Week Two Agenda
Attendance
Announcements
Review week one information
Current week information
Discuss lab assignment
Good example to review before starting
project.
Case Study: Read ACMC Hospital Network
Upgrade, page 121. Answers Appendix A.
Review Week One
Internetworking Terminology
Network segmentation is the breaking up of a
large network into smaller networks. Routers,
switches, and bridges are used to create
network segmentation.
Router is used to connect networks together
and route packets of data from one network to
another. By default, they break up broadcast
domains.
Review Week One
Internetworking Terminology
Switch is a device responsible for multiple
functions such as filtering, flooding, and
sending frames. It works using the destination
address of individual frames. By default,
switches break up collision domains.
Bridge is a device for connecting two
segments of a network and transmitting
packets between them. Both segments must
use identical protocols to communicate. Their
purpose is to filter, send, or flood any
incoming frame, based on the MAC address of
that particular frame.
Review Week One
Internetworking Terminology
Broadcast domain is a group of devices receiving
broadcast frames initiating from any device within the
group. Because they do not forward broadcast frames,
broadcast domains are generally surrounded by
routers. Provide example
Collision domain is the network area in Ethernet over
which frames that have collided will spread.
Collisions are propagated by hubs and repeaters, but
not by LAN switches, routers, or bridges. Provide
example
Review Week One
Internetworking Terminology
Flow control is implemented at the transport
layer to prevent the receiving host buffers from
being overflowed by the send host.
Buffer is used when a machine receives a flood
of datagram's to quickly for a process to
handle. Buffering can only solve the problem
temporarily if the burst is small.
Review Week One
Internetworking Terminology
Windowing is a flow control (Transport layer)
method used with TCP at the Transport layer.
Windows are used to control the amount in
outstanding, unacknowledged data segments.
Metric is the distance to the remote network.
Different routing protocols use different ways of
computing this distance.
Hop count is the number of routers a packet
passes through en route to a remote network.
Review Week One
Internetworking Terminology
Protocol is a send route update packets are called
routing protocols; examples of some common
ones are RIP, EIGRP, and OSPF.
Network addresses are protocol specific network
addresses (192.160.18.0). A router must maintain
a routing table for individual routing protocols
because each routing protocol keeps track of a
network with a different addressing scheme.
Interface is the exit interface a packet will take
when designated for a specific network.
Review Week One
Internetworking Terminology
The Media Access Control (MAC) defines how
packets are placed on the media. Contention
media access is “first come/first served” access
where everyone shares the same bandwidth. MAC
is a Data Link layer function.
Logical Link Control (LLC) is a sub-layer
responsible for identifying Network layer
protocols and then encapsulating them. An LLC
header tells the Data Link layer what to do with a
packet once the frame is received.
Review Week One
Internetworking Terminology
ARP protocol requests what is my MAC address?
RARP protocol requests what is my logical
address (IP)?
Broadcast storms are caused when there are
redundant paths. Provide example.
Spanning Tree Protocol (STP) looks for loops on
the network.
Review Week One
Internetworking Terminology
Logical address: IP address
Physical address: MAC address
Hub: Layer one (physical). No real intelligence.
Switch: Layer two.
Router: Layer three.
Unicast transmission: One source to one
destination.
Broadcast transmission: Distribute to all devices.
Multicast transmission: Group of devices.
Review Week One
Layered Approach
Software developers can use a reference model
to understand computer communication
processes and see what types of functions need
to be accomplished on any one layer. If they
are developing a protocol for a certain layer,
they only want to focus themselves with this
specific layers functions, not those of any other
layer. Another layer and protocol will handle
the other functions.
Review Week One
Layered Approach
Advantages of using the OSI layered model
are:
Allows multiple-vendor development through
standardization of network components.
Allows various types of network hardware and
software to communicate.
Allows changes in one layer from affecting
other layers, so it doesn’t hamper
development.
Review Week One
OSI Model
The top three layers define how the applications within
the end stations will communicate with each other and
with users. The bottom four layers define how data is
transmitted end-to-end.
Application provides a user interface.
Presentation presents data and handles encryption.
Session keeps different applications data separate.
Transport provides reliable or unreliable delivery.
Network provides logical addressing.
Data Link provides access to media using MAC
address.
Physical moves bits between devices, specifies voltage,
wire speed, and pin-out of cables.
Review Week One
OSI Model
Application - File, print, message, database,
and application
Presentation – Data encryption, compression,
and translation services
Session – Dialog control
Transport – End-to-end connection
(connection-oriented)
Network – Routing
Data Link - Framing
Physical – Physical topology
Review Week One
ISO Model
Why was standardization needed?
This standard was created to allow computing
installations to incorporate multiple vendor
hardware and software products within their
operation. Prior to this standardization,
computers could only communicate with
computers from the same manufacturer.
Review Week One
OSI Model
Connection-Oriented communications is a
transport operation. One device first
establishes a connection-oriented session with
its peer system. This is called three-way
handshake. Data is then transferred, and when
finished, a call termination takes place to tear
down the virtual circuit.
Review Week One
OSI Model
Connection-oriented communications threeway hand shake.
Synchronize ->
Negotiate connection <->
Synchronize <Acknowledge ->
Connection established
Data transfer (send segments) <->
Review Week One
TCP/IP Model
The TCP/IP model is basically a condensed
version of the OSI model. It is composed of
four layers.
Process/Application is the integration of the
first three layers of the OSI Model. The
Presentation/Application layer defines
protocols for node-to-node application
communication and also controls userinterface specifications.
Review Week One
TCP/IP Model
Host-to-Host parallels the Transport layer ,
defining protocols for setting up the level of
transmission service for applications. Issues
are addressed like reliable end-to-end
communication and ensuring the error-free
delivery of data. It handles packet sequencing
and maintains data integrity. In summary, this
layer shields the upper three layers from the
Internet layer.
Review Week One
TCP/IP Model
Internet layer exists for routing, and providing
a single network interface to the upper layers.
Network Access bottom layer that handles
similar functions as the Data Link and Physical
layers. It provides media access.
Review Week One
Internetwork Devices
A hub is really a multiple port repeater found
at the Physical layer. A repeater receives a
digital signal and re-amplifies or regenerates
that signal, and then forwards the digital signal
out all active ports without looking at any data.
Physical layer function
The switches and bridges work at the Data
Link layer and filter the network using
hardware (MAC) addresses.
Review Week One
Ethernet Networking
Ethernet is a contention media access method
that allows all hosts on a network to share the
same bandwidth of a link. Ethernet is popular
because it’s readily scalable, meaning it’s
comparatively easy to integrate new
technologies, like Fast Ethernet and Gigabit
Ethernet, into an existing network
infrastructure.
Ethernet networking uses Carrier Sense
Multiple Access with Collision Detect
(CSMA/CD).
Review Week One
Ethernet Networking
Ethernet addressing uses the Media Access Control
(MAC) burned into each and every Ethernet Network
Interface Card (NIC). The MAC, or hardware
address, is a 48 bit address written in a hexadecimal
format.
Review Week One
Half- and Full-Duplex Ethernet
Half duplex uses only one wire pair with a
signal running in both directions on the wire.
Half duplex Ethernet typically 10BaseT.
Full-duplex uses two pairs of wires. It uses a
point-to-point connection between the
transmitter of the transmitting device and the
receive of the receiving device. There are no
collisions to worry about because now it’s like
a freeway with multiple lanes instead of the
single-lane road provided by half-duplex.
Review Week One
Half- and Full-Duplex Ethernet
Typical speeds are 10Mbps, 100Mbps, and
200Mbps for Fast Ethernet. Full-duplex
Ethernet can be used in three situations:
With a connection from a switch to a host.
With a connection from a switch to a switch.
With a connection from a host to a host using a
crossover cable.
Review Week One
Ethernet at the Data Link Layer
Ethernet at the Data Link layer is responsible
for Ethernet addressing, framing packets
received from the Network layer and preparing
them for transmission on the local network
through the Ethernet contention media access
method.
Review Week One
Ethernet at the Physical Layer
Ethernet was first implemented by a group
called DIX (Digital, Intel, and Xerox). They
created and implemented the first Ethernet
LAN specification, which the IEEE used to
create the IEEE 802.3 Committee. This was a
10Mbps network that ran on coax, twistedpair, and fiber physical media.
The IEEE extended the 802.3 to two new
committees known as 802.3U (Fast Ethernet)
and 802.3Z (Gigabit Ethernet).
Review Week One
Ethernet Cabling
Straight-Through Cable
This type of Ethernet cable is used to connect:
Host to switch or hub (h/s <--> host)
Router to switch or hub (h/s <--> router)
Crossover Cable
This type of Ethernet cable is used to connect:
Switch to switch (h/s <--> h/s)
Hub to hub
Host to host
Review Week One
Ethernet Cabling
Rolled Cable
A rolled Ethernet cable can be used to connect
a host to a router console serial communication
(com) port.
(host <--> Router/Switch)
When preparing design drawings, you should
specify the types of cables used between one
device and another.
Review Week One
Data Encapsulation
Encapsulation is a technique used by layered
protocols in which a layer adds header
information to the Protocol Data Unit (PDU)
from the layer above.
Review Week One
Data Encapsulation
Application
Presentation
Session
Transport – PDU (Segment) TCP header/Data
Network – PDU (Packet) IP header/Data
Data Link – PDU (Frame)
LLC header/Data/FCS
MAC header/Data/FCS
Physical – PDU (Bits) 0101110101010101
Review Week One
Serial Transmission
Wide area network (WAN) services are
typically dedicated leased lines using HighLevel Data Link Control , Point-to-Point
(PPP), Integrated Services Digital Network
(ISDN), and Frame Relay. Typical speeds run
at 2400bps to 1.544 Mbps (T-1).
WAN serial connectors use serial transmission,
which is one bit at a time, over a single
channel.
Review Week One
Routing Protocols
Administrative distance (AD): Used to rate the
trustworthiness of routing information received on a
router from a neighboring router
Route Source
Default AD
Connected interface
0
Static route
1
EIGRP (Cisco)
90
IGRP (Cisco)
100
OSPF
110
RIP
120
External EIGRP
170
Review Week One
Cisco Three Layer Hierarchical Model
A hierarchy helps us to understand where
things belong, how things fit together, and
what functions go where. It brings order and
understandability to otherwise complex
situations.
Cisco’s network design model represents the
following three layers:
Core Layer
Distribution Layer
Access Layer
Review Week One
Cisco Three Layer Hierarchical Model
The core layer is responsible for transporting
large amounts of traffic both reliably and
quickly. The main purpose of the network’s
core layer is the switch traffic as fast as
possible. The traffic transported across the core
is common for a majority of users.
If there is a failure at the core layer, every user
can be affected. Fault tolerance at this layer is
a critical issue.
Review Week One
Cisco Three Layer Hierarchical Model
The core layer must be concerned about high levels of
traffic, and the speed and latency of the traffic.
Things you don’t want to do.
Don’t anything to slow down traffic. This includes
adding access lists, routing between virtual local
networks (VLANs), and packet filtering.
Don’t support workgroup access at this level.
Avoid expanding the core when the internetwork
grows (i.e., adding routers).
Review Week One
Cisco Three Layer Hierarchical Model
The core layer must perform at peak level of
efficiency and speed. If performance becomes
an issue in the core, give preference to
upgrades over expansion.
Review Week One
Core Layer Design Recommendations
Design the core for high reliability.
Design for speed as a major consideration.
Select routing protocols with low
convergence times.
Review Week One
Cisco Three Layer Hierarchical Model
The distribution layer is sometimes referred to
as the workgroup layer and is the
communication point between the access layer
and the core. The primary function of the
distribution layer are to provide routing,
filtering, and WAN access and to determine
how packets can access the core.
Review Week One
Cisco Three Layer Hierarchical Model
Distribution Recommendations:
Implement tools such as access lists, of
packet filtering, and of queuing.
Implementation of security and network
policies, including address translation and
firewalls.
Redistribution between routing protocols,
including static routing.
Routing between VLANs and other
workgroup support functions
Review Week One
Cisco Three Layer Hierarchical Model
The access layer controls user and workgroup
access to internetwork resources. The access
layer is sometimes referred to as the desktop
layer. The network resources most users will
be available locally.
Ethernet switching and static routing are
frequently seen in the access layer.
Review Week One
Review Week One
Network Addresses:
Class A: 0 – 127
Class B: 128 – 191
Class C: 192 – 223
Class D: multicast
Class E: Research
Review Week One
Sub netting:
Network address: 192.168.10.0
Dotted decimal notation: xxx.xxx.xxx.xxx
Default subnet: 255.255.255.0
nnnnnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh
Subnet mask: 255.255.255.192 or /26
nnnnnnnn.nnnnnnnn.nnnnnnnn.nnhhhhhh
Binary representation (192.168.10.0):
11000000.10101000.00001010.00000000
Binary representation (255.255.255.192):
11111111.11111111.11111111.11000000
Least significant byte (192): .11000000
Review Week One
Sub netting
10000000 128
11000000 192
11100000 224
11110000 240
11111000 248
11111100 252
11111110 254
/25
/26
/27
/28
/29
/30
/31
Review Week One
Subnet Questions
How many subnets?
How many hosts per subnet?
What are the valid subnets?
What is the broadcast address for each subnet?
What are the valid hosts?
Week Two
Internetworking Terminology
Packet-switched networks is one based on the
transmission of data packets. Dividing a continuous
stream of data into small units called packets, enables
data from multiple devices on a network to share the
same communications channel simultaneously, but
requires precise routing information.
Packet switch is a physical device that makes it
possible for a communication channel to share several
connections, its functions include finding the most
efficient transmission path for packets.
Week Two
Internetworking Terminology
Leased lines are permanent connection
between two points leased from the telephone
company.
Circuit-switched network is used with dial-up
networks such as PPP and ISDN. Passes data,
but needs to set up the connection first, similar
to making a phone call.
Week Two
Internetworking Terminology
DSL is a high-bandwidth connection over the
traditional copper telephone lines. DSL utilizes
modems at either end of the wire. It is another
technology that enables SPs to deliver a wide
range of services to their customers.
Week Two
Internetworking Terminology
Convergence this is the process for all routers
in an internetwork to update their routing
tables and create a consistent view of the
network, using the best possible path. No user
data is passed during a convergence time.
Latency is the time it takes a data packet to get
from one location to another.
Cable is a high-speed copper platform that
supports analog and digital video services over
coaxial cables.
Week Two
Internetworking Terminology
Internet Control Message Protocol (ICMP) is
used by IP for many different services. ICMP
is a management protocol and messaging
service provider for IP. Its messages are carried
as IP datagram's.
If a router receives a packet destined for a
network that the router doesn’t know about, it
will send an ICMP Destination Unreachable
messages back to the sender station.
Week Two
Internetworking Terminology
If a routers memory buffer for receiving an incoming
datagram is full, ICMP messages are sent out.
Each IP datagram is allotted a certain number of
routers, called hops, that it may go through.
An ICMP message is sent to the sending station
informing them that the packet was dropped.
The ping command uses ICMP echo messages to
check the physical connectivity of machines on an
internetwork.
Week Two
Internetworking Terminology
Flood (Broadcast and multicast frames).
Learning
Provide example
Week Two
Reasons Requiring Redesign
If troubleshooting network problems becomes
too frequent or even impossible to manage.
Week Two
Cisco Vision of Intelligent Networks
Network architecture exists today largely
because there is an enormous variety of
network application-level business solutions
and a constant need to integrate applications
into a new architecture. Cisco’s vision and
infrastructure enables customers to build a
more intelligent network infrastructure. The
Cisco Service Oriented Network Architecture
(SONA) focuses on service and applications
rather than a traffic transport-oriented view.
Week Two
Cisco Vision of Intelligent Networks
Integrating networked resources and
information that have been largely separate
entities.
Sharing intelligence across multiple products
and infrastructure layers.
Full network component participation in the
delivery of services and applications.
Week Two
Evolving to an Intelligent Information Network
Phase 1: Integrated transport is to consolidate
all services (data, voice, and video) into an IP
network for secure network convergence.
Phase 2: Integrate Services When the network
infrastructure is converged, IT resources can
be pooled and shared, or virtualized, to
flexibly address the organization’s changing
needs.
Week Two
Evolving to an Intelligent Information Network
Phase 3: Integrated application is where focus
to the network application-aware so that it can
optimize application performance and more
efficiently deliver networked applications to
users.
Week Two
SONA Framework
Networked Infrastructure layer: This layer
insures that all IT resources interconnect
across a converged network foundation. The
objective is to provide connectivity, anywhere
and anytime.
Interactive Services layer: This layer includes
both application networking services and
infrastructure services. This will enable
efficient allocation of resources to applications
and business processes delivered through the
network infrastructure.
Week Two
SONA Framework
Application layer: Includes business
applications and collaboration applications.
The objective of this layer is to meet business
requirements and achieve efficiencies by
leveraging the Interactive Services layer.
Week Two
Week Two
SONA Framework
What are the benefits?
Functionality: Supports the organizational
requirements.
Scalability: Supports growth and expansion of
organizational tasks by separating functions
and products into layers.
Availability: Provides the necessary services,
reliability, anywhere, anytime.
Week Two
SONA Framework
Performance: Provides the desired
responsiveness, throughput, and utilization on
a per application basis through the network
infrastructure and services.
Manageability: Provides control, performance
monitoring, fault detection.
Week Two
SONA Framework
Efficiency: Provides the required network
services and infrastructure with reasonable
operational costs and appropriate capital
investment on a migration path to a more
intelligent network, through step-by-step
network services growth.
Security: Provides for an effective balance
between usability and security while protecting
information assets and infrastructure from
inside and outside users.
Week Two
PPDIOO Network Lifecycle
Prepare phase: The network is built.
Plan phase: A network design specification is
produced.
Design phase: Includes fault detection and
correction and performance monitoring.
Implement phase: Network requirements are
identified.
Operate phase: Business requirements and
strategy related to the network are established.
Week Two
PPDIOO Network Lifecycle
Optimize phase: Based on proactive
management of the network.
Week Two
Design Methodology
Step 1: Identify your customer requirements.
Step 2: Characterize the existing network and
sites.
Step 3: Design the network topology and
solutions, which includes the following:
Possibly building a pilot or prototype
network.
Creating a detailed design document.
Week Two
Design Mythology
1. Planned application and network services.
2. Organizational goals.
3. Technical goals.
4. Technical constraints.
Week Two
Typical Organizational Design Constraints
Budget
Time frame for window of opportunity
Availability of personnel
Experienced
Trainable
Policies
Schedule
Timeline
New applications
Week Two
Typical Organizational Goals
1. Increase revenue
2. Shorter development cycles
3. Improved customer support
4. Open the organization’s information
infrastructure
Week Two
Determining Factors Affecting the Scope of the
Design Project
1. Is the design for a new network or is a
modification of an existing network?
2. Is the design for an entire enterprise network,
a subset of the network, or simply a single
segment or module?
3. Does the design address a single function or
the entire network’s functionality?
4. What OSI protocol layers are involved.
Week Two
New Application Schedule
New network designs often are driven by the
introduction of new network applications. The
implementation time frame for new
applications are often tightly connected and
influence the availability time for network
design.
Week Two
Evaluate Capacities
If parts of the network provide insufficient
bandwidth and cannot be increased because of
technical reasons, the situation must be
resolved by implementing other means.
Traffic analysis provides helpful information
about applications and protocols used in the
network and might reveal any shortcoming in
the network.
Audits can be useful in revealing marginal
situations that might require temporary
changes to the network.
Week Two
Evaluate Capacities
A saturated Ethernet segment occurs at 40
percent network utilization.
A WAN link saturates at about 70 percent
network utilization.
Network characterization can be a lengthy
process. Factors to consider are the size of the
network, and complexity, the experience of the
network engineer, the quality of the
documentation and communication, the
efficiency of the tools.
Week Two
Design Methodology
Use a design document to list and identify the
network. Categories are as follows:
Introduction
Design requirements
Existing network infrastructure
Design
Proof of Concept
Implementation plan
Appendixes
Week Two
Implementation Process
Step 1: Plan the implementation.
Step 2: Implement and verify the design.
Step 3: Monitor and optionally redesign.
Week Two
Network Design Tools
A pilot network: Tests and verifies the design
before the network is implemented to the real
world. Could be a subset of the existing
network.
A prototype network: Tests and verifies a
redesign in an isolated network before it is
applied to the existing network.
Week Two
Network Design Tools
Top-Down Approach can be used to design a
network solution, after the organizational
requirements and documenting the existing
network. This approach allows the designer to
view the picture before worrying about the
details.
Botton-up Approach has a limited usage. If the
network is small or if the network is faced with
a critical situation, should this approach be
used.
Week Two
Network Design Tools
Decision tables or truth tables are used to make
systematic decisions when there are multiple
choices. Decision tables facilitate the selection
of a certain choice from many choices and can
provide helpful justification why a certain
solution was chosen.
Simulation and verification tools and services.
Week Two
Design Verification
The network designer should be involved in
the implementation phase to assist in the
design verification and take corrective action if
necessary. He/she should be available after the
implementation phase for a period of time to
answer questions and provide training for
those performing network support.
Documentation should be in a central location
and maintained with to provide reliable
information for new personnel.
Week Two
Site Contact Information
Site location, name, address, and shipping
address
Site contact’s name and all the possible ways
to reach that person (phone, cell phone, pager,
and e-mail address).
Site owner
Hours of operation
Access procedures, including those for
security, safety, and union labor.
Specific location of equipment.