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24-port NWay Ethernet Switch User’s Guide

Switch Management 43

Untagging - The act of stripping 802.1Q VLAN information out of

the packet header. Ports with untagging enabled will take all

VLAN information out of all packets that flow into and out of a

port. If the packet doesn’t have a VLAN tag, the port will not alter

the packet, thus keeping the packet free of VLAN information.

Utagging is used to send packets from an 802.1Q-compliant switch

to a non-compliant device.

Ingress port - A port on a switch where packets are flowing into

the switch and VLAN decisions must be made. Basically, the switch

examines VLAN information in the packet header (if present) and

decides whether to forward the packet. If the packet is tagged with

VLAN information, the ingress port will first determine if the

ingress port itself is a member of the tagged VLAN and can thus

receive the packet (if the Ingress Filter is enabled), and then it

decides if the destination port is a member of the VLAN. Assuming

both ports are members of the tagged VLAN, the packet will be

forwarded. If the packet doesn’t have VLAN information in its

header (is untagged), the ingress port first determines if the ingress

port itself can receive the packet (if the Ingress Filter is enabled),

will tag it with its own PVID (if it defined as a tagging port) and

check to see if the destination port is on the same VLAN as its own

PVID and can thus receive the packet. If Ingress filtering is

disabled and the destination port is a member of the VLAN used by

the ingress port, the packet will be forwarded. If the ingress port is

an untagging port, it will only check the filter condition, if enabled,

before forwarding the packet and leave the packet untagged.

Egress port - A port on a switch where packets are flowing out of

the switch, either to another switch or to an end station, and

tagging decisions must be made. If an egress port is connected to an

802.1Q-compliant switch, tagging should be enabled so the other

switch can take VLAN data into account when making forwarding

decisions. If an egress connection is to a non-compliant switch or

end-station, tags should be stripped so the (now normal Ethernet)

packet can be read by the receiving device.

Удалено: Using the Console

Interface