Fast Ethernet Overview, Parameter | Cisco Systems PA-2FE-TX guide

Chapter 1 Overview

Fast Ethernet Overview

The term Ethernet is commonly used for all carrier sense multiple access collision detect (CSMA/CD) LANs that generally conform to Ethernet specifications, including Fast Ethernet under IEEE 802.3u.

Note 100BASE-TX is intended for Environment A, and 100BASE-FX is intended for Environment B. Both are described in the IEEE 802.3u standard.

IEEE 802.3u is well suited to applications where a local communication medium must carry sporadic, occasionally heavy traffic at peak data rates. Stations on a CSMA/CD LAN can access the network at any time. Before sending data, the station listens to the network to see if it is already in use. If it is in use, the station waits until the network is not in use, then transmits. This process is known as half-duplex operation. A collision occurs when two stations listen for network traffic, hear none, and transmit almost simultaneously. When simultaneous transmission occurs, both transmissions are damaged and the stations must retransmit. The stations detect the collision and use backoff algorithms to determine when they should retransmit.

Both Ethernet and IEEE 802.3u are broadcast networks, which means that all stations see all transmissions. Each station must examine received frames to determine whether it is the intended destination and, if it is, pass the frame to a higher protocol layer for processing.

IEEE 802.3u specifies the following different physical layers for 100BASE-T:

•100BASE-TX—100BASE-T, half- and full-duplex over Category 5 UTP, EIA/TIA–568-compliant cable

•100BASE-FX—100BASE-T, half- and full-duplex over optical fiber

Each physical layer protocol has a name that summarizes its characteristics in the format speed/signaling method/segment length, where speed is the LAN speed in megabits per second (Mbps), signaling method is the signaling method used (either baseband or broadband), and segment length is the maximum length between stations in hundreds of meters. Therefore, 100BASE-T specifies a 100-Mbps, baseband LAN with maximum network segments.

IEEE 802.3u 100BASE-T Specifications

This section provides specifications for IEEE 802.3u 100BASE-T. Table 1-1provides cabling specifications for 100BASE-TX Fast Ethernet transmission over UTP and foil twisted-pair (FTP), and 100BASE-FX Fast Ethernet over fiber-optic cables. It also summarizes IEEE 802.3u 100BASE-TX and 100BASE-FX physical characteristics. (See Figure 1-3.)

		Table 1-1	Cabling Specifications

		Parameter		100BASE-TX	100BASE-FX (Multimode)

		Cable specification		Category 51 UTP2, 22 to 24	62.5/125 multimode optical fiber
				AWG

		Maximum segment length		100 m	412 m
		(half-duplex)3
		Maximum segment length		100 m	2000 m
		(full-duplex)3
	PA-2FE-TX and PA-2FE-FX Two-Port Fast Ethernet Port Adapter Installation and Configuration


1-2					OL-3474-07
1-2					OL-3474-07

PA-2FE-FX, PA-2FE-TX specifications

Cisco Systems PA-2FE-TX and PA-2FE-FX are high-performance Ethernet interface modules designed to enhance the capabilities of Cisco 2600 and 3600 series routers. They provide businesses with flexible and reliable networking solutions that meet the increasing demand for bandwidth and connectivity.

One of the main features of the PA-2FE-TX module is its ability to support two 10/100 Mbps Fast Ethernet interfaces. This allows organizations to connect multiple devices while improving network performance. The PA-2FE-FX module, on the other hand, is designed for optical fiber connections. It features two Fast Ethernet interfaces that utilize an SC connector for easier cable management in fiber optic environments. This capability facilitates long-distance data transmission, making it suitable for backbone connections or inter-building links.

Both modules incorporate advanced technologies to ensure efficient data handling. They support Cisco's Auto-Negotiation feature, enabling devices to automatically select the optimal speed and duplex settings, thus simplifying deployment and reducing configuration errors. This functionality is vital in environments with varied device capabilities, allowing seamless communication across the network.

The PA-2FE-TX and PA-2FE-FX modules utilize Quality of Service (QoS) capabilities to prioritize traffic, ensuring that critical applications receive the necessary bandwidth. This is particularly beneficial for VoIP services, video conferencing, and other latency-sensitive applications. Additionally, the modules offer support for VLANs, allowing organizations to segment their networks effectively and enhance security by isolating sensitive data traffic.

Another important characteristic of these modules is their hot-swappable nature, enabling users to replace them without powering down the router, thus minimizing downtime. This feature is critical for businesses that require high availability and reliability from their networking equipment.

In summary, the Cisco Systems PA-2FE-TX and PA-2FE-FX interface modules stand out for their versatility, enabling businesses to implement customized networking solutions tailored to specific needs. With support for both copper and fiber connections, advanced QoS features, and seamless integration into existing Cisco routers, these modules reinforce Cisco’s commitment to providing innovative, robust network solutions that cater to the demands of modern enterprise environments.