Lecture Notes Telcom 2000 Telcom 2000 Protocols and Architecture • Standards reduce complexity • Protocol functions m Segmentation and reassembly m Encapsulation m Connection control m Ordered delivery m Flow control m Error control m Addressing m Multiplexing m Transmission Services Martin B.H. Weiss Internetworking - 1 University of Pittsburgh Telcom 2000 Segmentation and Reassembly • May be required to deal with heterogeneity in underlying layers • Block sizes may differ for different optimization reasons Martin B.H. Weiss Internetworking - 2 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 1 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Encapsulation PDU (N+1)th layer PDU SAP Nth layer SAP PCI PDU PCI PDU PDU (N-1)th layer PDU Martin B.H. Weiss Internetworking - 3 University of Pittsburgh Telcom 2000 Connection Control • Connection Setup • Information Transfer • Connection termination • Connectionless vs. Connection-oriented Martin B.H. Weiss Internetworking - 4 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 2 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Addressing • Network address should not be dependent on the physical location of the node • Network address should not contain specific routing information • Addressing level (Global/Local) Martin B.H. Weiss Internetworking - 5 University of Pittsburgh Telcom 2000 Multiplexing Data Data Stream Stream Data Connection Data Stream Stream Data Data Stream Stream Upward Multiplexing Connection Data Connection Data Stream Stream Connection Downward Multiplexing Martin B.H. Weiss Internetworking - 6 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 3 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 TCP/IP Protocol Suite • Application layer • Host-to-host (Transport) layer • Internet layer • Network access layer • Physical layer Martin B.H. Weiss Internetworking - 7 University of Pittsburgh Telcom 2000 TCP/IP Protocol Suite User Data Application Byte Stream TCP TCP Header Segment IP IP Header Datagram Network Network Header Packet Martin B.H. Weiss Internetworking - 8 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 4 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 TCP/IP Protocol Suite MIME BGP FTP HTTP SMTP Telnet SNMP TCP UDP OSPF ICMP IP Martin B.H. Weiss Internetworking - 9 University of Pittsburgh Telcom 2000 Internetworking • Interconnection of networks m Routers m Gateways • Terms m Subnetworks m End systems m Intermediate systems Martin B.H. Weiss Internetworking - 10 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 5 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Internetwork Architecture AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAAAAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAAAAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AA AAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AA AAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA A AA AAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAAAA AAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA Internet AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAAAAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAAAAAAAAA AAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAAAAAAAAA AAAAAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAAAAA AAAAAAA AAAA AAA AAAA AAAA AAAA AAAA AAAA AAAA AAAA AAAAAAAAAAA AAAAAAA AAAAAAA AAAAAAA AAAA AAAA AA AAAAAA A AAAA AAAA AA AAAAAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA AAAA AA AAAA AAAA AAAA AAAA AAAA Martin B.H. Weiss Internetworking - 11 University of Pittsburgh Telcom 2000 Internetworking in OSI ES 1 ES 2 Application Application Presentation Presentation Session Session Transport Transport IS 1 IS 2 IS 3 Relay Relay Relay Network Network Link Link Physical Physical Martin B.H. Weiss Internetworking - 12 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 6 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Internetworking Issues • Transparency m User (Transport Protocol) should be unaware of an Internet m Remote station should appear to be on the same network • Network service m LAN’s typically provide connectionless network service (CLNS) m WAN’s typically provide connection-oriented network service (CONS) Martin B.H. Weiss Internetworking - 13 University of Pittsburgh Telcom 2000 Internetworking Issues • Naming and addressing m Network Service Access Point (NSAP) addresses must be clobally unique m Network Point of Attachment (NPA) address m Addresses may have variable structure between LAN and WAN • Routing m Get packet from one NSAP to another m May need to navigate across several intermediate systems Martin B.H. Weiss Internetworking - 14 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 7 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Internetworking Issues • Quality of service m Defines the service level expected by a network service user m Sample parameters q Transit delay q Security q Cost q Error probability q Priority Martin B.H. Weiss Internetworking - 15 University of Pittsburgh Telcom 2000 Internetworking Issues • Packet Size m May vary across subnetworks m Packet size is selected to optimize transmission due to q Bit Error Rate: Higher BER => Smaller Packets q Transit Delay: Larger Packets => Higher Transit Delay q Buffer Size: Smaller Packets => Smaller Required Buffer Size q Processing Overhead: Numerous Smaller Packets => Higher Overhead m An IS may fragment a packet q Break it into smaller packets q Fragments are reassembled either at next IS or at ES • Intranet fragmentation • Internet fragmentation Martin B.H. Weiss Internetworking - 16 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 8 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Internetworking Issues • Flow Control m Control packet transmission rate m Needed to guarantee transmission if q Destination ES has limited buffers q Different transmission rates exist on transmission path • Congestion control • Error reporting Martin B.H. Weiss Internetworking - 17 University of Pittsburgh Telcom 2000 Structure of the Network Layer • End systems must run the same network layer protocol • Subnetworks may be using several differnet network layers • Therefore, we need a more detailed structure for the network layer • Problems m How do protocol translations take place across different subnetworks? m How are consistent network services provided? Martin B.H. Weiss Internetworking - 18 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 9 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Structure of the Network Layer NSAP NSAP Trans- Trans- port port Routing & Relaying SNICP SNICP SNICP SNDCP SNDCP SNDCP SNDCP SNDAP SNDAP SNDAP SNDAP Link Link Physical Physical Intermediate System Martin B.H. Weiss Internetworking - 19 University of Pittsburgh Telcom 2000 Subnet Independent Convergence Protocol (SNICP) • Provides interface to network user • Performs routing and relaying functions • Independent of subnetwork • Network protocol of the End Systems Martin B.H. Weiss Internetworking - 20 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 10 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Subnet Dependent Access Protocol (SNDAP) • Associated with specific subnet in the internet • Network protocol of the subnets • Defined by standards m DOD Internet Protocol (IP) m OSI IP m X.25 Martin B.H. Weiss Internetworking - 21 University of Pittsburgh Telcom 2000 Subnet Dependent Convergence Protocol (SNDCP) • Handles differences among SNDAP’s • Maps functions and services across subnetworks • Unique for each pair of SNICP’s and SNDAP’s Martin B.H. Weiss Internetworking - 22 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 11 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 Example: Ethernet Cards and Device Drivers NSAP Socket Number (Port) Trans- port TCP/IP Software SNICP SNDCP SNDAP Device Driver (ODI/NDIS) Link Ethernet Physical Card Martin B.H. Weiss Internetworking - 23 University of Pittsburgh Telcom 2000 Internet Protocol Standards • DOD Internet Protocol m Developed by the US Department of Defense m Supported the DARPANET project m Part of the TCP/IP protocol suite • ISO-IP m Developed in the OSI standards committees m Based on the experience of IP community Martin B.H. Weiss Internetworking - 24 University of Pittsburgh Copyright 1993, 1997 Martin B.H. Weiss Page 12 All Rights Reserved 3/31/97 Lecture Notes Telcom 2000 Telcom 2000 General IP Issues • Connectionless network protocol • Designed with internetworking in mind • Supports complex internets • Core IP functions m Support fragmentation and reassembly m Routing m Error reporting Martin B.H.