1. Protocols 1 Objective: Build a protocol foundation for Client / Server programming in an Internet Environment Note: RFCs available from http://www.isi.edu/rfc-editor/ References: RFC’s 791, 793, 768, 826

2. cs423 - cotter2 Objectives of C/S Architecture Improve system performance Get centralized applications closer to user Improve system reliability Improve intersystem (multi-vendor) communications Improve resource utilization (PCs on the desktop) Move towards standard inter-operating environment

3. cs423 - cotter3 Internetwork Communications Application

4. cs423 - cotter4 Layered Protocol Architectures Driven by interoperability Concerns Divide the communications process into tasks that can be managed by a protocol Allow multiple protocols to do each of the layers.

5. cs423 - cotter5 Simple Layered Model Network Access Internetwork Transport Application Ethernet, fiber, Token Ring Routing Connection Control FTP, e-mail, Client/Server

6. cs423 - cotter6 Standard Layered Architecture Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer OSI ModelInternet Application Layer TCP / UDP Layer Internet Protocol Physical Layer

7. cs423 - cotter7 Multiple Hop Communications Application Layer TCP / UDP Layer Internet Protocol Physical Layer Application Layer TCP / UDP Layer Internet Protocol Physical Layer Internet Protocol Physical Layer Host Router

8. cs423 - cotter8 Internet Addressing 32 bit universal identifier (4 octets) Normal Site Addresses Multicast Address Broadcast Address

9. cs423 - cotter9 Internet addressing 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| NETWORK | Local Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 0| NETWORK | Local Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 0| NETWORK | Local Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 1 0|MULTICAST ADDRESS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

10. cs423 - cotter10 Special Internet Addresses netid + hostid = 0’s:This host netid = 0’s, host id = HOST: HOST on this net netid + hostid = 1’s: local net broadcast netid = NET, hostid = 1’s: broadcast on NET high order octet = 127, rest = anything: loopback

11. cs423 - cotter11 Domain Name System Hierarchical Names –primus.cstp.umkc.edu Domain Name suffixes comedugov milnetorg arpaintcountry codes Domain Name resolution –name servers –local caching

12. cs423 - cotter12 Data Encapsulation Application Layer TCP / UDP Layer IP Layer Physical Layer User Data TCP PH IP

13. cs423 - cotter13 Protocol Relationships +------+ +-----+ +-----+ +-----+ |Telnet| | FTP | | TFTP|... |... | +------+ +-----+ +-----+ +-----+ | | | | +-----+ +-----+ +-----+ | TCP | | UDP |... |... | +-----+ +-----+ +-----+ | | | +--------------------------+----+ | Internet Protocol & ICMP | +--------------------------+----+ | +---------------------------+ | Local Network Protocol | +---------------------------+

14. cs423 - cotter14 Ethernet Frame Format Preamble DestinationSource Type Data FCS 86 6 2 46-1500 4 Preamble - used for synchronization Destination - Ethernet address of destination Source - IP address of source Ethertype - higher layer protocol type(0800=IP) Data - IP datagram FCS - Frame Check Sequence (32 bit CRC)

15. Ethernet Frame with QoS / VLAN 15 Upper Layer Protocol Payload (~> 1500 bytes) Tag / Protocol ID PrioVLAN ID 16 bits 3 bits 1 bit 12 bits

16. cs423 - cotter16 Address Resolution Protocol Conversion of 32 bit Network Protocol address to 48 bit Ethernet Address Specified in RFC 0826 Each host must know its own IP address. Hosts generally use dynamic discovery to identify mappings between IP and Ethernet addresses. Ethernet broadcast address: FF.FF.FF.FF.FF.FF

17. cs423 - cotter17 Internet Protocol functions Connectionless Datagram Delivery RFC 791 Benefits of connectionless delivery –Flexibility (requires little from networks) –Robustness (datagrams routed independently) –Connectionless application support

18. cs423 - cotter18 IP Design Issues Addressing Routing Datagram lifetime Fragmentation and reassembly Error control Flow control

19. cs423 - cotter19 IP Datagram Format 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| IHL |Type of Service| Total Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identification |Flags| Fragment Offset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time to Live | Protocol | Header Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options | Padding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

20. cs423 - cotter20 IP Service Primitives Services offered to higher layers Send –(source address, destination address, protocol, type of service indicators, identifier, don’t fragment indicator, time to live, data length, option data, data) Deliver –(Source address, destination address, protocol. type of service indicators, data length, option data, data)

21. cs423 - cotter21 User Datagram Protocol Functions Connectionless Data Transfer “Unreliable”

22. cs423 - cotter22 UDP Header 0 7 8 15 16 23 24 31 +--------+--------+--------+--------+ | Source | Destination | | Port | Port | +--------+--------+--------+--------+ | | | | Length | Checksum | +--------+--------+--------+--------+ | | data octets... +----------------...

23. cs423 - cotter23 UDP pseudo Header 0 7 8 15 16 23 24 31 +--------+--------+--------+--------+ | source address | +--------+--------+--------+--------+ | destination address | +--------+--------+--------+--------+ | zero |protocol| UDP length | +--------+--------+--------+--------+

24. 24 Summary Reviewed layered Protocol Architecture Discussed Internet Naming and Addressing Discussed Internet Protocol (IP) Functions and Header