CS 447 Networks and Data Communication Department of Computer Science Southern Illinois University Edwardsville Fall, 2015 Dr. Hiroshi Fujinoki IP Address Format, Classes Sub-Networking and Class-less Inter Domain Routing

Internet SIUE Domain IP_Address/001 IP address is the ID for each NIC at a host computer Internet Backbone Carrier (long distance carrier) ISPs Internet core routers Host X NIC Host Y What is IP address? CS 447 Networks and Data Communication

Internet SIUE Domain IP_Address/002 What is IP address? Advantage in using IP addresses You can use the same format of IP address no matter where your destination is. Host X Host Y Host Z Host Q Host S Every IP address must be unique CS 447 Networks and Data Communication

Class-A Private IP Addresses: Class-B Private IP Addresses: Class-C Private IP Addresses: IP_Address/004 What is IP address? CS 447 Networks and Data Communication

IP Address Format (for IPv4) 1. General Expression IP Address = “xxx. xxx. xxx. xxx” Each “xxx” = “0” to “255” Example “ ” 2. Internal Format “ ” = 32 bits 1 23 IP_Address/008 CS 447 Networks and Data Communication

32 bits 123 IP Address Format (for IPv4) Section 1: Class-ID Field (1 to 4 bits) 0: Class-A IP addresses 10: Class-B IP addresses 110: Class-C IP addresses 1110: Class-D IP addresses (Multicast Address) Section 2: Domain Address Field (7 to 21 bits) Section 3: Host Address Field (8 to 24 bits) IP_Address/009 CS 447 Networks and Data Communication

Internet Domain and host addresses IP_Address/010 Domain X Domain Y Gateway Router in Domain X Destination Host Routing using domain address Routing using host address Transmitting Host Gateway Router in Domain Y CS 447 Networks and Data Communication

0 IP Address Format (for IPv4) Class-A Domain Address Host Address 7 bits 24 bits Bit #s: 1 0 Class-B Domain AddressHost Address 14 bits 16 bits Bit #s: Class-C Domain AddressHost Address 21 bits 8 bits Bit #s: 13 IP_Address/011 CS 447 Networks and Data Communication

IP Address Format (for IPv4) Class-A Class-B Class-C IP_Address/012 Number of hosts in a domain Number of domains in the Internet = up to ( ) hosts/domain = up to 2 7 domains One of the addresses in a domain must be “domain broadcast” address Number of hosts in a domain = up to ( ) hosts/domain Number of domains in the Internet = up to 2 14 domains Number of domains in the Internet Number of hosts in a domain = up to ( ) hosts/domain = up to 2 21 domains CS 447 Networks and Data Communication

Example of IP address construction “ ” What are the bit patterns for “146”, “163” and “170”? MSBLSB  18  Weight “146” IP_Address/013 CS 447 Networks and Data Communication

MSBLSB  35  Weight “163” IP_Address/014 Example of IP address construction  3 1 CS 447 Networks and Data Communication

MSBLSB    Weight “170” IP_Address/015 Example of IP address construction CS 447 Networks and Data Communication

Example of IP address construction “ ” IP_Address/ SIUE’s IP Class = Class-B Internet domain SIUE’s domain address = “ ” Class-ID Domain Address Host Address It is customary to include the class-ID as a part of the domain address My server’s host address = “ ” CS 447 Networks and Data Communication

IP_Address/017 Two extensions in IP address formats 1. Subnet and Subnet Masks 2. CIDR (Class-less Inter Domain Routing) A mechanism to make managing IP addresses easier Partitioning a network domain within a domain A mechanism to increase the number of network domains Partitioning a network domain into more than one network domain Purpose Method CS 447 Networks and Data Communication

IP_Address/018 Subnet and Subnet Masks The problemManaging IP addresses in a large domain is not an easy job SIUE Domain ( X.X) SIUE domain has more than 1,000 host computers IP address must be unique You can’t assign an IP address to more than one host Assigned IP address CS 447 Networks and Data Communication

IP_Address/019 Subnet and Subnet Masks The problemManaging IP addresses in a large domain is not an easy job SIUE Domain ( X.X) Your job is to assign, maintain and manage all available IP addresses in SIUE domain. Assigned IP address You can not assign an IP address to more than one host (or NIC) CS 447 Networks and Data Communication

SIUE Domain ( X.X) IP_Address/020 Subnet and Subnet Masks Two solutions  Dynamic address assignment (DHCP)  Subnet working DHCP Server DHCP Query DHCP Reply 1ABF Problem in DHCP Every time you starts your PC, your IP address may be different MAC Address IP Address IPMAC ABF NULL CS 447 Networks and Data Communication

SIUE Domain ( X.X) IP_Address/021 Subnet and Subnet Masks Partition the entire domain Assign a group of IP addresses to each partition Each partition is called “subnet” Address range: Address range: Address range: CS 447 Networks and Data Communication

IP_Address/022 CIDR (Class-less Inter-Domain Routing) The “3-class” design in the existing IP (IPv4) is not very efficient Lack of flexibility in domain size Example Suppose that your organization has 5,000 host computers. - Which IP class you need? - What is the address space utilization? Class-B is required Class-C is up to 2 8 = 256 hosts Class-B is up to 2 16 = 6,5536 hosts Address space utilization = (what you have) (what you can have) = 5,000/6,5536 = 7.6% If this is usually the case, the IPv4’s address space is never big enough CS 447 Networks and Data Communication

IP_Address/023 Only three different address classes What is the cause of the problem? How can/should we increase “address classes”?  Restructure the IP address format IP address format needs to be re-defined How long will it take? How much will it cost?  Apply some extension to the exiting IP (IPv4) (IPv6 uses this approach) CIDR (Class-less Inter-Domain Routing) CS 447 Networks and Data Communication

IP_Address/024 CIDR (Class-less Inter-Domain Routing) How does CIDR work? 0 Class-A Domain Address Host Address 7 bits 24 bits Bit #s: 1 0 Class-B Domain AddressHost Address 14 bits 16 bits Bit #s: Class-C Domain AddressHost Address 21 bits 8 bits Bit #s: 13 This is the mistake in IPv4!! CS 447 Networks and Data Communication

IP_Address/025 CIDR (Class-less Inter-Domain Routing)  Eliminate “class IDs” This is how it is called “class-less”. Domain Address Host Address ? bits 32-bit IPv4 address  Only the source and destination network domains perform CIDR This is how it is called “inter-domain routing”. - The gateway routers in your transmitting host and the destination host perform CIDR CS 447 Networks and Data Communication

IP_Address/026 CIDR (Class-less Inter-Domain Routing) /16 “CIDR Prefix” = How many bits (from the top) are “network address” Network Address Bits Example If we need only up to 4,000 hosts? Since 2 12 = 4,096, we need only 12 bits for host address filed / Network Address Bits We can come up with (2 4 -1) more domains of the same size! CS 447 Networks and Data Communication

IP_Address/028 CIDR (Class-less Inter-Domain Routing) CIDR Block PreFix # Equivalent Class-C # of Host Addresses /272 (32-27) 1/8 of a Class-C 2 5 /2 8 = 1/2 3 /26 /25 /24 /14 /15 /16 / Class-C (Class-B) 1/4 of a Class-C 1/2 of a Class-C 1 Class-C 128 Class-C 512 Class-C 1024 Class-C 2 (32-26) 2 (32-25) (32-17) = 32 = 64 = 128 = 256 = 32,768 = 65,536 = 131,072 = 262,144 CS 447 Networks and Data Communication

Internet IP_Address/ Exception #1 Private IP addresses NAT IP Masquerade CS 447 Networks and Data Communication

Internet Exception #2 Multicast IP addresses (Class-D IP addresses) A transmitting host transmits once Multiple hosts receives at once Transmitting Host Multiple Receiving Hosts IP_Address/005 CS 447 Networks and Data Communication

Internet Exception #2 Multicast IP addresses (Class-D IP addresses) Transmitting Host All the receivers should receive messages A sender should transmit only once All the receivers should have the same multicast IP addresses IP_Address/006 CS 447 Networks and Data Communication

SIUE Domain Internet IP_Address/007 Transmitting Host Local-Domain Multicast Global-Internet Multicast FirstLast Categories Local-Domain Multicast Global-Internet Multicast Global-Internet Reserved We developed a UDP IP-multicast audio-streaming application applications in CS490 (Fall 2005) (as SIUE’s local-domain multicast). CS 447 Networks and Data Communication

Domain Address Host Address ? bits