Using Cisco Catalyst Products

Using Cisco Catalyst Products
Understanding the campus size and traffic is an important factor in network design. A large
campus is defined as several or many colocated buildings, and a medium campus is one or more
colocated buildings. Small campus networks have only one building.
By understanding your campus size, you can choose Cisco products that will fit your business
needs and grow with your company. Cisco switches are produced to fit neatly within its three-layer
model. This helps you decide which equipment to use for your network efficiently and quickly.
It should be noted that the Cisco range of switches is in a transitional phase between two
operating systems. The Catalyst Operating System (CatOS) is the traditional method and is
often referred to as using set commands because when configuring, the command often begins
with the word “set.” Switches in this line include the 4000 and the 6000/6500.
The switches based on the IOS are called Catalyst IOS (CatIOS) switches. The interface to
configure these switches resembles that of the IOS router but isn’t entirely the same. Anyone
familiar with configuring a router, though, will be comfortable configuring one of these
switches. The switches that use this include the 2950, the 3550, and the 8500 series.
With some switches—for instance, the 6000/6500 series—you have a choice
between the two types of operating systems. When this occurs, the CatOS is
the default OS. This is liable to change as Cisco promotes the transition to
IOS-based offerings.
Cisco Express Forwarding (CEF) allows for real layer 3 switches to forward traffic based on
a complete layer 3 topology map. This map is shared with the ASICs at each port, enabling each
port to know which port a packet should be forwarded to. Rather than forwarding based on
MAC address, forwarding is done by layer 3 address. Only switches that have true layer 3 capabilities
can do this type of switching. These devices include the 3550 series, the 4000 series, the
6000/6500 series with PFC2, and the 8500 series.
There are two general rules when it comes to Cisco switches: The lower model numbers usually
cost less, and purchasing a device with more ports drives down the per-port cost. In addition,
the model number may typically be split into two sections: For slot-based switches, the
second number usually refers to the number of physical slots it has. The 6509 is a nine-slot
device in the 6500 family of switches.