LANdesign

hellhollowreadingNetworking and Communications

Oct 26, 2013 (3 years and 9 months ago)

103 views

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LAN design

CCNA Exploration Semester 3

Chapter 1

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Topics


Networks and business needs


The 3
-
level hierarchical network design
model


Including voice and video over IP in the
design


Devices at each layer of the hierarchy


Cisco switches for each layer

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Semester 3

LAN Design

Basic Switch
Concepts

VLANs

VTP

STP

Inter
-
VLAN
routing

Wireless

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Hierarchical design model

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Hierarchical design model

High speed backbone.

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Hierarchical design model

Subnets, VLANs, routing, flow control,
security.

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Hierarchical design model

Connects end devices. Controls which
devices connect.

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Collapsed core


Small network: merged core and distribution

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Logical and physical layout


Logical


how
they connect.


Physical


where
they are.


Logical
connections not
obvious from
looking.

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Benefits of Hierarchical Network


Scalability



easy to expand


Redundancy



at core and distribution layers


Performance



route packets through fast
devices


Security



at access and distribution layers


Manageability



similar functions within layer


Maintainability

-

modular

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Design principles


Network diameter



how many devices must
packet pass through? Keep it low.


Bandwidth aggregation



combine ports
where high bandwidth is needed.


Redundant links/devices



in core and
distribution layers. Too expensive for access.


Start design at the access layer. How many
devices, how much bandwidth needed?

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Converged network


Combines data, voice, video.


(Not converged as in “all routers have
consistent information”. Same word used.)


Needs quality of service (QoS) to give priority
to voice and video.


Was very expensive, needed expertise,
needed to replace legacy equipment.


Now more affordable.

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Advantages of converged network


One network to manage/ keep up to date


One set of cabling and networking devices


One group of people to run it


One service provider


Can have voice and video on PC using
headset, webcam and software


no separate
equipment.


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Choosing switches


Carry out
Traffic Flow Analysis

using
software to monitor amount and source of
traffic. Allow for growth.


Carry out
User Communities Analysis
.
Group by job function. How many ports? How
much bandwidth? Allow for growth.


Carry out
Data Stores and Data Servers
analysis
. Traffic to, from, between.

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Topology Diagram

Ports?

Bandwidth?

Bottlenecks?

Layers?

Routes?

Redundancy?

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Topology Diagram

Ports?

Bandwidth?

Bottlenecks?

Layers?

Routes?

Redundancy?

Document it
now

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Choosing switches (cont
d
)

Form factor


Fixed configuration



ports on chassis


Modular



ports on
cards


Stackable



act as
one switch, linked by
special ports.

1 rack unit (1U)

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Choosing switches (cont
d
)


Port density



how many ports? (Allow for
links between switches.)


Forwarding rate



How many Gbps can it
process? Can all ports work simultaneously
at maximum speed?


Link aggregation

(EtherChannel)


up to 8
ports bound together, acting as one, with
combined bandwidth


can it do this?


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Choosing switches (cont
d
)


Power over Ethernet

(PoE) for IP phones,
network access points. Do you need it? It
adds to the cost.


Multilayer

switch needed? Typical switch
works at Data Link layer (2), uses MAC
addresses. Multilayer also works at Network
layer (3), routes between subnets.

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Access Layer Switch Features


Port security



choose which devices may
connect. All Cisco switches support this.


VLAN
s


connected devices on different
subnets.


Speed



Fast Ethernet (100Mbps) or Gigabit.


Power over Ethernet

(PoE)


expensive


Link aggregation



for uplinks


Quality of service

(QoS) if needed

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Distribution Layer Switch Features


Layer 3 support


route between VLANs


High forwarding rate (processing)


Port speed Gbps, 10Gbps ports


Redundancy


Security


Access control lists


Link aggregation


Quality of service


Availability. Hot swappable power supply?

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Core Layer Switch Features


Support for Network layer (3)
-

routing


Very high forwarding rate


Very high port speed (1Gbps, 10Gbps)


Redundancy


Link aggregation


Quality of service


Avoid security and other distractions here.

Go for speed.

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Catalyst Switch product lines

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Catalyst Switch product lines

Concentrate
on general
features

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The End