1. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Chapter 10 Panko’s Business Data Networks and Telecommunications, 7th edition © 2009 Pearson Education, Inc. Publishing as Prentice Hall May only be used by adopters of the book Network Management

2. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-2 10-1: Planning the Technological Infrastructure What-Is Analysis –Understand the current network in detail –Requires a comprehensive inventory

3. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-3 10-1: Planning the Technological Infrastructure Driving Forces for Change –Normal growth in application demand –Disruptive applications Video requires higher network capacity Voice requires high quality of service –Organizational changes –Changes in other aspects of IT (data center consolidation, etc.)

4. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-4 10-2: Scalability

5. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Traffic Management Capacity is expensive; it must be used wisely Especially in WANs, where capacity is expensive

6. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-6 10-3: Traditional Traffic Management Methods As we saw in Chapter 4, even in a network with adequate capacity, there will be occasional momentary traffic peaks when traffic exceeds capacity

7. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-7 10-3: Traffic Management Methods Traditional Approaches to Managing Momentary Traffic Peaks –Overprovisioning Install much more capacity than is needed most of the time This is wasteful of capacity Unacceptable in WANs, where capacity is expensive Does not require much ongoing management labor

8. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-8 10-3: Traffic Management Methods Traditional Approaches –Priority In Ethernet, assign priority to applications based on sensitivity to latency In momentary periods of congestion, switch sends high-priority frames through Substantial ongoing management labor Used heavily in WANs

9. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-9 Traditional Approaches –QoS Reservations In ATM, reserve capacity on each switch and transmission line for an application Allows strong QoS guarantees for voice traffic Wasteful if the reserved capacity is not sued Highly labor-intensive Usually, data gets the scraps—capacity that is not reserved for voice 10-3: Traffic Management Methods

10. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-10 Figure 10-5: Compression A fifth way to manage traffic is to use compression. Here, 3 Gbps and 5 Gbps traffic streams go into the network. Without compression, 8 Gbps of capacity would be needed. With 10:1 compression, only 800 Mbps of capacity is needed. A 1 Gbps line will be adequate.

11. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Network Simulation Software

12. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-12 Simulation –Build a model, study its implications –More economical to simulate network alternatives than to build several networks and see which one is best Purposes –Compare alternatives to select the best one –Sensitivity analysis to see what will happen if the values of variables were varied over a range –Anticipating bottlenecks because procurement cycles are long in business, so problems must be anticipated well ahead of time 10-6: Network Simulation

13. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-13 10-6: Network Simulation What Is: the existing situation Net 1 Net 2 Net 3 Net 4 Net 5 Net 6 Utilization in Peak Hour 95% Too high! R7 What Is analysis: Describe the current situation. Problem: Utilization in the peak hour Is too high (95%); this will create many momentary overloads

14. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-14 10-6: Network Simulation What-If: See the Impact of a Change Net 1 Net 2 Net 3 Net 4 Net 5 Net 6 Est. Utilization in Peak Hour 70% Added Router Added Link What If analysis: What will happen if something is done? Adding a new link between R3 and Net5 will give good peak hour utilization. R3 R7

15. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-15 The Simulation Process: Step 1: Before the Simulation, Collect Data –Data must be good –Otherwise, GIGO (garbage in, garbage out) –Collect data on the current network –Forecast growth 10-6: Network Simulation

16. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-16 16 10-7: OPNET IT Guru Node Template Dragged Icon The Process: 2. Add node icons to the simulation Work Area (clients, servers, switches, routers, etc.) Drag from the Object Palette Work Area

17. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-17 Specify the Topology 3. Specify the topology by adding transmission lines between nodes (and specifying line speeds). Click on two nodes, click on a transmission line icon in the object palette.

18. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-18 10-8: Configuring Elements in IT Guru 4. Configure EACH node and transmission lines (IP Time-to-Live value, etc.). In this case, Frame Relay burst speed rate.

19. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-19 10-9: Add Applications 5. Add applications, which generate traffic data Applications

20. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-20 10-6: Network Simulation 6. Run the simulation for some simulated period of time –Examine the output to determine implications –Validate the simulation if possible (compare with actual data to see if it is correct)

21. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-21 10-10: What-If Analysis 7. Do what-if analyses, trying different alternatives.

22. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-22 10-6: Network Simulation 8. Examine application performance, which goes beyond network performance –Involves host performance –Involves application configuration –OPNET’s Application Characterization Environment (ACE) can do this.

23. © 2009 Pearson Education, Inc. Publishing as Prentice Hall IP Subnetting

24. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-24 IP Addresses always are 32 bits long The firm is assigned a network part –Usually with 8 to 24 bits The firm can assign the remaining bits to the subnet part and the host part –Different choices give different numbers of subnets and hosts per subnet, as in the following examples –Firms must trade-off the number of subnets and the number of hosts per subnet in a way that makes sense for their organizational situation IP Subnetting

25. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-25 IP Subnetting Part Size (bits) 2N2N 2 N -2 42 4 = 1616-2 = 14 8?? 124,0964,094 65,53665,53416 10?? If a part has N bits, it can represent 2 N -2 subnets or hosts per subnet –2 N because if you have N bits, you can represent 2 N possibilities –Minus 2 is because you cannot have a part that is all zeros or all ones

26. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-26 10-11: IP Subnetting DescriptionStep 32 Total size of IP address (bits) 1 Size of network part assigned to firm (bits) 216 Remaining bits for firm to assign 316 Selected subnet/host part sizes (bits) 48 / 8 Number of possible Subnets (2 N -2) 254 (2 8 -2) Number of possible hosts per subnets (2 N -2) 254 (2 8 -2) By Definition Assigned to the firm Bits for the firm to assign The firm’s decision

27. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-27 10-11: IP Subnetting DescriptionStep 32 Total size of IP address (bits) 1 Size of network part assigned to firm (bits) 216 Remaining bits for firm to assign 316 Selected subnet/host part sizes (bits) 46/10 Number of possible Subnets (2 N -2) 62 (2 6 -2) Number of possible hosts per subnets (2 N -2) 1,022 (2 10 -2) By Definition Assigned to the firm Bits for the firm to assign The firm’s decision

28. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-28 10-11: IP Subnetting DescriptionStep 32 Total size of IP address (bits) 1 Size of network part assigned to firm (bits) 28 Remaining bits for firm to assign 324 Selected subnet/host part sizes (bits) 412/12 Number of possible Subnets (2 N -2) 4,094 (2 12 -2) Number of possible hosts per subnets (2 N -2) 4,094 (2 12 -2) By Definition Assigned to the firm Bits for the firm to assign The firm’s decision

29. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-29 10-11: IP Subnetting DescriptionStep 32 Total size of IP address (bits) 1 Size of network part assigned to firm (bits) 28 Remaining bits for firm to assign 324 Selected subnet/host part sizes (bits) 48/16 Number of possible Subnets (2 N -2) 254 (2 8 -2) Number of possible hosts per subnets (2 N -2) 65,534 (2 16 -2) By Definition Assigned to the firm Bits for the firm to assign The firm’s decision

30. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-30 10-11: IP Subnetting DescriptionStep Size of network part assigned to firm (bits) 220 Remaining bits for firm to assign 312 Selected host part sizes (bits) 4? Number of possible Subnets (2 N -2) ? Number of possible hosts per subnets (2 N -2) ? Selected subnet part sizes (bits) Added4

31. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-31 10-11: IP Subnetting DescriptionStep Size of network part assigned to firm (bits) 220 Remaining bits for firm to assign 312 Selected host part sizes (bits) 4? Number of possible Subnets (2 N -2) ? Number of possible hosts per subnets (2 N -2) ? Selected subnet part sizes (bits) Added6

32. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Network Address Translation (NAT) 32

33. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-33 10-12: Network Address Translation (NAT) NAT –Sends packets with false external IP addresses that are different from true internal IP addresses –NAT Operation (Figure 10-13)

34. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-34 10-13: Network Address Translation (NAT) When an internal host sends a packet, the NAT firewall changes the source IP address and the source port number. The NAT firewall records the original and changed information in a translation table for later use. 1

35. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-35 10-13: Network Address Translation (NAT) If an eavesdropper with a sniffer program captures and reads the source IP address and port number, it will not learn the true source IP address and port number of the sending host. This means that it cannot send attack packets to the sending host.

36. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-36 10-12: Network Address Translation (NAT) NAT is Transparent to Internal and External Hosts Expanding the Number of Available IP Addresses –Companies may receive a limited number of IP addresses from their ISPs –There are roughly 4,000 possible ephemeral port numbers for each IP address –So for each IP address, there can be 4,000 external connections

37. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-37 10-12: Network Address Translation (NAT) Expanding the Number of Available IP Addresses –If a firm is given 248 IP addresses, there can be roughly one million external connections –Even if each internal device averages several simultaneously external connections, there should not be a problem providing as many external IP connections as a firm desires

38. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-38 10-12: Network Address Translation (NAT) Private IP addresses –Can be used only inside firms –10.x.x.x –192.168.x.x (most popular) –172.16.x.x through 172.31.x.s

39. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-39 10-12: Network Address Translation (NAT) Protocol Problems with NAT –IPsec, VoIP, etc. do not work properly with NAT The protocol must know the true IP address of a host –Work-arounds must be considered very carefully in product selection

40. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Multiprotocol Label Switching 40

41. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-41 10-14: Multiprotocol Label Switching (MPLS) In normal routing, each router along the route must do a great deal of work to decide to do with each arriving packet, even if many packets are sent to the same destination host.

42. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-42 10-14: Multiprotocol Label Switching (MPLS) In Multiprotocol Label Switching (MPLS), the routers select the best route between two hosts before transmission begins. This routes is called the label-switched path. In other words, routing decisions are made only once, before any packets are sent.

43. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-43 10-14: Multiprotocol Label Switching (MPLS) The first label-switched router adds a Label to each packet. This label contains The number of the label-switched route. The final label- Switched router Removes the label. Other label-switched routers send the packet back out on the basis of the label number. 2

44. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-44 10-14: MPLS MPLS is invisible to the hosts –Label-switching routers add and delete the label MPLS Benefits –Reduced cost per packet because routing decisions are pre-made before any packets are sent –MPLS allows traffic engineering such as quality of service and load balancing to route packets around congestion

45. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Domain Name System (DNS) 45

46. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-46 10-15: Domain Name System (DNS) Lookup In Chapter 1, We Saw DNS Lookup –A host wishes to know the IP address of a another host –The host only knows the other host’s host name –The host sends a DNS request message to a DNS server This message contains the other host’s host name –The DNS server sends a DNS response message The message contains the IP address of the other host

47. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-47 10-15: Domain Name System (DNS) Lookup Often the local DNS server (in this case the Hawaii.edu DNS server) will not know the IP address. The local DNS server contacts the authoritative DNS server for the domain of the other host. The remote DNS server sends back the IP address.

48. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-48 10-15: Domain Name System (DNS) Lookup The local DNS server sends this IP address Back to the host that sent the DNS request.

49. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-49 Figure 10-16: Domain Name System (DNS) Hierarchy More generally, DNS is a hierarchical naming system for domains, which are collections of resources under the control of an organization. A host is only one type of named resource. The DNS naming system is hierarchical.

50. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-50 Figure 10-16: Domain Name System (DNS) Hierarchy At the top level is the Root, which contains All domains. There are 13 root DNS servers Below the root are Top-level domains by Type (.com,.edu) or by country (.uk,.ch, etc.)

51. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-51 Figure 10-16: Domain Name System (DNS) Hierarchy They can then internally name subnets and hosts. What companies really want are good second- level domain names, such as Microsoft.com. Every second-level domain must maintain an authoritative DNS server. 2

52. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Dynamic Host Configuration Protocol (DHCP) 52

53. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-53 10-17: Dynamic Host Configuration Protocol (DHCP) When a client PC boots up, it realizes that it does not have an IP address for itself. It sends a DHCP Request Message to a DHCP server. this DNS Request Message asks for an IP address for itself.

54. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-54 10-17: Dynamic Host Configuration Protocol (DHCP) The DHCP server has a pool of IP addresses to manage. It selects one for the client.

55. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-55 10-17: Dynamic Host Configuration Protocol (DHCP) The DHCP server sends this IP address to the client PC In a DHCP Response Message. This message also contains other configuration information, including a subnet mask, the IP address of the client’s default router, and the IP addresses of the firm’s DNS servers.

56. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-56 10-17: DHCP Servers Get Static (Permanent) IP Addresses –So that clients can find them Clients Could Also Be Configured Manually with Static IP Addresses –But this would be very time-consuming –In addition, every time a firm changed the IP addresses of its DNS servers or some other configuration parameter, all clients would have to be changed manually –With DHCP, clients always get “fresh” configuration data

57. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Simple Network Management Protocol (SNMP) 57

58. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-58 10-18: Simple Network Management Protocol (SNMP) Core Elements (from Chapter 1) –Manager program –Managed devices –Agents (communicate with the manager on behalf of the managed device) –Management information base (MIB) Stores the retrieved information “MIB” can refer to either the database on the manager or on the database schema

59. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-59 10-18: Simple Network Management Protocol (SNMP) Messages –Commands Get: Please give me the following data about yourself Set: Please change the following parameters in your configuration to the values contained in this message –Responses –Traps (alarms sent by agents) –SNMP uses UDP at the transport layer to minimize the burden on the network

60. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-60 10-18: Simple Network Management Protocol (SNMP) RMON Probes –Remote monitoring probes –A special type of agent –Collects data for a part of the network –Supplies this information to the manager Network Management Agent (Agent), Objects RMON Probe Network Management Software (Manager)

61. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-61 10-18: Simple Network Management Protocol (SNMP) Objects (see Figure 10-19) –NOT managed devices –Information about which information is stored –E.g., Number of rows in the routing table –E.g., Number of discards caused by lack of resources (indicates a need for an upgrade)

62. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-62 10-18: Simple Network Management Protocol (SNMP) Set Commands –Dangerous if used by attackers –Many firms disable set to thwart such attacks –However, they give up the ability to manage remote resources without travel –SNMPv1: community string shared by the manager and all devices –SNMPv3: each manager-agent pair has a different password

63. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-63 10-18: Simple Network Management Protocol (SNMP) User Functionality –Reports, diagnostics tools, etc. are very important –They are not built into the standard –They are added by SNMP manager vendors –Critical in selection

64. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Directory Servers Store corporate information Hierarchical organization of content LDAP standard to access directory servers

65. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-6565 10-20: Directory Server Organization and LDAP University of Waikiki (O) CN=Waikiki Astronomy (OU) Staff Chun CN Brown Ext x6782 Directory Server with Hierarchical Object Structure Ochoa Routers CprSci (OU) Brown Faculty E-Mail Brown@waikiki.edu Business (OU) O=organization OU=organizational unit CN=common name Centralized management requires centralized information storage. Directory servers do this. Directory server information is organized in a hierarchy

66. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-66 10-20: Directory Server Organization and LDAP University of Waikiki (O) CN=Waikiki Astronomy (OU) Staff Chun CN Brown Ext x6782 Ochoa Routers CprSci (OU) Brown Faculty E-Mail Brown@waikiki.edu Business (OU) LDAP Request: GET e-mail.Brown.faculty.business.waikiki LDAP Response: Brown@waikiki.edu Most directories use LDAP for data queries: (Lightweight Directory Access Protocol.)

67. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-67 10-21: Active Directory Domains and Domain Controllers

68. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-68 10-21: Active Directory Domains and Domain Controllers

69. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-69 10-21: Active Directory Domains and Domain Controllers

70. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10-70 10-21: Active Directory Domains and Domain Controllers