Draytek VigorSwitch G1260, Руководство пользователя

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VigorSwitch G1260 User’s Guide 34
Untagged frame: An Ethernet frame carries no VLAN tag information.
VLAN Identifier: Also referred to as VID. It is used to identify a member whether it
belongs to the VLAN group with the VID. The assignable number is
1- 4094. If VID=0, the tagged frame is a priority packet. Both the
value of 0 and 4095 also cannot be assigned in VLAN management.
Port VLAN Identifier: VLAN identifier of a port. It also can be referred to as PVID. When
an untagged frame or a priority-tagged frame is received, the frame
will be inserted the PVID of that port in the VLAN tag field. The
frame with VID assigned by a port is called PVID. Each port can
only be assigned a PVID. The default value for PVID is 1, the same
as VID.
Ingress filtering: The process to check a received packet and compare its VID to the
VLAN membership of the ingress port. The ingress filtering can be
set by per port. When receiving a packet, VLAN bridge examines if
the VID in the frame’s header presents.
If the VID of the received packet presents, the VID of the packet is
used. And VLAN bridge will check its MAC address table to see if
the destination ports are members of the same VLAN. If both are
members of the tagged VLAN, then the packet will be forwarded.
If the packet is an untagged or a null tag packet, the ingress port’s
PVID is applied to the packet. VLAN bridge will then look up the
MAC address table and determine to which ports the packet should
be forwarded. Next, it will check to see if the destination ports
belong to the same VLAN with that PVID. If the destination ports
are members of the VLAN used by ingress port, the packet will be
forwarded.
Note: VID can not be 0 or 4095.
Ingress Rule: Each packet received by a VLAN-aware bridge will be classified to
a VLAN.
The classification rule is described as follows.
1. If the VID of the packet is null VID (VID=0)or this packet is an
untagged packet:
a. If there are still some other ways(e.g. protocol, MAC address,
application, IP-subnet, etc.) to classify the incoming packets
beside port-based classification in implement and these
approaches can offer non-zero VID, then, use the value of
VID offered by other classifications for VLAN’s
classification.
b. If there is only port-based classification in implement or
other classification approaches cannot offer non-zero VID for
the incoming packets, then assign the PVID to the incoming
packets as VID for the classification of the VLAN group.
2. If the VID is not a null VID (VID
≠
0), then use the value to
classify the VLAN group.
Egress Rule: An egress list is used to make the tagging and forwarding decision
on an outgoing port. It specifies the VLANs whose packets can be
transmitted out and specifies if the packet should be tagged or not. It
can be configured for port’s VLAN membership, and tagged or