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Section 8: TCP/IP Protocol Suite and Utilities

Section 8: TCP/IP Protocol Suite and Utilities. CSIS 479R Fall 1999 “Network +” George D. Hickman, CNI, CNE. Objectives. Identify the components of the TCP/IP protocol suite as they relate to the OSI and DoD models Describe distance vector routing with IP

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Section 8: TCP/IP Protocol Suite and Utilities

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  1. Section 8: TCP/IP Protocol Suite and Utilities CSIS 479R Fall 1999 “Network +” George D. Hickman, CNI, CNE

  2. Objectives • Identify the components of the TCP/IP protocol suite as they relate to the OSI and DoD models • Describe distance vector routing with IP • Describe link state routing with IP • List the protocols that comprise TCP/IP

  3. Objectives (Con’t) • Use Windows TCP/IP utilities • Describe the IPX/SPX Protocol Suite and the OSI reference model • Describe routing with RIP/SAP • Describe the Protocols used in a Windows NT Network

  4. TCP/IP • TCP • Transmission Control Protocol • Responsible for establishing communication between two systems • IP • Internet Protocol • Responsible for the transfer of data

  5. Process/Application Acts as the User Interface; Provides applications that transfer data between hosts Host-to-Host Maintains data integrity; sets up reliable end-to-end communication; ensures error-free delivery (proper sequence, no loss or duplication) Internet Routing; Foundation of TCP/IP protocol suite Network Access Defines physical interconnection between hosts DoD Model

  6. TCP/IP Suite and OSI Model • See figure 8-2 on page 8-6 • TCP maps to Transport layer • IP maps to Network layer

  7. Routing IP • IP is the portion of the TCP/IP Suite that provides addressing and connectionless services for packet forwarding; packet switching • IP allows an internetwork to be divided into logical groups called autonomous systems

  8. Autonomous Systems • A group of networks administered by a single authority • IGPs: Interior gateway protocols route information within an autonomous system • EGPs: Exterior gateway protocols (or Border gateway protocols—BGP) interconnect autonomous systems

  9. Distance Vector Routing with IP • RIP • Routing Information Protocol • Routers advertise a “metric” of how many hops they are from a network • Can be advertised higher if needed • Costs of a route are 1-16 metrics • A route with a cost of 16 is considered unreachable

  10. Drawbacks of RIP and Distance Vector Routing • Convergence • The amount of time it takes all routers to synchronize their databases when a change occurs to the network • Slow convergence • Also called the count-to-infinity problem

  11. Count-to-infinity problem • Split Horizon • Destinations are not advertised at all to the interface from which they were learned • Figure 8-6 page 8-12 • Poison Reverse • All routes learned from a network are advertised back to the network with a cost of 16 • Enabling Poison Reverse reduces convergence time, but increases RIP traffic

  12. RIP and RIP II • RIP routers broadcast their routes every 30 seconds • RIP II routers add support for: • Authentication • Subnet masks • Next Hop Addresses • Multicast Packets • IP multicast address for RIP II is 224.0.0.9

  13. Link State Routing—OSPF • L. S. routing minimizes size of routing tables • Open Shortest Path First Protocol • Build route tables from packets distributed by other routers • “Hello packets” contain information about a routers directly connected interfaces and their costs. • They establish/maintain neighbor relationships between routers on same segment

  14. OSPF learning routes • 1. Identify neighboring routers (“Hello”) • Announces itself (address and mask) to other routers • Determines router’s neighbors • Establishes interval that routers send hello’s • Identifies DR (Designated Router) • Router with highest priority • Identifies BDR (Backup Designated Router) • Router with second highest priority

  15. OSPF learning routes (Con’t) • 2. Synchronizing link state advertisement databases • All routers create and synchronize their LS advertisement databases with the DR and BDR (after DR and BDR elected, neighbor list created) • Before synchronization routers communicate in two-way state • After synchronization, routers enter the full neighbor state. Routers then have adjacency

  16. Selecting Routes • Link State Advertisement DB is OSPF router’s view of the internetwork • OSPF algorithm determines path(s) and adds up the cost(s). Lowest cost wins, and is added to routing table. • Algorithm rebuilds table when change in LSDB occurs, after a hold-down interval

  17. Maintaining Route Information • Link State Update (LSU) packets are sent when changes occur or every 30 minutes (default) • DR floods packet to local network • Each router compares LSU to it’s DB. Resets aging timer. Entry dropped if age=4 times router dead interval • Router sends ACK to original router

  18. OSPF Terms • Autonomous System (AS) • A group of routers that exchange routing information using a common routing protocol in a single administrative unit. • Autonomous System Border Router (ASBR) • A router that exchanges routing information with routers belonging to other AS. ASBRs distribute routing info about external destinations

  19. OSPF Terms (Con’t) • Area • Large enterprise-area networks are logically divided into smaller contiguous networks. • Areas act like an AS, so OSPF routers do not have to maintain LSDB on other areas • Reduces LS Acknowledgements (LSA) sent • Reduces size of DB on each router • Reduces amount of time to recompute routes following a change to the internetwork

  20. OSPF Terms (Con’t) • Backbone • A logical area to which all other areas are connected. Address is always 0.0.0.0 • Stub area • An area with only one ABR • Transit area • Areas with more than one ABR • See page 8-23

  21. OSPF vs. RIP • OSPF is considered superior to RIP • Support for large Internetworks • RIP Metric <= 16; OSPF Metric <= 65535 • Variable Length Subnetting • LSA’s include subnet mask information about networks. Different segments can have different subnets • Rapid Convergence • No count-to-infinity problem • Reduced Internetwork Traffic • RIP broadcasts DB every 30 seconds; OSPF only when changes occur

  22. Protocols in the TCP/IP Suite • Internet Layer Protocols • IP • ICMP • Address resolution Protocols • ARP • RARP • BOOTP

  23. Protocols in the TCP/IP Suite • Host-to-Host layer Protocols • TCP • UDP • Process/Application layer Protocols • FTP / TFTP • HTTP • SMTP • POP3 • SNMP

  24. Internet Layer Protocols • Primary purpose is to route packets between hosts, often through many routers • Internet layer performs routing and packet switching

  25. IP • Provides specifications that allow routing, fragmentation, and reassembly to occur • Provides connectionless, non-guaranteed delivery of transport layer packets (TPDU) • IP can fragment TPDU into smaller parts for transmission and reassemble them later

  26. ICMP • Internet Control Message Protocol • Works with IP to provide internetwork error and other control info to TCP and other upper-layer protocols • ICMP messages are sent when • A packet cannot reach destination • A packets TTL expires • IP header problem • To notify internetwork of congested/failed links • Etc.

  27. Address Resolution Protocols • ARP/Reverse ARP • Maps 4-byte software-based IP addresses to 6-byte hardware-based Data Link addresses • RARP retrieves IP address from hardware address. Used by diskless workstations • BOOTP • BOOTP servers keep MAC and IP addresses • Newer, more commonly used than RARP

  28. DHCP • Dynamic Host Configuration Protocol • Provides configuration parameters to IP hosts • Automatic allocation • Permanent address assigned to host • Dynamic allocation • Address leased to host for a limited time • Manual allocation • DHCP delivers manually assigned numbers

  29. TCP • Transmission Control Protocol • Transport Protocol • Accepts messages of any length from UPLs, • Provides full-duplex, acknowledged, connection-oriented, flow controlled, transport to a TCP peer

  30. UDP • User Datagram Protocol • Transport Protocol • Not connection oriented • No acknowledgements • UDP just accepts and transports datagrams from a ULP • UDP has lower overhead, so is faster than TCP

  31. FTP • File Transfer Protocol • Move files between hosts • Allows login, directory inspection, file manipulation, command execution • Uses virtual circuits to establish a reliable path between hosts • TFTP Trivial FTP • No password, directory listings. Good for downloads • Runs on UDP—not as reliable

  32. HTTP • Hyper Text Transfer Protocol • Language of the WWW portion of Internet • Establishes connection with a server and sends a request • URL: Uniform Resource Locators

  33. SMTP • Simple Mail Transfer Protocol • A standard for exchanging mail between workstations • Relies primarily on TCP to route messages between network hosts • Does not provide user interface

  34. POP3 • Post Office Protocol 3 • Standard Mail server • Provides message store • Users connect and retrieve all pending messages and attachements at once • Uses SMTP messaging protocol

  35. SNMP • Simple Network Management Protocol • Allows management of a network from a “SNMP manager” workstation • Each host has a Management Information Base (MIB) that holds data about itself • When a threshhold is reached, a “trap” message is sent to the management console • Example: router sends SNMP trap when an interface goes down

  36. Windows TCP/IP Utilities • ARP.EXE • Diagnostic utility for ethernet TCP/IP • ARP stores a cache of host IP addresses and physical addresses • FTP .EXE • IPCONFIG.EXE (WinNT) WINIPCFG (Win9x) • Shows IP settings on local machine

  37. Windows TCP/IP Utilities • NBTSTAT.EXE • Displays statistics and existing TCP/IP connections using NetBIOS over TCP/IP • NETSTAT.EXE • Identifies status of TCP/IP connections and provides statistics on them

  38. Windows TCP/IP Utilities • PING.EXE • Packet InterNet Groper • Determine if a host is available; quality of the connection • TELNET.EXE • Remote Terminal Connection • TRACERT.EXE • Traces a connection route to a host and its hops

  39. IPX/SPX • Novell’s protocol suite based on Xerox Network System (XNS) protocol suite • IPX gets packets through internetwork • SPX offers connection-oriented guaranteed delivery of packets.

  40. IPX Addressing • Network Address • 8 digit hexadecimal number assigned to wire • Internal Network Address • 8 digit hexadecimal number assigned to server • MAC or Node Address • 12 digit hexadecimal number assigned to NIC • Socket number • Determines destination within a device (RIP, SPX)

  41. RIP/SAP Routing • RIP is IPX distance vector • Uses hop and tick counts to determine cost • SAP is Service Advertising Protocol • Advertise services of all known servers on the network • Periodic SAP Information broadcasts (60 seconds) • SAP Service Inquiries • SAP Service Responses • SAP traffic needs to be filtered to avoid bandwidth problems

  42. Windows NT Protocols • NetBEUI • NetBIOS Extended User Interface • Not Routable • NWLink IPX/SPX Compatible Transport • NDIS-compliant version of Novell IPX/SPX • Others • Apple Talk • DLC Protocol • IBM Mainframes and AS/400 • Print to HP JetDirect

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