An example, such as sending e-
mail, can illustrate this. There is first a protocol for sending and
receiving e-mail. This protocol defines a set of commands to
identify the sender, the recipient, and the content of the e-mail.
The e-mail protocol will not handle the actual communication
between the two computers, this is done by TCP/IP. TCP/IP
handles the actual sending and receiving of the packets that make
up the e-mail exchange.
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