redundant switches in the building distribution
submodule. Building distribution submodule (also
known as building distribution layer): Provides aggregation
of building access devices, often using Layer 3 switching. The
building distribution submodule performs routing, QoS, and
access control. Traffic generally flows through the building
distribution switches and onto the campus core or backbone.
This submodule provides fast failure recovery because each
building distribution switch maintains two equal-cost paths in
the routing table for every Layer 3 network number. Each
building distribution switch has connections to redundant
switches in the core. Campus backbone submodule
(also known as building core layer): Provides redundant and
fast-converging connectivity between buildings and the server
farm and edge distribution modules. The purpose of the campus
backbone submodule is to switch traffic as fast as possible
between campus infrastructure submodules and destination
resources. Forwarding decisions should be made at the ASIC
level whenever possible. Routing, ACLs, and processor-based
forwarding decisions should be avoided at the core and
implemented at building distribution devices whenever possible.
High-end Layer 2 or Layer 3 switches are used at the core for
high throughput, with optimal routing, QoS, and security
capabilities available when needed.
Content
1.1 Introducing Campus Networks
1.1.11 Reviewing Switch Configuration Interfaces In
the era of the early high-end Cisco Catalyst switches, the
Cisco Catalyst operating system (CatOS) and the command-line
interface (CLI) were significantly different from the Cisco IOS
mode navigation interfaces available on all newer Cisco
Catalyst platforms. The two interfaces have different features
and a different prompt and CLI syntax. Note: Desktop
Express-based switches use a Cisco Network Assist (GUI
interface) not a CLI. The original Cisco Catalyst interface is
sometimes referred to as the “set-based” or, more recently,
“Catalyst software” CLI. In the Cisco Catalyst software,
commands are executed at the switch prompt, which can be either
non-privileged (where a limited subset of user-level commands
is available) or at a password-protected privileged mode (where
all commands are available). Configuration commands are
prefaced with the keyword set. In the example below, the
Cisco Catalyst software commands execute the following: Step
1 Show the status of a port. Step 2 Move to enable
mode, which requires a password. Step 3 Enable the
port. Console> show port 3/5
.
.
Console> enable Enter password:
Console(enable)
set port enable 3/5 Cisco Catalyst switch platforms have
had a number of different operating systems and user
interfaces. Over the years, Cisco has made great strides in
converting the interface on nearly every Cisco Catalyst
platform to the Cisco IOS interface familiar to users of Cisco
routing platforms. Unlike the Cisco Catalyst software, various
modes are navigated to execute specific commands. Here is an
example of how switch port 3 might be enabled on an access
layer switch using the Cisco IOS interface and how its status
is verified after configuration. Compare how the Cisco IOS
interface is navigated here to the previous example using Cisco
Catalyst software. Switch# config terminal
Switch(config)# interface fastethernet 0/3
Switch(config-if)# no shut
Switch(config-if)#
end
Switch# show interface fastethernet 0/3
Some widely used Cisco Catalyst switch platforms that support
the Cisco IOS interface are 2950, 2960, 3550, 3560, 3750,
4500*, 6500*, and 8500. * These platforms have an option to use
either Cisco IOS or Cisco Catalyst software for Layer 2
configuration. The Catalyst software interface exists on
several modular Cisco Catalyst platforms, including the Cisco
Catalyst 4500, 5500, 6000, and 6500 Series. For example, on the
Cisco Catalyst 6500, you have the option of using the Cisco
Catalyst software, Cisco Catalyst software plus Cisco IOS
software, or Cisco IOS software functionality. The Cisco IOS
interface is used across a wide variety of Cisco Catalyst
switch platforms, particularly the fixed and stackable
switches, and is therefore the interface of reference
throughout the remainder of the course. Labs may provide
direction on the use of specific Cisco Catalyst software
commands, depending on the equipment provided.
Content
Summary The SONA framework guides the evolution of the
enterprise network toward IIN. The Cisco Enterprise
Architecture, with a hierarchical network model, facilitates
the deployment of converged networks. Non-hierarchical network
designs do not scale and do not provide the required security
necessary in a modern topology. Layer 2 networks do not provide
adequate security or hierarchical networking. Router-based
networks provide greater security and hierarchical networking;
however, they can introduce latency issues. Multilayer switches
combine both Layer 2 and Layer 3 functionality to support the
modern campus network topology. Multilayer switches can be used
in non-hierarchical networks; however, they do not perform at
the optimal level in this context. The enterprise composite
model identifies the key components and logical design for a
modern topology. Implementation of an ECNM provides a secure,
robust network with high availability. The Campus
Infrastructure, as part of an ECNM, provides additional
security and high availability at all levels of the campus.