IP Addressing (1.4 & 1.6) Flashcards
Internet Protocol (IP) Address
o An assigned numerical label that is used to identify Internet communicating devices on a computer network
▪ Layer 2
● Between two devices that are internal to own network or LAN
▪ Layer 3
● Between two different networks or even two different subnets
IPv4 Addressing
o Internet Protocol Version 4 (IPv4) Addressing
▪ Written in dotted-decimal notation
● 10.1.2.3
● 172.21.243.67
▪ Each IPv4 address is divided into 4 separate numbers and divided by dots
▪ Each of these divisions are called octets due to having 8 bits assigned
▪ 32-bits in length
IPv4 Addressing
▪ IPv4 address is divided into network and host portions
▪ Subnet mask defines the network portion
● Network portion if a binary 1
● Host portion if binary 0
Classes of IP Addresses
▪ Default subnet mask assigned by first octet
● Classful Masks if using default subnet mask
▪ Defines the Class of IP Address
Routable IPs
▪ Publicly routable IP addresses are globally managed by ICANN
● Internet Corporation for Assigned Names and Numbers
o ARIN, LACNIC, AFNIC, APNIC, and RIPE NCC
▪ Public IP’s must be purchased before use through your Internet Service Provider (ISP
Private IPs
▪ Private IP’s can be used by anyone
▪ Not routable outside your local area network
▪ Network Address Translation (NAT) allows for routing of private IPs through a public IP
Specialized IPs
▪ Loopback addresses (127.x.x.x range)
● Refers to the device itself and used for testing
● Most commonly used as 127.0.0.1
▪ Automatic Private IP Addresses (APIPA)
● Dynamically assigned by OS when DHCP server is unavailable and address not assigned manually
● Range of 169.254.x.x
Identifying Network and Hosts in IPv4
Virtual IP Addresses (VIP or VIPA)
▪ An IP address that does not correlate to an actual physical network interface
▪ respond to numerous IP addresses and have them resolve to your physical network interface to establish connectivity
Subinterfaces
▪ A virtual interface that is created by dividing up one physical interface into multiple logical interfaces
IPv4 Data Flows
o Unicast
▪ Data travels from a single source device to a single destination device
Multicast
▪ Data travels from a single source device to multiple (but specific) destination devices
Broadcast
▪ Data travels from a single source device to all devices on a destination network
Assigning IP Addresses
Static
▪ Simple
▪ Time-consuming
▪ Prone to human errors
▪ Impractical for large networks
Dynamic
▪ Quicker
▪ Easier
▪ Less confusing
▪ Simplistic for large networks
Components of an IP Address
▪ Information assigned from static or dynamic
● IP Address
● Subnet Mask
● Default Gateway
● Server addresses
o Domain Name System (DNS)
▪ Converts domain names to IP address
o Windows Internet Name Service (WINS)
▪ Converts NetBIOS computer name into an IP address
Dynamic Host Control Protocol (DHCP) Configuration
▪ Based on the older Bootstrap Protocol (BOOTP for short)
● Required static database of IP and MAC to assign
▪ DHCP service assigns an IP from an assignable pool (scope)
▪ IP Address Management is software used to manage the IP’s being assigned
Dynamic Host Control Protocol (DHCP)
▪ Provides clients with
● IP
● Subnet mask
● Default gateway
● DNS server
● WINS server
● Other variables needed for VoIP
▪ Each IP is leased for a given amount of time and given back to the pool when lease expires (TTL)
Automatic Private IP Address (APIPA)
▪ Used when device does not have a static IP address and cannot reach a DHCP server
▪ Allows a network device to self-assign an IP address from the 169.254.0.0/16 network
▪ Designed to allow quick configuration of a LAN without need for DHCP
▪ Non-routable but allows for network connectivity inside the local subnet
Zero Configuration (Zeroconf)
▪ Newer technology based on APIPA providing:
● Assigning link-local IP addresses
o Non-routable IP usable only on local subnet
● Resolving computer names to IP addresses without the need for DNS server on local network
o mDNS - Multicast Domain Name Server
● Locating network services
o Provides service discovery protocols
▪ Service Location Protocol (SLP)
▪ Microsoft’s Simple Service Discovery Protocol (SSDP)
▪ Apple’s DNS-based Service Discovery (DNS-SD)
Computer Mathematics
o Humans count using Base-10 numbers
▪ Decimals
▪ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, …
o Computers and networks do not understand decimal numbers natively
o Process numbers using Base-2 numbers
▪ Binary
▪ 0, 1, 10, 11, …
Converting Binary to Decimal
o Use table to convert from binary to decimal
o Each number is a factor of 2
o Starting from the right and go to the left
o Populate the table with the binary digits
o Add up any columns that contain a 1
Converting Decimal to Binary
o Use subtraction to convert decimal to binary
Computer Mathematics Practice
o You must be able to convert:
o Binary > Decimal
Decimal > Binary
Converting Binary to Decimal
Converting Decimal to Binary
Subnetting
o Default classful subnet masks are rarely the optimal choice for a subnet size
o Subnets can be modified using subnet masks to create networks that are better scoped
o Creating a subnet involves borrowing bits from the original host portion and adding them to the network portion
Purpose of Subnets
▪ More efficient use of IP addresses than classful default
▪ Enables separation of networks for security
▪ Enables bandwidth control
Subnet Masks
Subnetting Formulas
Classful vs Subnetted Networks
Classful subnet (192.168.1.0/24)
1 network (2^0), where s is the number of borrowed bits
256 IPs (2^8), where h is the number of host bits
Classless subnet (192.168.1.64/26)
4 networks (2^2), where s is the number of borrowed bits
64 IPs (2^6), where h is the number of host bits
Calculating Number of Subnets
192.168.1.0/26
*Default mask is /24, so we borrowed 2 bits from the host space
2^s = 2^2 = 4,
which means there are four created subnets
Calculating Number of IPs
Total bits are 32 and the mask is /26
32-26 = 6 host bits (h)
2h - 2 = 2^6 - 2 = 64 -2 = 62
62 assignable IPs in each subnet
Listing Subnets
Created 4 subnets of 62 usable IPs each
*Where does each network begin and end?
Network ID (First IP)
0, 64, 128, 192
Broadcast (Last IP)
63, 127, 191, 255
Classless Interdomain Routing (CIDR)
▪ Instead of advertising multiple individual routes, the routes can be summarized and advertised as a single route
▪ Used to summarize contiguous networks
● Called route aggregation
Variable-Length Subnet Masking (VLSM)
▪ Allows subnets of various sizes to be used
▪ Requires a routing protocol that supports it
● RIPv2, OSPF, IS-IS, EIGRP, and BGP
▪ Basically, it is subnetting subnets
▪ Without VLSM, all subnets would have to be the same size
Subnetting Exam Tip
CIDR
/30 /29 /28 /27 /26 /25 /24
of subnets (left to right)
64 32 16 8 4 2 1
of IPs (left to right)
4 8 16 32 64 128 256
Example Subnetting Practice (LOOK AT MORE OF THESE ON THE WAY)
How many assignable IP addresses exist in this network?
192.168.1.0 /28
If we look at the chart, /28 has 16 usable IPs, but subtract the network IP and broadcast IP = 16 -2 = 14 assignable IP addresses.
Internet Protocol Version 6 (IPv6) Addressing
o IPv6
▪ IPv4 essentially ran out of addresses due to proliferation of devices
▪ IPv6 addressing provides enough IP addresses for generations to come
▪ Enough IPv6 addresses for every person on the planet (5 x 1028)
IPv4 = 2^32 = 4.2 billion addresses
IPv6 = 2^128 = 340 undecillion addresses
▪ IPv5 was an experimental protocol that was abandoned, although some of its concepts have been incorporated into other protocols
IPv6 Benefits
▪ No broadcasts
▪ No fragmentation
● Performs MTU (maximum transmission units) discovery for each session
▪ Can coexist with IPv4 during transition
● Dual stack (run IPv4 and IPv6 simultaneously)
● IPv6 over IPv4 (tunneling over IPv4)
o Allows an existing IPv4 router to carry IPv6 traffic
o Encapsulates IPv6 packets within IPv4 headers to carry this IPv6 data over IPv4 routers and other infrastructure
▪ Simplified header
● 5 fields instead of 12 fields
Headers (IPv4 and IPv6)
Check chart of the different headers IPv4 vs IPv6
IPv6 Address Structure
▪ Each hexadecimal digit is 4-bits
▪ 128-bits in an IPv6 address
▪ No more than 32 hexadecimal digits
IPv6 Address Types
▪ Unicast Addresses
● Used to identify a single interface
o Globally routable unicast addresses
▪ Begins with 2000 to 3999
o Link-local address
▪ Begins with FE80
▪ It uses stateless address autoconfiguration, or SLAAC
▪ Multicast Addresses
● Used to identify a group of interfaces so that a packet can be sent to a multicast address and then be delivered to all of the interfaces in the group
o Begins with FF
▪ Anycast Addresses
● Used to identify a set of interfaces so that a packet can be sent to any member of a set
Do you need DHCP for IPv6?
▪ IPv6 uses auto configuration to discover the current network and selects its own host ID based on its MAC using the EUI64 process
▪ If you want to still use DHCP, there is a DHCPv6 protocol
▪ IPv6 uses Neighbor Discovery Protocol (NDP) to learn the Layer 2 addresses on the network
Stateless Address Autoconfiguration (SLAAC)
▪ Discovers the current network that an interface is located on and then select its own host ID based on its MAC address using the EUI64 process
● Extended Unique Identifier (EUI)
Neighbor Discovery Protocol (NDP)
▪ Used to learn Layer 2 addresses on network
▪ Router Solicitation
● Hosts send message to locate routers on link
▪ Router Advertisement
● Router advertise their presence periodically and in response to solicitation
▪ Neighbor Solicitation
● Used by nodes to determine link layer addresses
▪ Neighbor Advertisement
● Used by nodes to respond to solicitation messages
▪ Redirect
● Routers informing host of better first-hop routers
IPv6 Data Flows
o IPv6 Data Flows
▪ Three data flow methods, like IPv4
● Unicast
● Multicast
● Anycast (new to IPv6)
Unicast
▪ Data travels from a single source device to a single destination device
Multicast
▪ Data travels from a single source device to multiple (but specific) destination devices
Anycast
▪ Designed to let one host initiate the efficient updating of router tables for a group of hosts
▪ IPv6 can determine which gateway host is closest and sends the packets to that host as though it were a unicast communication
▪ That host can anycast to another host in the group until all routing tables are updated
▪ Data travels from a single source device to the device nearest to multiple (but specific) destination devices
