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Network Design and Management

Network Design and Management. Willis F. Marti. Understanding TCP/IP - Agenda. Introduction to the Internet Suite Core Protocols Management Protocols Application Protocols Protocols in Operation Firewalls & Security Routing Protocols Issues/Futures. Introduction to the Internet Suite.

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Network Design and Management

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  1. Network DesignandManagement Willis F. Marti

  2. Understanding TCP/IP -Agenda • Introduction to the Internet Suite • Core Protocols • Management Protocols • Application Protocols • Protocols in Operation • Firewalls & Security • Routing Protocols • Issues/Futures

  3. Introduction to the Internet Suite • Brief History • Overview of the Architecture • References

  4. Brief History & Status of the Internet • US DoD • Research Organizations • Operational Separation • MILNET • ARPANET • NSFNet • Commercialization • Anarchy ?

  5. History • What is an Internet? • Other contemporary communications architectures • Defense Advanced Research Project Agency (DARPA) • 1969 network of four universities • TCP/IP in mid-1970’s

  6. History, cont. • Growth of military and research use • “Operational” net in 1983 • Berkeley networking • National Science Foundation (NSF) 1985/6 • Supercomputer centers • Start of regional networks • Transition to open access 1990 -- ?

  7. (Partial) TCP/IP Stack FTP TELNET DNS TCP UDP IP ICMP ARP DIX Ethernet or ...

  8. Application Presentation Session Transport Network Data/Link Physical Example: OSI & the Internet NFS XDR RPC UDP IP DIX Ethernet IEEE 802.3

  9. TCP/IP Architecture • Theme: Communication over unreliable, heterogenous infrastructure • Universal Service • Standards, not Implementations • aka Internet Suite

  10. Universal Service • Virtual Network • Arbitrary Connectivity • IP -- One address end-to-end • Meaning of Hosts

  11. References TCP/IP • Overall -- Douglas Comer • Internetworking with TCP/IP, Vol I, 3d ed. • Internetworking with TCP/IP, Vol II • Internetworking with TCP/IP, Vol III (Sockets), 2d ed • Internetworking with TCP/IP, Vol III (TLI) • Unix Programming -- W. Richard Stevens • Unix Network Programming • Advanced Unix Network Programming • Stevens & Wright • TCP/IP Illustrated Vol I • TCP/IP Illustrated Vol II • TCP/IP Illustrated Vol III • http://www.qnx.com/~mphunter/tcpip_resources.html

  12. Core Protocols • ARP -- Address Resolution Protocol • IP -- Internet Protocol • ICMP -- Internet Control Message Protocol • UDP -- User Datagram Protocol • TCP -- Transmission Control Protocol • DNS -- Domain Name System • FTP -- File Transfer Protocol • TELNET -- Connectivty Application

  13. ARP • Address Resolution Protocol {translate network layer address to physical address} • Part of general resolution procedure: name {e.g., neuron.cs.tamu.edu} DNS IP Address {e.g., 128.194.133.1} ARP Ethernet address {e.g., 08:00:20:08:58:78}

  14. IP and ICMP • IP is the “Duct Tape” for the Internet • More details later • ICMP is an Internal protocol to IP • ICMP provides several services to network managers • ping • traceroute

  15. IP Functionality • Presents single, virtual network to user • Connectionless Delivery • Packet Routing • Interface to Lower Layers

  16. IP Addresses • “Dotted Decimal” 32 bit (4 byte) address, written by taking each byte as an unsigned number • Address Classes [first octet] • A - <net> < > <host> < > 1-126 • B - <net> < > <host> < > 128-191 • C -< > <net> < > <host> 192-223 • D - special subset of C 224-239 multicast • E - reserved 240-254 • Netmask • a 32 bit value which, when ANDed with an address, selects only the network part

  17. Netmask Usage “Do a bitwise AND then compare for equality of results” <src addr> & netmask =?= <dst addr> & netmask if comparison is equal, then both src & dst are on same (sub)net. Same netmask

  18. Netmask Examples S= 128.194.100.10 M= 255.255.255.0 result 128.194.100.0 D= 128.194.200.10 M= 255.255.255.0 result 128.194.200.0 Not Equal S= 128.194.12.10 M= 255.255.255.0 result 128.194.12.0 D= 128.194.12.110 M= 255.255.255.0 result 128.194.12.0 ? S= 67.194.18.10 M= 255.255.240.0 result 67.194.16.0 D= 67.194.10.10 M= 255.255.240.0 result 67.194. 0.0 ?

  19. Special Address Conventions • This host • Host on this net • Limited broadcast • Directed broadcast • Loopback all 0’s all 0’s host all 1’s net all 1’s 127 anything (usually 1)

  20. Bridges or Routers Address & Netmask 1: 131.122.24.12 255.255.255.0 2: 131.122.31.253 255.255.255.0 3: 131.121.18.12 255.255.240.0 4: 131.121.24.18 255.255.240.0 5: 131.121.31.254 255.255.240.0 1 3 A B C 2 5 D 4

  21. 0 4 8 16 19 24 31 VERS HLEN SERVICE TYPE TOTAL LENGTH IDENTIFICATION FLAGS FRAGMENT OFFSET TIME TO LIVE PROTOCOL HEADER CHECKSUM SOURCE IP ADDRESS DESTINATION IP ADDRESS IP OPTIONS (IF ANY) PADDING DATA ... IP Header

  22. IP Packet Handling (rcv) Sockets Transport Layer (TCP or UDP) Other IP Link {DIX Type or 802.3 DSAP} Physical receiving

  23. IP Packet Handling (xmit) Local or Non-Local ? sending Search Routing Table ARP Found! Missing! Send locally... ICMP Error

  24. ICMP • Reachability • Redirection • Information • “Are you there?”

  25. Ping • ICMP Echo Request/Echo Reply • Options for: • Routing • Timing • Size

  26. Traceroute • Echo Request/Reply with a twist: traceroute to falcon.ece.utexas.edu (128.83.196.10), 30 hops max, 40 byte packets 1 exit_133 (128.194.133.254) 2 ms 2 ms 2 ms 2 exit_128 (128.194.128.254) 2 ms 3 ms 2 ms 3 FDDI-T3.TAMU.EDU (128.194.1.13) 3 ms 3 ms 3 ms 4 FDDI-WAN.TAMU.EDU (165.91.128.17) 5 ms 4 ms 6 ms 5 sprint-gw-h1-0.the.net (129.117.16.161) 20 ms 5 ms 5 ms 6 ut8-h1-0.the.net (129.117.16.241) 8 ms 9 ms 21 ms 7 129.117.20.12 (129.117.20.12) 7 ms 11 ms 7 ms 8 ens.gw.utexas.edu (128.83.7.132) 16 ms 23 ms 21 ms 9 ece-e0.gw.utexas.edu (128.83.249.251) 12 ms 9 ms 9 ms 10 * * *

  27. 0 16 31 SOURCE PORT DESTINATION PORT MESSAGE LENGTH CHECKSUM DATA ... UDP • Your basic datagram • No acknowledgements, no reliability • Why use it?

  28. Managing Connections • Addressing • Identifying duplicate TPDUs • Three-way handshakes • Flow control • Crash recovery (largely ignored)

  29. TCP • Reliable, sequenced stream of bytes • Virtual circuit • Buffered transfer • Unstructured • Full Duplex • Positive Acknowledgements w/ Retransmission • Sliding Windows

  30. TCP Features • A protocol, not a package • Ports (Well Known Ports) • Out of Band, or URGENT, data • Timeouts • RTT Estimation (Karn’s Algorithm) • Congestion • Slow-Start Methodolgy • Limitations

  31. 0 4 10 16 24 31 SOURCE PORT DESTINATION PORT SEQUENCE NUMBER ACKNOWLEDGEMENT NUMBER HLEN RESERVED CODE BITS WINDOW CHECKSUM URGENT POINTER OPTIONS (IF ANY) PADDING DATA ... TCP Header

  32. Three Way Handshake SYN, SYN/ACK, ACK May be viewed as two Simplex connections Window management Advertising Zero Window Size Nagle’s algorithm Silly Window Syndrome TCP Connection Management

  33. Domain Name System • A heirarchial, distributed database • A service primarily aimed at mapping names to IP addresses • Partitioned for ease of administration

  34. . gov edu com utexas tamu ibm austin cs mac1 solar mac1 DNS Structure (partial)

  35. DNS -- How it Works • DNS Servers in a logical tree • DNS clients on every host • Iterative Queries • Recursive Queries

  36. TCP or UDP? • Application developers have to pick a Transport protocol • TCP • Simplicity • Reliability • UDP • Network ‘Awareness’ • Low Overhead • FTP vs FSP

  37. Information Gathering System Start up Address Management Management Protocols

  38. Decent Books • Network Management Standards 2d ed • Uyless Black • The Simple Book, 2d ed • Marshall T. Rose • Communication Networks Management, 2d ed • Kornel Terplan • Internetworking with TCP/IP, Vol I, 3d ed • Douglas E. Comer

  39. Network ManagementDefinition "...deploying and coordinating resources in order to plan, operate, administer, analyze, evaluate, design and expand communication networks to meet service-level objectives at all times, at a reasonable cost, and with optimum capacity."

  40. Network ManagementFunctional Areas • Fault Management detect -- diagnose -- repair •Configuration/Name Mgmt a database problem... •Performance Mgmt measure and predict •Accounting Mgmt look at individual usage •Security Mgmt access control and encryption

  41. Management Information Protocols • SNMP - Simple Network Management Protocol • Internet • CMIP - Common Management Information Protocol • ISO • TMN - Telecommunications Management Network • ITU-T

  42. Management ProtocolsPhilosophy • SNMP - Simple Network Management Protocol • keep it simple! (cf the Internet toaster) • CMIP - Common Management Information Protocol • the bazaar: whatever you want • TMN - Telecommunications Management Network • actually a separate network specification

  43. SNMP vs CMIP {round 1} SNMP CMIP Requirements from various vendors and user communities

  44. Fault Management Configuration Management Performance Management Security Management Accounting Management ISO Management Overview System Management Functions Object Mgmt Alarm Mgmt Event Report Mgmt Workload Monitoring State Mgmt Log Control Security Alarm Security Reporting Measurement Summarization Bill Verification Billing Resource Utilization Test Mgmt Relation Mgmt CMISE Services Initialize Event Report Terminate Action Create Abort Set Get Delete Cancel Confirmed Event Report Confirmed Get

  45. SNMP Architecture • Keep the agent as simple as possible • Support remote management operations to the fullest extent possible • Plan for future additions & expansion • Be independent of specific hosts or devices • Operate at the Application level

  46. Internet Management Model Managed Entities Agent Network Management Proxy Agent Managed Entities

  47. SNMP • Intersection of vendor/user requirements • Few ‘verbs’: • get / get-next • get-bulk {SNMPv2} • set • trap • Polled, Master-Slave, Request-Response

  48. SNMP Format • <header><verb><value><variable>[<verb><value><variable>] • ASN.1 subset to describe value format • MIB-II{Management Information Base} to identify variables • UDP as a Transport layer • Now out! SNMPv2

  49. The MIB • Standard set of data for managing network devices • Variable names are part of the ISO/CCITT object identifier namespace • Provides globally unique identifiers • Variables governed by Structure of Management Information (SMI) specification

  50. Accessing MIB Data • SNMP Communities • SNMP Views • SNMP Authentication

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