1. TCP/IP Explored
Jun Wu
11/11/2018

2. Contents 1. Introduction 2. IP explored 3. TCP explored
4. Other common protocols in TCP/IP
5. TCP/IP programming
6. Summary
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3. Introduction
TCP/IP – A suite of internet protocols named after Transmission Control Protocol/Internet Protocol, the de facto standard protocol for today’s internet.
TCP/IP over OSI (Open Systems Interconnection) - OSI layers : Application, Presentation, Session, Network, Data Link, Physical Included Protocols: FTP,SNMP, Telnet,TFTP, Finger, NFS, SMTP,DNS, POP,BOOTP,TCP, UDP, IP TCP/IP layers: Application, Host-to-Host transport, Internet, Network interface
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4. IP – Internet Protocol
Where does it work? Network layer, connectionless
Functions Receiving data bits from lower layer Assembling them into packets Selecting the “best” route to send packets to destinations.
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5. IP header format
Version IHL Type of Service Total Length Identification DF MF Fragment offset Time to leave Protocol Header checksum Source address Destination address Options
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6. IP address (IPv4) 32 bits ( 4 groups of 8 bits )
Example:
5 classes: A (0, 0~127), B(10, 128~191), C(110, 192~223), D(1110, 224~254), E(11110, reserved)
Two parts: Network ID & Host ID, different classes of IP address support different number of networks and hosts
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7. IP Subnet Partition a network address into separate subnetworks.
Why? Expanding limited IPv4 address space
Example: consider 1 class C IP address, it supports 1 network & 256 hosts (actually 254).
Now if “steal” 1 higher-bit of host ID and used as part of network ID -> 2 subnets; “steal” 2 bits -> 4 subnets, and so on.
Another solution: 128 bits IP address (IPv6)
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8. IP masking How to subnet? Masking!
Rule: if a bit in an IPv4 address is used as part of network ID, then set the corresponding mask bit to 1; if used as host ID, set mask to 0.
Example: IP address with mask > Network ID is , host ID is 0~254.
Now borrowing two leftmost bits of host ID, 4 subnets form ( , 64, 128, 192). Subnet mask , given , first routed to subnet , then to the host 15 on this subnet.
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9. Summary IP is a connectionless protocol on Network layer.
IP packs data bits from lower layer into packets with a header and routes these packets between nodes. It also fragments & resembles datagrams when necessary.
IPv4 address has only 32 bits – limited space!
Different classes of IP address supports different number of networks & hosts.
IPv4 address space can be expanded through subset and mask technique.
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