Transcript Week_Ten_Networkx

ITEC 275
Computer Networks – Switching, Routing, and
WANs
Week 10
Professor Robert D’Andrea
Winter 2017
Agenda
• The course is 2/3 completed
• Learning Activities
• SNMP – MIB
• PPP
• Cable Modems and DSL
• Leased Lines, SONET, Frame Relay, Metro
Ethernet, ATM
• Selecting a WAN Service Provider
• Metro Ethernet
Enterprise Technologies and Devices
• Remote access networks
• Wide area networks (WANs)
• Devices
– End user remote access devices
– Central site remote access devices
– VPN concentrators
– Routers
Enterprise Selection Criteria
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Business requirements and constraints
Cost
Technical goals
Bandwidth requirements
Quality of Service (QoS) requirements
Network topology
Traffic flow and load
Enterprise Selection Criteria
SNMP (Simple Network Management Protocol) is one of the
most commonly used technologies when it comes to network
monitoring.
SNMP components:
•Managed devices, agents, and network-management systems
(NMSs). A managed device is a node that has an SNMP agent and
resides on a managed network. These devices can be routers and
access servers, switches and bridges, hubs, computer hosts, or
printers.
•Agent is a software module residing within a device. This agent
translates information into a compatible format with SNMP.
•An NMS runs monitoring applications. They provide the bulk of
processing and memory resources required for network management.
Enterprise Selection Criteria
MIB (Management Information Base)
and is the collection of information, which is
organized hierarchically.
The pieces of information in the MIB are
accessed by SNMP. There are two types of
MIBs:
•Scalar objects define a single object instance.
•Tabular object define multiple related object
instances grouped in MIB tables.
Enterprise Selection Criteria
OIDs (Object Identifiers ) uniquely
identify the managed objects in an MIB
hierarchy. It can be depicted as a tree whose
nodes are assigned by different organizations.
Generally, the OID is a long sequence of
numbers, coding the nodes, separated by dots.
Top level MIB object IDs (OIDs) belong to
different standard organizations. Vendors
define private branches including managed
objects for their own products.
Enterprise Selection Criteria
1 iso
1.3 org
1.3.6 dod
1.3.6.1 internet
1.3.6.1.1 directory
1.3.6.1.2 mgmt
1.3.6.1.2.1 mib-2
1.3.6.1.2.1.2.2.1.3 ifType
1.3.6.1.2.1.10 transmission
1.3.6.1.2.1.10.23 transmission ppp
1.3.6.1.2.1.27 application
1.3.6.1.2.1.28 mta
1.3.6.1.2.2 pib
1.3.6.1.3 experimental
1.3.6.1.4 private
Enterprise Selection Criteria
SNMP basically works from the principle that
the network management systems send out a request
and the managed devices return a response. The four
operations are: Get, GetNext, Set, and Trap.
SNMP messages consist of a header and a PDU
(Protocol Data Unit). The headers consist of the
SNMP version number and the community name.
The community name is used as a password to
increase security in SNMP.
Enterprise Selection Criteria
MIBs are collections of definitions which
define the properties of the managed object within
the device to be managed.
Examples:
•Objects to monitor a printer - different
cartridge states and the number of printed files
•Objects to monitor a switch - incoming and
outgoing traffic and rate of package loss or the
number of packets addressed to a broadcast
address.
Enterprise Selection Criteria
Every managed device keeps a database
of values for each of the definitions written in
the MIB. So, the available data is actually not
dependent on the database, but on the
implementation. Each vendor of SNMP
equipment has their proper section of the MIB
tree structure at their disposition.
Enterprise Selection Criteria
From an organizational point of view, all
manageable features of all products (from each
vendor) are arranged in this MIB tree structure.
Each 'branch' of this tree has a number and a
name, and the complete path from the top of
the tree down to the point of interest forms the
name of that point. This complete path is the
OID, the "identifier of an object" respectively.
Enterprise Selection Criteria
In summary, nodes near the top of the
tree structure are general in nature. As you
traverse the tree, the names get more specific
until you reach the bottom, where each node
represents a particular feature on a specific
device or agent.
Remote Access Technologies
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The Point-to-Point Protocol (PPP)
Integrated Services Digital Network (ISDN)
Cable modems
Digital Subscriber Line (DSL)
Remote Access Technologies
So, what is Point Point Protocol?
PPP (Point-to-Point Protocol) is a protocol for
communication between two computers using a serial interface,
typically a personal computer connected by phone line to a
server. For example, your Internet server provider may provide
you with a PPP connection so that the provider's server can
respond to your requests, pass them on to the Internet, and
forward your requested Internet responses back to you. PPP uses
the Internet protocol (IP) (and is designed to handle others). It is
sometimes considered a member of the TCP/IP suite of protocols.
Relative to the Open Systems Interconnection (OSI) reference
model, PPP provides layer 2 (data-link layer) service. Essentially, it
packages your computer's TCP/IP packets and forwards them to
the server where they can actually be put on the Internet.
Point-to-Point Protocol (PPP)
• PPP is used with synchronous, asynchronous,
dial-up, and ISDN links
• PPP defines an encapsulation scheme for
transporting different network-layer protocols
• PPP supports authentication:
– Password Authentication Protocol (PAP)
– Challenge Handshake Authentication Protocol
(CHAP). CHAP more secure than PAP
Point-to-Point Protocol (PPP)
• The Internet Engineering Task Force (IETF)
developed PPP as a standard data link layer
protocol for transporting various protocols
across serial, point-to-point links.
• PPP can be used to create point-to-point links
between different vendor’s equipment.
• PPP uses a Network Control Protocol field in
the Data Link header to identify the Network
layer protocol.
Point-to-Point Protocol (PPP)
• PPP can be used to connect a single remote user
to a central office, or to connect a remote office
with many users to a central office.
• PPP is a data-link protocol that can be used over
either asynchronous serial (dial-up) or
synchronous serial (ISDN) media with the use
of LCP (Link Control Protocol) to build and
maintain data-link connections.
PPP Layers
Network Control Protocol (NCP)
Link Control Protocol (LCP)
Encapsulation based on
High-Level Data-Link Control Protocol (HDLC)
Physical Layer
PPP
Point-to-Point (PPP) is a data link protocol
commonly used in establishing a direct
connection between two networking nodes. It
provides connection authentication, transmission
authentication, and compression.
PPP is used over many types of physical
networks including serial cable, phone line, trunk
line, cellular telephone, and fiber optic links such
as SONET. PPP is also used over the Internet
access connections (broadband).
PPP
PPP
PPP
Leased lines: ISP is the service provider. PPP is the
protocol. The user does not want to share the wire or the
expense of leasing a wire with another user.
Packet Switching: Telco is the service provider. Frame
Relay protocol. The user shares the service with other
users to save money. Frame Relay is an alternate
technology to PPP.
Circuit Switching: POTS or ISDN are the service
providers. PPP is the protocol.
Data is sent encapsulated over the public
telephone network system.
PPP
Metro Ethernet: Telco is the service provider. Ethernet
protocol.
The user wants the data sent at a very high speed.
Broadband: Telco is the service provider. PPPoE,
PPPoA, Ethernet protocols.
PPP
PPP encapsulation includes:
1. Line set up using LCP. The link is established
during this phase.
2. Authentication, encryption and compression
(optional).
2.1 Password Authentication Protocol (PAP)
Avoid using PAP because it sends the password in ASCII
format (clear text).
2.2 Challenge Handshake Authentication
Protocol (CHAP) never sends the password, but sends a
challenged handshake processes.
PPP
3. PPP carries packets from many different
protocol suites using NCP. The NCP sends packets to
negotiate the needed settings.
Is all data encrypted?
No
Encryption is used to simply verify the passwords.
Multi Link PPP (MPPP)
An ordinary dial-up modem connection to the
Internet through an Internet service provider (ISP)
usually uses PPP as its wide area network (WAN) datalink protocol, but there are times when the 56-Kbps speed
provided by V.90 modems is insufficient. MPPP allows
multiple physical dial-up links to be inverse multiplexed
together to form a single high-bandwidth logical PPP
connection between the dial-up client and the ISP. MPPP
works by ordering the data frames from the client across
the multiple PPP channels and recombs them at the ISP’s
termination point, and vice versa.
Multi Link PPP (MPPP)
MPPP defines protocols for splitting the data
stream into PPP packets, sequencing the packets,
transmitting them over separate logical data links, and
then recombining them at the receiving station.
Multi Link PPP (MPPP)
Multilink MPPP
Inverse multiplexing speeds up data transmission
by dividing a data stream into multiple concurrent
streams that are transmitted at the same time across
separate channels (such as a T-1 or E-1 lines) and are
then reconstructed at the other end back into the original
data stream. Just the reverse of ordinary multiplexing ,
which combines multiple signals into a single signal,
inverse multiplexing is a technique commonly used
where data in a high-speed local area network (LAN)
flows back and forth into a wide area network (WAN)
across the "bottleneck" of a slower line such as a T-1
(1.544 Mbps).
Multilink MPPP
Various multiplexing methods are possible in
terms of the channel bandwidth and time, and the signal,
in particular the frequency, phase or time. The two basic
methods are:
•Frequency Division Multiplexing (FDM) is derived
from Amplitude Modulation (AM) technique in which
the signals occupy the same physical ‘line’ but in
different frequency bands. Each signal occupies its
own specific band of frequencies all the time, i.e. the
messages share the channel bandwidth.
AM vs FM
FDM
Multi Link Point Point Protocol (MPPP)
Multi Link PPP
• Adds support for channel aggregation of PPP.
Channel aggregation can be used for load
sharing and providing extra bandwidth. With
channel aggregation, a device can automatically
bring up additional channels as bandwidth
requirements increase.
• MPPP ensures that packets arrive in order at the
receiving device.
Multi-chassis MPPP
Cisco’s enhancement to PPP is MPPP.
MPPP allows WAN administrator to group
multiple access servers into a single stack group.
The user’s traffic can be split and reassembled
across multiple access servers in the stack group.
Multi-chassis Multi Link PPP
Stack group
ISDN
Offload
server
Analog
CHAP
Challenge-Handshake Authentication
Protocol (CHAP) is a more secure procedure for
connecting to a system than the Password
Authentication Procedure (PAP).
CHAP provides a three-way hand-shake.
Provides protection by verifying a remote node
with a three-way hand shake and a variable
challenge value that is unique and unpredictable.
CHAP
ISDN
• Digital data-transport service offered by regional
telephone carriers (Telcos).
• Circuit-switched service that carries voice and data.
• ISDN is a set of digital services that transmits voice and
data over existing phone lines.
• Cost-effective remote-access solution for telecommuters
and remote offices
– Cost of an ISDN circuit is usually based on a
monthly fee plus usage time
• Good choice as a backup link for another type of link,
for example, Frame Relay.
• Channel aggregation is popular with ISDN links.
ISDN Interfaces
Basic Rate Interface (BRI)
2B
64 Kbps
64 Kbps
D
16 Kbps
}
144
Kbps
Primary Rate Interface (PRI)
64 Kbps
23B or 30B
D
64 Kbps
}
1.544 Mbps in U.S.
2.048 Mbps in
Europe
ISDN Components
R
Non-ISDN
device
(TE2)
S/T
NT1
TA
2-wire
circuit
4-wire
circuit
ISDN
device
(TE1)
ISDN
device
(TE1)
U
S/T
U
To ISDN
service
NT1
S
T
NT2
To ISDN
service
U
To ISDN
service
NT1
U
ISDN device (TE1)
with built-in NT1
NT1
To ISDN
service
Cable TV Service
CATV (originally "community antenna television,"
now often "community access television") is more
commonly known as "cable TV." Television programs
were brought to millions of people throughout the world
who were connected to a community antenna, cable TV.
Today, CATV has become an increasingly popular
way to interact with the World Wide Web and other new
forms of multimedia information and entertainment
services.
Cable TV Service
• Operates over the coax cable used by cable TV
providers
• Much faster than analog modems, and usually
much faster than ISDN (depending on how many
users share the cable)
– 25 to 50 Mbps downstream from the head end
– 2 to 3 Mbps upstream from end users
• Standard = Data Over Cable Service Interface
Specification (DOCSIS)
Cable TV Service
• Coax Cable does not require dial-up.
• Cable modem operates more like a LAN.
• Cable-network providers offer hybrid fiber/coax
(HFC) systems that connect CATV networks to
the service provider’s high-speed fiber-optic
network.
• HFC systems allow connections of home PCs
and small LANs to high-speed access to the
Internet or to a private network using VPN.
Cable TV Service
• CATV (Cable Modem Termination System)
provides high-speed connectivity for cable
modems.
• Cable modem solution for remote users or
remote offices is the sharing a single cable and
the types of applications they use.
Digital Subscriber Line (DSL)
• High-speed digital data traffic over ordinary
telephone wires.
• Sophisticated modulation schemes mean higher
speeds than ISDN.
– Speeds range from 1.544 to 9 Mbps
• Actual bandwidth depends on type of DSL
service, DSL modem, and many physical-layer
factors.
• Symmetric communication (SDSL) traffic flow
travels at the same speed up to 1.544 Mbps.
• Asymmetric DSL (ADSL) very popular
– Downstream faster than upstream
Digital Subscriber Line (DSL)
PPP and ADSL
Asymmetric DSL (ADSL) uses two
popular PPP implementations.
1. PPP and ATM (PPPoA) the CPE
acts as an Ethernet-to-WAN router and the
PPP session is established between the
CPE and Layer 3 access concentrator in the
service provider’s network.
2. PPP and Ethernet (PPPoE) the CPE
acts as an Ethernet-to-WAN bridge.
PPP and ADSL
PPP and Ethernet (PPPoE) the CPE acts
as an Ethernet-to-WAN bridge. The client
initiates a PPP session by encapsulating PPP
frames in MAC frames and then bridging the
frames over ATM/DSL to a gateway router at
the service provider. From that point, the PPP
session can be established, authenticated, and
achieved. The client receives its IP address
from the service provider, using PPP
negotiation.
Provisioning WAN Bandwidth
• A critical network design is considering
capacity requirements. Selecting the right
amount of capacity for current and future needs.
• Provisioning requires an analysis of traffic
flows, and analysis of scalability goals.
WAN Technologies
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Leased lines
Synchronous Optical Network (SONET)
Frame Relay
Asynchronous Transfer Mode (ATM)
Leased Lines
• Dedicated digital, copper circuits that a
customer leases from a carrier for a
predetermined amount of time, usually for
months or years.
• Speeds range from 64 Kbps to 45 Mbps.
• Enterprises use leased lines for both voice
and data traffic.
Leased Lines
• Dedicated connection or Point-to-Point connection.
• Pre-established WAN communications path from
the Customer Premise Equipment (CPE) , through
the Data Communications Equipment (DCE)
switch, to the CPE of the remote site, then allowing
Data Terminal Equipment (DTE) networks to
communicate at anytime with no set up procedure
before transmitting data.
DTE and DCE
The end instrument is a piece of
equipment connected to the wires at the end of
a telecommunication link. End instruments that
relate to data terminal equipment (DTE)
include printers, computers, barcode readers,
automated teller machines (ATMs) and the
console ports of routers.
DTE and DCE
The data communication(s) equipment
(DCE) is a device that sits between the DTE
and a data transmission circuit.
The DCE performs functions such as
signal conversion, line clocking, and coding.
The DTE/DCE classification was
introduced by IBM.
DTE and DCE
DTE - DCE
Digital Signal (DS)
A channel in the NADH (North
American Digital Hierarchy) is called a digital
signal (DS). Digital signals are multiplexed
together to form high-speed WAN circuits. DS1 and DS-3 are the most commonly used
capacities.
The North American Digital Hierarchy
Synchronous Optical Network (SONET)
Synchronous Optical Network (SONET) is
the American National Standards Institute
standard for synchronous data transmission on
optical
SDH (Synchronous Digital Hierarchy) is a
standard technology for synchronous data
transmission on optical media.
Synchronous Optical Network (SONET)
• Physical-layer specification for high-speed
synchronous transmission of packets or cells
over fiber-optic cabling.
• Service providers and carriers make wide use of
SONET in their internal networks.
• Gaining popularity within private networks.
Synchronous Optical Network (SONET)
Goals of SONET and SDH
1. Define higher speeds than the ones used
by the NADH.
2. Support efficient multiplexing and
de-multiplexing of individual signals.
With SONET, it is easy to isolate one channel
from a multiplexed circuit. In some instances where
there are many different parts of the system are
almost , but not quite, perfectly synchronised. Like
the NADH and European E system, isolating one
channel is more difficult.
Synchronous Optical Network (SONET)
Terminating multiplexers (implemented in
switches and routers) provide user access to the
SONET network. Terminating multiplexers
convert electrical interfaces into optical signals
and multiplex multiple payloads into STS-N
(Synchronous Transport Signal) signals required
for optical transport.
SONET Optical Carrier (OC) Levels
aka Synchronous Transport Signal (STS) Levels
STS Rate
OC Level
Speed
STS-1
STS-3
STS-12
STS-24
STS-48
STS-96
STS-192
OC-1
OC-3
OC-12
OC-24
OC-48
OC-96
OC-192
51.84 Mbps
155.52 Mbps
622.08 Mbps
1.244 Gbps
2.488 Gbps
4.976 Gbps
9.952 Gbps
Typical SONET Topology
SONET Multiplexer
Backup Pair
Working Pair
SONET
Frame Relay
Frame relay is a telecommunication service designed
for cost-efficient data transmission for intermittent traffic
between local area networks (LANs) and between end-points in
a wide area network (WAN).
Frame relay puts data in a variable-size unit called
a frame and leaves any necessary error correction
(retransmission of data) up to the end-points, which speeds up
overall data transmission. For most services, the network
provides a permanent virtual circuit (PVC), which means that
the customer sees a continuous, dedicated connection without
having to pay for a full-time leased line, while the service
provider figures out the route each frame travels to its
destination and can charge based on usage.
Frame Relay
• Industry-standard data-link-layer protocol for
transporting traffic across wide-area virtual
circuits
• Optimized for efficiency on circuits with low
error rates
• Attractively-priced in most parts of the world
• Carriers agree to forward traffic at a
Committed Information Rate (CIR)
Frame Relay
Frame Relay
To Router B: DLCI
100
To Router A: DLCI
200
Router A
Router B
Virtual Circuit (VC)
Frame Relay Hub-and-Spoke Uses
Subinterfaces
Central-Site Router
DLCI 100
DLCI 200
hostname central site
interface serial 0
encapsulation frame-relay
interface serial 0.1
ip address 10.0.1.1 255.255.255.0
frame-relay interface-dlci 100
interface serial 0.2
ip address 10.0.2.1 255.255.255.0
frame-relay interface-dlci 200
Virtual Circuit
What is a virtual circuit?
OSI model used in example. TCP takes large blocks of
information from an application and breaks them into segments. It
numbers and sequences each segment so that the destination TCP
protocol can put the segments back into the order the application
intended. After the segments are sent, TCP (trans host) waits for
an acknowledgment of the receiving end’s TCP virtual circuit
session, retransmitting those that aren’t acknowledged.
Before a transmission occurs, a host sends segments down
the OSI model, the sender’s TCP protocol contacts the
destination’s TCP protocol to establish a connection. This type of
connection is considered to be connection-oriented. UDP is
connectionless connection.
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X.25
X.25 was optimized for excellent reliability on
physical circuits with high error rates.
X.25 was more complex to implement than
Frame Relay.
X.25 works at the physical, data link, and
network layers.
X.25 allows computers on different public
networks (CompuServe, TCP/IP) to
communicate through an intermediary computer
at the network layer level.
X.25
Split Horizon
A routing technique in which information about
routes is prevented from exiting the router interface
through which that information was received. Split
horizon updates are useful in preventing routing loops.
Use a sub-interface. This is a logical interface that
is associated with a physical interface. The central site
could have five PPP sub-interfaces defined, each
communicating with one of the remotes sites. With this
solution, the central site router applies the split horizon
rule based on logical sub-interfaces, instead of the
physical interface, and includes remote sites in the
routing updates it sends out the WAN interface.
Split Horizon
Split horizon can be eliminated using full
mesh design with physical circuits between each
site.
Split Horizon
Asynchronous Transfer Mode (ATM)
• Used in service provider internal networks
• Gaining popularity within private networks,
both WANs and sometimes LANs
• Supports very high bandwidth requirements
– Copper cabling: 45 Mbps (T3) or more
– Fiber-optic cabling: OC-192 (9.952 Gbps)
and beyond, especially if technologies
such as wavelength-division multiplexing
(WDM) are used
ATM
• Provides efficient sharing of bandwidth among
applications with various Quality of Service
(QoS) requirements
– Cell-based system inherently better for QoS than
frame-based system, because frame-based system,
large frames can monopolize
bandwidth
• ATM is with a connection-oriented technology
• Application can specify upon connection
establishment the QoS it requires
• Peak and minimum cell rates, cell-loss ratio, and
cell-transfer delay
ATM
ATM
Asynchronous transfer mode (ATM) is one of many network
transmission protocols included in Windows Server 2003. The most commonly
used transmission protocol included in Windows Server 20003 is TCP/IP,
which is a connectionless protocol. As such, TCP/IP cannot offer some of the
advantages that a connection-oriented, virtual circuit, packet-switching
technology, such as ATM, can. UnlikeMmost connectionless networking
protocols, ATM is a deterministic networking system — it provides
predictable, guaranteed quality of service.
The ideal environment in which to use ATM is one that combines
computer, voice, and video networking into a single network, and the
combination of existing networks into a single infrastructure.
ATM
• A disadvantages of ATM is that ATM
interfaces for routers and switches are
expensive.
Video:
https://www.youtube.com/watch?v=0dU1am2u1Jw
https://www.youtube.com/watch?v=WToiJS8x1CQ
Ethernet over ATM
• ATM router interfaces are expensive
• Some providers allow a customer to use an
Ethernet interface to access the provider’s
ATM WAN
• May require a converter
• Expected to gain popularity because it has
the advantages of both worlds
– Easy-to-use LAN
– QoS-aware WAN
Metro Ethernet
What is Metro Ethernet?
Metro Ethernet makes use of Carrier
Ethernet technology in metropolitan area
networks (MANs).
Carrier Ethernet is the use of highbandwidth Ethernet technology for Internet
access and for communication among business,
academic and government local area networks
(LANs).
Metro Ethernet
Widely available in larger cities, Metro
Ethernet offers efficient and scalable network
services within a specific metropolitan region.
These regions are frequently meshed in fiber
optic networks, making Ethernet more widely
available in the specified metropolitan area.
Comcast Metro Ethernet offers a simple
solution for users that have a complex network.
Metro Ethernet
• A service offered by providers and carriers
that traditionally only offered WAN services
• Carriers offer Metro Ethernet to customers
who are looking for cost-effective method to
interconnect campus networks and to access
the Internet.
• Metro Ethernet allow users to continue using
10/100 Mbps Ethernet interfaces.
• Supports copper and fiber optics interfaces.
Metro Ethernet
• Allows providers to offer bandwidth in 1Mbps increments.
Metro Ethernet
Selection Criteria for Remote Access
Devices
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Support for VPN features
Support for NAT
Reliability
Cost
Ease of configuration and management
Support for one or more high-speed Ethernet
interfaces
• If desired, wireless support
Selection Criteria for VPN Concentrators
• Support for:
– Tunneling protocols such as IPsec, PPTP, and L2TP
– Encryption algorithms such as 168-bit Triple DES,
Microsoft Encryption (MPPE), RC4, AES
– Authentication algorithms, including MD5, SHA-1,
HMAC
– Network system protocols, such as DNS, RADIUS,
Kerberos, LDAP
– Routing protocols
– Certificate authorities
– Network management using SSH or HTTP with SSL
Selection Criteria for VPN Concentrators
Selection Criteria for Enterprise Routers
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Number of ports
Processing speed
Media and technologies supported
MTTR and MTBF
Throughput
Optimization features
Selection Criteria for a WAN Service
Provider
• Extent of services and technologies
• Geographical areas covered
• Reliability and performance characteristics of
the provider’s internal network
• The level of security offered by the provider
• The level of technical support offered by the
provider
• The likelihood that the provider will continue to
stay in business
Selecting a Provider
• The provider’s willingness to work with you to
meet your needs
• The physical routing of network links
• Redundancy within the network
• The extent to which the provider relies on other
providers for redundancy
• The level of oversubscription on the network
• QoS support
Summary
• A major task during the physical design phase is
selecting technologies and devices for enterprise
networks
– Remote access networks
– WANs
– Service providers
– Devices
• End user remote access devices
• Central site remote access devices
• VPN concentrators
• Routers
Review Questions
• Compare and contrast technologies for
supporting remote users.
• Compare and contrast WAN technologies.
• What selection criteria can you use when
purchasing internetworking devices for
enterprise network customers?
• What criteria can you use when selecting a
WAN service provider?
This Week’s Outcomes
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PPP
Frame Relay
Cable Modems and DSL
Leased Lines, SONET, Frame Relay, Metro
Ethernet, ATM
• Selecting a WAN Service Provider
Lab Assignment Due
• Lab #2 March 12, 2017
Next week
• Read Chapters 12 and 13 in Top-Down Network
Design
Q&A
• Questions, comments, concerns?