D-Link DES-3225G Bedienungsanleitung PDF herunterladen (Seite 60)

24-port NWay Ethernet Switch User’s Guide

46 Switch Management Concepts

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 the ingress filter is

enabled - before forwarding the packet.

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.

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D-Link DES-3225G Bedienungsanleitung Seite 60