PRV-1059
User Manual
When a frame comes in, the MAC address gets hashed into the database. If no match is found, the
MAC address/port association needs to be learned. Learning consists of the following: the frame is
forwarded to all of the ports, awaiting a response from one the ports. Once a port responds, the
association is made and “learned” into the address table. If multiple ports respond, the associations are
not learned. Once a MAC address/port is learned, all future packets directed to that address will be
forwarded solely to that port.
Address Aging
Continuous address aging ensures an up-to-data address table and rapid address look-up. Once a
node is disconnected from the network segment, or if it becomes inactive, its entry is removed from the
address table. Every time a MAC address is found in the address table, the age is refreshed, keeping it
active. Aging occurs by default every 5 minutes.
Each MAC address entry in the address table contains an age value, Entry_State. The initial value of
Entry_State is 0xE. Aging occurs with a sweep of the table, the ATU reads each entry in the address
table and decrements its Entry_State. Once the Entry_state of a MAC address reaches zero, the entry
is killed and purged from the table. The speed at which aging occurs is default at 300 seconds.
Auto-Negotiation
Auto negotiating occurs when the switch negotiates with a link partner to determine the speed and duplex with
which to operate. It the partner is unable to negotiate, the switch goes to a detection mode to determine the
speed and the duplex will lock at half-duplex.
Auto MDI-/MDIX Crossover
The board determines whether or not it needs to cross over between pairs, virtually eliminating the need for an
external crossover cable. If it interoperates with a device that cannot automatically correct for crossover, the
switch makes the necessary adjustment prior to commencing auto-negotiation. Similarly, if the switch
interoperates with a device that implements MDI-MDIX crossover, a random algorithm determines which device
performs the crossover.
Port-Based VLAN
Select models of the PRV-1059 support field programmable, port-based VLAN functionality. Port-based VLANs
are a type of VLAN where packet forwarding decisions are based on the MAC address of the destination and its
associated port. With this powerful feature any combination of ports can be connected together in subnets for
use in a small secure or non-secure network.
The following diagrams are similar to those which can be seen within the Parvus VLAN software and are
included to illustrate the concept of VLAN on the PRV-1059. Figure 1 below shows a switch and all five ports
with no restrictions; any port can talk to any other port. This is the state of non-VLAN switches and is also the
factory default setting for the VLAN-enabled switch.
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MNL-0490-01 RevD4
REF. ECO-3163
Effective: 01 Feb 10
Содержание PRV-1059
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