1. 1 System support & Management Protocols Lesson 13 NETS2150/2850 School of Information Technologies

2. 2 Lecture Outline Simple Network Management Protocol- SNMP Domain Name System- DNS Dynamic Host Configuration Protocol- DHCP

3. 3 Network Management - SNMP Simple Network Management Protocol Networks are becoming indispensable More complexity makes failure more likely Require automatic network management tools Standards required to allow multi-vendor networks Covering: –Services –Protocols –Management information base (MIB )

4. 4 Network Management Systems Collection of tools for network management Single operator interface Powerful, user friendly command set Performing most or all management tasks Minimal amount of separate equipment –i.e. use existing equipment View entire network as unified architecture Active elements provide regular feedback

5. 5 Key Elements Management station or manager Agent Management information base Network management protocol

6. 6 Management Station Stand alone system or part of shared system Interface for human network manager Set of management applications –Data analysis –Fault recovery Interface to monitor and control network Translate manager ’ s requirements into monitoring and control of remote elements Data base of network management information extracted from managed entities

7. 7 Management Agent Hosts, bridges, hubs, routers equipped with agent software Allow them to be managed from management station Respond to requests for information Respond to requests for action Asynchronously supply unsolicited information

8. 8 Management Information Base MIB Representation of network resources as objects Each object a variable representing one aspect of managed object MIB is collection of access points at agent for management of station Objects standardized across class of system –Bridge, router etc.

9. 9 Network Management Protocol Link between management station and agent TCP/IP uses SNMP OSI uses Common Management Information Protocol (CMIP)

10. 10 Protocol Capabilities Get Set Notify

11. 11 Management Layout May be centralized in simple network May be distributed in large, complex network –Multiple management servers –Each manages pool of agents –Management may be delegated to intermediate manager

12. 12 Example of Distributed Network Management Configuration

13. 13 Network Management Protocol Architecture Application-level protocol Part of TCP/IP protocol suite Runs over UDP From management station, three types of SNMP messages issued –GetRequest, GetNextRequest, and SetRequest –Port 161 Agent replies with GetResponse Agent may issue trap message in response to event that affects MIB and underlying managed –Port 162

14. 14 SNMP v3: The latest version Addresses security issues of SNMP v1/2 RFC 2570-2575 Proposed standard January 1998 Defines overall architecture and security capability To be used with SNMP v2

15. 15 SNMP v3 Services Authentication –Part of User-Based Security (UBS) –Assures that message: Came from identified source Has not been altered Has not been delayed or replayed Privacy –Encrypted messages using DES Access control –Can configure agents to provide a number of levels of access to MIB –Access to information –Limit operations

16. 16 Domain Name System – DNS Name Space  Flat  Hierarchical

17. 17 Domain Name Space Was designed in order to have a hierarchical name space Label Domain Name

18. 18 Domain name space

19. 19 Domain names and labels

20. 20 Domain Names: FQDN and PQDN

21. 21 Domains

22. 22 Distribution of Name Spaces Hierarchy of Name Servers Zone Root Server Primary and Secondary Servers

23. 23 Hierarchy of name servers

24. 24 Zones and domains A primary server loads all information from the disk file; the secondary server loads all information from the primary server. Note

25. 25 DNS In The Internet Generic Domain Country Domain Inverse Domain

26. 26 DNS in the Internet

27. 27 Generic domains

28. 28 New generic domain labels LabelDescription aeroAirlines and aerospace companies bizBusinesses or firms (similar to com) coopCooperative business organizations infoInformation service providers museumMuseums and other nonprofit organizations namePersonal names (individuals) proProfessional individual organizations

29. 29 Country domains

30. 30 Inverse domain

31. 31 Resolution Resolver Mapping Names to Addresses Mapping Addresses to Names Recursive Resolution Iterative Resolution Caching

32. 32 Recursive resolution

33. 33 Query and response messages

34. 34 DNS can use the services of UDP or TCP, using the well-known port 53. Note:

35. 35 Dynamic Address Configuration Each computer attached to the Internet must have: –Its own IP address –Its subnet mask –The IP address of a Router – The IP address of a name server Usually stored in a config file –Used at bootup

36. 36 Dynamic Address Configuration… How about first-time bootup? Diskless terminal? Or, the movement of a computer from one subnet to another? –Protocols needed for on-demand config (dynamically) –Example: DHCP

37. 37 DHCP Client-server program DHCP server: two databases –First one: Statically binds physical addresses to IP addresses (Static db) –Second one: makes DHCP dynamic (Dynamic db) Temporary IP addresses are assigned consulting available (unused) address pool Valid for a negotiated time period only (leased) –Must renew or stop using after the lease expires –Renewal may or may not be granted by the server

38. 38 DHCP: Client Transition States

39. 39 Recommended Reading: –Stallings 22.3 (SNMP), –Forouzan 25 (DNS) & 19.2 (DHCP)