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Local Area & IP Networking

Local Area & IP Networking. Review of Week #1. Course Overview. LAN WAN 425. Network Fundamentals (w1) Medium Access Control (w2-3) Local Area Networking (w4) Routing Protocols (w5) Transport Protocols (w6) Examples/Review (w7) TEST 1 IP Networking Support Protocols (w8)

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Local Area & IP Networking

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  1. Local Area & IP Networking Review of Week #1

  2. Course Overview LAN WAN 425 Network Fundamentals (w1) Medium Access Control (w2-3) Local Area Networking (w4) Routing Protocols (w5) Transport Protocols (w6) Examples/Review (w7) TEST 1 IP Networking Support Protocols (w8) IP Design (w9-10) Group Presentations Application Support Protocols (w11-12) Network Security (w13) Makeup Week (w14) TEST 2 Final Project Due last week of class

  3. Required Reading Computer Communications & Networking Technologies pp. 229-274 RFC 1180 “A TCP/IP Tutorial” Sections 1-5

  4. Lecture Outline IEEE Standard LAN: IEEE Standard LAN vs. OSI Model • LLC • MAC Ethernet – 802.3 • Overview • Frame Format Other LAN Protocols: FDDI – ANSI X.3 (X3T9.5) • Operation • Frame format MAC Addressing

  5. Lecture Outline IP Addressing: The IP Address Subnetting (Classful, VLSM, CIDR) Supernetting (CIDR) Private vs. Public Addresses • Address Resolution Protocol: ARP Binding RARP

  6. IP Addressing The IP Address

  7. IP Addressing Scheme A host is assigned a unique address for each network connection. The IP address is divided into a network ID and host ID. The host ID indicates the host’s connection to the network.

  8. IP Addressing Scheme (Cont..) • The IP address is represented by 32 bits. It is often convenient to represent the address in decimal-dot notation as shown below: Decimal-dot : 111.23.129.8 Binary: 1101111.0010111.10000001.00001000 • The Min value of an Octet (8bits) is 0, Max is 255 • Network Ids assigned globally, host Ids assigned locally

  9. Dotted Decimal Notation

  10. IP AddressingThree Primary Classes • Class A : N.H.H.H • Class B : N.N.H.H • Class C : N.N.N.H N = Network number assigned globally H = Assigned by network administrator (host & subnets)

  11. Internet Classes Class Range of Vaules A 0 through 126 B 128 through 191 C 192 through 223 D 224 through 239 E 240 through 255

  12. Internet Classes (Cont..)

  13. Internet Classes (Cont..) • Class A, B and C are primary classes • Class D is used for multicast - Internet hosts join a multicast group - Packets are delivered to all members of group - Routers manage delivery of single packet from source to all members of multicast group - Used for mbone (multicast backbone) • Class E is reserved

  14. Computing The Class Of An Address

  15. Class Ranges Of Internet Addresses

  16. IP Addressing - Class A (example) • 1.222.222.222 • Network # : 1 • Host # : 222.222.222 • Range of network numbers is : 1-126 (0 and 127 reserved) • Maximum number of class A networks : 126 • Number of available hosts : 16,777,214 (all 0’s and all 1’s reserved)

  17. IP Addressing - Class B (example) • 128.128.222.222 • Network # : 128.128 • Host # : 222.222 • Range of network numbers is : 128 - 191 • Maximum number of networks : 16384 • Number of available hosts : 65,534

  18. IP Addressing - Class C (example) • 192.192.192.222 • Network # : 192.192.192 • Host # : 222 • Range :192- 223 • Maximum number of networks : 2097152 • Number of available hosts : 264 per network

  19. IP First Octet Rule • 1 - 126 : Class A • 128 - 191 : Class B • 192 - 223 : Class C • 224 - 239 : Class D • 240 - 254 : Class E

  20. Summary of Special IP Addresses Prefix Suffix Type Purpose all 0s all 0s this computer used during bootstrap network all 0s network identifies a network network all 1s directed broadcast broadcasts on a specified net all 1s all 1s limited broadcast broadcast on a local net 127 any loopback testing

  21. IP Addressing Example

  22. Reference Information

  23. CLASSFUL & SUBNET MASKING PART 1

  24. CLASSFUL & SUBNET MASKING • Subnetting • Simplified the address management process • Better address optimization • Original classful addressing • Did not anticipate Internet growth • Originally allocated based on organization, not need • Classful A, B, and C addressing • A concept that is easy to understand • Still wasteful • Classic natural mask addresses • Difficult to manage devices on each network • A Class B address, for example, must manage large numbers of devices

  25. THE CONCEPT OF MASKING A Class B address: NetID HostID 184 . 10 . 0 . 0 1011 1000 . 0000 1010 . 0000 0000 . 0000 0000 The Mask: 1111 1111 . 1111 1111 . 0000 0000 . 0000 0000 255 . 255 . 0 . 0 Or: / 16 184 . 10 . 0 . 0 In other words, we can write this as: 184.10.0.0/16

  26. CLASSFUL ADDRESSES A Class A classful address: 28.0.0.0/8 0001 1100 . 0000 0000 . 0000 0000 . 0000 0000 A Class B classful address: 183.248.0.0/16 1011 0111 . 1111 0000 . 0000 0000 . 0000 0000 A Class C classful address: 208.136.58.0/24 1101 0000 . 1000 1000 . 0011 1010 . 0000 0000

  27. JUST A NOTE The Class A address: 127.0.0.0 Also written: 127/8 Or: 127.0.0.0/8 Has been reserved for “Loopback” interface where a client and server are allowed to communicate with one another when they are located on the same host.

  28. HOW MANY NETWORKS/HOSTS ARE ALLOWED? • Class B address ID allows for 214 - 2 networks, or 16,382 • Because first 2-bits define a Class B address, and • All Os (set aside for an initialization process) and all 1s (set aside for broadcast) • Class B host ID allows for 216 - 2 hosts, or 65,534 • Because all 0s are set aside for meaning “this network” and • All 1s are set aside for broadcasting to all hosts on this network • This applies to Class A and Class C addresses as well

  29. SUBNETTING CLASSFUL ADDRESSES 141 . 6 . 0 . 0 1000 1101 . 0000 0110 . 0000 0000 . 0000 0000 141 . 6 . 0 . 0 1000 1101 . 0000 0110 . 0000 0000 . 0000 0000 141 . 6 . 0 . 0 1000 1101 . 0000 0110 . 0000 0000 . 0000 0000 141 . 6 . 0 . 0 1000 1101 . 0000 0110 . 0000 0000 . 0000 0000 • You are given a Class B address 141.6.0.0/16 • This will give you 216 - 2 hosts or 65,534 devices on this network • Subnetting this classful address potentially makes this more manageable NOTE: Subnetting steals from the HOSTs to give to the Network ID / 16 / 18 4 subnets & 16,382 hosts / 24 256 subnets & 254 hosts / 28 4096 subnets & 14 hosts

  30. SUBNETTING CLASSFUL ADDRESSES • Let us focus on the classful address 141.6.0.0/28 141 . 6 . 0 . 0 / 28 1000 1101 . 0000 0110 . 0000 0000 . 0000 0000 • 212 = 4096 subnets are possible but • All 0s and all 1s are potentially not allowed - RFC 950 • Function of the Interior Gateway Protocol (IGP) in use • Today, all 0 and all 1subnet addresses ARE available • 24 = 16 hosts are possible, but • All 0s and all 1s are still not allowed • Or 24 - 2 = 30 hosts on each subnetwork • Therefore • 4096 subnests and • 30 hosts on each subnet

  31. AN EXAMPLE Subnet O (000002) Subnet 1 (000012) • • • Subnet 30 (111102) Subnet 31 (111112) • You are given the Class C address of 198 . 6 . 1 . 0 / 29 32 subnets & 6 hosts 1100 0000 . 0000 0110 . 0000 0001 . 0000 0000 • Defining Subnet Numbers • Thus, the address of Host 5 on Subnet 30 is 188.6.1.21 or 1100 0000 . 0000 0110 . 0000 0001 . 1111 0101

  32. A 2nd EXAMPLE OF MASKING USING LOGICAL ‘AND’ Subnet O (000x00xx2) Host O (xxx0xx012) Host 1 (xxx0xx102) Subnet 1 (000x01xx2) • • • • • • Subnet 30 (111x10xx2) Host 4 (xxx1xx012) Subnet 31 (111x11xx2) Host 5 (xxx1xx102) • You are given the Class C address and mask of 198 . 6 . 1 . 0 255 . 255 . 255 . 236 1100 0110 . 0000 0110 . 0000 0001 . 0000 0000 32 subnets & 6 hosts 1111 1111 . 1111 1111 . 1111 1111 . 1110 1100 • Defining Subnet and Host Numbers • Thus, the address of Subnet 30 & Host 5 is 188.6.1.250 or 1100 0110 . 0000 0110 . 0000 0001 . 1111 1010

  33. TERMINOLOGIES • You are given the Class B address of 130 . 101 . 0 . 0 / 24 1000 0010 . 0110 0101 . 0000 0000 . 0000 0000 • Masking terms • Natural mask also called the network-prefix 1000 0010 . 0110 0101 . 0000 0000 . 0000 0000 • Subnet mask 1000 0010 . 0110 0101 . 0000 0000 . 0000 0000 • Extended-network-prefix = natural plus subnet masks 1000 0010 . 0110 0101 . 0000 0000 . 0000 0000

  34. PART 2 VARIABLE LENGTH SUBNET MASKS (VLSMs)

  35. VARIABLE LENGTH SUBNET MASK (VLSM) • With subnet masking, one network, one mask • With VLSM, one network can be configured with different masks • Example: You are assigned a Class C address of 196.4.1.0/24. You need to divide that network into 3 subnets • Example: You are assigned a Class C address of 190.4.1.0/24. You need to divide that network into 3 subnets • Subnet 1 needs to host 100 devices • Subnet 2 needs to host 50 devices, and • Subnet 3 needs to host 50 devices. • Subnet masking choices given X : 196.4.1.0/24 255.255.255.X

  36. VLSM EXAMPLE • Subnet masking choices given X : 196.4.1.0/24 255.255.255.X X = 252 (1111 1100) - 64 subnets with 2 hosts each X = 248 (1111 1000) - 32 subnets with 6 hosts each X = 240 (1111 0000) - 16 subnets with 14 hosts each X = 224 (1110 0000) - 8 subnets with 30 hosts each X = 192 (1100 0000) - 4 subnets with 62 hosts each X = 128 (1000 0000) - 2 subnets with 126 hosts each

  37. VLSM EXAMPLE - CONT’D • Subnet masking choices given X : 196.4.1.0/24 255.255.255.X X = 192 (1100 0000) - 4 subnets with 62 hosts each X = 128 (1000 0000) - 2 subnets with 126 hosts each Subnet 1 - 126 hosts Subnet 1 - 62 hosts Subnet 2 - 62 hosts Subnet 3 - 62 hosts Router Subnet 2 - 126 hosts Subnet 4 - 62 hosts

  38. VLSM EXAMPLE - CONT’D 196.4.1.0/24 E0 1100 0100 . 0000 0100 . 0000 0001 . xxxx xxxx 196.4.1.0/25 E1 1100 0100 . 0000 0100 . 0000 0001 . 0xxx xxxx 196.4.1.0/25 E2 1100 0100 . 0000 0100 . 0000 0001 . 1xxx xxxx 196.4.1.0/26 E3 1100 0100 . 0000 0100 . 0000 0001 . 10xx xxxx 196.4.1.0/26 E4 1100 0100 . 0000 0100 . 0000 0001 . 11xx xxxx E1 126 hosts E1 126 hosts E3 126 hosts E3 62 hosts E4 62 hosts • The VLSM solution :

  39. VLSM EXAMPLE - CONT’D 196.4.1.0/24 E0 1100 0100 . 0000 0100 . 0000 0001 . xxxx xxxx 196.4.1.0/25 E1 1100 0100 . 0000 0100 . 0000 0001 . 0xxx xxxx 196.4.1.0/25 E2 1100 0100 . 0000 0100 . 0000 0001 . 1xxx xxxx 196.4.1.0/26 E3 1100 0100 . 0000 0100 . 0000 0001 . 10xx xxxx 196.4.1.0/26 E4 1100 0100 . 0000 0100 . 0000 0001 . 11xx xxxx 196.4.1.0/27 E5 1100 0100 . 0000 0100 . 0000 0001 . 110x xxxx 196.4.1.0/27 E6 1100 0100 . 0000 0100 . 0000 0001 . 111x xxxx E1 126 hosts E3 62 hosts E0 254 hosts E5 30 hosts E6 30 hosts • More splitting :

  40. ANOTHER VIEW OF VLSM Ethernet Hub E1 126 hosts E0 254 hosts E3 62 hosts E2 126 hosts E5 30 hosts E4 62 hosts E6 30 hosts E1 126 hosts E3 62 hosts E0 254 hosts E5 30 hosts E6 30 hosts VLSM Cascaded Routers Single VLSM Router

  41. AGGRIGATION & ADVERTIZMENTS IP Network A real advantage. Here’s why: Two-Level Classful Hierarchy Network-Prefix Host-Number Three-Level Classful Hierarchy Subnet Number Host Number Network-Prefix E1 141.6.32.0 E2 141.6.64.0 E3 141.6.96.0 E4 141.6.128.0 E5 141.6.160.0 E6 141.6.192.0 E7 141.6.224.0 E0 141.6.0.0/ 24

  42. VLSM PERMITS ROUTE TABLE AGGRIGATION & ADVERTIZEMENT Autonomous Network 11.1.0.0/16 A 11.1.0.0/16 11.2.0.0/16 11.3.0.0/16 • • 11.252.0.0/16 11.253.0.0/16 11.254.0.0/16 11.1.1.0/24 11.1.2.0/24 • • • 11.1.253.0/24 11.1.254.0/24 D 11.0.0.0/8 or 11/8 C B IP Network 11.253.0.0/19 11.1.253.0/27 11.253.32.0/19 11.253.64.0/19 • • 11.253.160.0/19 11.253.192.0/19 11.1.253.32/27 11.1.253.64/27 • • 11.1.253.160/27 11.1.253.192/27 NOTE: It may help to write these numbers in dot binary and use a marker to define the appropriate mask

  43. VLSM PERMITS ROUTE TABLE AGGRIGATION & ADVERTIZEMENT (con’d) Autonomous Network 27 11.1.0.0/16 11.1.0.0/16 11.2.0.0/16 11.3.0.0/16 • • 11.252.0.0/16 11.253.0.0/16 11.254.0.0/16 11.1.1.0/24 11.1.2.0/24 • • • 11.1.253.0/24 11.1.254.0/24 000 1011.0000 0001.1111 1101.0010 0000 32 000 1011.0000 0001.1111 1101.0100 0000 64 000 1011.0000 0001.1111 1101.0110 0000 96 000 1011.0000 0001.1111 1101.1000 0000 128 000 1011.0000 0001.1111 1101.1010 0000 160 000 1011.0000 0001.1111 1101.1100 0000 192 D C 19 B 11.253.0.0/19 11.1.253.0/27 000 1011.1111 1101. 0010 0000 32 000 1011.1111 1101. 0100 0000 64 000 1011.1111 1101. 0110 0000 96 000 1011.1111 1101. 1000 0000 128 000 1011.1111 1101. 1010 0000 160 000 1011.1111 1101. 1100 0000 192 11.253.32.0/19 11.253.64.0/19 • • 11.253.160.0/19 11.253.192.0/19 11.1.253.32/27 11.1.253.64/27 • • 11.1.253.160/27 11.1.253.192/27

  44. SUMMING UP SUBNETS & VLSM SO FAR • Subnetting • Simplified the address management process • Better address optimization • Classic natural mask addresses • Difficult to use • Very address wasteful • VLSM • Also simplifies address management • Also improves address optimization over subnetworking • Simplifies routing tables • Simplifies address advertising

  45. SUMMING UP SUBNETS & VLSM SO FAR • Not all routing protocols can handle VLSM. Early network protocols did not • Routing Information Protocol (RIP) Version 1 • Interior Gateway Routing Protocol (IGRP) which is Cisco proprietary • Today’s routing protocols do support VLSM • Open Shortest Path First (OSPF) • Enhanced Internet Gateway Protocol (EIGRP), a Cisco proprietary protocol • Intermediate System-to-Intermediate System (IS-IS) • RIP Version 2

  46. Private vs. Public Addresses • Some IP Addresses have been reserved for private use meaning that they cannot be routed over the Internet. Specifically, the following networks are reserved for private use.

  47. Private IP Addresses Private addresses can only be used for internal networks. RFC 1918 spells out a set of addresses which are prohibited from being used on the Internet. Network Address Available Allocation 10.0.0.0 1 Class A network 172.16.0.0 through 172.31.0.0 16 Class B networks 192.168.255.0 through 192.168.255.0 255 Class C networks

  48. ARP - Binding The interface between IP Addresses and MAC Addresses

  49. What Is Binding ? Association between a protocol address and a hardware(MAC) address is called a binding

  50. What Is Address Resolution ? Translation from a computer’s protocol address to an equivalent hardware address or Mapping between a protocol address and a hardware address

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