Transcript Managed Layer 2 Switches

Wired and Wireless network
management
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PART1: NETWORK COMPONENTS AND
TRANSMISSION MEDIUM
Outline
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 Network components
 Transmission medium
 The three-layer hierarchical design model
Network components
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 Hubs
 Bridges/Switches/Multilayer Switches
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Unmanaged Layer 2 Switches
Managed Layer 2 Switches
Managed Layer 3 Switches (Multilayer Switches)
 Routers
 Firewalls (VPN Concentrators)
 Access Points
 Content Filters
 Load balancer.
 Packet Shapers/Policers
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Hubs
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 This is a very simple device that connects together
multiple local area network (LAN) devices.
 The only function of the hub is repeating the
electrical signals received on one port, relaying those
signals to all other connected ports.
 Hubs work at Open Systems Interconnection (OSI)
Layer 1.
Bridges/Switches/Multilayer Switches
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 A bridge is used to connect multiple LAN segments
together, forming multiple collision domains.
 By separating two or more LAN segments into
multiple collision domains, the bridge reduces the
number of collisions that could potentially occur on a
LAN segment (fewer LAN speakers on the same
segment), which improves network performance.
Bridges/Switches/Multilayer Switches
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 In its simplest form, a switch is a multiport bridge
with some additional functionality.
 The switch almost completely ended the risk of
collisions on hub-centered networks.
 There are a few categories of switches, distinguished
by function:
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Unmanaged (Layer 2) switch
Managed (Layer 2) switch
Managed Layer 3 switch (multilayer switch)
Unmanaged Layer 2 Switches
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 A modern unmanaged switch provides the
functionality of a multiport bridge; each of the switch
ports is on its own collision domain.
 Like bridges, the switch has built-in support for the
Spanning Tree Protocol (STP), which provides loop
prevention.
 A switch also keeps an internal database of the
known MAC addresses connected to each port.
Managed Layer 2 Switches
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 A modern managed switch provides all the
functionality of an unmanaged switch;
 in addition, it can control and configure the
behavior of the device. This typically introduces the
ability to support virtual LANs (VLANs),
Managed Layer 3 Switches (Multilayer
Switches)
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 This type of device provides a mix of functionality
between that of a managed Layer 2 switch and a
router.
Routers
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 A router performs network layer functions
 It is used to connect Internet Protocol (IP) networks
 Routers also provide the ability to separate IP
broadcast domains. This feature is important, as
some protocols use broadcast heavily to
communicate with hosts.
 Modern routers support a number of features that
are not limited to OSI Layer 3, including support for
network address translation (NAT), firewalling
services, access control lists (ACLs), packet
inspection, and many others.
Firewalls (VPN Concentrators)
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 The principal function of a firewall is to protect
some portion of a network.
 A number of different techniques are used; which
ones are supported depends greatly on the specific
firewall vendor and model. Techniques include
access control lists, stateful packet inspection (SPI),
and others.
Access Points
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 An access point (AP) is used in wireless Ethernet
networks in place of an Ethernet switch.
 Typical APs also provide bridging functionality
between wired Ethernet and wireless Ethernet hosts.
 There are three categories of access points:
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consumer APs,
enterprise autonomous APs,
and enterprise lightweight APs.
Content Filters
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 Content filters are used on some networks to control
the type of data that is allowed to pass through the
network
Load balancer
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 One term commonly seen in older documentation is the
concept of a load balancer, as a separate piece of equipment
that solely performed this function.
 They're not limited to performing load-balancing
functionality. Their functionality has extended to perform a
number of different activities, including the following:
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Local and global load balancing
Network and device health monitoring
TCP multiplexing
Support for common network routing protocols
Application acceleration
Denial-of-service protection
Web application firewall
Support for virtualization and multi-tenancy
Packet Shapers/Policers
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 A packet shaper or policer controls the flow of
information into or out of a specific device
 The shaping or policing functionality is typically
built into routers (and some switches) to deal with
times when network demand outpaces the ability of a
device or its port.
 In situations of no congestion, the shaping and/or
policing functionality is not used. When there is
congestion, these features will control how the
excessive traffic is handled.
Transmission medium
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The choice of media type affects:
 The type of network interface cards installed.
 The speed of the network.
 The ability of the network to meet future needs.
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Transmission medium
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 Table 4-1 compares the features of the common
network media, including UTP, STP, coaxial cable,
fiber-optic, and wireless connections.
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 Before implementing a network, you need to
determine the requirements for the network. You can
remember a few common recommendations on how
various Ethernet technologies can be used in a
campus network environment.
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Importance of choosing appropriate Ethernet
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 In many modern installations, infrastructure costs
for cabling and adapters can be high. Using the
appropriate Ethernet connectivity provides the
necessary speed for the parts of the network that
require it while controlling costs.
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http://www.mordor.org/CISCO/DOC_ROOT/uni
vercd/cc/td/doc/cisintwk/ito_doc/ethernet.htm
The three-layer hierarchical design model
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 A hierarchical network design model breaks the
complex problem of network design into smaller,
more manageable problems.
 Each level, or tier in the hierarchy addresses a
different set of problems
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The three-layer hierarchical design model
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https://www.pinterest.com/pin/19323264023184
3394/
The three-layer hierarchical design model
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In the three-layer network design model, network
devices and links are grouped according to three
layers:
• Core
• Distribution
• Access
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The three-layer hierarchical design model
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 Devices at each layer have similar and well-defined
functions.
 This allows administrators to easily add, replace, and
remove individual pieces of the network.
 This kind of flexibility and adaptability makes a
hierarchical network design highly scalable.
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The three-layer hierarchical design model
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At the same time, layered models can be difficult to
comprehend because the exact composition of each
layer varies from network to network. Each layer of
the three-tiered design model may include the
following:
• A router
• A switch
• A link
• A combination of these
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The Core Layer
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 The core layer provides an optimized and reliable
transport structure by forwarding traffic at very high
speeds.
 Devices at the core layer should not be burdened
with any processes that stand in the way of switching
packets at top speed. This includes the following:
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• Access-list checking
• Data encryption
• Address translation
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The Distribution Layer
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 The distribution layer is located between the access and
core layers and helps differentiate the core from the rest
of the network
 The purpose of this layer is to provide boundary
definition using access lists and other filters to limit what
gets into the core.
 Therefore, this layer defines policy for the network. A
policy is an approach to handling certain kinds of traffic,
including the following:
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• Routing updates
• Route summaries
• VLAN traffic
• Address aggregation
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The Distribution Layer
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 If a network has two or more routing protocols,
information between the different routing domains is
shared, or redistributed, at the distribution layer.
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The Access Layer
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 The access layer supplies traffic to the network and
performs network entry control.
 End users access network resources by way of the
access layer.
 Acting as the front door to a network, the access
layer employs access lists designed to prevent
unauthorized users from gaining entry.
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The three-layer hierarchical design model
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