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1
Everything You Always Wanted to Know About
Network Access
Chapter 5 –Layered Communication & Internet
Access
2
Knowledge Checkpoints
PSTN Infrastructure How the OSI model works Message exchange sequence How routers work Cookies HTTP protocol DOS commands for the network
3
Student Notes
Chapter 4 & 5 give background information to understand the network that represents the Internet
The content in these chapters will be more useful when we study WANs
Most of the material in this slide set is not in the book but is necessary for you to understand using networks
Check out the web sites on the course web page for additional information
4
Vocabulary that is Important
HTTP OSI & layers TCP/IP Cookie Router CSU DLC Compression T and E carrier SDH/SONET Frame Packet OC SS7 Architecture Header Encapsulation Router forwarding IP address DNS DHCP
Domain Host Auto-configuration Adaptor Bindings HTML Tags Next hop PSTN PDH
5
PSTN
Infrastructure and design to support voice, only Call length is a component of the
differences between data vs voice carried on network
Channel capacity is narrow band (64 Kbps)
Backbone based on PDH (T-carrier)
6
Array of Service Providers
LEC-local exchange carrier ILEC-incumbent local carrier (monopoly rights) CLEC-competitive local exchange carrier DLEC-data competitive local exchange carrier
(supports data services) IXC-inter-exchange carrier (long distance)
Who are the LEC,ILEC,CLEC,DLEC & IXC for Utah?
7
Access Services
Categories for access services include: Trunks (2-way, DID, DOD) Analog (POTS) or digital services (3 types)
T-1 (1.5 Mbps), J-1 (2.048 Mbps), E-1 (1.544 Mpbs)
ISDN (BRI & PRI)DSL
8
Transport Services
Switched services Local, long distance, toll free, international,
directory assistance, operator, emergency services
Nonswitched services Leased lines, foreign exchange
VPNs Network where customer traffic is isolated
over shared service provider facilities
9
PTSN Architecture
CPE nodes located at customer site Switching nodes interconnect transmission facilities to route
traffic Local Exchange (CO) point of termination for customer line and
location of switching equipment Tandem Office in large metro areas connects switching offices to
route local traffic Toll office is a switching center where long distance connections
are made International gateway is where international services begin Transmission nodes carry user traffic and control information Service nodes handle signaling to control connections and billing
10
PDH Infrastructure
PDH is asynchronous (clocking rates of all components vary slightly)
Digital network Offers different transmission rates Defines the availability of channels
11
Elements of PDH Infrastructure
Transmission media Operates on 4 wire (full-duplex) but higher
bandwidths require coax or fiber CSU-terminates each end and equalizes signal Multiplexers consolidates voice and data
channels to travel over high speed line DLCs concentrates lines DCS allows dynamic rerouting of network traffic
12
SDH/SONET Infrastructure
Family of transmission standards using different fiber optic products
Uses a frame format (how bits are packaged) to travel over fiber
Rapid restoration of interrupted service possible with dual ring configuration
Uses optical carrier levels of OC Synchronous infrastructure (clocking rate
from 1 source)
13
SS7 Architecture
Signaling information carried o a different path from voice and data traffic
Allows passage of information about caller (enhanced services)
SSPs are switches that begin and end calls SS7 networks act as a backbone for AIN
(service independent allows interconnects)
14
Looking Deeper into Data
How Does Data Know Where to Go on a Network?
15
Layered Communication
16
The OSI Layers
OSI ModelLayer User Application Data Format Enabling
Technology
7 Application Common application services (email)
6 Presentation Encryption, code translation,compression
5 Session Establishes, maintains, terminates node-to-node interactive sessions
Session Distributed applications, middleware, NOS
4 Transport Ensures reliability of end-to-end connections
Assembles packets into messages
NOS
3 Network Establishes, maintains, and terminates end-to-end network connections
Packets NOS
2 Data Link Logical link control sub-layer and media access control (802.x) that ensures reliability of point-to-point data links
Frames NICs
1 Physical Establishes, maintains, and terminates point-to-point data links
Bits Media
18
Nested Protocol Headers
Each layer adds information as it passes through
19
Under the Covers
20
Indirect Communication
Application programs on different machines cannot communicate directly--They are on different machines!
BrowserBrowser
TransTrans
IntInt
DLDL
PhyPhy
User PC
Web AppWeb App
TransTrans
IntInt
DLDL
PhyPhy
Webserver
HTTP RequestHTTP Request
21
Indirect Communication
Two processes on different machines cannot communicate directly with one another because they are physically separated
So they communicate indirectly, using cooperation with lower layers
Requests are layered on the sending machine and stripped on the host machine
22
Layer Cooperation on the Source Host
Transport layer process passes the TCP segment down to the internet layer process
ApplicationApplication
TransportTransport
InternetInternet
Data LinkData Link
TCP segmentTCP segment
PhysicalUser PC
23
OSI Model
7
6
5
4
3
2
1
0
APPLICATION LAYER
PRESENTATION LAYER
SESSION LAYER
TRANSPORT LAYER
NETWORK LAYER
DATA LINK LAYER
PHYSICAL LAYER
MEDIA
T H
A H
user data
DL H
DATA
P H
S H
N H
DL T
T H
A H
user data
DATA
P H
S H
N H
A H
user data
DATA
P H
S H
T H
A H
user data
DATA
P H
S H
A H
user data
DATA
P H
user data
DATA
A H
1001001011100011110010Bit Stream
7
6
5
4
3
2
1
APPLICATION LAYER
PRESENTATION LAYER
SESSION LAYER
TRANSPORT LAYER
NETWORK LAYER
DATA LINK LAYER
PHYSICAL LAYER
T H
A H
user data
DL H
DATA
P H
S H
N H
DL T
T H
A H
user data
DATA
P H
S H
N H
A H
user data
DATA
P H
S H
T H
A H
user data
DATA
P H
S H
A H
user data
DATA
P H
user data
DATA
A H
1001001011100011110010Bit Stream
Client to Server Communication
KEY: H header T trailer
Client running front-end application.
Server running back-end engine application.
COMMUNICATIONS PATH
user data
GOLDMAN & RAWLES: ADC3e FIG. 05-02
user data
24
Data Structure
Data --The information to be delivered to another system
Data FieldData Field
Trailer Fields(if there are any)
HeaderFields
25
The Data Structure
Header Fields Initial fields in a message before the data field Source and destination address, error handling
information, etc., Like address and greeting in a written letter
Data FieldData Field
Header Fields
Header Field
26
How Does Data Find It’s Way?
IP Addresses!
27
Assigning Network PartsAssigning Network Parts
An organization applies to an Internet IP address registrar Registrar gives organization a network
part Organization assigns the local part to its
hosts internally Only large organizations and ISPs get
network parts
Registrar Firm128.171
128.171.17.13
128.171.123.130
28
IP Addresses
Each Organization is Given a Network Part Number
For Weber, this is 137.190 All IP Addresses in that organization’s
network begin with that Network Part
Network Part
IP Address
128.171
29
IP Addresses
Local Part The part of the IP address after the
network part is called the local part Total address is 32 bits, so if the
network part is 8, the local part is 24
Network Part Local Part
IP Address (32 bits total)
30
Assigning Parts
IP address registrar gives Weber State University the network part 137.190
Weber State could give the College of Business Administration the subnet part 62
College of Business Administration can give the host part 157 and a host name plogan.cba.hawaii.edu
So the computer’s IP address became 137.190.62.157
31
IP Addresses
Most Organizations Have Multiple Subnets within the Organizational Network
Usually represent each as a Subnet Part within the Local Part
Remaining Bits are the Host Part, designating a particular host on that subnet
Network Part Subnet Part
IP Address (32 bits total)
Host Part
Local Part
32
The First Router
The first router receives an IP message packet in one port (interface)
The router must make a router forwarding decision: which port to use to send it back out
B?
D?
C?
Router A
B
C
DPacket
33
IP Addresses
Between different organization networks, routers look first at the Network Part of an arriving IP packet’s destination address
If the network part is not that of the organization, the router cannot deliver the IP packet locally
Passes the IP packet on to another router, called a next-hop router, to move the IP packet closer to the destination host
Network Part
34
IP Addresses
For IP, Routers Take the Place of Post Offices There are hundreds of millions of IP
addresses on the Internet Routers cannot store decision rules for
reaching each address individually Router simply asks if a destination IP
address is that of a host on one one of the networks or subnets connected to the router or must be passed on to another router
This is the router forwarding decision
35
IP Addresses
To Simplify Router Decisions, IP Addresses are Hierarchical
The Internet is Made of Many Individual Networks Owned by Different Organizations
First route packets to a single network; only need one “sorting bin” for each network!
In the next step, route packet to host on the network
36
Layer Cooperation on the First Router
Routers only have physical, data link, and internet layer processes
So internet layer process is the highest-layer process on a router for router forwarding
Internet layer process decides where to send the packet next: another router or the destination host
Data LinkData Link Data LinkData Link
InternetInternet
First Router
37
Layer Cooperation on the First Router
The data link and physical layer process on the selected port sends the frame encapsulating the IP packet onto the next router (or destination host)
InternetInternet
Data LinkData Link
InternetInternet
Data LinkData LinkFrame
Selected Output PortOn First Router
Input PortOn Next Router
(Or Destination Host)
PhysicalLayer
38
Domain Names
Internet uses hierarchical naming A domain is a collection of resources managed
by an organization Generic top level domains by type of
organization .com for commercial organizations .edu for educational institutions
National top level domains by country .UK United Kingdom .AU Australia
39
Domain Names
Organizations register second-level domain names Microsoft.com weber.edu uahc.org Whitehouse.gov
40
Domain Names
Organizations can create lower-level domain names cba.weber.edu (for the College of
Business Administration) The lowest level domain name is the host
name for an individual host or router www.cba.weber.edu www.microsoft.com
41
Domain Name System (DNS)
Only IP addresses are official--e.g., 137.190.62.157 These are 32-bit binary numbers Only they fit into the 32-bit destination and source
address fields of the IP headers
IP Packet
32-bit Source and Destination Addresses (110011...)
42
Domain Name System (DNS)
Users typically only know host names Plogan.cba.weber.edu or weber.edu
IP Packet
Weber.eduNO
43
Domain Name System (DNS)
User’s computer sends a DNS host the target host’s host name in a DNS Request message
Sending an IP address (URL) is a request that is data
DNS host returns the target host’s IP address in DNS Response message
User PCInternetLayer
Process
DNSHost
Weber.edu
157.190.3.212
44
Domain Name System (DNS)
Organizations or ISPs have local DNS hosts These hosts must know only local host
names and IP addresses For other host names, local DNS host
passes request to another DNS host
User PCInternetLayer
Process
LocalDNSHost
RemoteDNSHost
45
Domain Name System (DNS)
Remote DNS host passes information back to the local DNS host Local DNS host passes information back to
user PC Browser only talks to local DNS host
User PCInternetLayer
Process
LocalDNSHost
RemoteDNSHost
46
A Closer Look at HTTP
HyperText Transfer Protocol
47
Protocols
A protocol is a standard for communication between peer processes, that is, processes at the same layer, but on different machines
HTTP: Browser and webserver application programs are at the same layer but on different machines
AppApp AppAppHTTPMessage
48
Protocols
A protocol is a standard for communication between peer processes, that is, processes at the same layer, but on different machines
TCP (Transmission Control Protocol) is the protocol governing communication between transport layer processes on two hosts
TransTrans TransTransTCPMessage
49
HTTP: A Closer Look
World Wide Web Standards HTTP (HyperText Transfer Protocol) governs
requests and responses between the browser and the webserver application program
HTML (HyperText Markup Language) governs the structure of the HTML webpage
BrowserWebserverProgram
HTML
HTTP
50
HTTP: A Closer Look
HTML Pages Contain Text to be displayed HTML Pages Contain Tags
Some tags say “place a graphic here”, “place a JAVA applet in a box here”, etc.,
For instance, the tag <img src=“big.jpg> says “Get file big.jpg and place it here in the HTML document”
Graphics, Java programs, are separate files
51
Web Page Code
52
HTTP: A Closer Look
Downloading a “page” may require several downloads One for the HTML document One each for the other files it calls for
HTML
Big.jpg
App.java
WebserverUserPC
File Downloads
2
3
1
53
HTTP: A Closer Look
Each download requires a separate HTTP request-response cycle! So downloading complex webpages may
require many HTTP request-response cycles
HTML
Big.jpg
App.java
WebserverUserPC
HTTPRequest-Response
Cycle 1
2
3
54
HTTP: A Closer Look
HTTP is Unreliable No error detection and correction for
transmission errors HTTP is simple, allowing browsers and
webserver application programs to be simple and inexpensive
TCP at the transport layer is reliable, offering error detection and correction
TCP gives HTTP clean data, so there is no need for HTTP to do error checking
55
HTTP: A Closer Look
HTTP is Connectionless No connection (agreement to communicate) is made
between the browser and webserver application before an HTTP message is sent
Like sending a letter or an E-mail message (connectionless) as compared to taking on the telephone, where a conversation (connection) must be opened, managed, and closed
BrowserWebserverApplication
HTTPRequest
56
A Special HTTP Message --Cookies
Server HTTP responses can include an object to be stored on the client
Cookies (name/value pairs are used to identify user File name of cookie is site Request for URL generates response to look
for cookie Unique ID & other info (Expiration date, PW)
57
Cookies
58
Cookie ContentsRMID
ac83d90b3d70eca0
sportingnews.com/
0
3567004032
30124358
3072481984
29511946
*
SaneID
172.131.217.11-1030810793354
sportingnews.com/
0
2020141696
29879224
3097781984
29511946
*
GUID
000989680F730D8E748BE01CAC10000D
advanstar.com/
0
589457792
29622048
2000816672
29516393
*
59
Cookie Contents
RMID
ac8942ee3d8750c0
www.usatoday.com/
0
3567004032
30124358
1703131552
29515363
*
pluto
110689700|0|
fastclick.net/
0
3444658176
29658594
114276224
29513756
*
m1
5694:1:13601:1:1031587872|||||||||||||||||||||||||
fastclick.net/
0
3635990528
29514157
114276224
29513756
*
60
TCP: A Closer Look
Transmission Control Protocol
61
TCP: A Closer Look
Browser does not send HTTP Requests directly to the webserver application
The application layer programs are not physically connected
Browser sends HTTP Request to the user PC’s transport layer process for delivery
Browser
TransportProcess
HTTP Request
62
TCP: A Closer Look
Transport layer process stores the HTTP Request Temporarily
Browser
TransportProcess
TransportProcess
63
TCP: A Closer Look
User PC transport process opens a connection to the webserver transport layer process
This connection can be used to send several TCP segments to handle a each HTTP request-response cycle
Browser
TransportProcess
TransportProcess
64
Delivering the HTTP Response
Transport layer process on the webserver receives the TCP segment delivering the HTTP Request
The transport process on the webserver passes the HTTP Request in the TCP segment data field to the webserver application program
WebserverApplication
TransportProcess
HTTP Request
65
Delivering the HTTP Response
Webserver application creates the HTTP Response message
Webserver application passes the HTTP Response message to the webserver transport layer process for delivery to the user PC transport layer process
WebserverApplication
TransportProcess
HTTP Response
66
Delivering the HTTP Response
Webserver Transport Process Delivers the Response User PC transport process sends an
acknowledgement
User PCTransportProcess
WebserverTransportProcess
TCP segment containingHTTP Response
ACK
67
TCP: Error Handling
TCP is reliable--it Places TCP Segments in Order
TCP segments are encapsulated in IP packets
IP does not guarantee that packets will arrive in order
TCP can place TCP segments in order based on their sequence numbers
68
TCP: Error Handling
TCP Reliability in Perspective
Provides clean application data to application program
If data link layer frame or IP packet is lost at lower layers, receiving transport process will not acknowledge a segment
The sending transport process will resend automatically
So TCP protects against errors at lower layers as well as transport layer errors
69
More on the IP
Internet Protocol
70
Internet Layer Process
Transport layer process passes EACH TCP segment to the internet layer process for delivery
Transport LayerProcess
Internet LayerProcess
TCP segment
71
IP: Connectionless Service
The Internet Protocol (IP) Internet layer protocol IP messages are called IP packets
No connections are established No open, close, error correction, flow control Low overhead
InternetProcess
InternetProcess
IP Packet
72
IP: Connectionless Service
IP is unreliable No error handling (Let TCP catch errors!) No sequence numbers, so no way to put arriving IP
packets in order (Let TCP put the TCP segments these IP packets contain in order!)
InternetProcess
InternetProcess
IP Packet
73
TCP/IP Partnership
TCP checks for errors once, at the destination host
IP is used in many hops between routers Not checking for errors at each step greatly
reduces overall processing work Reduces router costs
Transport Transport
Internet Internet Internet
Check Only Once
Host Router Host
74
Connectionless IP
IP is unreliable (does not catch errors) But this is not bad
First, errors are caught--at the next-higher layer (transport) if TCP is used
Second, avoiding error checking at each hop between routers lowers router costs
Less expensive to check for errors on one destination host than on many routers along the way
75
IP is a Best-Effort Service
IP Only Offers Best-Effort Service
Does its best to get packets through
No guarantees of delivery
No way to give priority to time-sensitive traffic, such as voice
Overall, low overhead but limited Quality of Service (QoS)
QoS should change in the future
76
IP Addresses and Router Forwarding
Routers use the destination IP address of an incoming packet in the router forwarding decision, that is, to decide what output port to use to send the packet back out to the destination host or to another router
B?
D?
C?
Router A
B
C
DPacket
77
Assigning Subnet Parts
Organization Assigns Subnet Parts Assigns subnet parts to suborganizations Suborganization assigns host bits to hosts
Registrar Firm
128.171 128.171.17.13
128.171.17.13
Suborganization
Host
78
IP Addresses Within an organizational Network
Router looks at Network Plus Subnet Part Combined If destination host is on a subnet attached to the
router, delivers the IP packet to the host Otherwise, passes the packet on to a next-hop
router
Network Part Subnet Part
IP Address (32 bits total)
Host Part
Local Part
79
IP Addresses
In IP Addresses, “Network” and “Subnet” are Organizational Concepts, not Technical Concepts
Network is the collection of individual networks and routers owned by an organization
Subnet is a collection of individual networks and routers owned by a suborganization Often a single physical network (subnet)
80
Importance of Part Sizes
Determine Number of Possible Networks, Subnets, or Hosts
If There are N Bits in the Part, there can be 2N possible Networks, Subnets, or Hosts
Actually, 2N-2 All zeros cannot be used for a part All ones cannot be used for a part
Example: if part has 8 bits, 28-2 possibilities (254)
81
Masks
IP Addresses are Always Paired with a Second 32-bit Number Called a Mask
Two Types: Network Masks and Subnet Masks Network Mask Tells the Length of the
Network Part Subnet Mask Tells the length of the
Network Plus Subnet Parts (not just subnet part)
IP Address will be paired with one or the other, but not both simultaneously
82
Router Delivery
If Destination Host is On the Source Host’s Subnet, Source Host Delivers the Packet Directly No router is involved
Subnet
Subnet
SourceHost
Destination Host
83
Router Delivery
If Destination Host is NOT On the Source Host’s Subnet, Source Host Sends the Packet to a Router for Delivery
Subnet
Subnet
84
Router Delivery
If Destination Host is On One of the Router’s Subnets, the Router Sends the Packet to the Destination Host for Delivery
Subnet
Subnet
85
Router Delivery
If Destination Host is NOT On One of the Router’s Subnets, the Router Sends the Packet to a Next-Hop Router for Delivery
May have to choose among several possible next-hop routers for delivery
Subnet
Subnet
86
Router Delivery
Border Routers Connect Networks, Not Subnets Select between next-hop router on own network
or on another network
Own Network
Other Network
87
Router Forwarding Tables
Allow Routers to Decide Whether Local Delivery is Possible to Destination Host
Allow Routers to Select Next-Hop Router if Local Delivery is Not Possible
88
Router Forwarding Tables
Router Compares Destination IP Address to Each Row in Router Forwarding Table
If matches IP address, delivers according to Delivery rule So if destination address of IP packet is 128.171.17.13,
router delivers packet locally
IP Address Delivery
128.171.17.13 Local
142.99.171.3 Next-Hop Router A
89
Router Forwarding Tables
Metric If same length of match, turn to metric column Metric describes the desirability of a choice If metric is cost, choose lowest cost For other metrics (speed, etc.), may chose largest
value
IP Address Part
Mask Metric (Cost)
Delivery
128.171 16 23 Local
128.171 16 45 Next-Hop Router A
90
Router Forwarding Tables
There May be No Matches One IP Address Part is Always 0.0.0.0 If there is no match, choose its next-hop router
(called the Default Router)
IP Address Delivery
128.171.17.13 Local
0.0.0.0 Next-Hop Router C
91
Router Forwarding Tables
Recap of Selection Rules
Compare destination IP address of an arriving packet against ALL rows within the router forwarding table because there may be multiple matches
Select the single row that matches
If multiple rows match, select the longest match
If multiple rows tie on the longest match, select the row with the largest or smallest metric, depending on the specific metric
If there is no match, select the default router row
92
Router Forwarding Tables
Delivery Table not only designates local delivery or a next
hop router Also designates the router interface (port) that
will be used for delivery
Interface Delivery
2 Local
3 Next-Hop Router C
3 Next-Hop Router D
93
Dynamic Routing Protocols
How Do Routers Get Information for their Router Forwarding Tables?
Share router forwarding table information Standards for these exchanges are called dynamic
routing protocols
Router ForwardingTable Information
94
Dynamic Routing Protocols
How Do Routers Get Information for their Router Forwarding Tables?
Thanks to dynamic routing protocols, the Internet needs no central point of control
Routers create their router forwarding tables strictly by information from peers and their own knowledge
Router ForwardingTable Information
95
IP Version 6
Current Version of IP is IP Version 4 This is the version we have been discussing Has 32-bit IP address fields Not long enough; running out of IP addresses
Next Version will be IP Version 6 Will have 128-bit IP address fields Will allow vast numbers of IP addresses (2128) Being adopted slowly
96
Autoconfiguration
Every computer attached to the Internet is a host Including desktop PCs
Every host must have an IP address Some hosts, such as routers and
webservers, get permanent IP addresses
97
Autoconfiguration
User PCs do not need permanent IP addresses They only need to be found within a use
session They usually are given temporary IP
addresses each time they use the Internet
They may get a different IP address each time they use the Internet
98
Autoconfiguration Request-Response Cycle
User software requests IP address for the user PC in Autoconfiguration Request message
Autoconfiguration Response message contains temporary IP address to use in current session
User PCAutoconfiguration
Host
AutoconfigurationRequest
TemporaryIP Address in
Autoconfiguration Response
99
Autoconfiguration
Most popular autoconfiguration protocol is DHCP Dynamic Host Configuration Protocol Built into Windows after Win 3.1 Supplies host with temporary IP address
DHCP can give more information too Usually gives IP address of a default
gateway (Microsoft terminology for router)
Can give IP address of a local DNS host
100
DOS Commands
Ping Tracert IPCONFIG
101
102
103
Windows 98 IP Configuration
0 Ethernet adapter :
IP Address. . . . . . . . . : 172.193.231.170Subnet Mask . . . . . . . . : 255.255.0.0Default Gateway . . . . . . : 172.193.231.170
1 Ethernet adapter :
IP Address. . . . . . . . . : 0.0.0.0Subnet Mask . . . . . . . . : 0.0.0.0Default Gateway . . . . . . :
IPCONFIG
104
Internet Setup in Microsoft Windows
105
Windows Layering vs.
TCP/IP-OSI Protocols
TCP/IP is only one possibility
IPX/SPX for older Novell NetWare servers; Microsoft sometimes calls this NW Link
NetBEUI for some Microsoft servers on small PC networks
106
Windows Layering vs.
TCP/IP-OSI Adapters
Combination of data link layer and physical layer protocols
The subnet layers
Dial-Up adapter sets up a modem and PPP
Other “adapters,” including Ethernet for a network interface card (NIC)
107
Bindings Bindings
Bindings create communication paths between adjacent layer processes
Client for MS Windows Other Added Client
IPX/SPX Protocol TCP/IP Protocol
Ethernet Adapter Dial-Up Adapter
Binding
Binding
108
Configuring Networking in
Windows In Windows 95 and Windows 98
Go to the Start Button Choose Settings Choose Control Panel Double click the Network icon This opens the Network Dialog Box
109
The Network Dialog Box
Be sure the Configuration tab is selected You will see adapters, protocols, clients, and
services that have already been added
Operations Add: To add an adapter, protocol, client, or
service Remove: To remove one Properties: To see or change the properties
of the selected adapter, protocol, client, or service
110
The Network Dialog Box
The Add Button
Clicking the “Add” button takes you to the Select Network Component Type dialog box
Choose client, protocol, adapter, or service, then hit Add
Assume you chose “protocol” You then go to the Select Network Protocol dialog box
Other choices will take you to the relevant Select Network … dialog box
111
112
Broader Perspective
113
You Will Not Always Use TCP/IP-OSI Standards
You almost always will use OSI standards for the data link and the physical layers
At higher layers, you may use Non-TCP protocols IPX/SPX in some Novell NetWare file
servers SNA for mainframes AppleTalk for Macintoshes NetBEUI for servers on some small LANs
114
Implications of Non-TCP/IP
Why does it cause problems?When would it happen?What could be done about it?
115
Important Information
Review Figure 5.1 p. 117 Figure 5.6 p 127 Table 5.1 p. 130 Figure 5.8 p. 134 Table 5.3 p. 135 Figure 5.17
116
Try the Following
All DOS commands must be executed from a DOS shell
Use the DOS command ping to check on a live connection Do this from home as ping is blocked on campus Try weber.edu and another such as Yahoo or
microsoft Use the DOS command tracert to check the route to a
web site Can you tell the last hop router IP address?
Use the DOS command Ipconfig to identify the IP address assigned to your computer
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