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PENGANTAR TCP/IP DAN ROUTING

Internet dan Jaringan Komputer. PENGANTAR TCP/IP DAN ROUTING. Dr. Tb. Maulana Kusuma mkusuma@staff.gunadarma.ac.id http://staffsite.gunadarma.ac.id/mkusuma. Internet Protocol (IP). IP Addressing Basics.

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PENGANTAR TCP/IP DAN ROUTING

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  1. Internet dan Jaringan Komputer PENGANTAR TCP/IP DAN ROUTING Dr. Tb. Maulana Kusuma mkusuma@staff.gunadarma.ac.id http://staffsite.gunadarma.ac.id/mkusuma Magister Manajemen Sistem Informasi

  2. Internet Protocol(IP) Magister Manajemen Sistem Informasi

  3. IP Addressing Basics • Symbolic names are easier to remember a string, such as www.course.com, than a numeric address, such as 199.95.728—computers are the opposite • They deal with network addresses in the form of bit patterns that translate into decimal numbers • IP uses a three-part addressing scheme, as follows: • Symbolic • Logical numeric • Physical numeric Magister Manajemen Sistem Informasi

  4. IP Addressing Basics • In keeping with the layered nature of network models, it makes sense to associate the MAC layer address with the Data Link layer (or TCP/IP Network Access layer, if you prefer to think in terms of that model), and to associate IP addresses with the Network layer (or the TCP/IP Internet layer) • As data moves through intermediate hosts between the original sender and the ultimate receiver, it does so between pairs of machines, where each pair resides on the same physical network Magister Manajemen Sistem Informasi

  5. IP Addressing Basics • At the Network layer, the original sender’s address is represented in the IP source address field in the IP packet header, and the ultimate recipient’s address is represented in the IP destination address field in the same IP packet header • The IP destination address value, in fact, is what drives the sometimes-long series of intermediate transfers, or hops, which occur as data makes its way across a network from sender to receiver Magister Manajemen Sistem Informasi

  6. Anatomy of an IP Address • Numeric IP addresses use dotted decimal notation when expressed in decimal numbers, and take the form n.n.n.n., in which n is guaranteed to be between zero and 255 for each and every value • The numeric values in dotted decimal representations of numeric IP addresses are usually decimal values, but may occasionally appear in hexadecimal (base 16) or binary (base 2) notation Magister Manajemen Sistem Informasi

  7. Anatomy of an IP Address • Duplication of numeric IP addresses is not allowed because that would lead to confusion • Also, there is a notion of “neighborhood” when it comes to interpreting numeric IP addresses • Proximity between two numeric IP addresses (especially if the difference is only in the rightmost one or two octets) can sometimes indicate that the machines to which those addresses correspond reside close enough together to be on the same general network, if not on the same physical cable segment Magister Manajemen Sistem Informasi

  8. IP Address Classes • Initially, these addresses were further subdivided into five classes, from Class A to Class E • For the first three classes of addresses, divide the octets as follows to understand how they behave: Class A n h.h.h Class B n.n h.h Class C n.n.n h • If more than one octet is part of the network or host portion of the address, then the bits are simply concentrated to determine the numeric address Magister Manajemen Sistem Informasi

  9. IP Address Classes • The network portion of that address is 10, whereas the host portion is 12.120.2, treated as a three-octet number • Address Classes D and E are for special uses • Class D addresses are used for multicast communications, in which a single address may be associated with more than one network host machine • This is useful only when information is broadcast to more than one recipient at a time so it should come as no surprise that video and teleconferencing applications, for example, use multicast addresses Magister Manajemen Sistem Informasi

  10. More About Class A Addresses • Expressed in binary form (ones and zeroes only), Class A addresses always take the form: 0bbbbbbb.bbbbbbbb.bbbbbbbb.bbbbbbbb • The leading digit is always zero, and all other digits can be either ones or zeroes • On any IP network, addresses consisting of all zeroes and all ones are reserved for special uses, so of those 128 possible network addresses, only those from 00000001 to 01111110 (or 1 to 126, in decimal terms) are considered usable Magister Manajemen Sistem Informasi

  11. More About Class A Addresses • The address for network 10 is reserved for private network use • Also, by convention, the address 127.n.n.n is reserved for loopbacktesting (or checking the integrity and usability of a TCP/IP protocol stack installed on any computer Magister Manajemen Sistem Informasi

  12. More About Class B Addresses • Class B addresses always take the form: 10bbbbbb.bbbbbbbb.bbbbbbbb.bbbbbbbb • The leading two digits are 10, and the remaining digits can be either ones or zeroes • RFC 1918 stipulates that 16 Class B addresses, from 172.16.0.0 to 172.32.255.255, are reserved for private use • This means that the maximum number of public IP addresses for Class B is 16,382-16, or 16,366 Magister Manajemen Sistem Informasi

  13. Class B Address Facts and Figures Magister Manajemen Sistem Informasi

  14. More About Class C Addresses • Class C addresses always take the form: 110bbbbb.bbbbbbbb.bbbbbbbb.bbbbbbbb • The leading three digits are 110, and the remaining digits can be either ones or zeroes • Note that this scheme reduces the total number of networks possible by the most significant three bits Magister Manajemen Sistem Informasi

  15. More About Address Classes D and E • Class D addresses always take the form: 1110bbbb.bbbbbbbb.bbbbbbbb.bbbbbbbb • Class E addresses always take the form: 11110bbb.bbbbbbbb.bbbbbbbb.bbbbbbbbb • Class D is used for multicast addresses so that multiple users can “share” a single IP address and receive the same broadcast across a network from a single transmission Magister Manajemen Sistem Informasi

  16. The Vanishing IP Address Space • IP addresses were assigned for public use, they were assigned on a per-network basis • With the ever-increasing demand for public IP addresses for Internet access, it should come as no surprise that, as early as the mid-1990s, experts began to predict that the Internet would “run out” of available IP addresses Magister Manajemen Sistem Informasi

  17. The Vanishing IP Address Space • The causes for concern have abated somewhat, Here’s why: • The technocrats at the IETF introduced a new way to carve up the IP address space—Classless Inter-Domain Routing (CIDR) • A brisk trade in existing IP network addresses sprung up during the same time • RFC 1918 reserves three ranges of IP addresses for private use—a single Class A (10.0.0.0-10.255.255.255), 16 Class Bs (172.16.0.0-172.31.255.255), AND 256 Class Cs (192.168.0.0-192.168.255.255). When used in tandem with a technology called Network Address Translation (a.k.a NAT), private IP addresses can help lift the “cap” on public IP addresses Magister Manajemen Sistem Informasi

  18. IP Networks, Subnets, and Masks • If two network interfaces are on the same physical network, they can communicate directly with one another at the MAC layer • In fact, each of the three primary IP address classes—namely A, B, and C—also has an associated default subnet mask Magister Manajemen Sistem Informasi

  19. IP Subnets and Supernets • A subnet mask is a special bit pattern that “blocks off” the network portion of an IP address with an all-ones pattern • The reason why concepts like subnets and supernets are important for TCP/IP networks is because each of these ideas refers to a single “local neighborhood” on such a network, seen from a routing perspective Magister Manajemen Sistem Informasi

  20. IP Subnets and Supernets • Thus, a subnet mask that is larger than the default mask for the address in use divides a single network IP address into multiple subnetworks • The network prefix identifies the number of bits in the IP address, counting from the left that represents the actual network address itself, and the additional two bits of subnetting represent the bits that were borrowed from the host portion of that IP address to extend the network portion Magister Manajemen Sistem Informasi

  21. IP Subnets and Supernets • The entire network address, including the network prefix and the subnetting bits, is called the extended network prefix • This activity of stealing bits from the host portion of further subdivide the network portion of an address is called subnetting a network address, or subnetting Magister Manajemen Sistem Informasi

  22. IP Subnets and Supernets • When a computer on one subnet wishes to communicate with a computer on another subnet, traffic must be forwarded from the sender to a nearby IP gateway to send the message on its way from one subnet to another • Supernetting takes the opposite approach: by combining contiguous network addresses, it steals bits from the network portion and uses them to create a single, larger contiguous address space for host addresses Magister Manajemen Sistem Informasi

  23. Calculating Subnet Masks • The simplest form of subnet masking uses a technique called constant-length subnet masking (CLSM), in which each subnet includes the same number of stations and represents a simple division of the address space made available by subnetting into multiple equal segments • Another form of subnet masking uses a technique called variable-length subnet masking (VLSM) and permits a single address to be subdivided into multiple subnets, in which subnets need not all be the same size Magister Manajemen Sistem Informasi

  24. Calculating Supernets • Supernets “steal” bits from the network portion of an IP address to “lend” those bits to the host part • As part of how they work, supernets permit multiple IP network addresses to be combined and make them function together as if they represent a single logical network Magister Manajemen Sistem Informasi

  25. Classless Inter-Domain Routing (CIDR) • CIDR gets its name from the notion that it ignores the traditional A, B, and C class designations for IP addresses, and can therefore set the network-host ID boundary wherever it wants to, in a way that simplifies routing across the resulting IP address spaces Magister Manajemen Sistem Informasi

  26. Classless Inter-Domain Routing (CIDR) • Creating a CIDR address is subject to the following limitations: • All the addresses in the CIDR address must be contiguous • When address aggregation occurs, CIDR address blocks work best when they come in sets that are greater than one, and equal to some lower-order bit pattern that corresponds to all ones • CIDR addresses are commonly applied to Class C addresses • To use a CIDR address on any network, all routers in the routing domain must “understand” CIDR notation Magister Manajemen Sistem Informasi

  27. CIDR Notation • CIDR notation of an IP address: 192.0.2.0/18 • "18" is the prefix length. It states that the first 18 bits are the network prefix of the address (and 14 bits are available for specific host addresses) • CIDR notation can replace the use of subnetmasks (but is more general) • IP address 128.143.137.144 and subnetmask 255.255.255.0 becomes 128.143.137.144/24 • CIDR notation allows to drop traling zeros of network addresses: 192.0.2.0/18can be written as192.0.2/18 Magister Manajemen Sistem Informasi

  28. CIDR address blocks • CIDR notation can nicely express blocks of addresses • Blocks are used when allocating IP addresses for a company and for routing tables (route aggregation) CIDR Block Prefix # of Host Addresses /27 32 /26 64 /25 128 /24 256 /23 512 /22 1,024 /21 2,048 /20 4,096 /19 8,192 /18 16,384 /17 32,768 /16 65,536 /15 131,072 /14 262,144 /13 524,288 Magister Manajemen Sistem Informasi

  29. Public Versus Private IP Addresses • The private IP address ranges may be expressed in the form of IP network addresses, as shown in Table 2-4 • Private IP addresses have one other noteworthy limitation Magister Manajemen Sistem Informasi

  30. Public Versus Private IP Addresses • Some IP services require what’s called a secure end-to-end connection—IP traffic must be able to move in encrypted form between the sender and receiver without intermediate translation • Most organizations need public IP addresses only for two classes of equipment: • Devices that permit organizations to attach networks to the Internet • Servers that are designed to be accessible to the Internet Magister Manajemen Sistem Informasi

  31. Managing Access to IP Address Information • Although use of private IP addresses mandates NAT or a similar address substitutions or masquerade capability, some organizations elect to use address substitutions or masquerade even when they use perfectly valid public IP addresses on their internal networks • Proxy servers can provide what is sometimes called reverse proxying • This permits the proxy server to front for servers inside the boundary by advertising only the proxy server’s address to the outside world, and then forwarding only legitimate requests for service to internal servers for further processing Magister Manajemen Sistem Informasi

  32. Obtaining Public IP Addresses • Unless you work for an organization that has possessed its own public IP addresses since the 1980s (or acquired such addresses through merger or acquisition), it’s highly likely that whatever public IP addresses your organization uses were issued by the very same ISP who provides your organization with Internet access • Because all devices accessible to the Internet must have public IP addresses, changing providers often means going through a tedious exercise called IP renumbering Magister Manajemen Sistem Informasi

  33. IP Addressing Schemes • To the uninitiated, it may appear that all these IP addresses are randomly assigned, or perhaps generated automatically by some computer somewhere • A great deal of thought has gone into the strategy for allocating IP addresses around the world Magister Manajemen Sistem Informasi

  34. The Network Space • There are a number of critical factors that typically constrain IP addressing schemes, and we look at these in two groups • The first group of constraints determines the number and size of networks • These are: • Number of physical locations • Number of network devices at each location • Amount of broadcast traffic at each location • Availability of IP addresses • Delay caused by routing from one network to another Magister Manajemen Sistem Informasi

  35. IPv6 - IP Version 6 • IP Version 6 • Is the successor to the currently used IPv4 • Specification completed in 1994 • Makes improvements to IPv4 (no revolutionary changes) • One (not the only !) feature of IPv6 is a significant increase in of the IP address to 128 bits (16 bytes) • IPv6 will solve – for the foreseeable future – the problems with IP addressing • 1024 addresses per square inch on the surface of the Earth. Magister Manajemen Sistem Informasi

  36. IPv6 Header Magister Manajemen Sistem Informasi

  37. IPv6 vs. IPv4: Address Comparison • IPv4has 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 Magister Manajemen Sistem Informasi

  38. Notation of IPv6 addresses • Convention: The 128-bit IPv6 address is written as eight 16-bit integers (using hexadecimal digits for each integer) CEDF:BP76:3245:4464:FACE:2E50:3025:DF12 • Short notation: • Abbreviations of leading zeroes: CEDF:BP76:0000:0000:009E:0000:3025:DF12  CEDF:BP76:0:0:9E:0:3025:DF12 • “:0000:0000:0000” can be written as “::” CEDF:BP76:0:0:FACE:0:3025:DF12  CEDF:BP76::FACE:0:3025:DF12 • IPv6 addresses derived from IPv4 addresses have 96 leading zero bits. Convention allows to use IPv4 notation for the last 32 bits. ::80:8F:89:90  ::128.143.137.144 Magister Manajemen Sistem Informasi

  39. IPv6 Provider-Based Addresses • The first IPv6 addresses will be allocated to a provider-based plan • Type:Set to “010” for provider-based addresses • Registry: identifies the agency that registered the address The following fields have a variable length (recommeded length in “()”) • Provider: ID of Internet access provider (16 bits) • Subscriber: ID of the organization at provider (24 bits) • Subnetwork: ID of subnet within organization (32 bits) • Interface: identifies an interface at a node (48 bits) 010 Registry ID Provider ID Subscriber ID SubnetworkID Interface ID Magister Manajemen Sistem Informasi

  40. Transmission Control Protocol(TCP) Magister Manajemen Sistem Informasi

  41. Understanding Connectionless Transport Protocols • Connectionless protocols provide the simplest kind of transport services because they simply package messages, taken as is from the TCP/IP Application layer, into datagrams • A datagram slaps a header onto the higher-layer data and passes it to the IP layer, where that datagram is fitted with an IP header and packetized, after which it may be transmitted across the network Magister Manajemen Sistem Informasi

  42. Understanding Connectionless Transport Protocols • This method is called best-effort delivery • UDP runs up to 40% faster than TCP, under some conditions, because it does next to nothing • It’s also typical for connectionless protocols to handle the following kinds of tasks: • Message checksum • Higher-layer protocol identification Magister Manajemen Sistem Informasi

  43. User Datagram Protocol (UDP) • It’s appropriate to provide the following detailed description for UDP: • No reliability mechanisms • No delivery guarantees • No connection handling • Identifies Application layer protocol conveyed • Checksum for entire message carried in UDP header • No buffering services • No segmentation Magister Manajemen Sistem Informasi

  44. UDP Header Fields and Functions • UDP is defined in RFC 768 • When the Protocol field of an IP header contains the value 17 (0x11), the UDP header follows the IP header Magister Manajemen Sistem Informasi

  45. UDP Port Numbers and Processes Magister Manajemen Sistem Informasi

  46. Understanding Connection-Oriented Protocols • Connection-oriented protocols create a logical connection directly between two peers on an internetwork • Connection-oriented protocols track the transfer of data, and ensure it arrives successfully through acknowledgements and sequence number tracking • An acknowledgement is a positive response, indicating a set of data arrived Magister Manajemen Sistem Informasi

  47. Understanding Connection-Oriented Protocols • Connection-oriented peers use sequence number tracking to identify the amount of data transferred, and any out-of-order packets • Connection-oriented protocols have a timeout mechanism that indicates when a host waited too long for a communication, and such communication should be assumed lost • Connection-oriented protocols also have a retry mechanism that enables them to recover lost data by retransmitting it a specified number of times Magister Manajemen Sistem Informasi

  48. Transmission Control Protocol (TCP) • TCP offers connection-oriented services with sequencing, error recovery, and a sliding window mechanism • Because of TCP’s end-to-end reliability and flexibility, TCP is the preferred transport method for applications that transfer large quantities of data and require reliable delivery services • TCP hosts create a virtual connection with each other using a handshake process Magister Manajemen Sistem Informasi

  49. Transmission Control Protocol (TCP) • TCP transfers data as a continuous stream of bytes, with no knowledge of the underlying messages or message boundaries that might be contained in that byte stream Magister Manajemen Sistem Informasi

  50. TCP Startup Connection Process (TCP Handshake) • TCP offers a connection-oriented transport that begins with a handshake between two hosts • One host initiates the handshake to another host to: • Ensure the destination host is available • Ensure the destination host is listening on the destination port number • Inform the destination host of the initiator’s sequence number so the two sides can track data as it is transferred Magister Manajemen Sistem Informasi

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