Transcript No Slide Title

Chap 1 – LAN Design
Learning Objectives
•
•
Describe how a hierarchical network supports the
voice, video and data needs of a small and mediumsized business.
Match the appropriate Cisco switch to each layer in
the hierarchical network design model.
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Chapter 1
Hierarchical Design Model
The use of a hierarchical design model will make it
easier to make changes to the network as the
organization grows. Cisco currently recognize the
following layers:
•Access layer provides users in workgroups access to
the network.
•Distribution layer provides policy-based connectivity.
•Core layer provides optimal transport between sites the backbone.
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Chapter 1
Hierarchical Design Model
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Hierarchical Design Model – Access Layer
•Shared Bandwidth
•Switched
Bandwidth
•MAC Layer filtering
•Micro-segmentation
The access layer is the entry point for user
workstations and servers to the network – typical
devices being switches or hubs.
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Chapter 1
Hierarchical Design Model – Distribution
Layer
•Aggregation of the wiringcloset connections
•Broadcast/multicast domain
definition
•VLAN routing
•Any media transitions that
need to occur (copper to FO)
•Security (ACLs)
•The purpose of this layer is to provide a boundary
definition in which packet manipulation can take
place.
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Chapter 1
Hierarchical Design Model – Core Layer
•Doesn’t perform any packet
manipulation - would slow down
the switching of packets.
• Provide redundant alternate
paths.
•Can be designed to use Layer 2
or Layer 3 switching - ATM or
Ethernet.
The core layer is a high-speed switching backbone.
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Chapter 1
LAN Design Goals
•Scalability - Hierarchical networks scale very well, as the modularity of
the design allows the replication of design elements as the network grows.
•Redundancy - As a network grows, availability becomes more important.
Availability can be increased through easy redundant implementations with
hierarchical networks.
•Performance - enhanced by avoiding the transmission of data through lowperforming, intermediary switches.
•Security - Access layer switches can be configured with various port
security options that provide control over which devices are allowed to
connect to the network.
•Manageability - Each layer of the hierarchical design performs specific
functions that are consistent throughout that layer – easy to manage.
•Maintainability - Because hierarchical networks are modular in nature and
scale very easily, they are easy to maintain.
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Chapter 1
Switched LAN Design Principles
•Links between specific switches can
be aggregated, which is called link
aggregation. Link aggregation allows
multiple switch port links to be
combined so as to achieve higher
throughput between switches.
•Redundancy is one part of creating
a highly available network.
Redundancy can be provided by
doubling up the network connections
between devices, or doublinge the
devices themselves.
•Network diameter - number of
devices that a packet has to cross
before it reaches its destination – a
low number ensures low and
predictable latency between devices.
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Chapter 1
Converged Networks
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Many separate communications networks have evolved to support
various different types of communication.
Traditionally, data and voice networks remained separate.
Circuit Switch
Aggregate Link
Traditional Phones/Video
To PSTN
DCE
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Link IP Network
Chapter 1
Converged Networks
Convergence is the process of combining voice and video
communications on a data network.
Traditional Phones/Video
•It is less expensive to implement a
single network infrastructure than
multiple network infrastructures.
DCE
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Link IP Network
Chapter 1
Considerations for Hierarchical Network
Switches
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Traffic Flow Analysis - Traffic flow analysis is the
process of measuring the bandwidth usage on a network
and analyzing the data for the purpose of performance
tuning, capacity planning, and making hardware
improvement decisions.
Analysing the various
traffic sources and
their impact on the
network, allows more
accurate tuning and
upgrading of the
network to achieve
the best possible
performance.
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Chapter 1
Considerations for Hierarchical Network
Switches
User community analysis - the process of identifying
various groupings of users and their impact on network
performance. The way users are grouped affects issues
related to port density and traffic flow, which, in turn,
influences the selection of network switches
•Future Growth - 24port switch has only 4
spare ports, so future
growth of the
department is not
considered.
•A stackable or modular
switches that can scale
would probably be a
better initial solution.
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Chapter 1
Considerations for Hierarchical Network
Switches
Server Placement
Servers can be categorized as either enterprise
servers or workgroup servers:
•Enterprise servers support all the users on the
network as it offers services, such as e-mail or Domain
Name System (DNS).
•Workgroup servers support a specific set of users and
offers services such as word processing and file
sharing.
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Chapter 1
Considerations for Hierarchical Network
Switches
Server Placement
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Chapter 1
Considerations for Hierarchical Network
Switches
LAN Design Goals - Documentation
Topology Diagram
Cut Sheet
Addressing
Map
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Chapter 1
Switch Features – Form Factors
•Fixed configuration - can’t
add features or options to the
switch.
•Modular switches – chassis
allows for the installation of
different numbers of modular
line cards containing switch
ports.
•Stackable switches - interconnected using
a special backplane cable that provides
high-bandwidth throughput between
switches.
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Chapter 1
Switch Features – Port Density
•Port density is the number of ports available on a single switch.
•Modular switches can support very high port densities through the
addition of multiple switch port line cards - Catalyst 6500 switch can
support in excess of 1,000 switch ports on a single device.
•Without using a high-density modular switch, the network would need
many fixed configuration switches to accommodate the number of
devices that need network access. This approach can consume many
power outlets and a lot of closet space.
• Fixed configuration switches may consume many additional ports for
bandwidth aggregation between switches . Less of an issue with modular
switches because the backplane of the chassis can provide the necessary
bandwidth.
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Chapter 1
Switch Features – Port Forwarding
•Forwarding rates define the
processing capabilities of a
switch by rating how much
data the switch can process
per second.
Switch
24 x 100Mbps
Switch
Ports
•Wire speed is the data rate
that each port on the switch
is capable of attaining
•If the forwarding rate is not
equal to or greater than the
sum of the port speed, ports
can not run at wire speed
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Chapter 1
Switch Features – Link Aggregation
•Link aggregation helps to
reduce bottlenecks of traffic
by allowing up to eight switch
ports to be bound together
for data communications,
providing up to 8 Gb/s of data
throughput when Gigabit
Ethernet ports are used.
•Cisco uses the term
EtherChannel when describing
aggregated switch ports.
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Chapter 1
Access Layer Switch Features
•Port Security
•VLANs
•Fast Ethernet/Gigabit Ethernet
•Power over Ethernet (PoE – 802.3af)
•Link Aggregation
•Quality of Service (QoS)
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Chapter 1
Distribution Layer Switch Features
•Layer 3 Support
•High Forwarding Rate
•Gigabit Ethernet / 10 Gigabit Ethernet
•Redundant Components
•Security Policies / Access Control Lists
•Link Aggregation
•Quality of Service (QoS)
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Chapter 1
Core Layer Switch Features
•Layer 3 Support
•Very High Forwarding Rate
•Gigabit Ethernet / 10 Gigabit Ethernet
•Redundant Components
•Link Aggregation
•Quality of Service (QoS)
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Chapter 1
Typical Network Switches
Access
•Catalyst
•Catalyst
•Catalyst
•Catalyst
2960
3560
4000
5000
Distribution
series
series
series
series
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•Catalyst 5000 family
•Catalyst 6000 family
Core
•Catalyst 6500 series
•Catalyst 8500 series
•IGX 8400 series
•Lightstream 1010
Chapter 1
Chap 1 – LAN Design
Learning Objectives
•
•
Describe how a hierarchical network supports the
voice, video and data needs of a small and mediumsized business.
Match the appropriate Cisco switch to each layer in
the hierarchical network design model.
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Chapter 1
Any
Questions?
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Chapter 1