Foundry NetIron M2404C and M2404F Metro Access Switches
Configuring Interfaces (Rev. 03)
Fast Ethernet and Giga Ethernet Port
© 2008 Foundry Networks, Inc.
Page 3 of 57
Fast Ethernet and Giga Ethernet Port
The Foundry NetIron M2404C and M2404F Metro access switches support simultaneous, parallel
conversations between Ethernet segments. Switched connections between Ethernet segments last
only for the duration of the packet. New connections can be made between different segments for
the next packet.
The devices solve congestion problems caused by high-bandwidth devices and a large number of
users by assigning each device to its own 100 or 1000 Mbps segment.
Because the major bottleneck in Ethernet networks is usually due to collisions, an effective solution
is full-duplex communication, an option for each port on the devices (note that Gigabit Ethernet
ports also support half duplex). Normally, Ethernet operates in half-duplex mode, which means that
stations can either receive or transmit. In full-duplex mode, two stations can transmit and receive at
the same time. When packets can flow in both directions simultaneously, the effective Ethernet
bandwidth is 200 Mbps for Fast Ethernet ports and 2 Gbps for Gigabit Ethernet ports.
Switching Frames between Segments
Each Ethernet port on the device can be connected to a single workstation or server, or to a hub
through which workstations or servers connect to the network.
When stations on different ports need to communicate, the device forwards frames from one port to
the other at wire-speed to ensure that each session receives the full available bandwidth.
To device frames between ports efficiently, the device maintains an address table. When a frame
enters the device, it associates the Media Access Control (MAC) address of the sending station
with the port on which it was received.
Building the Address Table
The device builds the address table by using the source address of the frames received. When the
device receives a frame for a destination address not yet listed in its address table, it floods the
frame to all ports of the same virtual LAN (VLAN) except for the port that received the frame.
When the destination station replies, the device adds its relevant source address and port ID to the
address table. The device then forwards subsequent frames to a single port without flooding them
to all ports.
The address table can store up to 16K address entries The device uses an aging mechanism, defined
by a configurable aging timer, so that if a station remains inactive for a specified number of
seconds, its address is removed from the address table,.
Fast and Giga Ethernet Ports Default Configuration
Table 1
shows the default Fast Ethernet and Giga Ethernet Ports configuration.
Table 1: Fast Ethernet and Giga Ethernet Ports Default Configuration
Parameter
Default Value
Interface state
Enabled