IP Addressing

IPv4 NETWORK ADDRESES

• Binary notation refers to the fact that computers communicate in 1s and 0s.
• Position notation converting binary to decimal requires an understanding of the mathematical basis of numbering system

Binary Notation

Converting Binary Address to Decimal

Converting From Decimal To Binary
168 = ? Binary

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

Examining the Prefix Length

Pv4 Network, Host, and Broadcast Address					10.1.1.0/24
	Network Potion			Host Portion
	10	1	1	0
	00001010	00000001	00000001	00000000	All 0s - NETWORK ADDRESS
	10	1	1	10
	00001010	00000001	00000001	00001010	0s AND 1s in host portion
	10	1	1	255
	00001010	00000001	00000001	11111111	All 1s - BROADCAST ADDRESS

First Host and Last Host Addresses					10.1.1.0/24
	Network Potion			Host Portion
	10	1	1	1	First Host
	00001010	00000001	00000001	00000001	All 0s and a 1 in the host portion
	10	1	1	254	Last Host
	00001010	00000001	00000001	11111110	All 1s and a 0 in the host portion

Bitwise AND Operation
1 AND 1 = 1, 1 AND 0 = 0, 0 AND 1 = 0, 0 AND 0 = 0

Assigning IPv4 Address to Host
STATIC
LAN Interface Properties	Configuring a Static IPv4 Address
DYNAMIC
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

IPv4 Communication Transmission

In an IPv4 network, the hosts can communicate one of three different ways: Unicast, Broadcast, and Multicast

Unicast Transmission	Broadcast Transmission
the process of sending a packet from one host to an individual host	the process of sending a packet from one host to all hosts in the network

NOTE: Routers do not forward a limited broadcast!

Directed broadcast

• Destination 172.16.4.255
• Hosts within the 172.16.4.0/24 network

Multicast Transmission

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)

Types of IPv4 Address

Private address blocks:

• 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

Legacy Classful Addressing

IP Address Classes

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

ISPs & Regional agencies: IP address registries

Global	Regional	Internet	Registries
IANA	AfriNIC	Africa	Region

Assignment of IP Addresses

Regional Internet Registries (RIRs)

	ISPs are large national or international ISPs that are directly connected to the Internet backbone
	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.

IPv6 NETWORK ADDRRESSES

• 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 undecillionaddresses
• IPv6 fixes the limitations of IPv4 and includes additional enhancements, such as ICMPv6.

IPv4 and IPv6 Coexistence

The migration techniques can be divided into three categories:
Dual-stack, Tunnelling, Translation

	Allows IPv4 and IPv6 to coexist on the same network. Devices run both IPv4 and IPv6 protocol stacks simultaneously
	Dual-Stack
	A method of transporting an IPv6 packet over an IPv4 network. The IPv6 packet is encapsulated inside an IPv4 packet
	Tunnelling
	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

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.

Look at the binary bit patterns that match the decimal(#) and hexadecimal(HEX) values

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

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 hextetcan 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.

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.

#Example 1

#Example 2

Types of IPv6 Addresses

• 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

/64 Prefix

Types of 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.

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)

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

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 Prefixis 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.

IPv6 / 48 Global Routing Prefix

• 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.

Reading a Global Unicast Address

Static Configuration of a Global Unicast Address

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
• 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

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.

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 7thbit (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.

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.

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

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

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

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 theipv6 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.

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

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

ICMP

Conectivity Verification

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.

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.

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

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.