Transcript The Internet and Its Uses - Genesee Community College

Chapter 6
Addressing The
Network – IPv4
Modified by Profs. Chen and Cappellino
Objectives

In this chapter, you will learn to:






Explain the structure IP addressing and demonstrate
the ability to convert between 8-bit binary and decimal
numbers.
Given an IPv4 address, classify by type and describe
how it is used in the network.
Explain how addresses are assigned to networks by
ISPs and within networks by administrators.
Determine the network portion of the host address and
explain the role of the subnet mask in dividing
networks.
Given IPv4 addressing information and design criteria,
calculate the appropriate addressing components.
Use common testing utilities to verify and test network
connectivity and operational status of the IP protocol
stack on a host.
The Anatomy of an IPv4 Address

At the Network layer, the packets need to be identified with
the _________________________ of the two end systems.
Each
device on a network must be ________________________
Each address is ________________________________
___________ use the addresses in _______________ format
__________ represent IPv4 addresses using _________________


Easier to remember and work with
Addresses expressed as dotted decimals separate each
decimal number with a dot
Dotted

Each byte of the binary pattern, called an ______________.


decimal address: ______________________________
An octet = _________________ = one decimal number of the address
Binary address (32- bit address):

10101100 00010000
00000100 00010100
The Anatomy of an IPv4 Address cont.

Network Portions
For
each IPv4 address, some portion of the high-order
bits represents the network address.
A _____________________________________
_____________________________________________
____________________________________________

Host Portions
The
number of bits used in this host portion ________
_____________________________________________
___________________________________________

For example, to assign a unique address to 200 hosts, we would use
the entire last octet. With 8 bits, a total of 256 different bit patterns can
be achieved. This would mean that the bits for the upper three octets
would represent the network portion.
Note: Calculating the number of hosts and
determining which portion of the 32 bits refers to
the network will be covered later in this chapter.
Please see the board for…
Binary to Decimal and
Decimal to Binary
conversions…
Types of Addresses in an IPv4 Network

Within the IPv4 network, there are _____ types of addresses:
________________
- The address by which we refer to the network
______________________ - A special address used to send data to all
hosts in the network
______________________ - The unique addresses assigned to the
end devices in the network

Network Address  10.0.0.0 /24
Example:
 All
shown below is "the 10.0.0.0 network."
hosts in the 10.0.0.0 / 24 network will have the same network bits.
The lowest address is reserved for the network address.
 This address has a 0 for each host bit in the host portion of the address.
Types of Addresses in an IPv4 Network cont..

Broadcast Address
A
special address that ______
_________________________
_________________________
The broadcast address uses
the highest address in the
network range.

This is the address in which the bits
in the ________________________
Example:
For the network
10.0.0.0 /24 the broadcast
address would be 10.0.0.255

Host Addresses
______________
between the
network address and the
broadcast address _________
________________________
Network Prefixes

How do we know how many bits represent the
network portion and how many bits represent the
host portion?
A

prefix length.
The ____________________________
______________________________________
For
example, in 172.16.4.0 /24, the /24 is the prefix
length. This leaves the remaining 8 bits, the last octet,
as the host portion.

Prefix values vary and ____________________
____________________ _________________
________________________ for each network.
Example…
Calculating Network, Hosts, and Broadcast Address


For example: 172.16.20.0 /25.  (32 – 25 = 7 bits)
Network Address:
 With
a 25 bit prefix, the last 7 bits are host bits.
 To represent the network address, all of these host bits
are '0'.
 This makes the network address 172.16.20.0 /25.

First Host Address:
 This is always ______________________________.
 In this case, the ______________________________
 This makes the lowest host address is 172.16.20.1.

Broadcast Address
 __________________________________________
 This makes the broadcast address is 172.16.20.127.

Last Host Address:
 The
_______________________________________
________________________________________
 It means the lowest host bit is a '0' and all other host bits
as '1s'.
 This makes the highest host address 172.16.20.126.
Note: when working these problems- you need only expand from the
divided octet to the end of the address (no need to expand all)
IPv4 Communication via

Unicast, Broadcast, or Multicast
_________ - _______________________
__________________________________
__________
address is the address of the __________
host and the _______________ address is the address
of the _____________________ device
Can be routed through an internetwork
Considered normal host-to-host communication
Throughout the course,
communications are assumed
Unicast unless otherwise noted
IPv4 Communication via

Unicast, Broadcast, or Multicast
______________________-__________________________
___________________________________________
 Source
address used is that of the originating host
Uses a special broadcast address destined for the destination devices
All
hosts that receive a broadcast packet, process the packet as if it
were a _______________________________

Broadcast transmission is used for purposes such as
Mapping
upper layer addresses to lower layer addresses (_______)
Requesting an address (________________)
______________________________ by routing protocols

When a host needs information, the host sends a request,
called a query, to the broadcast address.
All
hosts in the network receive and process this query.
One or more of the hosts with the requested information will ________,
typically using ____________________.
Broadcast Traffic cont…


Broadcast packets usually ________________
_______________ (aka limited broadcast).
There are __________________________:
________________ sent to all hosts on a _______________.



Useful for sending a broadcast to all hosts on a non-local network.
Routers do not forward directed broadcasts by default, they may be configured
to do so.
For example, for a host outside of the network to communicate with
the hosts within the 172.16.4.0 /24 network, the destination address of
the packet would be 172.16.4.255.
____________________ used for communication to hosts
_______________________________

Routers do not forward this broadcast to other directly connected networks
Routers form the boundary for a broadcast domain.

These packets use a destination IP address 255.255.255.255.


Broadcast traffic should be limited so it does not adversely
affect network or device performance
IPv4 Communication via

Unicast, Broadcast, or Multicast
______________ transmission is designed to conserve
bandwidth of the network.
It
is the ______________________________________________
______________________________



The source host can send a single packet that can reach thousands of
destination hosts both locally and through an internetwork
Can someone give an example of multicast transmission?
Multicast clients and multicast group
__________________________________________________
called _______________________________________.

are
The multicast clients use services initiated by a client program to subscribe to the
multicast ____________ a group that _________________________________.
Each
multicast group is represented by a single multicast destination
address.


Hosts within a multicast group process packets addressed to a multicast address as
well as packets addressed to its uniquely allocated unicast address.
IPv4 has set aside a special block of addresses from 224.0.0.0 to
239.255.255.255 for multicast groups addressing.
Reserved IPv4 Address Ranges


The IPv4 address range is 0.0.0.0 to 255.255.255.255.
Unicast ________________ Addresses



_________________ Addresses



Host address range of _____________________________
within this range are many addresses that are already
reserved for special purposes as we will see next section…
Experimental address range __________________________
Reserved for research or experimentation but may be converted
to usable addresses in the future
Multicast Addresses

SEE NEXT SLIDE…
Reserved IPv4 Address Ranges cont...

Multicast Addresses
_________________________________________

Multicast addresses subdivided into:
________________________________
The multicast addresses
224.0.0.0 to 224.0.0.255.


Addresses used for multicast groups on a local network
Routers use this type of multicast transmission to exchange routing
information
___________________________________:
The globally scoped
addresses are 224.0.1.0 to 238.255.255.255.

Used to ____________________________________
__________________
addresses AKA Administratively scoped:
The multicast addresses 239.0.0.0 to 239.255.255.255

_____________________________________________
Public and Private Addresses

___________________ Addresses
Used
by networks that are _____________________________
Addresses must be __________________ to the Internet

______________________ addresses
Addresses
that are _____________________________________
________________________________________
Private address blocks :



10.0.0.0 to 10.255.255.255 (_______________________)
172.16.0.0 to 172.31.255.255 (___________________________)
192.168.0.0 to 192.168.255.255 (_____________________________)
Hosts
in _________________ may use the ________________
private addresses.
The hosts within the private networks use IP addresses that are
_________________________________________
The ____________ or firewall device at the perimeter of these
private networks __________________________ these addresses.
Network Address Translation (___)

______________________________________
________________ for communicating to
outside networks and across the Internet
 translates

private addresses to public addresses
The NAT can be implemented- by a device such
as a router- at the edge of the private network.
NAT will be covered in detail
in a subsequent course.
Special IPv4 Addresses


Certain addresses cannot be assigned to hosts or can be
assigned but with restrictions.
Review: Describe the _______ and _________ Addresses
Can

not be assigned to hosts
_____________________________
The
default route is _____________________________The default route is __________________________________.
Reserves all addresses in the 0.0.0.0 - 0.255.255.255 range so
those addresses can not be assigned to hosts

_____________________________A
reserved address which hosts use to ____________________
The loopback address __________________________.
You can ping the loopback address to ____________________
_____________________________________

Also used to test if the NIC on that device is functioning
Addresses
in 127.0.0.0 to 127.255.255.255 are all reserved
Special IPv4 Addresses cont…

______________________Addresses
Reserved
addresses that can be ____________________
_______________________________ if needed
Address block 169.254.0.0 to 169.254.255.255
(_____________) are reserved as link-local addresses.
Address block used when a host __________ automatically
obtain an address from a ____________________

If this address appears in our configuration- tell us there’s a good
chance something is wrong with the DHCP server
Hosts
using link-local addresses can only _____________
________________________________

__________________________Addresses
Reserved for __________________________________
 In documentation, network examples etc.
Address block 192.0.2.0 to 192.0.2.255 (______________)
 Network devices will accept these addresses in their configurations
but will not appear on the Internet
Legacy IPv4 Addressing- Classes


Address ranges used to be grouped into specific
sizes: class A, class B, class C, class D (multicast),
and class E (experimental) addresses.
Known as _______________________________
Defined
_________________________ as well as
_____________________________________
Classes – cont…

Class A Blocks
Used for extremely large networks with more than 16 million host
addresses.
____________________________________



first octet indicating the network portion of the address
remaining three octets used for host portion
128
possible class A networks, 0.0.0.0 /8 to 127.0.0.0 /8 excluding
reserved addresses- 0. network, 10. network and the 127. network -- why?


Few companies could have or would need an entire class A address
Class B Blocks
Support
the moderate to large size networks with more than 65,000
host addresses
_____________________________________


first two octets indicating the network portion of the address
remaining two octets used for host portion
Approximately
16,000 public class B networks, 128.0.0.0 /16 to
191.255.0.0 /16- excluding which addresses??
Legacy IPv4 Addressing

Class C Blocks
Used
for small networks with a maximum of 254 hosts.
__________________________________


first three octets indicating the network portion of the address
last octet used for host portion
Approximately
2 million class C networks, 192.0.0.0 /16 to
223.255.255.0 /16 excluding reserved addresses- Which ones??

Limitations to the Class-based System
_____________________________________________
which
exhausted the availability of IPv4 addresses.
Classful system began phasing out in the late 1990s

______________________ Addressing
The

system we __________________________________
_________________________________________ are assigned to
companies or organizations without regard to the unicast class.
Planning to Address the Network

The allocation of addresses inside the network
needs to be planned and documented for the
purpose of:
________________________________________

Each host in an internetwork must have a unique address.
______________________________________

Especially important for hosts providing resources both internally and
externally
__________________________________________


If we have proper planning and documentation of the network
addressing, we can analyze traffic patterns and identify problems
Within a network, there are different types of hosts.
What are some examples?
Planning to Address the Network

An important part of planning an
IPv4 addressing scheme is
deciding _______________
________________________
If
there are more devices than
available public addresses, only
those devices that will directly
access the Internet - such as web
servers - require a public address.
________________________
could be used for the rest

Another consideration- will
devices need to be accessed
from outside the local network?
Static or Dynamic Addressing for End User Devices

With a _______________________
_______________________________
________________ for a host (figure).
Necessary
to ___________________ of
statically assigned IP address

Static address advantages:
Used

when addresses should not change
________________________________
________________ that need to be
accessible to clients on the network.
Additionally,

static assignment of
addressing information ____________
______________________________
Disadvantage: it can be_________________
to enter the information on each host.
Static or Dynamic Addressing for End User Devices

____________________________
_______________________________
_______________________ and other
configuration information to hosts
because it ____________________
_________________________
The
configuration of the DHCP server
requires the definition of a block of address,
called an ____________________


Pool should exclude any addresses used by
devices in manual assignment
Benefit of DHCP is that an address is
_______________________________
______________________________
When
no longer needed by a host,
addresses can be returned to the pool for
reuse.
Assigning Addresses to Devices other than hosts

Recall: addresses for servers and
peripherals should be _________________.
Predictable
necessary

addresses for these devices are
Hosts (usually servers) that are accessible
from Internet must have a ___________
__________________________
If
using private addressing within the network,
the router or firewall at the perimeter of the
network must be configured to translate the
internal address of the server into a public
address
Assigning Addresses to other Devices

(cont.)
Intermediary devices are a concentration point for network
traffic.
Almost
all traffic within a network or between two networks passes
through an intermediary device
Either for device management or for their operation- these
intermediary devices should be __________________________
layer 3 address


Best practices is to assign these devices a network block in a different
range than user device addresses
_______________________________________________
_______________________________________
Each
interface is in a different network and serves as the gateway
for the hosts in that network.
The router interface uses _____________________________ in
the network and this should be __________________ throughout all
networks in the company
Many packets flow through a router’s interfaces so routers play a
key role in _____________________________________
Good example graphic…
Who Assigns the Different Address?




A company that wishes to have network hosts accessible from the
Internet must have a block of public addresses assigned.
Internet Assigned Numbers Authority (______________)
(http://www.iana.net) is the master holder of the IP addresses.
In the mid-1990’s remaining IPv4 addresses were allocated to five
other registries to manage for regional areas.
The 5 Regional Internet Registries (RIRs) are:
ISPs

To get access to the Internet, we have to connect
our network to the Internet using an Internet Service
Provider (ISP).
_____________________________________________
___________________, etc.

Most companies obtain their IPv4 address blocks on
loan from an ISP.
If
an ISP is changed, the new ISP will provide new
addresses from their address blocks.

ISPs are designated by a ______________ based
on their proximity to the Internet backbone.
Lower
tiers connect to the backbone via the next higher
tier up
See three tier graphic on
next slide
Which ISP tier are we looking for…

Which tier would be most
reliable?

Which tier offers primarily
only Internet connectivity and
support?

Which tier is most expensive?

Which tier offers the most
services to it’s customers?
Overview of IPv6

IPv6 came about as a result of the depletion of IPv4 addresses and offers
the following features:
 ________________________________
- to expand addressing capabilities
 Header format simplification - to _____________________________
 Improved support for extensions and options - for increased
__________/longevity and ____________________________________
 Flow labeling capability - as QoS mechanisms
 Authentication and privacy capabilities - to ________________________


IPv6 is a complete Layer 3 protocol suite including new routing protocols etc.
Transition to IPv6 is slow as new ways of dealing with IPv4 challenges keep
it a widely used protocol suite.
Subnet Mask – Defining the network and Host Portions




A subnet mask is ____________________
Recall: IPv4 address has a network
portion and a host portion.
To _____________________________,
the devices use a separate 32-bit pattern
called a subnet mask.
We express the subnet mask in the same
dotted decimal format as the IPv4 address.
A
__________________ in a bit position
represents the ___________________
 ______________________ in a bit position
represents the ___________________

As shown, a /24 prefix is expressed as a
subnet mask: 255.255.255.0
(11111111.11111111.11111111.00000000)
 The
zeroes represent the host portion of the
address
 NOTE: the ________________________
___________________________________
__________________________________
ANDing – What is in our network?

Use the logical operator AND to _________
____________ when ANDing is _________
_________________________________
 Host
address is ANDed with its subnet mask
to determine the network address to which
the host is associated.

The AND Operation


[true AND true = true]
[true AND false = false]
[false AND true = false]
[false AND false = false]




Host bits of a subnet mask are represented
by 0’s so the host portion of the address will
always be 0’s thereby giving us our network
address
All the bits of the subnet mask that indicate
___________________________
 ANDing
will result in bits that are identical to
the original network portion of the address
When is ANDing used?

As a packet arrives at a router, the __________________
on the _______________________________________
_________________________________________
The
resulting network address is compared to possible routes from
the routing table to determine an acceptable route

An __________________________________________
__________________________ with it’s own subnet mask
The
host can then decide if a packet should be sent to a host in the
local network or be sent to the gateway.


If the host network and destination network addresses do not match, the
packet is sent to the gateway.
ANDing used in network
May
need to determine what network a host is on or if two hosts are
on the same network.
May need to use ANDing to troubleshoot routing issues
No calculators of any kind are permitted during certification exams
Example: Given 172.16.4.35/27
What is the Network Address?


First convert the IP address and Subnet Mask into binary
IP address
172.16.20.35


Subnet mask – how do we get the subnet mask value?
255.255.255.224


Network address
172.16.20.32

Basic Subnetting

Subnetting allows for ____________________
________________ from a single address block.
smaller



divisions of networks
A.K.A. ______________________
Recall from Chpt. 5: subnets are created by
using one or more host bits as subnet bits.
Subnetting works by _____________________
to _____________________________________
of the address to create additional network bits.
The
more host bits used, the more subnets that can
be defined.
 fewer host addresses are available per subnet.
Advantages of Subnetworks
Subnet addresses provide ________
and are assigned locally by a network
administrator.
 Improve ________________ through
better use of host addressing
 Can __________________________
on a subnetted network

 ________________________
into smaller,
more efficient and manageable subnets
Subnet Addresses


Includes ___________ portion plus a ________
field and a ________________ field.
Bits are borrowed from the host field and are
designated as the subnet field.
Network
Subnet
Original Host portion (field)
Host
Subnet Example
Network
S
Network
S
H
H
Network
H
H
Host
H
H
Say Two Bits are Borrowed from the Host Field to
form a third layer of hierarchy - A Subnet Field
Subnets Created
Network
S
Network
S
H
H
Network
H
H
Host
H
H
The number of Subnets Created is calculated using the
following formula:
# of Subnets Created = ______________
Subnets created after borrowing
S
S
H
H
H
H
H
H
Borrow 2 Bits = 22= 4 Subnets
S
S
S
H
H
H
H
H
Borrow 3 Bits = 23= 8 Subnets
S
S
S
S
H
H
H
H
Borrow 4 Bits = 24= 16 Subnets
How Many Hosts Per Subnet?
Network
S
Network
S
H
H
Network
H
H
Host
H
H
How is the number of Hosts per subnet
calculated?
# Hosts = 26 = 64 hosts/subnet?
?
How Many Usable Hosts/Subnet?
6 Host Bits Remain = 26 = 64 Hosts



If there are 6 Host Bits remaining you do NOT
get 64 Hosts/Subnet. Why?
Each subnet has its own ______________
______________________ - Both of these
______________________________________!
Thus only _____ Usable Hosts are available.
6 Host Bits Remain = 26-2 = ____
Usable Hosts
SUMMARY: Formulas to Remember!
# Usable Subnets = 2# Borrowed Bits
# Usable Hosts/Subnet =
2# Host Bits Remaining-2

Remember to subtract 2 for the Subnetwork
Address and Subnetwork Broadcast Address.
Example- 205.16.12.0
Requirement is 3 subnets
 What is the default subnet mask?


 This
could also be written 205.16.12.0/24
Borrow 2 bits for the subnet mask
 NNNNNNNN.NNNNNNNN.NNNNNNNN.
SShhhhhh

Example- 205.16.12.0 cont…

What is the subnet mask (including
borrowed bits)?

11111111.11111111.11111111.11000000

Value of the 4th octet=
 27+26

= 128+64 = 192
255.255.255.192
The Default
Resulting from the
subnet
Step by Step EXAMPLE #2

We will subnet the IP address:
 199.14.17.0

NOTE: For the reminder of the example,
we will focus only the forth octet
Step #1

Determine the default subnet mask

Default subnet mask:

Step #2
You will be given the number of subnets
needed. Use this info to determine how
many bits to borrow from the host field.
 Requirement:

6
subnets
Step #3
Figure the actual number of subnets by
borrowing bits from host field.
 Let’s see how many subnets we will have
by borrowing 3 bits from the host.

Step #3 continued…
199.14.17.0
SSS
8 subnets
How did we get 8?
HHHHH
30 hosts for
each subnet
How did we get 30?
Step #3 continued…
Recall:
 You cannot use the first and last address
within each subnet- they are reserved!

 One
is the broadcast address and one is the
network address.
Step #4

Determine the subnet mask.
Default subnet
mask for given
example
255.255.255.0
BIT VALUE OF
4TH OCTET
SSS
111
128

64
HHHHH
00000
32
Where S represents the borrowed bits for
subnetting.
Step #4 continued…

Add the place values of S together to get
the last octet decimal value of the subnet
mask.
128 + 64 + 32 = 224
The subnet mask is: 255.255.255.224
 The subnet mask is used to reveal the
subnet and host address fields in IP
addresses.

Step 5

Determine the ranges of host addresses
for each subnet.
Step 5 continued…
Subnet # Subnet Bits Host Bits
0
000
00000-11111
1
001
00000-11111
2
010
00000-11111
3
011
00000-11111
4
100
00000-11111
5
101
00000-11111
6
110
00000-11111
7
111
00000-11111
In Decimal
.0 -.31
.32 - .63
.64 - .95
.96 - .127
.128 - .159
.160 - .191
.192 - .223
.224 - .255
Cont. on next slide…
Step 5 continuedIn Decimal
Focusing in on the decimal portion…
Network
Address
Host Range
199.14.17.0/27
199.14.17.1 - .30
199.14.17.31
.32 - .63
199.14.17.32/27
199.14.17.33 - .62
199.14.17.63
.64 - .95
199.14.17.64/27
199.14.17.65 - .94
199.14.17.95
.96 - .127
199.14.17.96/27
199.14.17.97 - .126
199.14.17.127
.128 - .159
199.14.17.128/27
199.14.17.129 - .158
199.14.17.159
.160 - .191
199.14.17.160/27
199.14.17.161 - .190
199.14.17.191
.192 - .223
199.14.17.192/27
199.14.17.193 - .222
199.14.17.223
.224 - .255
199.14.17.224/27
199.14.17.225 - .254
199.14.17.255
.0 -.31
Broadcast
Address
25 -2 = 30 hosts
Subnetting and VLSM

Network administrators need to devise an internetwork
addressing scheme to accommodate the maximum
number of hosts for each network.

Point-to-point WAN links, only require a
_____________________
 Large building or department LAN, may need to accommodate
_________________________________
 Must also take into account projected future growth

_______________________________________ is an
efficient addressing scheme for network admins. to use
when breaking down a large network


Also referred to as using Variable Length Subnet Mask
(________)
VLSM was designed to ___________________________

If all the subnets have the same requirements for the number
hosts, these fixed size address blocks would be efficient. (see
example to come…)
When using VLSM



(or subnetting a subnet)…
First consider the ________________________
_______________________________ including
devices, servers, router interfaces etc
Next, consider the _______________________
____________________________ required
based on common groupings of hosts.
Next, we need to start allocating addresses
 We
start with the ___________________________
__________________________________________
Pre- VLSM example
Using “traditional”
subnetting
• waste of 28 host addresses
from each subnet to simply
address three point-to-point
WAN networks
•NO ROOM FOR NETWORK
GROWTH!
See next slide for a better way …
Same scenario now using VLSM
Break the address into subnets of varying
sizes
 Use one of the three subnets which had
previously been used to assign to a WAN
link, and subnet it again with a 30-bit mask
 See the next slide and the board for
details…

VLSM example #1
VLSM example #1 cont…

Questions:
 Could
we have selected ANY subnet to divide
down further or did we NEED to choose
subnet #6?
Why was /27 chosen to begin with?
 Why was /30 subsequently chosen?

Graphic for Example #2 to follow…
500
200
Subnetting and VLSM – Example #2

In our example, the total number of hosts required by the
entire corporate network including devices, servers, router
interfaces etc is 800 hosts
To
accommodate 800 hosts, we use binary arithmetic to allocate a
______________________________________________________
_______________________________________

Next, we consider the number of networks and the size of
each required based on common groupings of hosts.
In
our example: The company has 4 locations (4 LANs).
Each WAN link is a network. We create subnets for the WAN that
interconnect different geographic locations.

Now we will need to start allocating addresses __________
_______________________________________________
_____________________________________________
See graphic on next slide
Where shall we start?
500
Recall:
Number of
network bits
200
See board to understand this example…
What is Ping?

Ping is a utility for _____________________
_________________________________
Ping
uses a _____________ that is a part on the TCP/IP
suite called Internet Control Message Protocol (______).
Ping uses an ________________________ datagram.
If the host receives the Echo request, it ___________
________________________________ datagram.
Ping measures the time required for the reply and
______________________________________

Recall: Pinging the Local Loopback- _______ tests
the internal configuration of IP on the local host.
A
_________________________________________
_________________________________________

Response is _____________________________________, or
gateways are _________________________________.
Ping Gateway – Testing Connectivity to the Local LAN

Use ping to test the _______________
________________________________
_______________________ the IP
address of the __________________
A
ping to the gateway indicates that the host
and the router's interface serving as that
gateway are both operational on the local
network.

If gateway address does not respond:
Try _____________________________ in
the local network.
If the gateway does not respond but another
host does, possible ________________
____________________________________
___ serving as the gateway.


If
If ________________ to that interface, that
may ________________________ or
responding to ping requests.
either the gateway or another host responds, then the local
hosts can successfully communicate over the local network.
Ping Remote Host – Testing Connectivity to Remote LAN

You can also __________________________
______________________________________
If
this ping is successful, it means that we have verified
our host's communication on the local network, all the
way through to the network of the remote host.

Remember, ____________________________
________________________________________
_________ into or out of the corporate network.
Lack
of a ping response could be due to security
restrictions and not because of non-operational
elements of the networks.
Tracertout (tracert) – Testing the Path

Traceroute (tracert) is ______________________
__________________________________
___________________________________
that were
successfully reached along the path.

Used for ______________________________
If
the data fails at some hop along the way, we have the
address of the last router where the problem occurred or
security restrictions are

Round Trip Time (RTT)
__________________________________________
and for the response from the host to return.
An ________________ (*) is used to indicate a
_____________________________
What do you think a high response time indicates?
Tracertout (tracert) – Testing the Path

Time to Live (TTL)
Used
to ________________
_________________________
When the TTL reaches zero, a
router will not forward the packet
and the packet is dropped.

The ____________________
_______________________
will be sent to the originating
host and contain the IP address
of the router that responded.
Sample Traceroute.
ICMPv4 – The Protocol Supporting Testing and Messaging

Although IPv4 is not a reliable protocol, it does
_______________________________________
about issues related to the processing of IP
packets under certain conditions- to be sent, using
ICMPv4
__________________________________
and are
often not allowed for security reasons.

ICMP messages that may be sent include the
following five:
1.
Determines if a host is
 basis of the ping utility.
operational
ICMPv4 messages cont…
2.
Used
to notify the sending host that the destination or
service is unreachable
Destination Unreachable codes indicating why the
packet could not be delivered are:




0 = net unreachable
1 = host unreachable
2 = protocol unreachable
3 = port unreachable
3.
Used
by the router to indicate that a packet cannot be
forwarded because the TTL field has expired.
ICMP Time Exceeded message also sent to the source
host to inform the host of the reason the packet was
dropped.
ICMPv4 messages cont…
4.
A
router may use the ICMP Redirect Message to notify
the hosts on a network that a _____________________
for a particular destination.
5.
Can
be used to tell the source to temporarily _______
______________________________ due to a lack of
buffer space in which to receive incoming packets
Also notifies the source host for every message that it
discards due to the lack of buffer space
A destination host may send a source quench message
if datagrams arrive too fast to be processed.
The Transport layer at the source host end can use the
TCP flow control mechanisms to adjust the transmission.