Specifications

Escala Tower PL & S, E, T System Hardware
Chapter 3: External Storage and SAN Subsystems 78/116
9es3s1c3.doc
Rev 5.9
02/12/2003
6.3.3. Fibre Channel Networks
Fibre Channel networks are implemented with respect of some rules defined by the ANSI standards,
and using some equipment to implement the network infrastructure.
6.3.3.1. Point to Point Connection
The point to point connection between two devices is the simplest cabling solution. The cable types
and distance limitations have been described in 6.3.2. Cabling.
Point-to-point cablin
g
1 cable, full-duplex
capability
6.3.3.2. Loops and Hubs
The loop has been very popular at the beginning of Fibre Channel. It enables to interconnect up to 126
equipment at a very low cost. The principle of this topology is to chain the transmitter of a port to the
receiver of the next port, thus creating a loop. The loop protocol is defined by the FC-AL standard.
loop cablin
g
Tx
Tx
Tx
Rx
Rx
Rx
The loop has several main drawbacks:
•
The bandwidth is shared by the connected devices, and only two devices can communicate
simultaneously.
•
Each device of the loop is a single point of failure: if the device fails, the loop is broken, and none
of the connected devices may communicate.
•
Inserting or removing devices causes a loop disruption.
•
The connectivity is limited to 126 devices.