Fibre Channel Primer

Chapter 6: Topologies

preemption. Class 6 is ideal for video broadcast applications and real-

time systems that move large quantities of data.

Intermix

Fibre Channel has an optional mode called Intermix. Intermix

allows the reservation of full Fibre Channel bandwidth for a dedicated

(Class 1) connection. It also allows connectionless traffic within the

switch to share the link during idle Class 1 transmissions. An ideal

application for Intermix is linking multiple large file transfers during

system backup. During a Class 1 file transfer, a Class 2 or 3 message

can be sent to the server to set up the next transfer. Upon completion

of one transfer, the next will immediately start, increasing efficiency.

Hunt Groups

A hunt group is a set of associated N_Ports attached to a single

node. This set is assigned an alias identifier that allows any frames

containing this alias to be routed to any available (i.e., non-busy)

N_Port within the set. This improves efficiency by decreasing the

chance of reaching a busy N_Port. A simple application can improve

server response with multiple host bus adapters, giving the server

multiple nodes in the Fibre Channel network. The net result is better

utilization of the server and faster delivery to users.

Multicast

Multicast delivers a single transmission to multiple destination

N_Ports. This includes sending to all N_Ports on a fabric (broadcast)

or to only a subset of the N_Ports on a fabric (multicast). This provides

the ability to implement effective workgroup segmentation on high-

performance Fibre Channel networks.

TOPOLOGIES

Fibre Channel nodes login with each other and the switch to exchange

operating information on attributes and characteristics. This

information is used to establish interoperability parameters.