Transcript Week One Agenda - Computing Sciences

Week One Agenda
Attendance
Announcements
Course description
Review previous week information
Review current week information
Quiz
Week One Review
Course Objective
This course was developed to parallel the Certified
Design Professional (CCDP) certification.
Build upon the base level of the CCNA knowledge
and experience.
Design simple routed LAN, routed WAN, and
switched LAN and ATM networks.
Use Network-layer lists.
Filter with access lists.
Use and propagate VLAN.
Evaluate existing network components.
Week One Review
History of Cisco
Len and Sandy Bosack, 1980s
Worked in different departments at Stanford
University. They were having trouble getting
their individual system to communicate.
They built a gateway server that made it easier
for their disparate computers to communicate
using the IP protocol.
Week One Review
Internetworking Basics
Networks and networking have grown exponentially
over the last 30 years. This technology has evolved at
light speed just to keep up with the huge increases in
basic mission-critical user needs. Currently, there is a
basic need to use VoIP, increase transmission speeds,
and combine voice, data, and video for medium and
enterprise sized networks. This will involve the
design of new and/or the re-design of existing
networks.
Network is where data is sent and received via cables
(e.g., telephone lines or fiber optics ) or wireless relay
systems. Networks contain a variety of hardware
devices and software implementations to accomplish
transmitting data.
Week One Review
Internetworking Basics
Network segmentation is the breaking up of a
large network into smaller networks. Routers,
switches, and bridges are used to create
network segmentation.
Routers are used to connect networks together
and route packets of data from one network to
another. By default, they break up broadcast
domains.
Week One Review
Internetworking Basics
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.
Bridges 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.
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.
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.
Week One Review
Internetworking Models
Open Systems Interconnection (OSI) reference
model was introduced in the late 1970s. Created
by the International Organization for
Standardization.
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.
Week One Review
Layered Approach
A reference model is a conceptual blueprint of
how communications should take place. It
addresses all the processes required for
effective communication and divides these
processes into logical groupings called layers.
Designs such as the OSI Model, are known as
layered architecture.
Example: Start up company. Identify the tasks
involved. Group similar tasks into
departments. These departments are a
metaphor for the layers in this scenario.
Week One Review
Layered Approach
Similarly, 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.
Week One Review
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.
Week One Review
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.
Week One Review
OSI Model
Application - File, print, message, database,
and application
Presentation – Data encryption, compression,
and translation services
Session – Dialog control
Transport – End-to-end connection
Network – Routing
Data Link - Framing
Physical – Physical topology
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OSI Model
Network devices that operate at all seven
layers of the OSI model include:
Network management stations
Web servers
Gateways
Network hosts
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OSI Model
Flow control is implemented at the transport layer to prevent
the receiving host buffers from being overflowed by the send
host. This is an event that can result in data loss. Reliable data
transport employs a connection-oriented communications
session between systems, and the protocols involved ensure
that the following is achieved:
The segment delivered are acknowledged back to the sender
upon their reception.
Any segments not acknowledged are retransmitted.
Segments are sequenced back into proper order upon arrival
at their destination.
A manageable data flow is maintained in order to avoid
congestion overloading, and data loss.
Week One Review
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.
Week One Review
OSI Model
Connection-oriented communications threeway hand shake.
Synchronize ->
Negotiate connection <->
Synchronize <Acknowledge ->
Connection established
Data transfer (send segments) <->
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OSI Model
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. If the flood of
datagram's is too intense and the capacity is
exhausted, it will discard any additional
datagram's that arrive.
Week One Review
OSI Model
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.
The data and route update packets are used at
the Network layer. The data packet to
transport user data through the internetwork.
Route update packets are used to update
neighboring routers about the networks
connected to all routers within the
internetwork.
Week One Review
OSI Model
Protocols that 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. 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 destinated for a specific network.
Week One Review
OSI Model
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.
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.
Week One Review
OSI Model
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.
Week One Review
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.
Week One Review
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.
Week One Review
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.
Week One Review
Internetwork Devices
Hubs are really multiple port repeater found
at the Physical layer. A repeater receives a
digital signal and reamplifies 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.
Week One Review
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 FastEthernet and Gigabit
Ethernet, into an existing network
infrastructure.
Ethernet networking uses Carrier Sense
Multiple Access with Collision Detect
(CSMA/CD).
Week One Review
Ethernet Networking
CSMA/CD is a protocol that helps devices
share the bandwidth evenly without having
two devices transmit at the same time on the
network medium. This protocol was created to
overcome the problem of those collisions that
occur when packets are transmitted
simultaneously from different nodes.
Week One Review
Ethernet Networking
A good collision management protocol is
needed like CSMA/CD because when a node
transmits in a network, all other nodes on the
network receive and examine that
transmission. Only bridges and routers can
effectively prevent a transmission from
propagating throughout the entire network.
Week One Review
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.
Week One Review
Half- and Full-Duplex Ethernet
Typical speeds are 10Mbps, 100Mbps, and
200Mbps for FastEthernet. 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.
Week One Review
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.
Week One Review
Ethernet at the Data Link Layer
There are four different types of Ethernet
frames available:
Ethernet_II
IEEE 802.3
IEEE 802.2
SNAP
Week One Review
Ethernet at the Data Link Layer
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.
Week One Review
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 (FastEthernet)
and 802.3Z (Gigabit Ethernet).
Week One Review
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
Week One Review
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)
Week One Review
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.
Week One Review
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
Week One Review
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. Parallel transmission sends at least 8
bits at a time.
Week One Review
Data Terminal Equipment and Data
Communication Equipment
What is a DTE and DCE?
DTE – router interface and they connect into
DCE. A channel service unit/data service unit
(CSU/DSU). The CSU/DSU then plugs into a
demarcation location (demarc) and is the
service provider’s last responsibility. The
demarc is usually an RJ-45 female connector
located near your equipment.
Week One Review
Data Terminal Equipment and Data
Communication Equipment
A DCE supplies the physical connection to the
network, forwards traffic, and provides a
clocking signal to synchronize data
transmission between DTE and DCE devices.
Handout network product icons
Week One
Routing Protocols
Administrative distance (AD) is used to rate
the trustworthiness of routing information
received on a router from a neighboring
router. AD values range from 0 to 255, where
0 is the most trusted and 255 means no traffic
will pass via this route.
Week One
Routing Protocols
Route Source
Connected interface
Static route
EIGRP (Cisco)
IGRP (Cisco)
OSPF
RIP
External EIGRP
Default AD
0
1
90
100
110
120
170
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
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.
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.
Do anything to slow down traffic. This includes
adding access hosts, 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).
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.
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.
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 premiary function of
the distribution layer are to provide routing,
filtering, and WAN access and to determine
how packets can access the core.
Week One
Cisco Three Layer Hierarchical Model
Distribution Recommendations:
Implement tools such as access lists,
packet filtering, and 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
Week One
Cisco Three Layer Hierarchical Model
Distribution Recommendations:
Definitions of broadcast and multicast
domains.
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.
Week One
Network Terms
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.
Week One
Network Terms
ARP protocol: What is my MAC address?
RARP protocol: What is my logical address?
Broadcast storms: Caused when there are
redundant paths.
Spanning Tree Protocol (STP): Looks for loops on
the network.
Week One
Network Addresses:
Class A: 0 – 127
Class B: 128 – 191
Class C: 192 – 223
Class D: multicast
Class E: Research
Week One
Subnetting:
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
Week One
Subnetting
10000000 128
11000000 192
11100000 224
11110000 240
11111000 248
11111100 252
11111110 254
/25
/26
/27
/28
/29
/30
/31
Week One
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?