Chapter 8 : IP addressing

© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 1
Chapter 8:
IP Addressing
Introduction to Networks

Presentation_ID 2© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 8
8.0 Introduction
8.1 IPv4 Network Addresses
8.2 IPv6 Network Addresses
8.3 Connectivity Verification
8.4 Summary

Chapter 8: Objectives
Upon completion of this chapter, you will be able to:
 Describe the structure of an IPv4 address.
 Describe the purpose of the subnet mask.
 Compare the characteristics and uses of the unicast, broadcast, and
multicast IPv4 addresses.
 Compare the use of public address space and private address space.
 Explain the need for IPv6 addressing.
 Describe the representation of an IPv6 address.
 Describe types of IPv6 network addresses.
 Configure global unicast addresses.
 Describe multicast addresses.
 Describe the role of ICMP in an IP network. (Include IPv4 and IPv6.)
 Use ping and traceroute utilities to test network connectivity.

8.1 IPv4 Network
Addresses

IPv4 Address Structure
Binary Notation
 Binary notation
refers to the fact that
computers
communicate in 1s
and 0s
 Positional notation -
converting binary to
decimal requires an
understanding of the
mathematical basis
of a numbering
system

Binary Number System

Converting a Binary Address to Decimal
Practice

Practice
Answer = 176
Answer = 255

Converting from Decimal to Binary
168 = ? binary

Converting from Decimal to Binary (Cont.)

IPv4 Subnet Mask
Network Portion and Host Portion of an IPv4 Address
 To define the network and host portions of an address, a devices
use a separate 32-bit pattern called a subnet mask
 The subnet mask does not actually contain the network or host
portion of an IPv4 address, it just says where to look for these
portions in a given IPv4 address

IPv4 Subnet Mask
Network Portion and Host Portion of an IPv4
Address (cont.)
Valid Subnet Masks

IPv4 Subnet Mask
Examining the Prefix Length

IPv4 Subnet Mask
Examining the Prefix Length (cont.)

IPv4 Subnet Mask
IPv4 Network, Host, and Broadcast Address
10.1.1.0/24

IPv4 Subnet Mask
First Host and Last Host Addresses
10.1.1.0/24

IPv4 Subnet Mask
Bitwise AND Operation
1 AND 1 = 1 1 AND 0 = 0 0 AND 1 = 0 0 AND 0 = 0

IPv4 Unicast, Broadcast, and Multicast
Assigning a Static IPv4 Address to a Host
LAN Interface Properties Configuring a Static IPv4 Address

Assigning a Dynamic IPv4 Address to a Host
DHCP – The preferred method of assigning IPv4 addresses to hosts on
large networks because it reduces the burden on network support staff
and virtually eliminates entry errors.
Verification

Unicast Transmission
#1 Unicast – the
process of sending a
packet from one host to
an individual host.
In an IPv4 network, the hosts can communicate one of three different ways:
Unicast, Broadcast, and Multicast

Broadcast Transmission
In an IPv4 network, the hosts can communicate one of three different
ways: Unicast, Broadcast, and Multicast.
NOTE: Routers do
not forward a
limited broadcast!
Directed broadcast
• Destination
172.16.4.255
• Hosts within the
172.16.4.0/24
network
#2 Broadcast – the
process of sending a
packet from one host to
all hosts in the network.
Directed broadcast
 Destination
172.16.4.255
 Hosts within the
172.16.4.0/24 network

Multicast Transmission
#3 Multicast – The process of sending a packet from one host to a
selected group of hosts, possibly in different networks.
 Reduces traffic
 Reserved for addressing multicast groups – 224.0.0.0 to
239.255.255.255.
 Link local – 224.0.0.0 to 224.0.0.255 (Example: routing information
exchanged by routing protocols)
 Globally scoped addresses – 224.0.1.0 to 238.255.255.255 (Example:
224.0.1.1 has been reserved for Network Time Protocol)
In an IPv4 network, the hosts can communicate one of three different ways:
Unicast, Broadcast, and Multicast.

Types of IPv4 Address
Public and Private IPv4 Addresses
Private address blocks are:
 Hosts that do not require access to the Internet can use private
addresses
 10.0.0.0 to 10.255.255.255 (10.0.0.0/8)
 172.16.0.0 to 172.31.255.255 (172.16.0.0/12)
 192.168.0.0 to 192.168.255.255 (192.168.0.0/16)
Shared address space addresses:
 Not globally routable
 Intended only for use in service provider networks
 Address block is 100.64.0.0/10

Special Use IPv4 Addresses
 Network and Broadcast addresses – within each network the first
and last addresses cannot be assigned to hosts
 Loopback address – 127.0.0.1 a special address that hosts use to
direct traffic to themselves (addresses 127.0.0.0 to 127.255.255.255
are reserved)
 Link-Local address – 169.254.0.0 to 169.254.255.255
(169.254.0.0/16) addresses can be automatically assigned to the local
host
 TEST-NET addresses – 192.0.2.0 to 192.0.2.255 (192.0.2.0/24) set
aside for teaching and learning purposes, used in documentation and
network examples
 Experimental addresses – 240.0.0.0 to 255.255.255.254 are listed
as reserved

Legacy Classful Addressing

Legacy Classful Addressing (cont.)
Classless Addressing
 Formal name is Classless Inter-Domain Routing (CIDR, pronounced
“cider
 Created a new set of standards that allowed service providers to
allocate IPv4 addresses on any address bit boundary (prefix length)
instead of only by a class A, B, or C address

Assignment of IP Addresses
Regional Internet Registries
(RIRs)

Assignment of IP Addresses (Cont.)
Tier 2 ISPs generally
focus on business
customers.
Tier 3 ISPs purchase their
Internet service from Tier 2
ISPs.
Tier 3 ISPs often bundle
Internet connectivity as a part of
network and computer service
contracts for their customers.
ISPs are large national
or international ISPs that
are directly connected to
the Internet backbone.

8.2 IPv6 Network
Addresses

IPv4 Issues
The Need for IPv6
 IPv6 is designed to be the successor to IPv4.
 Depletion of IPv4 address space has been the motivating factor for
moving to IPv6.
 Projections show that all five RIRs will run out of IPv4 addresses
between 2015 and 2020.
 With an increasing Internet population, a limited IPv4 address space,
issues with NAT and an Internet of things, the time has come to begin
the transition to IPv6!
 IPv4 has a theoretical maximum of 4.3 billion addresses, plus private
addresses in combination with NAT.
 IPv6 larger 128-bit address space provides for 340 undecillion
addresses.
 IPv6 fixes the limitations of IPv4 and includes additional
enhancements, such as ICMPv6.

IPv4 Issues
IPv4 and IPv6 Coexistence
The migration techniques can be divided into three categories:
Dual-stack, Tunnelling, and Translation.
Dual-stack: Allows IPv4 and IPv6 to coexist on the same network.
Devices run both IPv4 and IPv6 protocol stacks simultaneously.
Dual-stack

IPv4 Issues
IPv4 and IPv6 Coexistence (cont.)
Tunnelling: A method of transporting an IPv6 packet over an IPv4
network. The IPv6 packet is encapsulated inside an IPv4 packet.
Tunnelling

IPv4 Issues
IPv4 and IPv6 Coexistence (cont.)
Translation: The Network Address Translation 64 (NAT64) allows
IPv6-enabled devices to communicate with IPv4-enabled devices
using a translation technique similar to NAT for IPv4. An IPv6 packet
is translated to an IPv4 packet, and vice versa.
Translation

IPv6 Addressing
Hexadecimal Number System
 Hexadecimal is a base
sixteen system.
 Base 16 numbering
system uses the
numbers 0 to 9 and the
letters A to F.
 Four bits (half of a byte)
can be represented with
a single hexadecimal
value.

IPv6 Addressing
Hexadecimal Number System (cont.)
Look at the binary bit
patterns that match the
decimal and hexadecimal
values

IPv6 Addressing
IPv6 Address Representation
 128 bits in length and written as a string of hexadecimal values
 In IPv6, 4 bits represents a single hexadecimal digit, 32 hexadecimal
value = IPv6 address
2001:0DB8:0000:1111:0000:0000:0000:0200
FE80:0000:0000:0000:0123:4567:89AB:CDEF
 Hextet used to refer to a segment of 16 bits or four hexadecimals
 Can be written in either lowercase or uppercase

IPv6 Addressing
IPv6 Address Representation (cont.)

IPv6 Addressing
Rule 1- Omitting Leading 0s
 The first rule to help reduce the notation of IPv6 addresses is any
leading 0s (zeros) in any 16-bit section or hextet can be omitted.
 01AB can be represented as 1AB.
 09F0 can be represented as 9F0.
 0A00 can be represented as A00.
 00AB can be represented as AB.

IPv6 Addressing
Rule 2 - Omitting All 0 Segments
 A double colon (::) can replace any single, contiguous string of one or
more 16-bit segments (hextets) consisting of all 0’s.
 Double colon (::) can only be used once within an address otherwise
the address will be ambiguous.
 Known as the compressed format.
 Incorrect address - 2001:0DB8::ABCD::1234.

IPv6 Addressing
Rule 2 - Omitting All 0 Segments (cont.)
Example #1
Example #2

Types of IPv6 Addresses
IPv6 Prefix Length
 IPv6 does not use the dotted-decimal subnet mask notation
 Prefix length indicates the network portion of an IPv6 address using
the following format:
 IPv6 address/prefix length
 Prefix length can range from 0 to 128
 Typical prefix length is /64

IPv6 Address Types
There are three types of IPv6 addresses:
 Unicast
 Multicast
 Anycast.
Note: IPv6 does not have broadcast addresses.

IPv6 Unicast Addresses
Unicast
 Uniquely identifies
an interface on an
IPv6-enabled
device.
 A packet sent to a
unicast address is
received by the
interface that is
assigned that
address.

IPv6 Unicast Addresses (cont.)

Global Unicast
 Similar to a public IPv4 address
 Globally unique
 Internet routable addresses
 Can be configured statically or assigned dynamically
Link-local
 Used to communicate with other devices on the same local link
 Confined to a single link; not routable beyond the link

Loopback
 Used by a host to send a packet to itself and cannot be assigned to a
physical interface.
 Ping an IPv6 loopback address to test the configuration of TCP/IP on
the local host.
 All-0s except for the last bit, represented as ::1/128 or just ::1.
Unspecified Address
 All-0’s address represented as ::/128 or just ::
 Cannot be assigned to an interface and is only used as a source
address.
 An unspecified address is used as a source address when the device
does not yet have a permanent IPv6 address or when the source of
the packet is irrelevant to the destination.

Unique Local
 Similar to private addresses for IPv4.
 Used for local addressing within a site or between a limited
number of sites.
 In the range of FC00::/7 to FDFF::/7.
IPv4 Embedded (not covered in this course)
 Used to help transition from IPv4 to IPv6.

IPv6 Link-Local Unicast Addresses
 Every IPv6-enabled network interface is REQUIRED to have a link-
local address
 Enables a device to communicate with other IPv6-enabled devices
on the same link and only on that link (subnet)
 FE80::/10 range, first 10 bits are 1111 1110 10xx xxxx
 1111 1110 1000 0000 (FE80) - 1111 1110 1011 1111 (FEBF)

IPv6 Link-Local Unicast Addresses (cont.)
Packets with a
source or
destination link-local
address cannot be
routed beyond the
link from where the
packet originated.

Structure of an IPv6 Global Unicast Address
 IPv6 global unicast addresses are globally unique and routable on the
IPv6 Internet
 Equivalent to public IPv4 addresses
 ICANN allocates IPv6 address blocks to the five RIRs

Structure of an IPv6 Global Unicast Address (cont.)
Currently, only global unicast addresses with the first three bits of 001 or
2000::/3 are being assigned

A global unicast address has three parts: Global Routing Prefix, Subnet
ID, and Interface ID.
 Global Routing Prefix is the prefix or network portion of the address
assigned by the provider, such as an ISP, to a customer or site,
currently, RIR’s assign a /48 global routing prefix to customers.
 2001:0DB8:ACAD::/48 has a prefix that indicates that the first 48 bits
(2001:0DB8:ACAD) is the prefix or network portion.

 Subnet ID is used by an organization to identify subnets within its site
 Interface ID
 Equivalent to the host portion of an IPv4 address.
 Used because a single host may have multiple interfaces, each
having one or more IPv6 addresses.

Static Configuration of a Global Unicast Address

Static Configuration of an IPv6 Global Unicast Address
(cont.)
Windows
IPv6
Setup

Dynamic Configuration of a Global Unicast Address
using SLAAC
Stateless Address Autoconfiguraton (SLAAC)
 A method that allows a device to obtain its prefix, prefix length and
default gateway from an IPv6 router
 No DHCPv6 server needed
 Rely on ICMPv6 Router Advertisement (RA) messages
IPv6 routers
 Forwards IPv6 packets between networks
 Can be configured with static routes or a dynamic IPv6 routing
protocol
 Sends ICMPv6 RA messages

Dynamic Configuration of a Global Unicast Address using
SLAAC (cont.)
 The IPv6 unicast-routing command enables IPv6 routing.
 RA message can contain one of the following three options:
 SLAAC Only – Uses the information contained in the RA message.
 SLAAC and DHCPv6 – Uses the information contained in the RA
message and get other information from the DHCPv6 server,
stateless DHCPv6 (for example, DNS).
 DHCPv6 only – The device should not use the information in the
RA, stateful DHCPv6.
 Routers send ICMPv6 RA messages using the link-local address as
the source IPv6 address

using SLAAC (cont.)

Dynamic Configuration of a Global Unicast Address using
DHCPv6 (cont.)
Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
 Similar to IPv4
 Automatically receives addressing information, including a global
unicast address, prefix length, default gateway address and the
addresses of DNS servers using the services of a DHCPv6 server.
 Device may receive all or some of its IPv6 addressing information
from a DHCPv6 server depending upon whether option 2 (SLAAC
and DHCPv6) or option 3 (DHCPv6 only) is specified in the ICMPv6
RA message.
 Host may choose to ignore whatever is in the router’s RA message
and obtain its IPv6 address and other information directly from a
DHCPv6 server.

using DHCPv6 (cont.)

EUI-64 Process or Randomly Generated
EUI-64 Process
 Uses a client’s 48-bit Ethernet MAC address and inserts another 16
bits in the middle of the 46-bit MAC address to create a 64-bit
Interface ID.
 Advantage is that the Ethernet MAC address can be used to
determine the interface; is easily tracked.
EUI-64 Interface ID is represented in binary and comprises three parts:
 24-bit OUI from the client MAC address, but the 7th bit (the
Universally/Locally bit) is reversed (0 becomes a 1).
 Inserted as a 16-bit value FFFE.
 24-bit device identifier from the client MAC address.

EUI-64 Process or Randomly Generated (cont.)

Randomly Generated Interface IDs
 Depending upon the operating system, a device can use a randomly
generated Interface ID instead of using the MAC address and the EUI-
64 process.
 Beginning with Windows Vista, Windows uses a randomly generated
Interface ID instead of one created with EUI-64.
 Windows XP (and previous Windows operating systems) used EUI-64.

Dynamic Link-local Addresses
Link-Local Address
 After a global unicast address is assigned to an interface, an IPv6-
enabled device automatically generates its link-local address.
 Must have a link-local address that enables a device to communicate
with other IPv6-enabled devices on the same subnet.
 Uses the link-local address of the local router for its default gateway
IPv6 address.
 Routers exchange dynamic routing protocol messages using link-
local addresses.
 Routers’ routing tables use the link-local address to identify the next-
hop router when forwarding IPv6 packets.

Dynamic Link-local Addresses (cont.)
Dynamically Assigned
The link-local address is dynamically created using the FE80::/10 prefix
and the Interface ID.

Static Link-local Addresses
Configuring Link-local

Static Link-local Addresses (cont.)
Configuring Link-local

IPv6 Global Unicast Addresses
Verifying IPv6 Address Configuration
Each interface has
two IPv6 addresses -
1. global unicast
address that was
configured
2. one that begins
with FE80 is
automatically
added as a link-
local unicast
address

IPv6 Global Unicast Addresses
Verifying IPv6 Address Configuration (cont.)

IPv6 Multicast Addresses
Assigned IPv6 Multicast Addresses
 IPv6 multicast addresses have the prefix FF00::/8
 There are two types of IPv6 multicast addresses:
 Assigned multicast
 Solicited node multicast

Assigned IPv6 Multicast Addresses (cont.)
Two common IPv6 assigned multicast groups include:
 FF02::1 All-nodes multicast group –
 All IPv6-enabled devices join
 Same effect as an IPv4 broadcast address
 FF02::2 All-routers multicast group
 All IPv6 routers join
 A router becomes a member of this group when it is enabled
as an IPv6 router with the ipv6 unicast-routing global
configuration mode command.
 A packet sent to this group is received and processed by all
IPv6 routers on the link or network.

Assigned IPv6 Multicast Addresses (cont.)

Solicited Node IPv6 Multicast Addresses
 Similar to the all-nodes
multicast address,
matches only the last 24
bits of the IPv6 global
unicast address of a
device
 Automatically created
when the global unicast or
link-local unicast
addresses are assigned
 Created by combining a
special
FF02:0:0:0:0:0:FF00::/104
prefix with the right-most
24 bits of its unicast
address

Solicited Node IPv6 Multicast Addresses (cont.)
The solicited node multicast
address consists of two parts:
 FF02:0:0:0:0:0:FF00::/104
multicast prefix – First
104 bits of the all solicited
node multicast address
 Least significant 24-bits –
Copied from the right-most
24 bits of the global unicast
or link-local unicast address
of the device

8.3 Connectivity Verification

ICMP
ICMPv4 and ICMPv6 Messages
 ICMP messages common to both ICMPv4 and ICMPv6 include:
 Host confirmation
 Destination or Service Unreachable
 Time exceeded
 Route redirection
 Although IP is not a reliable protocol, the TCP/IP suite does provide
for messages to be sent in the event of certain errors, sent using the
services of ICMP.

ICMP
ICMPv6 Router Solicitation and Router
Advertisement Messages
 ICMPv6 includes four new protocols as part of the Neighbor Discovery
Protocol (ND or NDP):
 Router Solicitation message
 Router Advertisement message
 Neighbor Solicitation message
 Neighbor Advertisement message
 Router Solicitation and Router Advertisement Message – Sent
between hosts and routers.
 Router Solicitation (RS) message – RS messages are sent as an
IPv6 all-routers multicast message.
 Router Advertisement (RA) message – RA messages are sent by
routers to provide addressing information.

ICMP
ICMPv6 Router Solicitation and Router
Advertisement Messages (cont.)

ICMP
ICMPv6 Neighbor Solicitation and Neighbor
Advertisement Messages
 Two additional message types:
 Neighbor Solicitation (NS)
 Neighbor Advertisement (NA) messages
 Used for address resolution is used when a device on the LAN
knows the IPv6 unicast address of a destination, but does not
know its Ethernet MAC address.
 Also used for Duplicate Address Detection (DAD)
 Performed on the address to ensure that it is unique.
 The device sends an NS message with its own IPv6 address
as the targeted IPv6 address.

ICMP
ICMPv6 Neighbor Solicitation and Neighbor
Advertisement Messages (cont.)

Testing and Verification
Ping – Testing the Local Stack

Ping – Testing Connectivity to the Local LAN

Ping – Testing Connectivity to Remote

Traceroute – Testing the Path
Traceroute
 Generates a list of hops that were successfully reached along the
path.
 Provides important verification and troubleshooting information.
 If the data reaches the destination, then the trace lists the interface
of every router in the path between the hosts.
 If the data fails at some hop along the way, the address of the last
router that responded to the trace can provide an indication of
where the problem or security restrictions are found.
 Provides round-trip time for each hop along the path and indicates
if a hop fails to respond.

IP Addressing
Summary
 IP addresses are hierarchical with network, subnetwork, and host
portions.
 An IP address can represent a complete network, a specific host, or
the broadcast address of the network.
 The subnet mask or prefix is used to determine the network portion of
an IP address. Once implemented, an IP network needs to be tested
to verify its connectivity and operational performance.
 DHCP enables the automatic assignment of addressing information
such as IP address, subnet mask, default gateway, and other
configuration information.

IP Addressing
Summary (cont.)
 IPv4 hosts can communicate one of three different ways: unicast,
broadcast, and multicast.
 The private IPv4 address blocks are: 10.0.0.0/8, 172.16.0.0/12, and
192.168.0.0/16.
 The depletion of IPv4 address space is the motivating factor for moving to
IPv6.
 Each IPv6 address has 128 bits verses the 32 bits in an IPv4 address.
 The prefix length is used to indicate the network portion of an IPv6
address using the following format: IPv6 address/prefix length.

IP Addressing
Summary (cont.)
 There are three types of IPv6 addresses: unicast, multicast, and
anycast.
 An IPv6 link-local address enables a device to communicate with other
IPv6-enabled devices on the same link and only on that link (subnet).
 Packets with a source or destination link-local address cannot be
routed beyond the link from where the packet originated.
 IPv6 link-local addresses are in the FE80::/10 range.
 ICMP is available for both IPv4 and IPv6.

Chapter 8 : IP addressing

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Chapter 8 : IP addressing