Transcript Chapter 3: Planning Network Data Flow

70-293: MCSE Guide to Planning
a Microsoft Windows Server
2003 Network, Enhanced
Chapter 3:
Planning Network Data Flow
Objectives
• Describe the three types of network traffic
• Understand unique characteristics of Ethernet
• Use physical components of a network to control data
flow
• Monitor network performance
• Optimize network settings
• Use network troubleshooting utilities
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Types of Network Traffic
• Network traffic is defined as packets of data sent on
the network
• Three types of IPv4 packets:
• Unicast
• Broadcast
• Multicast
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Unicast Packets
• A unicast packet is addressed to a single computer
• The destination IP address in a unicast packet is a
Class A, B, or C IP address
• This type of traffic can communicate on the Internet
and perform file and printer sharing in the network
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Broadcast Packets
• Local broadcasts are used by applications to
announce status and ensure that all interested hosts
are informed
• Broadcast packets are inefficient because they are
processed by all hosts on a subnet
• On a busy host this may reduce performance levels
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Activity 3-1: Analyzing a Broadcast
• The purpose of this activity is to view the contents of
a broadcast packet
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Multicast Packets
• Multicast packets are addressed to a group of
computers using a Class D IP address
• Multicast packets are an improvement over broadcast
packets because multicast packets are processed by
all hosts up to only the Internet layer rather than up to
the Application layer
• This reduces the processing load on busy hosts
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Ethernet
• Ethernet is the most common network technology
used for LAN connectivity
• Popularity of Ethernet is due to its high performance
and low price
• Three important Ethernet concepts are:
• Collisions
• Collision domains
• Transmission modes
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Collisions
• If two computers happen to transmit information on
the network at the same time, then a collision results
• Ethernet uses Carrier Sense Multiple Access/Collision
Detection (CSMA/CD) as the access method to
determine which computer is allowed to send data on
the network and when
• When a collision occurs, the two computers that are
transmitting data stop and wait for a random period of
time before resending
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Transmission Modes
• A transmission mode is how data is sent on the
network
• Ethernet networks are capable of transmitting at:
• Half-duplex mode
• can send data or receive data, but cannot do both at the same
time
• Full-duplex mode
• can transmit and receive information at the same time
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Activity 3-2:
Viewing Ethernet Settings
• The purpose of this activity is to view various
Ethernet settings
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Media
• Media is the physical component that connects all of
the devices together
• The most common media types used in computer
networks are:
• Twisted-pair
• Fiber optic
• Coaxial
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Media (continued)
• Twisted-pair cabling is the most common type of
cabling used in computer networks
• On an Ethernet network, it can carry data at up to 1
Gbps at a maximum distance of 100 meters over a
single segment
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Media (continued)
• Fiber-optic cabling is used for network backbones
where twisted-pair cabling cannot transmit the
distance needed
• On an Ethernet network, it can carry data at up to 10
Gbps for a 2 kilometers
• Two fibers are required for each connection: one for
sending data, the other for receiving
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Media (continued)
• Coaxial cabling was common on older Ethernet
networks, but has been removed from most networks
• Coaxial cable cannot transmit in full-duplex mode
• Coaxial cabling is now expensive compared to
twisted-pair cabling
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Media (continued)
• Wireless connectivity is not part of the Ethernet
standard; very popular now
• A major cost savings in wireless implementations is
the lack of cabling installation
• Security is a concern with wireless connectivity
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Hubs
• A hub acts as a central connection point on a network
that allows multiple computers to communicate with
each other
• A hub can also be used to extend the network for
greater distance
• A hub operates at the Physical layer of the OSI model
and is responsible for media characteristics and
electrical signaling
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Latency
• When a signal passes through a hub, it takes a small
amount of time for the signal to be regenerated
• The delay between receiving the signal and sending it
out again is called latency
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Latency (continued)
• When many hubs are linked, a high level of latency is
introduced and the carrier sense portion of
CSMA/CD becomes unreliable
• When the latency is high, the number of collisions
increases because a computer at one end of the
collision domain can begin sending a packet while
another computer at the other end is sending a packet
at the same time
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Switches
• A switch divides network traffic based on MAC
addresses
• Switches can operate at full-duplex
• Switches operate at the Data Link layer of the OSI
model
• Switches can perform tasks that deal with full packets
of data and MAC addresses
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Switches (continued)
• A switch has several benefits over a hub:
• Each port on a switch is a separate collision domain
allowing the division of large networks and a reduction in
the number of collisions
• A switch can direct traffic only to the port to which the
destination computer is attached, which reduces overall
levels of network traffic
• Switches can connect dissimilar network architectures,
such as Ethernet and wireless
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Switches (continued)
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Switches (continued)
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Routers
• Routers are used to move traffic between networks
• A router operates at the Network layer of the OSI
model which allows the control of network traffic
based on logical IP addresses
• Routers maintain a list of IP networks called a routing
table
• Routers are more scalable than switches
• Routers can control traffic for hundreds of thousands
of computers, whereas switches normally can track
thousands of computers
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Monitoring and Optimizing Network
Performance
• A bottleneck is any point in the communication
process that cannot perform at the same level as other
components
• Bottlenecks can occur in the physical network or in
server components
• Network performance is limited by bottlenecks
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Network Performance Problems and
Solutions
• The tools used to monitor network performance
include:
•
•
•
•
Protocol analyzers
Cable testers
Task Manager
Performance snap-in
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Protocol Analyzers
• Protocol analyzers can capture network traffic and
monitor network performance
• A protocol analyzer can be used to look at each
packet in the communication process to see where the
problem lies
• Network Monitor is a limited protocol analyzer
included with Windows Server 2003
• Ethereal is an alternative packet analyzer that is very
popular and free
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Cable Testers
• A cable tester checks the ability of a cable to carry the
electrical signals properly that are sent by the
computers
• Each cable tester can verify the proper installation of
only certain types of cabling
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Task Manager
• Task Manager is a simple tool that can be used to:
• Check memory
• Processor
• Network utilization
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Performance Snap-in
• The Performance snap-in located in Administrative
Tools can be used to generate graphs and log many
Windows Server 2003 performance indicators
• The graphs generated by the Performance snap-in can
capture short- and medium-term information
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Activity 3-3:
Monitoring Network Performance
• The purpose of this activity is to view network
utilization using Network Monitor, Task Manager,
and the Performance snap-in
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Optimizing Network Settings
• Network performance gains can be made by
modifying the network configuration of the servers
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Utilizing the Binding Process
• Binding is the process in which a network protocol is
configured to use a network adapter
• When a protocol is added to a network connection, it
is bound to the network adapter and the services that
are part of that connection
• Windows Server 2003 allows you to optimize your
network connectivity by
• Adjusting the order in which protocols are used
• Defining the priority of network services
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Minimizing Network Protocols
• If a protocol is required to support older clients,
explore centralizing all services using that protocol on
a single server
• This reduces the service advertisements produced by
other servers and reduces the processing required on
other servers
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Implementing the Maximum
Transmission Unit (MTU) Setting
• The Maximum Transmission Unit (MTU) setting sets
the maximum packet size that TCP/IP will try to
negotiate when creating a TCP connection
• The default MTU setting is 1,500 bytes on an
Ethernet network
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Troubleshooting Utilities
• Windows Server 2003 has a wide variety of utilities
that can be used to troubleshoot network problems
• It is important to understand what each tool does and
when it is appropriate to use
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Ping
• Ping confirms that a host is active at an IP address
• Ping can be used to test for DNS resolution problems
• When you ping a host, the Ping utility indicates how
long it took for the remote host to respond
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Tracert
• The Tracert utility is used to view the routers that a
packet passes through between the local host and a
remote host
• When using the Tracert utility to troubleshoot Internet
connectivity, look for the router that stops
responding; this one is preventing users from
accessing a particular server
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Pathping
• Pathping can be used to view the routers used to
move a packet from the local host to a remote host
• However, the Pathping utility sends 100 packets to
each router in the path to provide a more accurate
measure of response times
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Activity 3-4: Testing for Network
Congestion with Pathping
• The purpose of this activity is to test to see if the
network is congested using the pathping command
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Nbtstat
• Nbtstat is used to view NetBIOS over TCP/IP
statistics
• It can view the list of NetBIOS services available on
the local host or remote hosts, and it can view the
local NetBIOS name cache
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Netstat
• Netstat displays TCP connection information and
various IP statistics, such as the number of UDP and
TCP packets and the IP routing table
• Viewing TCP connections is useful for finding rogue
services
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Network Diagnostics
• Network Diagnostics can be used to view a variety of
settings on your server
• It builds a list of information about your server and
tests services such as DNS and WINS to ensure
availability
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Activity 3-5: Viewing TCP
Connections with Netstat
• The purpose of this activity is to view open
connections and running services with the Netstat
utility and view the current network configuration
with Network Diagnostics
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Ipconfig
• The ipconfig command can be used to:
• View IP configuration information
• Release and renew IP addresses that are obtained from a
DHCP server
• Flush the DNS cache because Windows Server 2003 caches
all DNS lookups
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Netsh
• Netsh is a command-line utility that can be used to
modify and view IP configuration information
• It is useful for remotely managing IP configuration
when Terminal Services is unavailable and via scripts
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Nslookup
• Nslookup is used to query DNS servers
• Can be configured to query any DNS server you
want, making it easy to confirm the configuration of a
particular DNS server that is having problems
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Summary
• Types of network traffic: unicast, broadcast, and
multicast
• Ethernet is the most common network architecture
• A collision domain is an area of a network where
collisions occur
• Transmission modes are half-duplex and full-duplex
• Hubs operate at the Physical layer of the OSI model
and send received data to all ports except the one
from which it was received
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Summary (continued)
• Switches operate at the Data Link layer of the OSI
model and control data flow based on MAC addresses
• Routers operate at the Network layer of the OSI
model and control data flow based on IP addresses
• Tools used to identify bottlenecks include protocol
analyzers, cable testers, Task Manager, and the
Performance snap-in
• Can optimize network settings by adjusting bindings,
minimizing number of protocols, and adjusting MTU
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Summary (continued)
• IP troubleshooting utilities:
•
•
•
•
•
•
•
•
•
Ping
Tracert
Pathping
Nbtstat
Netstat
Network Diagnostics
Ipconfig
Netsh,
Nslookup
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