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CCNA 1 Module 9: TCP/IP Protocol Suite and IP Addressing
TCP/IP – History and Future • Created by US DoD as a model able to withstand intense military attack and not fail. • Data transmission was possible to any destination on the network under any circumstances.
TCP/IP – History and Future • Standardized in 1981 • The TCP/IP model is now the standard on which the Internet is based. • There are similarities and differences between the TCP/IP model and the nine layer OSI model.
TCP/IP Application Layer • Ensures that the data is properly packaged before being passed on. • Handles high-level protocols, representation, encoding, and dialog control. • Simple Network Management Protocol (SNMP) – allows network managers to manage configurations, statistics, performance, and security. • Domain Name System (DNS) – used to translate domain names into IP addresses. Application
TCP/IP Application Layer • Has protocols to support file transfer, e-mail, and remote login: • File Transfer: • Trivial File Transfer Protocol (TFTP) – unreliable, connectionless User Datagram Protocol (UDP) service used to transfer configuration files, Cisco IOS images, and to transfer files in a LAN. • File Transfer Protocol (FTP) – reliable, connection-oriented service that uses TCP to transfer files between systems • Network File System (NFS) – allows file access to a remote storage device such as a hard disk Application
TCP/IP Application Layer • E-mail: • Simple Mail Transfer Protocol (SMTP) – administers the transmission of plain text e-mail over computer networks. • Remote access: • Telnet –remotely access a computer, enabling a user to log into an Internet host and execute commands. A Telnet client is called a local host. A Telnet server is called a remote host. Application
TCP/IP Transport Layer • Provides a logical connection between a source host and a destination host. • Transport Layer protocols segment and reassemble data sent by applications, into the same data stream, between end points. • Provides end-to-end control and reliability as data travels through the cloud, accomplished through: • sequence numbers, acknowledgments and sliding windows. Transport
TCP/IP Transport Layer I just sent #10 I just received #10 Now I need #11 Transport This shows sequence numbers and acknowledgements.
TCP/IP Transport Layer Sliding Windows I just sent #11, 12 and 13 I just received #12 Now I need #13 Transport This indicates that packet 13 either did not arrive, or arrived with errors, and needs retransmission.
TCP/IP Transport Layer Sliding Windows I just sent #13 and 14 I just received #14 Now I need #15 Transport The sliding window has worked as the last packet sent has arrived.
TCP/IP Transport Layer • The only Transport layer protocols are TCP and UDP. • Transmission Control Protocol (TCP) • Connection-oriented protocol • End-to-end operation • Flow control – sliding windows • Reliability – sequence numbers and acknowledgments • User Datagram Protocol (UDP) • Connectionless • Unreliable (no acknowledgments or error checking) Transport
TCP/IP Internet Layer • Two purposes are determining the best path and packet-switching. • No error checking or correction • Protocols: • Internet Protocol (IP) - connectionless, best-effort delivery routing of packets; determines best path to destination • Internet Control Message Protocol (ICMP) – control and messaging • Address Resolution Protocol (ARP) - determines the MAC address, for a known IP address. • Reverse Address Resolution Protocol (RARP) - determines the IP address for a known MAC address. Internet
TCP/IP Network Access Layer • Allows an IP packet to make a physical link to the network media • Maps IP addresses to MAC addresses • Encapsulates IP packets into frames • Drivers for software applications, modem cards, and other devices operate at the network access layer. • Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP) provide network access. • ARP and RARP also work at this layer. Network Access
Comparing TCP/IP and OSI TCP/IP Model OSI Model Application 7 Application Layers Application Presentation 6 Session 5 Transport Transport 4 Internet 3 Data Flow Layers Network 2 Data Link Network Access Physical 1
Similarities Both have layers. Both have application layers, though they include different services. Both have comparable transport and network layers. Both use packet-switched instead of circuit-switched technology. Differences TCP/IP combines the OSI application, presentation, and session layers into its application layer. TCP/IP combines the OSI data link and physical layers into its network access layer. TCP/IP appears simpler as it has fewer layers. The TCP/IP transport layer uses UDP (not reliable) delivery of packets. The transport layer in the OSI model is always reliable. Comparing TCP/IP and OSI
Internet Architecture • The Internet is based on the principle of networklayer interconnection. • This means that it is independent of the lower layers and the upper layers. • This functionality allows for different Layer 1 and 2 LAN technologies (media; protocols; LAN design, etc.) • It also allows for a diversity of applications at Layers 5, 6, and 7.
Internet Architecture • This means that one network with one set of Layer 1 and 2 LAN media, design etc. and its own upper layer Applications can communicate with a very different LAN. • This capability means that the Internet is scalable; now with over 90,000 core routers and 300 million users, and growing.
IP Addressing • Each computer (computer interface) in a TCP/IP network must have two addresses: • An IP (logical, layer 3) address, is a combination of the network address and the host address creating a unique address for each device on a network. This address is needed to deliver the packet to the correct network. • A unique MAC (physical, layer 2) address. Once the data (packet) has arrived at the network, this address is needed to deliver it to the destination device.
IP Addressing • An IP address is a 32-bit sequence of ones and zeros. • It is commonly represented in dotted decimal format, as it is easier to understand and less prone to error. 11000000.10101000.00000001.00001000 192.168.1.8
Decimal and Binary Conversion • Review the binary to decimal and the decimal to binary conversions in 9.2.2
Address Classes • A router uses the IP address of the destination network to deliver a packet to the correct network. • Every IP address has two parts • The first part identifies the network where the device is connected and the second part identifies the device. • There are four octets, each ranging from 0-255, representing 256 possible addresses.
Address Classes • An IP address is always divided up into a network portion and a host portion.
Address Classes • IP addresses are hierarchical, meaning an address can be referenced back to a particular group address.
Address Classes • There are five address classes: • Class A – for very large networks • Class B – for medium networks • Class C – for small networks • Class D – for multicast groups; no need for network and host parts • Class E – for research purposes
Address Classes Learn these tables!
Address Classes Class A: • One network octet and three host octets. • The first bit of a Class A address is 0. • The lowest number that can be represented is 00000000, decimal 0. • The highest number that can be represented is 01111111, decimal 127. • Usable 1st octet addresses: 1 126 • (0 and 127 are reserved addresses)
Address Classes Class B: • Two network octets and two host octets. • The first two bits of a Class B address are 10. • The lowest number that can be represented is 10000000, decimal 128. • The highest number that can be represented is 10111111, decimal 191. • Usable 1st octet addresses: 128 191
Address Classes Class C: • Three network octets and one host octet. • The first three bits of a Class C address are 110. • The lowest number that can be represented is 11000000, decimal 192. • The highest number that can be represented is 11011111, decimal 223. • Usable 1st octet addresses: 192 223
Address Classes Class D: • Created to enable multicasting. A destination address is a group of addresses. • The first four bits of a Class D address must be 1110. • The first octet range for Class D addresses is 11100000 to 11101111, or 224 to 239.
Address Classes Class E: • Reserved for IETF research. • Not used on the Internet. • The first four bits of a Class E address are always 1111. • The first octet range for Class E addresses is 11110000 to 11111111, or 240 to 255.
What is the Address Class? • 1. 176.186.14.112 176 = 10110000 = • 2. 197.76.210.100 197 = 11000101 = • 3. 129.118.32.189 129 = 10000001 = • 4. 113.26.172.106 113 = 01110001 = • 5. 201.200.100.90 201 = 11001001 = • 6. 47.145.148.211 47 = 00101111 = B C B A C A What do you notice about each of the Class addresses? What is common with the Class A addresses? What is common with the Class B addresses? What is common with the Class C addresses?
Address Classes • This is a very important table. • Copy it into your journal. • MEMORISE IT!
Reserved addresses • Two addresses on any network cannot be used by hosts. • Network address – Used to identify the network itself • Broadcast address – Used for broadcasting packets to all the devices on a network • The HOST bits of a network address are all 0s. • The HOST bits of a broadcast address are all 1s.
Reserved addresses • IP Address –10.18.127.100 • Subnet Mask – • Network address = • Broadcast address = 255.0.0.0 10.0.0.0 10.255.255.255 The first question to ask is, ‘What class is this address?’ Class A
Reserved addresses • IP Address –131.234.12.66 • Subnet Mask – • Network address = • Broadcast address = 255.255.0.0 131.234.0.0 131.234.255.255 What class is this address? Class B
Reserved addresses • IP Address –199.218.4.56 • Subnet Mask – • Network address = • Broadcast address = 255.255.255.0 199.218.4.0 199.218.4.255 What class is this address? Class C
Reserved addresses • IP Address – 210.189.137.100 • Subnet Mask – 255.255.255.240 • Network address = • Broadcast address = 210.189.137.96 210.189.137.111 What class is this address? Class C
Reserved addresses • IP Address – 180.43.120.39 • Subnet Mask – 255.255.255.192 • Network address = • Broadcast address = 180.43.120.0 180.43.120.63 What class is this address? Class B
Public and Private Addresses • No two devices on the Internet can have the same IP address. • Ensuring this does not happen is handled by the Internet Assigned Numbers Authority (IANA). • With the growth of the Internet, available Internet addresses have nearly run out. • To help deal with this problem, RFC 1918 sets aside three blocks of IP addresses for private, internal use.
Public and Private Addresses • One Class A, a range of Class B addresses, and a range of Class C addresses are not routed on the Internet. • 10.0.0.0 – 10.255.255.255 • 172.16.0.0 – 172.31.255.255 • 192.168.0.0 – 192.168.255.255 • A router uses Network Address Translation (NAT) to translate private addresses to public addresses.
Subnets • Subnetting a network means to use the subnet mask to divide a up a network into smaller, segments, or subnets. • Subnetting has prevented the wasting of usable host addresses. • To create a subnet address, some bits from the host field are borrowed, and designated as subnet bits.
Subnets • The minimum number of bits that can be borrowed is two. • The maximum is two less than the available number of host bits.
IPv4 vs IPv6 • Class A and Class B addresses make up three quarters of the four billion possible addresses. These are virtually used up. • Class C addresses only allow 254 hosts, too small for many organisations. • In 1992 the Internet Engineering Task Force (IETF) began work on IP version 6.
IPv4 vs IPv6 • IPv4 addresses are 32 bits long. • IPv6 addresses are 128 bits long. • IPv6 addresses are assigned to interfaces, not nodes. • IPv6 addresses are written in hexadecimal, and separated by colons.
