3. Advanced Functions
To help a better understanding about the software management interfaces, this chapter describes some advanced functions provided by the switch.
3.1 Abbreviation
Ingress Port : Ingress port is the input port on which a packet is received.
Egress Port : Egress port is the output port from which a packet is sent out.
IEEE 802.1Q Packets : A packet which is embedded with a VLAN Tag field
VLAN Tag : In IEEE 802.1Q packet format,
#of bits | 16 | 3 | 1 | 12 |
Frame field | TPID | User priority | CFI | VID |
TPID :
User Priority :
CFI : The Canonical Format Indicator for the MAC address is a 1 bit field.
VID : VLAN identifier,
Untagged packet : A standard Ethernet frame with no VLAN Tag field
PVID (Port VID)
PVID is the default VID of an ingress port. It is often used in VLAN classification for untagged packets. It is also often used for egress tagging operation.
DSCP : Differentiated Service Code Point,
VLAN Table lookup : The process of searching VLAN table to find a VLAN which matches the given VID index
MAC address table lookup : The process of searching MAC address table to find a MAC entry which matches the given destination MAC address and the port where the MAC address is located
Packet forwarding : also known as packet switching in a network switch based on MAC address table and VLAN table information
VLAN forwarding : the operation that a packet is forwarded to an egress destination port based on VLAN table information
VLAN group : configuration information about a VLAN which can be recognized in the switch. The information includes a VID associated to the VLAN, member ports, and some special settings.