Allied Telesis AT-CV5000 - Manual (Page 34)

Chapter 1: Overview
34
A Few Basics about Media Converters
An Ethernet media converter can interconnect network devices over large
distances by transferring Ethernet traffic between twisted pair ports and
fiber optic cabling.
MAC Address
Table
A Converteon™ media converter line card has a MAC address table that
can store up to 2K to 32 K MAC addresses, depending on the line card
model. Refer to the Converteon™ Media Converter Line Cards Reference
Guide for the number of MAC addresses that each line card can store.
The line card uses the table to store the MAC addresses of the network
end nodes connected to the ports, along with the port number on which
each address was learned.
A line card learns the MAC addresses of the end nodes by examining the
source address of each packet received on a port. It adds the address and
port on which the packet was received to the MAC table if the address had
not already been entered in the table. The result is a table that contains all
the MAC addresses of the devices that are connected to the line card’s
ports, and the port number where each address was learned.
When the line card receives a packet, it also examines the destination
address and, by referring to its MAC address table, determines the port on
which the destination end node is connected. It then forwards the packet
to the appropriate port and on to the end node.
If the line card receives a packet with a destination address that is on the
same port on which the packet was received, it discards the packet
without forwarding it on to any port. Because both the source end node
and the destination end node for the packet are located on the same port
on the line card, there is no reason for the line card to forward the packet.
Duplex Mode Duplex mode refers to the manner in which an end node receives and
transmits data. If an end node can receive or transmit data, but not both
simultaneously, the end node is operating in half-duplex mode. If an end
node can both receive and transmit data simultaneously, the end node is
operating in full-duplex mode. An end node capable of operating in full-
duplex can handle data much faster than an end node that can only
operate in half-duplex mode.
The twisted pair ports on the Converteon™ line cards can operate in either
half- or full-duplex mode. The twisted pair ports are IEEE 802.3u-
compliant and will Auto-Negotiate the duplex mode setting for you.
You can disable Auto-Negotiation on the line card ports so that you can
set the duplex mode manually through the management software.
In order for a line card port to successfully Auto-Negotiate its duplex mode