Vigitron MaxiiNet Vi30126 Series, Operation Manual

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UDP is an alternative to the Transmission Control Protocol (TCP) that uses the
Internet Protocol (IP). Unlike TCP, UDP does not provide the service of dividing a
message into packet datagrams, and UDP doesn't provide reassembling and
sequencing of the packets. This means that the application program that uses
UDP must be able to make sure that the entire message has arrived and is in the
right order. Network applications that want to save processing time because they
have very small data units to exchange may prefer UDP to TCP.
UDP provides two services not provided by the IP layer. It provides port numbers
to help distinguish different user requests and, optionally, a checksum capability
to verify that the data arrived intact.
Common network applications that use UDP include the Domain Name System
(DNS), streaming media applications such as IPTV, Voice over IP (VoIP), and
Trivial File Transfer Protocol (TFTP).
User Priority
User Priority is a 3-bit field storing the priority level for the 802.1Q frame. It is also
known as PCP.
V
VLAN
Virtual LAN is a method to restrict communication between switch ports. VLANs
can be used for the following applications:
VLAN unaware switching: This is the default configuration. All ports are VLAN
unaware with Port VLAN ID 1 and members of VLAN 1. This means that MAC
addresses are learned in VLAN 1, and the switch does not remove or insert
VLAN tags.
VLAN aware switching: This is based on the IEEE 802.1Q standard. All ports are
VLAN aware. Ports connected to VLAN aware switches are members of multiple
VLANs and transmit tagged frames. Other ports are members of one VLAN, set
up with this Port VLAN ID, and transmit untagged frames.
Provider switching: This is also known as Q-in-Q switching. Ports connected to
subscribers are VLAN unaware, members of one VLAN, and set up with this
unique Port VLAN ID. Ports connected to the service provider are VLAN aware,
members of multiple VLANs, and set up to tag all frames. Untagged frames
received on a subscriber port are forwarded to the provider port with a single
VLAN tag. Tagged frames received on a subscriber port are forwarded to the
provider port with a double VLAN tag.
VLAN ID
VLAN ID is a 12-bit field specifying the VLAN to which the frame belongs.