S7 - IP Addressing
IPv6 Multicast Address
· Used to identify a set of interfaces and begins with FF
Subinterfaces
- A virtual interface that is created by dividing up one physical interface into multiple logical interfaces
Variable-Length Subnet Mask (VLSM)
- Allows subnets of various sizes to be used and requires a routing protocol that supports it - All modern routing protocols support it · -- RIP, OSPF, IS-IS, EIGRP, BGP
Stateless Address Autoconfiguration (SLAAC)
A feature of IPv6 in which a host or router can be assigned an IPv6 unicast address without the need for a stateful DHCP server. - The address is created by padding the MAC address in the middle with extra bits FF:FE. Then the 7th bit of the MAC is flipped to make it unique.
Port Address Translation (PAT)
A variant of NAT in which multiple inside local IP addresses share a single inside global IP address. PAT can distinguish between different flows based on port numbers.
subnet mask
In IPv4 addressing, a 32-bit number that, when combined with a device's IP address, indicates what kind of subnet the device belongs to.
Reserved IP addresses
- 1. Network address of all 0s - Interpreted to mean "this is a network or segment - 2. Network address of all 1s - Interpreted to mean "all networks" - 3. Network 127.0..0.x - Reserved for loopback tests. - 4. Host address of all 0s - "network address" or any host on specified network. -5. Host address of all 1's - "all hosts" on the specified network. EX: 126.255.255.255 . (Class A network, with all ones for host bits. - 6. Entire IP address set to all 0s - Used by Cisco routers to designate the default route. Could also mean "any network" - 7. Entire IP address set to all 1s (ie. 255.255.255.255) - Broadcast to all hosts on the current network.
Automatic Private IP Addressing (APIPA)
- Allows a networked device to self-assign an IP address from the 169.254.0.0/16 network. Note that this address is only usable on the device's local subnet (meaning that the IP address is not routable). - The IP address range for APIPA is 169.254.0.1 through 169.254.255.254. The client also configures itself with a default Class B subnet mask of 255.255.0.0.
CIDR Notation (classful subnet masks)
Class A IP range - 255.0.0.0 - /8 Class B IP range - 255.255.0.0 - /16 Class C IP range - 255.255.255.0 - /24
IPv6 Data Flows - unicast
-- Same as IPv4 except as IP address is IPv6 format
3 types of IPv6 addressing
-- Unicast address - Used to identify a single interface -- Multicast address - · Used to identify a set of interfaces and begins with FF -- Anycast address - · Used to identify a set of interfaces so that a packet can be sent to any member of a set o Note: more than one IPv6 addresses can be used for a single device. These address assignments can be a mixture of these different types.
IPv4 address classes
-IP addresses are grouped into logical divisions called classes. The IPv4 address space has five address classes (A through E); although, only three (A, B, and C) assign addresses to clients. Class D is reserved for multicast addressing, and Class E is reserved for future development. - Of the three classes available for address assignments, each uses a fixed-length subnet mask to define the separation between the network and the node address.
Subnetting Method Rules (page 90 in notes)
o 1. Use given CIDR/Mask to find column on sheet -- CIDR/Subnet Mask map to each other -- Locate Group Size -- Start at ".0" in relevant octet -- Increase by Group size until you pass target IP o 2. Number BEFORE target IP is Network ID o 3. Number After target IP is the Next Network o 4. IP address BEFORE Next Network is Broadcast o 5. IP address AFTER Network ID is FIRST HOST o 6. IP address BEFORE Broadcast IP is LAST HOST o 7. 2^(32-CIDR) is the total # of IP addresses ---- Don't forget to subtract 2 if necessary
Powers of 2 Chart (0 - 12) (practice making chart)
o 2 ^0 = 1 , 2 ^1 = 2 , 2 ^2 = 4 , 2 ^3 = 8 , 2 ^4 = 16 , 2 ^5 = 32 , 2 ^6 = 64 , 2 ^7 = 128 , o 2 ^8 = 256 , 2 ^9 = 512 , 2 ^10 = 1024 , 2 ^11 = 2048 , 2 ^12 = 4096
Max # of valid subnets - (how to calculate)
o 2^n , where n = # of host bits borrowed -- Ex: 172.20.0.0 255.255.255.224 or (/27) -- Class B address, subnetted with a class C subnet -- Borrowed bits from 3rd octet plus bits from 4th octet -- 8 bits from 3rd octet and 3 bits from the 4th octet -- 2^11 = 2048 maximum number of valid subnets
Ranges for private IP addresses
o Class A -- Starting Value: 10 -- 10.0.0.0 - 10.255.255.255 -- 16.7 million addresses (256x256x256) o Class B -- 172.16.x.x - 172.31.x.x -- 172.16.0.0 - 172.31.255.255 -- 1.05 million (16x256x256) o Class C -- 192.168.x.x -- 192.168.0.0 - 192.168.255.255 -- 65,536 (256x256)
Subnetting Method Chart (Practice creating chart) page 90 in notes
o Group size | 128 64 32 16 8 4 2 1 | o Subnet Mask | 128 192 224 240 248 252 254 255 | o NW Bits | 1 2 3 4 5 6 7 8 | o Host Bits | 7 6 5 4 3 2 1 0 | o CIDR (4th) | /25 /26 /27 /28 /29 /30 /31 /32 | o CIDR (3rd) | /17 /18 /19 /20 /21 /22 /23 /24 | o CIDR (2nd) | /9 /10 /11 /12 /13 /14 /15 /16 | o CIDR (1st) | /1 /2 /3 /4 /5 /6 /7 /8 |
IPv6 Addressing (facts)
o IPv4 limited in address space -- IPv4 = 2 32 · --4.2 billion addresses -- Address Exhaustion · --Running out of network addresses in IPv4 -- IP Next Generation (IPng) · --IPv6 -- IPv6 2 128 - 128 bit address · --340 undecillion addresses -- IPv5 was an experimental protocol but some of its concepts have been incorporated into IPv6
Subnetting
o Taking a large network and split it up into smaller networks -- All about logical IP addressing o Subnet masks modify subnets and create better scoped networks o Subnetting is a more efficient use of IP addresses than using the classful default.
IPv6 Address (notation and shorthand)
o uses hexadecimal digits and allows the use of shorthand notation -- Ex: 2018:0000:0000:0000:0000:0000:4815:54ae · 8 sets of 4 hexadecimal digits · 8 x 16bits per segment -- IPv6 shorthand rules · If all zero's are represented in a group you can display 1 zero per group. o 2018:0:0:0:0:0:4815:54ae · Or, use :: and remove the zero's completely o 2018::4815:54ae
Available host addresses
- Number of Host IP addresses available to assign - Ex: /25 -- 32 total bits - 25 network bits = 7 host bits 2^7 = 128 host addresses 128 - 2 = 126 addresses available to assign -- Why do I subtract 2 ? - Every network has to use two addresses in the following manner o 1st address in the host range (for network) -- Network ID o Last address in the host range (for network) -- Broadcast ID
Virtual IP Address (VIP or VIPA)
- An IP address that does not correlate to an actual physical network interface. · NAT · Fault-tolerance · Virtualization - Routers often use virtual IP addresses to provide redundancy in their connectivity options
Internet Protocol (IP) Address
- An assigned numerical label that is used to identify Internet communicating devices on a computer network - IP addresses used at layer 3 of the OSI model - Used by routers to send data from one network to another network - Note. When dealing with two devices that are internal to our own network or LAN we are working with Layer 2 MAC address. When we start working with forwarding data between two networks or subnets we are working with Layer 3 IP addressing. - IPv4 - Internet Protocol v4 - IP v6 - Internet Protocol v6
APIPA
- Automatic Private IP Addressing (APIPA) - Used when a device does not have a static IP address or cannot reach a DHCP Server - Address range 169.254.x.x - Class B address range - Allows for the quick configuration of a LAN without the need for a DHCP server - Private IP addresses, cannot be routed outside our local area network - APIPA-assigned devices cannot communicate outside the LAN or with non-APIPA devices
BOOTP
- Bootstrap Protocol (BOOTP) - Dynamically assigns IP addresses and allows a workstation to load a copy of their boot image over the network - Oldest and least used option - Uses a static database of IPs and MAC addresses - DHCP replaced BootP
Loopback Address
- Creates a loopback to the host and is often used in troubleshooting and testing network protocols on a system - 127.0.0.x is considered a loopback address (or, local host) · Most people only use 127.0.0.1 but the entire class A 127.0.0.0 /8 range is reserved. · Class A range 1 - 127
IPv6 Data Flows - Anycast
- Data travels from a single source device to the device nearest to multiple (but specific) destination devices. - Unique to IPv6 - Similar to broadcast, used to update router tables hear the host - Much more efficient way to update router tables in IPv6 - Note: no broadcast in IPv6
Network portion of IPv4 address
- Devices that share the same network portion are on the same network and can communicate through a switch. - If devices are not one the same network data must be routed between networks
IPv4 Addressing
- Dotted-Decimal Notation · Ex: 10.1.2.3 · 32 bit address · Each 8 bit number can be from 0 - 255 - Dotted-decimal consisting of 4 octets of 8 bits each - Each octet made up of binary digits - Subnet mask · Breaks the ip address into two part o Network ID o Host ID · 255.255.255.0 - Default class c subnet mask o Network bits & Host bits -- IPv4 Address - 192.168.1.4 -- Subnet mask - 255.255.255.0
DHCP
- Dynamic Host Control Protocol (DHCP) - Assigns an IP address based on an assignable scope or pool of addresses and provides the ability to configure numerous other options within it - Allows the alignment of a range of IP addresses or pool of addresses - Each IP is leased for a period of time and returns to the pool when the lease expires - The DHCP server (IP Address Management) manages the Ips being assigned and returned - DHCP server assigns: IP Address, Subnet Mask, Default gateway, DNS/WINS server (wins server is an optional component that may or may not be set). - DHCP is the modern implementation of BOOTP - Need to know the 4 items DHCP assigns to hosts for the exam.
Subnet mask example
- IP address: 192.168.1.4 - class c address - Subnet Msk: 255.255.255.0 - default class c subnet mask · This is a classful address with a classful subnet mask · However, we can use other subnet masks than the default
Number of hosts
- If looking at the number of assignable IP addresses · 2^h - 2, where h = number of host bits -- Total bits - # network bits = # host bits
IPv6 Data Flows - Multicast
- Same as IPv4 we use multicast groups - Multicast IPv6 addresses begin with FF
Classless Interdomain Routing (CIDR)
- Shortens a classful subnet mask by removing right-justified 1s from a classful mask. -- As a result, CIDR allows contiguous classful networks to be aggregated. This process is sometimes called route aggregation. -- Def: Shorthand notation used to summarize continuous networks called using route aggregation
Three ways Data can flow in IPv4
- 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
o Automatic Private IP Addresses (APIPA)
- Used when a device does not have a static IP address or cannot reach a DHCP server - APIPA address range: 169.254.0.0 - 169.254.255.255 · Class B range - 128 - 191 - If machine received an apipa address the machine cannot contact the DHCP server · When booting up a machine requests an IP from a DHCP server o DORA - Discover, Offer, Request, Acknowledge
Classless Inter-Domain Routing (CIDR)
- We don't need to stick to classful addressing, instead we can use a classless subnet mask if we want to. - Allows for the borrowing host bits and reassigning them to the network portion.
IPv6 Anycast address
-- An IPv6 anycast address is a single address that can be assigned to multiple interfaces. -- For example, an IPv6 address is assigned to a multi-homed computer. A packet sent to an anycast address is delivered to the first available interface of a device. An anycast address is used to provide load-balancing and automatic failover. Currently, anycast addresses are used only as destination addresses and can be assigned only to routers.
4 ways to dynamically assign IP addresses
-- BOOTP - Bootstrap Protocol -- DHCP - Dynamic Host Control Protocol -- APIPA - Automatic Private IP Addressing -- ZeroConf - Zero Configuration
ZeroConf
- Zero Configuration (ZeroConf) -- A newer technology based on APIPA which provides a lot of the same features and some new ones. -- Assign an IPv4 link-local address to a client -- Resolve computer names to IP addresses without the need for DNS by using mDNS (or multicast domain name service) -- Can perform a service discovery on a network -- On Apple - zeroconfig is called Bonjour - used for service discovery -- On Windows it is called - Link-Local Multicast Name Resolution (LLMNR) o Provides name resolution and service discovery -- On Linux, ZeroConf is implemented using SystemD
Subnetting
- breaking down a classful subnet into smaller networks for better manageability - Allows for the use of a classless subnet mask to create smaller networks with fewer hosts in each network - Def. - Strategy used to partition a single physical network into more than one smaller logical sub-networks (subnets)
Neighbor Discovery Protocol (NDP)
-- (an IPv6 protocol ) Used to learn the Layer 2 addresses that are on a given network -- Used to discover · Router solicitation · Router advertisement · Neighbor solicitation · Neighbor advertisement · Redirection - locates the best, most efficient, routes
Tunneling
-- A method or technique used for transporting data across a network by encapsulating or wrapping packets inside of other packets. · -- Allows an IPv4 router to carry IPv6 traffic
DHCPv6 Protocol
-- Allows DHCP to automatically assign addresses from a DHCPv6 server -- Don't need to use DHCPv6 but can if you choose to. · IPv6 will assign each device an address using (SLAAC), using the MAC address to create a globally routable address, by default if DHCPv6 is not used.
o Benefits of IPv6
-- Larger address space · 128 bit addresses · No broadcasts · More secure o No packet or datagram fragmentation · Can coexist with IPv4 · Simplified header
Dual Stack
-- Running both the IPv4 and IPv6 protocols by your network devices simultaneously
Router Advertisement
A router advertisement is part of a new system configuration option in IPv6. This is a packet sent by routers to give the host a network ID (called a prefix in IPv6) so that the host can generate its own IPv6 address derived from its MAC address.
CIDR Notation
A shorthand method for denoting the distinction between network and host bits in an IP address. · Ex: 192.168.1.4/24 -- abbreviation for the following o IP Address: 192.168.1.4 o Subnet Mask: 255.255.255.0 o Binary: 11111111.11111111.11111111.00000000
Classful Subnet Mask
In TCP/IP Version 4, the default subnet mask that is used if a network is not divided into subnets. --It is called a classful subnet mask because the network portion of the IP address aligns with the class license. --For example, 11111111.11111111.11111111.00000000 or 255.255.255.0 is the classful subnet mask for a Class C license. (IP 1st octet range 192 - 223)
2 types of IPv4 addresses
Public (Routable) · Can be accessed over the Internet and is assigned to the network by an Internet service provider. · Globally managed by ICANN o Internet Corporation for Assigned Names and Numbers (ICANN) - Globally manages and leases publicly routable IP addresses Private (Non-routable) · Can be used by anyone any time, but only within their own local area network · Private IP ranges include those that start with either 10, 172, or 192 · Network address translation (NAT) - allows for routing of private IPs through a public IP.
IP Address Class Summary
Subdividing an IP address into a network and host address is determined by the class designation of your network. - Class A (1st octet) 0 - 127 (127 reserved) - Class B (1st octet) 128 - 191 - Class C (1st octet) 192 - 223 - Class D (1st octet) 224 - 239 - Reserved for Multicast - Class E (1st octet) 240 - 255 - Reserved for scientific purposes
Extended Unique Identifier, 64-bit (EUI-64)
The last 64 bits of the IPv6 address, which are determined based on a device's MAC address. 1. split the mac address in half and insert ff:fe to make it a 64 bit address. 2. flip the 7th bit of the mac to make it universally unique 3. append the newly created host portion to the network portion of the IPv6 address.
Private IP Addresses (RFC 1918)
The people who created the IP addressing scheme also created what we call private IP addresses. These addresses can be used on a private network, but they're not routable through the Internet. - Private IPs: - Class A - 10.0.0.0 - 10.255.255.255 (prefix /8) - Class B - 172.16.0.0 - 172.31.255.255 (prefix /12) - Class C - 192.168.0.0 - 192.168.255.255 (prefix /16)
Network Address Translation (NAT)
Translates the private IP address to a public address for routing over the Internet
Unicast
a form of message delivery in which a message is delivered to a single destination
Class A IPv4 Address
· 1st Octet Value o 1 - 127 · Default subnet mask o 255.0.0.0 -- 255 - represents network bits -- 0.0.0 - represents host bits - Possible hosts o 16.7 million -- (256x256x256)
Class B IPv4 Address
· 1st Octet Value o 128 - 191 · Default subnet mask o 255.255.0.0 -- 255.255 - represents network bits -- 0.0 - represents host bits · Possible hosts o 65,536 -- (256x256)
Class C IPv4 Address
· 1st Octet Value o 192 - 223 · Default subnet mask o 255.255.255.0 -- 255.255.255 - represents network bits -- .0 - represents host bits · Possible hosts o 256
Class D IPv4 Address
· 1st Octet Value o 224 - 239 o No subnet mask o Reserved for multicast or multicast routing -- Multicast Address - A logical identifier for a group of hosts in a computer network
Class E IPv4 Address
· 1st Octet value o 240 - 255 · No subnet mask · Possible hosts o 268 million · Reserved for research, development, study only
Unicast (IPv4)
· Data travels from a single source device to a single destination device. · Two way conversation, like a phone call.
Broadcast (IPv4)
· Data travels from a single source device to all devices on a destination network --Example: talking on a radio. Broadcasting to anyone who will tune in and listen.
Multicast (IPv4)
· Data travels from a single source device to multiple (but specific) destination devices · Data sent to a multicast group. All machines in the group get a copy of the message · Example: conversation between an instructor and students in a classroom. The instructor can speak to several students at once.
Dynamic IP address assignment
· Dynamically Assign o IP address, Subnet mask, default gateway, DNS server address · Domain Name System (DNS o Converts the domain names used by a website to the IP address of its server · Windows Internet Name Service (WINS) o Identifies NetBIOS systems on a TCP/IP network and converts those NetBIOS names to IP address o Used within a LAN
IPv6 Unicast - Stateless address autoconfiguration (SLAAC)
· Eliminates the need to obtain addresses or other configuration information from a central server o Extended Unique Identifier (EUI) - Allows a host to assign itself a unique 64-bit IPv6 interface identifier called a EUI-64 -- o In-between the first portion (OUI) and second portion (NIC) of the MAC address a 16 bit number is inserted (FF FE). This creates the 64 bit EUI
Creating a subnet
· In order to subnet a network you must borrow bits from the hosts and move them to the network, thereby creating less hosts. o Created subnets -- 2^s where s= number of borrowed bits
Static IP address assignment
· Manually typing in the IP address for the host, its subnet mask, default gateway, and DNS server · Static assignment of IP addresses is impractical on large enterprise networks
IPv6 Unicast - Globally routed
· Similar to IPv4's unicast class A, B, and C addresses and begins with 2000 - 3999
IPv6 Unicast - Link local address
· Used like a private IP in IPv4 that can only be used on the local area network and begins with FE80
IPv6 Unicast address
· Used to identify a single interface · Globally routed - Similar to IPv4's unicast class A, B, and C addresses and begins with 2000 - 3999 · Link-local - Used like a private IP in IPv4 that can only be used on the local area network and begins with FE80 · Stateless Address Autoconfiguration (SLAAC) - Eliminates the need to obtain addresses or other configuration information from a central server o Extended Unique Identifier (EUI) - Allows a host to assign itself a unique 64-bit IPv6 interface identifier called a EUI-64 ---- o In-between the first portion (OUI) and second portion (NIC) of the MAC address a 16 bit number is inserted (FF FE). This creates the 64 bit EUI
