Chapter 2 Fundamental Network

1. Chapter 2Fundamental Network

2. Reviewing the core components of Microsoft TCP/IP and other network protocols • Fundamental concepts of Networking: TCP/IP DNS DHCP WINS

3. Network Protocols • NetBEUI • NWLink (IPX/SPX) • TCP/IP

4. Network configuration on W2K3 • Click Start > Control Panel > Network Connection • Right-click the network interface • Select Properties (see your installed network services and protocols listed) • Click the Install button to install additional services and protocols. • See page 10

5. NetBEUI • Enhance User Interface protocols • Windows 95/98 • Small office/home office (SOHO) scenarios • It is not routable • Limiting its communication to a single network subnet • It was not supported by XP,WinS2003

6. NWLink (IPX/SPX) • Microsoft's implementation of Novell's IPX/SPX protocol • Its packages data to be compatible with client/server services on NetWare Networks • Be aware of some of the basic functionality of IPX/SPX - Frame type - Internal network number - External network number

7. Frame Type • In IPX network indicate the mean by which data is encapsulated in IPX packets Frame type: • Ethernet II • 802.3 • 802.2 • SNAP • Arcnet

8. Problems • Window System can only integrate with one frame type on an IPX network. • Auto detection and first come first serve

9. Internal Network Number • It is unique number assigned to all NetWare server • It required on Windows servers in the following situations: • Win servers with tow or more NICs • Win servers with a single NIC with 2 different IPX frame type bound to it • Run File and Print Services for NetWare on the Win server • If required by an IPX application on the Win server • It is made up of eight hexadecimal characters (00000001 to FFFFFFFE)

10. External Network Number • It used to provide a unique logical identifier to represent a single network segment. • TCP/IP concepts: - the INN = the host ID - the ENN = the network ID

11. TCP/IP Basic • Transmission Control Protocol/Internet Protocol • Protocol Suite • Referred to as “IP” or “TCP/IP” • Subprotocols include TCP, IP, UDP, ARP • Developed by US Department of Defense • ARPANET (1960s) • Internet precursor

12. Advantages of TCP/IP • Open nature • Costs nothing to use • Flexible • Runs on virtually any platform • Connects dissimilar operating systems and devices • Routable • Transmissions carry Network layer addressing information • Suitable for large networks

13. The TCP/IP Model • Four layers • Application layer • Transport layer • Internet layer • Network access layer (or Link layer)

14. The TCP/IP model compared with the OSI model

15. The TCP/IP Core Protocols • TCP/IP suite subprotocols • Operate in Transport or Network layers of OSI model • Provide basic services to protocols in other layers • Most significant protocols in TCP/IP suite • TCP • IP

16. TCP (Transmission Control Protocol) • Transport layer protocol • Provides reliable data delivery services • Connection-oriented subprotocol • Establish connection before transmitting • Uses sequencing and checksums • Provides flow control • TCP segment format • Encapsulated by IP packet in Network layer • Becomes IP packet’s “data”

17. A TCP segment

18. Three segments establish connection • Computer A issues message to Computer B • Sends segment with SYN bit set • SYN field: Random synchronize sequence number • Computer B receives message • Sends segment • ACK field: sequence number Computer A sent plus 1 • SYN field: Computer B random number • Computer A responds • Sends segment • ACK field: sequence number Computer B sent plus 1 • SYN field: Computer B random number • FIN flag indicates transmission end

19. Establishing a TCP connection

20. IP (Internet Protocol) • Network layer protocol • How and where data delivered, including: • Data’s source and destination addresses • Enables TCP/IP to internetwork • Traverse more than one LAN segment • More than one network type through router • Network layer data formed into packets • IP packet • Data envelope • Contains information for routers to transfer data between different LAN segments

21. Two versions • IPv4: unreliable, connectionless protocol • IPv6 • Newer version of IPv6 • IP next generation • Released in 1998 • Advantages of IPv6 • Provides billions of additional IP addresses • Better security and prioritization provisions

22. An IPv4 packet

23. An IPv6 packet header

24. IPv4 Addressing • Networks recognize two addresses • Logical (Network layer) • Physical (MAC, hardware) addresses • IP protocol handles logical addressing • Specific parameters • Unique 32-bit number • Divided into four octets (sets of eight bits) separated by periods • Example: 144.92.43.178 • Network class determined from first octet

25. Commonly used TCP/IP classes

26. Class A devices • Share same first octet (bits 0-7) • Network ID • Host: second through fourth octets (bits 8-31) • Class B devices • Share same first two octet (bits 0-15) • Host: second through fourth octets (bits 16-31) • Class C devices • Share same first three octet (bits 0-23) • Host: second through fourth octets (bits 24-31)

27. IPv4 addresses and their classes

28. Class D, Class E rarely used (never assign) • Class D: value between 224 and 239 • Multicasting • Class E: value between 240 and 254 • Experimental use • Eight bits have 256 combinations • Networks use 1 through 254 • 0: reserved as placeholder • 255: reserved for broadcast transmission

29. Loop back address • First octet equals 127 (127.0.0.1) • Loopback test • Attempting to connect to own machine • Powerful troubleshooting tool • Windows XP, Vista • ipconfig command • Unix, Linux • ifconfig command

30. Binary and Dotted Decimal Notation • Dotted decimal notation • Common way of expressing IP addresses • Decimal number between 0 and 255 represents each octet • Period (dot) separates each decimal • Dotted decimal address has binary equivalent • Convert each octet • Remove decimal points

31. Decimal numbers to Binary • Find the largest number in conversion chart that is less than or equal to the number you are working with (128, 64, 32, 8, and so on) and place a 1 in its column. • Subtract the number from the marked column from the number you started with. • Find the largest number in the conversion chart that is less than or equal to the number that you were left with after step1, and place a 1 in its column. • Subtract the number from the marked column from the number you were left with after step 2. • Repeat steps 3 and 4 until you reach 0; then place a 0 in all column that do not have a 1. That is your binary number.

32. Subnet Mask • 32-bit number identifying a device’s subnet • Combines with device IP address • Informs network about segment, network where device attached • Four octets (32 bits) • Expressed in binary or dotted decimal notation • Assigned same way as IP addresses • Manually or automatically (via DHCP)

33. Default subnet masks

34. IPv6 Addressing • Composed of 128 bits • Eight 16-bit fields • Typically represented in hexadecimal numbers • Separated by a colon • Example: FE22:00FF:002D:0000:0000:0000:3012:CCE3 • Abbreviations for multiple fields with zero values • 00FF can be abbreviated FF • 0000 can be abbreviated 0

35. Multicast address • Used for transmitting data to many different devices simultaneously • Anycast address • Represents any one interface from a group of interfaces • Modern devices and operating systems can use both IPv4 and IPv6

36. Assigning IP Addresses • Government-sponsored organizations • Dole out IP addresses • IANA, ICANN, RIRs • Companies, individuals • Obtain IP addresses from ISPs • Every network node must have unique IP address • Error message otherwise

37. Static IP address • Manually assigned • To change: modify client workstation TCP/IP properties • Human error causes duplicates • Dynamic IP address • Assigned automatically • Most common method • Dynamic Host Configuration Protocol (DHCP)

38. IP Address Structure • It divided into 2 parts - Host ID - Network ID Example: Network ID Host ID 10.8.32.8 = 00001010|00001000.00100000.00000110 255.0.0.0 = 11111111|00000000.00000000.00000000 Network ID = 10.0.0 Host ID = x.8.32.6 = 10.8.32.6

39. Nonroutable IP Address • Internal Network Address: 10.0.0.0 to 10.255.255.255 169.254.0.0 to 169.254.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255

40. TCP/IP in a Routed Environment • Using Router to connect to the Internet • Router has its own IP address and subnet mask • Router is used to sent IP packets • Router uses its routing table routing table is a cross-reference table that stores information on how to get to IP networks

41. Default Gateway - the same network ID and subnet mask - send data beyond their local subnet - Any computer its default gateway is where it sends all packets that don’t have the network ID of their local subnet. - where it goes, where do I sent it?

42. NetBIOS Name V.S. FQDNs • Both give you the ability to associate a friendly name with a network object • Difference is how you see the name written • NetBIOS name is a simple name used to represent a system but is limited in size to 15 characters. • FQDN is typically <computer name>.<domain name>.<domain extension>

43. NetBOISNaming Rules • The names can’t begin with a number • The names can be no larger than 15 characters • The name can use the characters A-Z, a-z, 0-9, hyphens, and is not case sensitive • The name can have spaces (a space counts as on character)

44. FQDN Naming Rules • The name can begin with anumber • The name can be no larger than 255 characters (domain controllers are limited to 155 characters) • The name can us the characters A-Z, a-z, 0-9, hyphens, and is not case sensitive • The names cannot have spaces • Portions of the name are separated by periods (www.microsoft.com)

45. Name Resolution Methods There are several ways on a network for a name to become associated with an IP address • Domain Name Service – The server that resolves FQDNs to IP address • Windows Internet Naming Service – The server that resolves NetBIOS names to IP address • LMHosts file – The file stored locally on every computer that maps IP addresses to NetBIOS names • Broadcast – A way for your computer to shout out to the network. (It only work on the subnet connected to the system)

46. Name Resolution with DNS • DNS is a TCP/IP service that is used to map IP address to FQDNs or vice versa • Win 2K and newer systems try to resolve the name to an IP address in the following order: • Resolver cache and Hosts file • DNS • NetBIOS cache • WINS • Broadcast • LMHosts

47. 1. Resolver cache and Hosts file • Its own resolver cache which is where the local computer stores its previously queried FQDN to IP address mappings • Run ipconfig/displaydnsto display • Run ipconfig/flushdnstoclear • Wins system cache positive entries for the Time to Live (TTL)value provided to them by the authoritative DNS server that answered the request, but never longer than 24 hours

48. Negative entries are cached for 5 minutes • Both entries values can be changed by editing HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNSCache\Parameters Registry key • Change the maximum lifetime for positively cached entries by create the DWORD value MaxCacheEntryTtlLimit and set its value to the desired maximum second • Change the duration that negatively cached queries ar e kept in the cache, create the DWORD value NegativeCacheTime and set its value to the number of seconds that your system to maintain negative name resolution queries

49. Host File • The contents of its Host file are automatically loaded into the resolver cache when a system boots • Your alter and save a Host file, it is automatically reloaded into the resolver cache • A client’s own local “mini DNS server” • Manually configure or deploy the Host file to every system where you would like to have th FQDN-to-IP address mappings • %systemroot%\system32\drivers\etc folder (C:\Windows\system32\drivers\etc by default) • Notepad to view and edit

50. 2.DNS Query Types • The client will perform a recursive query to its primary DNS server • A recursive query: it is a request for IP address resolution of the entire FQDN. • Not answer: it may make several iterative queries to root-level name servers. • An iterative query: it is a request to resolve only a portion of an FQDN