Packet Forwarding - D-Link DES-3326SR User Manual

DES-3326SR Layer 3 Fast Ethernet Switch User's Guide
operation). This process however can be quite involved, since
you must know the MIB OIDs and retrieve them one by one.

Packet Forwarding

The Switch enters the relationship between destination MAC or
IP addresses and the Ethernet port or gateway router the
destination resides on into its forwarding table. This
information is then used to forward packets. This reduces the
traffic congestion on the network, because packets, instead of
being transmitted to all ports, are transmitted to the
destination port only. Example: if Port 1 receives a packet
destined for a station on Port 2, the Switch transmits that
packet through Port 2 only, and transmits nothing through the
other ports. This process is referred to as 'learning' the
network topology.
MAC Address Aging Time
The Aging Time affects the learning process of the Switch.
Dynamic forwarding table entries, which are made up of the
source MAC addresses and their associated port numbers, are
deleted from the table if they are not accessed within the aging
time.
The aging time can be from 10 to 1,000,000 seconds with a
default value of 300 seconds. A very long aging time can result
in dynamic forwarding table entries that are out-of-date or no
longer exist. This may cause incorrect packet forwarding
decisions by the switch.
If the Aging Time is too short however, many entries may be
aged out too soon. This will result in a high percentage of
received packets whose source addresses cannot be found in
the forwarding table, in which case the switch will broadcast
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