Week Five Agenda
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Review Week Four
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Review Week Four
Designing an Enterprise Campus
The Enterprise Campus is the foundation for delivering
the applications, services, and user requirements.
Network application characteristics (requirements)
Organizational requirements
Services
Applications
Environment characteristics (requirements)
Geography
Transmission media
Infrastructure device characteristics (requirements)
High availability
High throughput
Network Application Characteristics
Peer-Peer Applications
The peer-peer applications are designed with the
majority of users in mind. It is likely to be
most heavily traffic path from one network
edge device to another through the
organizational network.
Instant messaging
IP phone calls (strict network requirements
for QoS)
File sharing
Videoconferencing systems (requirements
similar to IP phone QoS)
Network Application Characteristics
Quality of Service (QoS)
A set of metrics used to measure the quality of
transmission and service availability of any
given transmission system.
Network Application Characteristics
Client-Local Server Applications
80/20 Workgroup Rule
Because the traffic on corporate networks has
typically increased, it has resulted in more
isolated segments. These isolated segments
resemble departments within a corporate
structure, where segments have their own local
servers, users, and applications. This design
configuration usually has the local servers and
users in the same VLAN. The traffic leaving the
network segment will connect to the campus
backbone to connect to other VLANs or
destinations.
Network Application Characteristics
Client-Server Farm Applications
Large organizations require their users to have
fast, and reliable access to critical applications.
Today, banks, state, and other governmental
organizations needed this access in order to verify
and maintain the integrity of individuals.
Because of this high accountability requirement,
high-performance multilayer switches are
implemented, increased network bandwidth, and
locating the servers in a central location rather
than a workgroup has been achievable due to
scale of economies. These configurations require
high-end LAN switches connected to the fastest
LAN technologies, such as Gigabit Ethernet.
Network Application Characteristics
Client-Server Farm Applications
20/80 Rule
Server farms include the following:
Organizational mail servers (Microsoft
Exchange)
File servers (Microsoft and Sun)
Database servers (Oracle)
Network Application Characteristics
Client-Enterprise Edge Application
The Enterprise Edge application is used to
transmit data between the organization and its
public servers. Data transmission exchange can
come from web based technologies, external
mail, and DNS servers.
Communications with these servers is crucial,
because two-way replication of data. In order to
sustain this high accountability, redundancy and
security are the most important requirements for
these applications.
Network Application Characteristics
Client-Enterprise Edge Application
Connectivity has increased the use of LAN
switching at Layer 2. LAN switching has resulted
in increased performance and more bandwidth for
specific applications requirements of new
organizational applications.
Throughput is the average rate of successful
message delivery over a communication channel.
This data may be delivered over a physical link,
and/or pass through a certain network node. The
throughput is usually measured in bits per second
(bit/s or bps), and sometimes in data packets per
second or data packets per time slot. Throughput
varies between user workgroups and high capacity
links to servers, and/or server farms.
Network Application Characteristics
Client-Enterprise Edge Application
High Availability is a function of the application
and the entire network between the client
workstation and server(s) located in the network.
Summary
Project costs are driven by it’s size and
applications used. If your implementing a peerpeer environment, normally the cost will be low.
If your designing a network with redundancy and
with high end application(s), your costs will be
significantly higher. The types of applications
used will also raise the cost
Environment Characteristics
Environmental characteristics play a significant role
in determining the location of the Enterprise Campus,
the distance between buildings, the size and shapes of
the buildings, and which technology to use to
maximize the organizations investment.
Normally, the distance between nodes and their
locations within an Enterprise Campus drive the type
of technology utilized. In addition to the node (s)
proximity, organizational requirements also influence
the type of technology to be used.
Environment Characteristics
Intra-building campus network structure provides
connectivity for all terminating nodes located in the same
building and provides external access to network
resources. The Building Access and Building
Distribution layers are located in the same building.
User workstations are usually connected to the
Building Access switches in the floor wiring closet with
twisted-pair copper cable. Wireless technology can also
be used to provide connectivity within the building and/or
between buildings without the use of UTP and cables.
WLAN was developed because of the demand for LAN
connections over the air waves in intra-building
environments.
Environment Characteristics
Structural considerations within the network geography
The access layer switches connect to the Building
Distribution switches over optical fiber.
This building configuration could have a
compressed hierarchical network where the
Building Distribution switches and Campus Core
switches are combined.
Environment Characteristics
Structural considerations within the network geography
Interbuilding characterics is where there are two
or more individual buildings connected to each
other. These buildings could have the same
configuration (compressed hierarchical network)
or contain only the Building Access layer. The
distance between buildings is within close
proximity, typically within a few hundred meters
to a few kilometers apart. The medium used to
interconnect campus buildings is normally
customer owned, high-speed optical fiber.
Environment Characteristics
Structural considerations within the network geography
A distant remote building is when the buildings
exceed more than a few kilometers, but are in the
same metropolitan area. For this situation, the
physical media is the most important factor. The
speed and cost are directly related to the media
selection.
Some companies own their own media, like
copper lines , or fiber. However, if they do not
have the connectivity to their remote locations,
the Enterprise Campus must connect through the
Enterprise edge using connectivity options from
public service providers, such as WAN links or
Metro Ethernet.
Environment Characteristics
Structural considerations within the network geography
The service level agreement (SLA) and the risk of
downtime must be addressed if inexpensive and
unreliable links are used. Mission critical application(s)
demand fast-speed links and high-reliability connections.
Enterprise Campus Device Connectivity
An Enterprise Campus can use a variety of different
physical media to connect to their devices. The type of
media used will normally set the precedence for the
next 10 years. The cost of the media should be inline
with the companies budget, and the technical
requirements that would influence signal attenuation
and electromagnetic interference.
Transmission Media
Copper: Twisted-pair cable of four pairs of
isolated wires that are wrapped together in
plastic cable.
Category 5, and 5e for greater speeds of
100 megabits (Mbps) or higher
Category 6 is recommended for Gigabit
Ethernet.
Because of the possibility of signal attenuation
in wires, the maximum cable length is usually
100 meters.
Transmission Media
Signal attenuation affects the propagation of
waves and signals in electrical circuits, in
optical fibers, as well as in air (radio waves). It
is a damping affect on the original signal
strength.
Distances greater than 100 meters may require
Long-Reach Ethernet (LRE). LRE is a Cisco
proprietary technology that runs on voice
grade copper wire, and it accommodates the
greater distance to access the technologies in
WANs.
Transmission Media
Different types of fiber
Multimode (MM) fiber carries multiple
light waves or modes concurrently, each at
a slightly different reflective angle within
the optical fiber core. Because modes tends
to spread out over longer lengths,
multimode fiber is used for shorter
distances. The diameter of multimode
fiber is 50 to 62.5 micrometers.
Transmission Media
Different types of fiber
Single-mode (SM) fiber carries a single wave
(laser) of light. The diameter of a single-mode
fiber is 2 to 10 micrometers. Single-mode fiber
preserves the dispersion and loss of light, and
therefore is used for distant transmissions. SM is
an excellent solution for future high-speed
connectivity.
In summary, optical fiber is used where the
transmission distance exceeds 100 meters and
immunity to electromagnetic interference is
required.
Transmission Media
Wireless is also referred to as a radio receiver. The
term refers to without cables or cords, chiefly using
radio frequencies and inferred rays.
WLAN are useful when it comes to extending
an existing network or replacing a traditional
cabled network.
Inside buildings, the WLAN equipment includes
an access point (AP), which acts similar to a
wired hub, and PC client adapter.
Transmission Media
IEEE Standards
802.11g allow speeds up to 54 Mbps in the 2.4 GHz
band over a range of 100 feet.
802.11b supports speeds up to 11 Mbps in the 2.4
GHz band.
802.11a supports speeds up to 54Mbps in the 5 GHz
band.
See chart on page 233 in your Designing for Cisco
Internetwork Solutions (DESIGN) text.
Infrastructure Device Characteristics
Today, most network end users are connected using
switched technology and not shared media segment.
The benefits of switched technology are dedicated
network bandwidth for each device on the network.
Switched networks also support infrastructure
services, like QoS, security, and network
management.
LAN switches in the recent past were for Layer 2
devices. Now, Layer 2 switching supports multiple
simultaneous frame flows. Multilayer switching
performs packet switching and several functions at
Layer 3 and higher up in the OSI layers. The
technology is moving in the direction of replacing
routers in the LAN switched environment.
Infrastructure Device Characteristics
Differences between Layer 2 and Multilayer
Switching
Multilayer switching provides different
information inside the frame to determine the
correct output interface.
Multilayer switching forwards frames based on
network layer information rather than MAC
address.
Multilayer switching is a hardware based
switching and routing integrated into a single
platform.
Infrastructure Device Characteristics
IP Multicast
IP multicast technology is a way to sending
one data stream to multiple end users and
maintain required bandwidth. The data stream
is sent from one source, and replicated for the
registered users at the destination.
Class D IP address ranges from 224.0.0.0 to
239.255.255.255.
Cisco Protocols for Routers and Hosts
Internet Group Management Protocol (IGMP)
The IGMP protocol is used between the router
and the registered hosts intended to receive
multicast data. The hosts notify the router to
join or leave a specific multicast group.
Cisco Group Management Protocol (CGMP)
The CGMP protocol is used by switches and
routers. The router informs the switches
directly connected to them about the IGMP
registration(s) from it’s hosts to receive
multicast data stream.
Cisco Protocols for Routers and Hosts
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.
QoS Considerations
Classification and marking
Packet classification – partitioning traffic into
multiple priority levels, or class of service
Marking – changing the frame priority or class of
service
Congestion management
Queuing – separating traffic into different queues.
The marking inside the frame or packet is used to
determine which queue
Scheduling – is used to determine the order in
which the queues are serviced
QoS Considerations
Policing and shaping is a process of identifying
violations of threshold levels and reduces a stream of
data to a predetermined rate or level.
Traffic shaping buffers the frames for a short period
of time. Policing drops or lowers the priority of the
frame in violation.
Traditional WAN Technologies
Introduction to WANs
A wide area network (WAN) is a computer network
that covers a broad area. Typically, it is any network
whose communications links cross metropolitan,
regional, or national boundaries. WAN transmission
facilities are generally provided by service providers
(SP), such as telephone companies.
Service providers charge for the switching and
connectivity they provide. This charge is called a
tariff, for the services provided by the WAN.
WAN Connection Types
Connecting LANs together over a data communications
equipment (DCE) network
Dedicated WANs utilize synchronous serial
connections.
Circuit-switched WANs use telephone company
networks with asynchronous serial, and ISDN.
Packet-switched WANs use a service provider with
synchronous serial.
WAN Connection Types
Leased lines are typically point-to-point connections
or a dedicated connection. The WAN connection path
from the Customer Premise Equipment (CPE),
through the DCE switch, to the CPE of the remote
site, allowing DTE to communicate at any time with
no setup procedures before transmitting data. It uses
synchronous serial lines up to 45 Mbps.
Time Division Multiplexing (TDM) is a technique for
assigning bandwidth on a single wire, based on preassigned time slots, to data from several channels.
Bandwidth is allocated to each channel regardless of
a station’s ability to send data.
WAN Connection Types
Circuit-switching sets up a line like a phone call. No
data can transfer before the end-to-end connection is
established. Circuit switching uses dial-up modems
and ISDN. It is used for low-bandwidth data
transfers.
WAN Connection Types
Packet switching is a WAN switching method that
allows you to share bandwidth with other companies
to save money. Packet switching is excellent for
bursty data transfers, packet switching can save you
money. However, if you have constant data transfers,
you will need a leased line. Frame relay and X.25 are
packet-switching technologies . Speeds can range
from 56Kbps to 2.048Mbps.
WAN Protocols
Point-to-Point Protocol (PPP) is an industry standard
protocol. PPP can be used to create point-to-point
links between different vendors’ equipment. It allows
authentication and multilink connections and can be
run over asynchronous and synchronous links.
Asynchronous Transfer Mode (ATM) was created for
time sensitive traffic, providing simultaneous
transmission of voice, video, and data. ATM uses
cells rather than packets that are a fixed 53-bytes
long.
WAN Protocols
High-Level Data Link Control (HDLC) was derived
from Synchronous Data Link Control (SDLC), which
was created by IBM as a Data Link layer connection
protocol. HDLC is a connection-oriented protocol at
the Data Link layer. HDLC was not intended to
encapsulate multiple Network layer protocols across
the same link. The HDLC header carries no
identification of the type of protocol being carried
inside the HDLC encapsulation. Because of this, each
vendor that uses HDLC has their own way of
identifying the Network layer protocol, which means
that each vendor’s HDLC is proprietary for their
equipment.
WAN Protocols
Link Access Procedure, Balanced (LAPB) was
created to be used as a connection-oriented protocol
at the Data Link layer for use with X.25. It can be
used as a simple Data Link transport. LAPB has a
tremendous amount of overhead because of its strict
timeout and windowing techniques. You can use
LAPB instead of the lower-overhead HDLC if your
link is very error prone.
WAN Protocols
Integrated Services Digital Network (ISDN) is a set
of digital services that transmit voice and data over
existing phone lines. ISDN can offer a cost-effective
solution for remote users who need a higher speed
connection that analog dial-up links offer. ISDN is
also a good choice as a backup link for other links.
ISDN allows voice and data to be transmitted
simultaneously across the world using end-to-end
digital connectivity. In addition, it offers increased
bandwidth, reduced call setup time, reduced latency,
and lower signal-to-noise ratios, compared to analog
dialup.
WAN Protocols
Frame Relay is a packet-switched technology that has
been around since the 1980s. Frame Relay is an
industry standard networking protocol that handles
multiple virtual circuits (VC) using a derivation of
HDLC encapsulation between connecting devices.
Frame Relay is a Data Link and Physical layer
specification that provides high performance. Frame
relay typically can run at speeds of 64Kbps to
1.544Mbps. Frame Relay provides features for
dynamic bandwidth allocation and congestion
control.
WAN Protocols
Multiprotocol Label Switching (MPLS) replaces the
hop-by-hop, individually routed packet model with a
connection-oriented model that establishes ‘paths’ to
destinations. Instead of routing each packet based
upon its destination address, each packet is labeled
such that it can be switched along a pre-defined
path. In addition, MPLS defines traffic engineering
methods that enables these paths to have associated
quality-of-service attributes. Thus, a single
destination may have multiple paths leading to it,
with one path used for voice, one for video, and one
for data.
WAN Protocols
Which WAN service is the best one to use?
Answer: None of them. The best WAN service is the
one you can get in your neighborhood or at your
company. Since you don’t have many options to
choose from, call your local service provider and ask
what they can provide to you.
Transmission Modes
For digital transmission, all information is converted
into binary codes of 0 and 1 for transmission. It is
necessary to notify the other end of precise
information such as where the data starts and how
long the interval of data is.
“Synchronous”and“asynchronous”are the two modes
for communicating this information, and it is
necessary to confirm which mode each end supports.
With Synchronous Transmission Mode, 64 kbps is the
highest available transmission speed, while 57.6 kbps
is the highest for Asynchronous Transmission Mode.
Transmission Modes
Synchronous signals, signals that play the role of
signs, are added to the top of the data to be
transmitted. With these signals, computers can
precisely determine the first position of the
characters. This mode can transmit data accurately,
making it appropriate for corporate information
networks.
Asynchronous signals, instead, use a portion of the
data that has arrived as a clue, the first position of the
character is identified. Two bits are added to each
character, a start bit for the beginning and an end bit
for the end, making the transmission speed slower.
Packet-Switched Network Topologies
Star topology is a LAN physical topology with
endpoints on the network converging at a common
central switch (known as a hub) using point-to-point
links. A logical ring topology can be configurated as a
physical star topology using a unidirectional closedloop star rather than point-to-point links. That is,
connections within the hub are arranged in an internal
ring.
Full mesh topology is where every node has either a
physical or a virtual circuit linking it to every other
network node. A full mesh supplies a great deal of
redundancy but is typically reserved for network
backbones because of its expense.
Packet-Switched Network Topologies
Partially meshed topology is where some network
nodes form a full mesh, but others are attached to
only one or two nodes in the network.
WAN Transport Technologies
DS0 Rate is known as the base channel bandwidth of
64Kbps. A bandwidth of 64Kbps is the bandwidth
required for an uncompressed digitized phone
conversation.
Standard speech less then 4KHz; analog speech is
filtered at 4KHz before being sampled.
Nyquist Theorem sample at a rate at least two
times the input frequency to obtain a signal that
represents the true signal.
Each sample is encoded into 8 bit octets. This
DS0 rate is 8KHz. Per second times 8 bits per
sample, which is 64Kbps.
Technologies
Metro Ethernet technology is based on Ethernet
technology to offer the best cost-effective, high speed
connectivity for MAN and WAN.
DSL technology is a high-bandwidth technology over
the traditional copper lines. It is designed to work
with two modems at either end of the wire. DSL is a
transmission technology that is used by SPs to deliver
a wide range of services to subscribers.
Asymmetric DSL (ADSL) used over short distances
(less then 21meters). Most common type used.
Frequency range 100KHz to 1.1Hz. ADSL allows
PSTN tetphone service concurrently on the same line.
Technologies
Symmetric (SDSL) DSL allows traffic to be
transmitted in both directions at the same speed over
a single twisted pair. The distance served with SDSL
is 10K feet or 3048.8 meters. SDSL is often referred
to as single-pair DSL. SDSL is excellent for running
applications like email and web servers.
Long Reach Ethernet (LRE) is a WAN access
technology which allows for greater distance than the
traditional Ethernet provides.
Cable technology is another high-speed copper
platform that supports both analog and digital video
services over a coaxial cable.
Technologies
• Lineshare ADSL includes speeds ranging from 1.5 Mbps to 6.0
Mbps. Prices start at $55/month.
• Dedicated ADSL is a data line designed for customers who
want the benefits and features of DSL on a dedicated
connection, with speeds up to 15 Mbps. Prices start at
$79/month.
• SDSL (or symmetric DSL) is an affordable alternative to T1.
With SDSL, information downloads and uploads at the same
speed. Prices start at $120/month.
• IDSL is a symmetrical technology providing equal upload and
download speeds. Due to its wide availability, it is
recommended for users unable to obtain other DSL services
at their location. Prices start at $120/month.
Technologies
Cabling technology makes use of channels for
upstream and downstream data flow. One application
channel in the coaxial cable is used to upstream
signals from the modem to the Cable Modem
Termination System (CMTS). The output from the
CMTS is handed to either the WAN or the PSTN. A
different channel is used for the downstream signals
from these Internet Service Providers to the CMTS to
the modem.
The CMTS converts signals from the modem to IP
packets prior to handing them to the IP router for
transmission across the Internet. Downstream signals
are modulated for transmission across the cable to the
modem.
Technologies
Internet download bandwidth over a cable TV line is
shared 27 Mbps.
Internet upstream bandwidth over the same shared
cable is 2.5 Mbps.
Wireless technology electromagnetic waves carry RF
signals. It is the option of some, that these waves
could be harmful to humans.
Synchronous Optical Network/Digital Hierarchy
(SONET/SDH) is the ANSI standard for synchronous
transmission on fiber optic media. It specifies a base
signal rate of 51,84 Mbps and a set of multiples of
that rate, known as Optical Carrier levels, up to 2.5
Gbps.
Technologies
OC-1 = 51.85 Mbps
OC-3 = 155.52 Mbps
OC-12 = 622.08 Mbps
OC-24 = 1.244 Gbps
OC-48 = 2.488 Gbps
OC-192 = 9.952 Gbps
OC-255 = 13.21 Gbps
Technologies
SONET/SDH is a circuit based technology that
provided uses high speed circuits using TDM
framing.
Dark fiber is a fiber optic cable(s) leased from an SP.
Fiber is typically connected to a company’s own
infrastructure. Dark fiber got its name after the dotcom burst. Many of the companies that had the rights
to these fiber networks either went bankrupt, or, had
to abandon their goals of utilizing this fiber. This
resulted in hundreds of thousands of miles of “unlit”
(dark) fiber. Dark fiber is optical fiber that is lying in
the ground unutilized
WAN Design
The network designer should design the Enterprise
Edge based on the PPDIOO methodology.
Analyzing customer requirements
Characterizing the existing network and sites.
Designing the network topology and solutions.
Observe the WAN Physical Media Bandwidths table
in your text book on page 320.
WAN Bandwidth Optimization
Compression is used to reduce the data size to
conserve transmission time.
Upcoming Assignments
Assignment 5-1, Concept Question 4 due May 30, 2011
Assignment 6-1, Concept Question 5 due June 6, 2011
Assignment 4-1-2, Basic Routing and LAN Switching
Configuration due June 27, 2011
Assignment 4-1-3, Basic Network Troubleshooting due
July 25, 2011