Introduction to TCP/IP

Protocols are a set of rules that govern how computers exchange data over a network There is two type of protocols: LAN protocols: defines how communication is carried out over various LAN media Exp: NetBEUI, IPX/SPX, TCP/IP WAN protocols: defines how communication is carried out over various WAN media Exp: SLIP, HDLC,PPP

TCP/IP The Transmission Control Protocol/Internet Protocol (TCP/IP) suite of protocols was developed as a part of the research done by the Defense Advanced Research Projects Agency (DARPA) It is the protocol of the internet It is route information from the source to destination by performing the following tasks: Defining the packet and addressing the scheme Moving data between link layer and transport layer Routing the packets to remote hosts Performing fragmentation and reassembly of packets

TCP/IP suite protocols IP (Internet protocol) Best effort delivery routing of the packets Connectionless and unreliable ICMP ( Internet Control Message Protocol) Defines an small number of messages used for diagnostic and management purposes ICMP uses IP to carry out the following function: Announces network error Announces network congestion Assists troubleshooting Announces timeouts

Cont… ARP ( Address Resolution Protocol) Determine the MAC address for known IP address Two messages ARP Request and ARP reply RARP ( Reverse Address Resolution Protocol) Determine the IP address when MAC address known Two messages RARP Request and RARP reply

Cont... DHCP (Dynamic Host Configuration Protocol) Provides automatic configuration of IP addresses DNS (Domain Name System) Resolves hosts names to their respective IP addresses SNMP Simple network management protocol Monitor remote devices

Cont… SMTP (Simple mail Transfer protocol) Transfer mail over internet NNTP ( Network News Transfer protocol) Used to setup Bulletin Discussions over internet FTP ( File Transfer protocol) Download or upload files over internet Uses connection oriented protocol (TCP) TFTP ( Trivial File Transfer protocol) Copy files from one device to anther Uses a connectionless protocol (UDP)

IP Addressing Different devices within an internetwork are identified by an IP address IP address Uniquely identifies network to which host is attached Network ID Host ID Identifies host uniquely given the network

Cont… The network part has not been allocated a fixed address space It is 32 bits, dotted-decimal notation, 4 byte Network Host 0-255

Cont… 0.0.0.0 reserved for network addresses 255.255.255.255 reserved for broadcast address Numbers assigned to network or host 1-254

Subnet Mask To determine which part from the IP address is network ID and which is Host ID Anding operation with the IP address to determine the network address

Cont… 36.48.54.255 36.48.255.255 36.255.255.255 0010 0010 . 0011 0000 . 0011 0110 . 0001 1011 36 . 48 . 54 .27 1111 1111 . 1111 1111 . 1111 1111 . 0000 0000 255.255.255. 0 0010 0010 . 0011 0000 . 0011 0110 . 0000 0000 36 . 48 . 54 . 0

Default Gateway (router) The network ID of the destination used to check whether the destination is in the same network with the computer or not Yes, use the ARP to determine the MAC address and forward the frame to it No, send it to the router (using the ip of the router) and the router looks into the Routing table for the destination network and forwarding the packet to the corresponding interface.

IP address classes A 001 to 126 224 – 2 = 16,777,214 B 128 to 191 216 -2 = 65,534 C 192 to 223 28 -2 = 254 D 224 to 239 E 240 to 254

Problems IPv4 address scheme is limited by its 32 bits problems for the long-term growth of the internet Class D and class E reserved Networks 0.0.0.0 , 255.0.0.0 , 127.0.0.0 are reserved for protocol operations Class A and Class B addresses were gone and goes to individual organizations like HP (3 As) unused IP addresses within these blocks is very large Class C networks used to entire country in some countries in Asia and Africa because they arrive late to the internet limited number of hosts reduce the number of available globally unique IP address

Cont… The global internet routing table is huge and continues to grow go beyond the capacity of routers

Solutions Subnet masking Address allocation for private internet Hierarchical addressing Variable-length subnet masks Route summarization Classes interdomain routing Network address translation

Subnet addressing Networks divided into subnets thus saving IP address spaces, reduce broadcasting and use the network address more efficient Done by reserving bits from host address Any number of bits can be borrowed as long as two bits remain. Computers see subnetwork address in 3 parts ( Net,subnet,host )

Subnetting a class C network In a class C network (exp: 200.36.48.0) Network address part 200.36.48 can’t be change Reserved bits from host part Reserving one bit : cannot be use to create subnet because only two numbers are possible 0,1 . 0 reserved for networks while 1 reserved for broadcasting Minimum two bits for subnetting

Cont… With to bits , 4 numbers are possible 00 reserved for network 01 200.36.48.01000000  200.36.48.64 10 200.36.48.10000000  200.36.48.128 11 Reserved for broadcast The direct broadcast address for the produced two subnet will be: 200.36.48.01111111  200.36.48.127 200.36.48.10111111  200.36.48.191

Cont... From the remaining 6 bits in the host part  62 hosts The range of IP addresses in each subnet: 1. 200.36.01000001 to 200.36.01111110 200.36.48.65 to 200.36.48.126 2. 200.36.10000001 to 200.36.10111110 200.36.48.129 to 200.36.48.190 The default subnet mask for this network will be 255.255.255.11000000  255.255.255.192

In a class C network

Cont… See in the notes Subnetting in class C using 3 bits Class B Subnetting

Private addressing IP can be assigned to devices in private network .But this IPs may conflict with IPs over the internet Sol1: assigned to them public IP address  exhausting IP address space Sol2: use IP networks numbers called private internets  must be no internet connectivity

Cont… Address Allocation for Private Internets It is a set of networks that will never be assigned to any organization as a registered network number

IPv6 Is the successor to the currently used IPv4 Specification completed in 1994 Makes improvements to IPv4 (no revolutionary changes) significant increase of the IP address to 128 bits (16 bytes) IPv6 will solve – for the foreseeable future – the problems with IP addressing IPv4 has a maximum of 232  4 billion addresses IPv6 has a maximum of 2128 = (232)4  4 billion x 4 billion x 4 billion x 4 billion addresses improves routing, security and Quality of Service (QoS)

Cont… The 128-bit IPv6 address is written as eight 16-bit integers (using hexadecimal digits for each integer) Exp: CEDF:BP76:3245:4464:FACE:2E50:3025:DF12

IPv6 Prefix (subnet mask) IPv4 subnet mask called as address prefix in IPv6 and it used to determine which part of the IP is network ID and which is host ID Its format: the IP address with a slash (/) followed by the prefix length Exp: CEDF:BP76:3245:4464:FACE:2E50:3025:DF12 /64 The prefix is a decimal value that indicates the number of high order contiguous bits that is the network portion of the IP address