Module 6
IP Address and Routing
(The Internetworking Layer)
By Dr. Percy DIAS
Internet Addresses
3
IP Address as a 32-Bit Binary Number
• Network number identifies the network to which a
device is attached (high order o...
4
IP Addressing Fundamentals
Note: The IP protocol has begun what will be a long conversion
from IP version 4 to IP versio...
5
Dual-Homed Computer
• Device cannot be said to have an address, but each of
its connection points (or interfaces) to a n...
6
Network Layer Addressing
• Network ID enables a router to put a packet onto the
appropriate network segment. Host ID hel...
7
How IP Routing Uses IP Addresses
• Routers learn routes to directly connected networks easily
• Routers can forward pack...
8
Hierarchical IP addresses
•MAC address: Flat address, locally significant
•IP address: Globally significant
9
Address Class (Classful Addresses)
•Allocation of addresses is managed by American
Registry for Internet Numbers (ARIN)
10
Identifying Address Class
IP Address Class Higher Order Bits First Octet Address
Range
Class A 0 0-127*
Class B 10 128-...
11
IP Address Range
12
Analyzing the Structure of IP Addresses
• The value of the first octet denotes class
of address
13
Calculating the Number of Hosts per Network
• Count the number of bits in the host portion of
the address
• For a Class...
14
Number of Hosts in Each Class A, B, and C
Network
15
Number of Class A, B, and C Networks
• Class A networks have a one-octet network
field
- Might think that there are 28
...
16
Number of Different Class A, B, and C Networks
17
Reserved IP Addresses: Network Address
• All zeros in the host portion of the address are
reserved for the entire netwo...
18
Network Address
19
Reserved IP Addresses: Broadcast Addresses
• All ones in the host portion of the address
specifies the broadcast addres...
20
Broadcast Address
21
Correct Convention for Classful Network
Numbers
22
IP Network Number and the Broadcast
Address
• Two numbers in each network must be
reserved for special purposes
- Canno...
23
IP Network Number and the Broadcast
Address
• Two numbers in each network must be reserved for
special purposes (contin...
24
Public and Private Address
• Public IP addresses are unique
• No two machines that connect to a public
network can have...
25
Private IP Addresses
• Internet routers immediately discard private
addresses
26
NAT and Private IP Networks
• Connecting a network to the Internet using private
addresses requires translating the pri...
27
Network Address Translation (NAT )
28
IPv6
• IPv6 uses hexadecimal numbers to represent the
128 bits
Obtaining an IP Address
30
Windows Static IP Configuration
31
Static Assignment of an IP address
• IP addresses can be assigned either statically or
dynamically
• When IP addresses ...
32
Dynamic Host Configuration Protocol (DHCP) IP
Address Assignment
33
Dynamic Host Configuration Protocol (DHCP)
IP Address Assignment
• DHCP uses the concept of the client making a request...
34
Problems in Address Resolution
• In TCP/IP communications, a datagram on a
local-area network must contain both a
desti...
35
Problems in Address Resolution
• Hannah Knows her own name, IP address, and MAC
address because those things are config...
36
Hannah knows Jessie’s Name, Needs IP Address
and MAC Address
37
DNS Request and Reply
38
DNS Hierarchy
39
Address Resolution Protocol (ARP)
• Some devices keep ARP tables which contain MAC
address and IP addresses of other de...
40
Address Resolution Protocol (ARP)
• When a network devices analyze the incoming data
frames to determine if the transmi...
41
ARP operation within a subnet
• If host knows the IP address,
but not MAC address, host
build an ARP request (ARP
broad...
42
Simple ARP Process
43
Example of the ARP Process
44
Default Gateway
• IP address of the interface on the router that connect to
the network segment on which the source hos...
45
Default Gateway
• With a default gateway set on a computer, the
destination IP address is compared with the
host source...
46
Gateways Enable Communications between
Networks
47
Host Logic: Sending a Packet to Another Subnet
by Using a Default Gateway
172.16.10.2
48
IP Routing Logic Including Data Link Perspective
Routing Fundamentals and
Subnets
50
Path Determination
• Path determination enables a router to compare the
destination address to the available routes in ...
51
Routing Overview
• Routing is the process of finding the most
efficient path from one device to another
• Router has tw...
52
IP Routing Logic, from IP Perspective
53
Use of the ARP Cache in Routing
Network
54
Comparing Routing and Switching Logic
55
Comparing the Benefits of Routing and
Switching
• Switches provide the performance benefits of making
collision domains...
56
Comparing Routers and Switches
57
Routed Protocol vs Routing Protocol
Routing protocols determine the path that
routed protocols follow to their destinat...
58
Routed Protocol
• Protocols that transfer data from one host to
another across a router are routed or routable
protocol...
59
Routing Protocol
• Routers use routing protocols to exchange routing tables and
share routing information
• Provides pr...
60
Connected Routes Only, on R1 and R2
61
Routing Protocols
62
Basics of Learning Routes with Routing
Protocols
• Each router sends messages to other
routers attached to the same sub...
63
R1 Learns Multiple Routes for 172.16.3.0
64
Using Metrics to Pick the Best Routes
• A router can learn of multiple routes when there is
redundancy in the network
•...
65
R1 Learning One Metric 1 and One Metric 2 Route
66
Other Metric Components
• Cisco proprietary routing protocols such as
Interior Gateway Routing Protocol (IGRP) and
Enha...
67
EIGRP’s Use of Constraining Bandwidth
68
Routing Table
• Protocol type
– Type of routing protocol that created the routing table entry
• Destination/ next-hop a...
69
Routing Tables
70
Route Types
• Static Routes:
–Routes learned by the router when an administrator
manually establishes the route. The ad...
71
Dynamic Routing
72
Interior Gateway Protocols (IGP) and Exterior
Gateway Protocols (EGP)
•16-bit number assigned by IANA
73
IGP and EGP
• IGPs route data within an autonomous
system.
–RIP, RIPv2, IGRP, EIGRP, OSPF, IS-IS
• EGPs route data betw...
74
Type of Routing Protocols
• Examples of distance-vector protocols:
–Routing Information Protocol (RIP)
–Interior Gatewa...
Mechanics of Subnetting
76
Subnetworks
To create a subnet address, a network
administrator borrows bits from the original host
portion and designa...
77
Subnetworks
78
Introduction to Subnetting
• Host bits must are reassigned (or “borrowed”) as
network bits.
• The starting point is alw...
79
Introduction to Subnetting
5 bits borrowed allows 25
-2 or 30 subnets
12 bits borrowed allows 212
-2 or 4094 subnets
80
Reasons for Subnetting
• Provides addressing flexibility for the network
administrator.
Each LAN must have its own netw...
81
Subnet Addresses
• Internet knows your network as a whole,
subnet field will become additional routing
bits, routers wi...
82
Subnet Mask
• Determines which part of an IP address is the network
field and which part is the host field.
• Follow th...
83
Subnet mask in decimal = 255.255.240.0
Subnet Mask
84
Subnet Mask
27
26
25
24
23
22
21
20
128 64 32 16 8 4 2 1
1 0 0 0 0 0 0 0 =128
1 1 0 0 0 0 0 0 =192
1 1 1 0 0 0 0 0 =224...
85
Four Practice Problems: Subnet Masks Listed
8
9
9
86
Subnet Scheme (3 bits to the subnet field)
87
Subnetting Chart
• The “slash format” is a shorter way of
representing the subnet mask:
• /25 represents the 25 bits in...
88
Creating Subnet
• Borrow at least 2 bits
• At least 2 bits must remain for host numbers
• Number of usable subnets: 2n
...
89
Four Practice Problems: Finding the Number of
Subnet and Host Bits
90
Subnetting Class A and B Networks
• The available bits for assignment to the
subnet field in a Class A address is 22 bi...
91
The address 197.15.22.131 would be on
the subnet 197.15.22.128.
11000101 00001111 00010110 100 00011
Network Field SN H...
92
Calculating the Subnetwork With ANDing
• ANDing is a binary process by which the router
calculates the subnetwork ID fo...
93
Subnetting Example with AND Operation
94
Broadcast Addresses
95
Broadcast Addresses
• Local or flooded broadcasts
(255.255.255.255) are not propagated by
Layer 3 internetworking devic...
96
Cisco Academy 3 References
Slide 3,5 CCNA1 9.2.1
Slide 6,8,10 CCNA1 9.2.3
Slide 9,11 CCNA1 9.2.4
Slide 17-20 CCNA1 9.2....
97
Cisco Academy 3 References
Slide 49,69 CCNA1 10.2.4
Slide 50 CCNA1 10.2.1
Slide 56-58 CCNA1 10.2.3
Slide 67-68 CCNA1 10...
98
Cisco Academy 4 Exploration Reference
Slide 3-4 Networking Fundamentals 6.1.1
Slide 9-11 Networking Fundamentals 6.2.6-...
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IP adress and routing(networking)

  1. 1. Module 6 IP Address and Routing (The Internetworking Layer) By Dr. Percy DIAS
  2. 2. Internet Addresses
  3. 3. 3 IP Address as a 32-Bit Binary Number • Network number identifies the network to which a device is attached (high order or left most bits) • Host portion identifies the specific device on that network (lower order or right most bits)
  4. 4. 4 IP Addressing Fundamentals Note: The IP protocol has begun what will be a long conversion from IP version 4 to IP version 6. This section focuses on IP version 4. • Basic Facts About IP Addresses -They must be unique inside a particular network -They are 32-bit numbers -They are typically written, entered and displayed as dotted-decimal numbers (e.g., 10.1.5.66) -Each decimal number in a dotted-decimal IP address represents 8 bits of the IP address (often called an octet) -Each of the four decimal values in an IP address is between 0 and 255, inclusive
  5. 5. 5 Dual-Homed Computer • Device cannot be said to have an address, but each of its connection points (or interfaces) to a network has an address that allows other computers to locate it on that particular network
  6. 6. 6 Network Layer Addressing • Network ID enables a router to put a packet onto the appropriate network segment. Host ID helps the router deliver the packet to a specific host.
  7. 7. 7 How IP Routing Uses IP Addresses • Routers learn routes to directly connected networks easily • Routers can forward packets to networks that are not directly connected by sending them to another router, called the next- hop router • IP routing relies on organization of IP addresses into groups to allow efficient routing: - IP addresses on the same physical network must have the same value in the first part of the addresses - Routers can scale their routing tables because they need only one entry for each IP network
  8. 8. 8 Hierarchical IP addresses •MAC address: Flat address, locally significant •IP address: Globally significant
  9. 9. 9 Address Class (Classful Addresses) •Allocation of addresses is managed by American Registry for Internet Numbers (ARIN)
  10. 10. 10 Identifying Address Class IP Address Class Higher Order Bits First Octet Address Range Class A 0 0-127* Class B 10 128-191 Class C 110 192-223 Class D 1110 224-239
  11. 11. 11 IP Address Range
  12. 12. 12 Analyzing the Structure of IP Addresses • The value of the first octet denotes class of address
  13. 13. 13 Calculating the Number of Hosts per Network • Count the number of bits in the host portion of the address • For a Class A network, there are 24 host bits, which gives 224 addresses (16,777,216 addresses) • However, the 1st and last addresses are reserved for the network and network broadcast addresses • Actual host addresses = 2n - 2
  14. 14. 14 Number of Hosts in Each Class A, B, and C Network
  15. 15. 15 Number of Class A, B, and C Networks • Class A networks have a one-octet network field - Might think that there are 28 or 28 – 2 networks available - Since all Class A networks start with a binary 0, only 7 bits are available for network numbers - 27 – 2 = 126 Class A networks • Same logic can be applied to Class B and C networks, but no need to subtract two networks as there are not any reserved network addresses
  16. 16. 16 Number of Different Class A, B, and C Networks
  17. 17. 17 Reserved IP Addresses: Network Address • All zeros in the host portion of the address are reserved for the entire network
  18. 18. 18 Network Address
  19. 19. 19 Reserved IP Addresses: Broadcast Addresses • All ones in the host portion of the address specifies the broadcast address for that network
  20. 20. 20 Broadcast Address
  21. 21. 21 Correct Convention for Classful Network Numbers
  22. 22. 22 IP Network Number and the Broadcast Address • Two numbers in each network must be reserved for special purposes - Cannot be assigned as unicast address to any host - The network number is one of the reserved addresses - The network broadcast address is a dotted- decimal number that, when a packet is sent to this address, it is sent to every host on the network
  23. 23. 23 IP Network Number and the Broadcast Address • Two numbers in each network must be reserved for special purposes (continued) - The network broadcast address has all 1s in the host portion of the address - The network number is numerically the smallest number in the network, and the network broadcast address is the largest number in the network - The term host address is often used to describe any address that can be assigned to an interface in a network
  24. 24. 24 Public and Private Address • Public IP addresses are unique • No two machines that connect to a public network can have the same IP address • Private networks that are not connected to the Internet can have any valid address as long as it is unique within the private network • Grabbing “just any address” is strongly discouraged because that network might eventually be connected to the Internet
  25. 25. 25 Private IP Addresses • Internet routers immediately discard private addresses
  26. 26. 26 NAT and Private IP Networks • Connecting a network to the Internet using private addresses requires translating the private address to public address: Network Address Translation (NAT) • NAT allows a company to use a few registered IP addresses instead of an entire network • Hosts inside the company network typically use private IP addresses
  27. 27. 27 Network Address Translation (NAT )
  28. 28. 28 IPv6 • IPv6 uses hexadecimal numbers to represent the 128 bits
  29. 29. Obtaining an IP Address
  30. 30. 30 Windows Static IP Configuration
  31. 31. 31 Static Assignment of an IP address • IP addresses can be assigned either statically or dynamically • When IP addresses are assigned statically, each device must be configured with an IP address • Assign static IP address, if the device need to be referenced by other devices (like an address of a building) • Records of the address assignments to be kept, because problem can occur if duplicated IP addresses are used • Servers should be assigned a static IP address so workstations and other devices know how to access needed service • Other devices that should be assigned static IP addresses are network printers, application servers and routers
  32. 32. 32 Dynamic Host Configuration Protocol (DHCP) IP Address Assignment
  33. 33. 33 Dynamic Host Configuration Protocol (DHCP) IP Address Assignment • DHCP uses the concept of the client making a request and the server supplying the IP address to the client, plus other information such as the default gateway, subnet mask, DNS IP address • Allows a host to obtain IP address using a defined range of IP addresses on a DHCP server • As host come online, contact DHCP server and request an address • DHCP server choose an address and leases it to a device and then reclaim that IP address for another user after the first user release it • DHCP request UDP port number 67 and reply port number 68
  34. 34. 34 Problems in Address Resolution • In TCP/IP communications, a datagram on a local-area network must contain both a destination MAC address and a destination IP address. • TCP/IP needs a way to let a computer find the IP address of another computer based on its name. • TCP/IP also needs a way to find MAC addresses associated with other computers.
  35. 35. 35 Problems in Address Resolution • Hannah Knows her own name, IP address, and MAC address because those things are configured in advance • To find Jessie’s IP and MAC address, Hannah uses the Domain Name System (DNS) and the Address Resolution Protocol (ARP). • DNS server IP address can be preconfigured or learned using Dynamic Host Configuration Protocol (DHCP). • Hannah simply sends a DNS request to the server, supplying the name jessie, or jessis.skylinecomputer.com, and the DNS replies with the IP address.
  36. 36. 36 Hannah knows Jessie’s Name, Needs IP Address and MAC Address
  37. 37. 37 DNS Request and Reply
  38. 38. 38 DNS Hierarchy
  39. 39. 39 Address Resolution Protocol (ARP) • Some devices keep ARP tables which contain MAC address and IP addresses of other devices that are connected to the same LAN
  40. 40. 40 Address Resolution Protocol (ARP) • When a network devices analyze the incoming data frames to determine if the transmission for them, part of this process adds the IP-MAC source addresses to the ARP table. • ARP table is dynamically updated, adding and removing entries based on segment activity and timeout values (time to keep an entry in the table). • Length of time is depend on the OS, typically a few hours.
  41. 41. 41 ARP operation within a subnet • If host knows the IP address, but not MAC address, host build an ARP request (ARP broadcast) and sends it to all devices (MAC broadcast) • Destination device responds by sending its MAC address (ARP reply)
  42. 42. 42 Simple ARP Process
  43. 43. 43 Example of the ARP Process
  44. 44. 44 Default Gateway • IP address of the interface on the router that connect to the network segment on which the source host is located (default gateway’s IP address must be the same network segment as the source host)
  45. 45. 45 Default Gateway • With a default gateway set on a computer, the destination IP address is compared with the host source address • If the destination is in another network, destination MAC address is default gateway MAC address.
  46. 46. 46 Gateways Enable Communications between Networks
  47. 47. 47 Host Logic: Sending a Packet to Another Subnet by Using a Default Gateway 172.16.10.2
  48. 48. 48 IP Routing Logic Including Data Link Perspective
  49. 49. Routing Fundamentals and Subnets
  50. 50. 50 Path Determination • Path determination enables a router to compare the destination address to the available routes in its routing table, and to select the best path.
  51. 51. 51 Routing Overview • Routing is the process of finding the most efficient path from one device to another • Router has two key functions – Maintain routing table and make sure other routers know of changes in the network topology – When packets arrive at an interface, the router must use the routing table to determine where to send the packets. (It switches them to appropriate interface)
  52. 52. 52 IP Routing Logic, from IP Perspective
  53. 53. 53 Use of the ARP Cache in Routing Network
  54. 54. 54 Comparing Routing and Switching Logic
  55. 55. 55 Comparing the Benefits of Routing and Switching • Switches provide the performance benefits of making collision domains smaller, and providing for full duplex transmission • Routers provide a method of using sophisticated security tools such as access control lists (ACLs)
  56. 56. 56 Comparing Routers and Switches
  57. 57. 57 Routed Protocol vs Routing Protocol Routing protocols determine the path that routed protocols follow to their destinations.
  58. 58. 58 Routed Protocol • Protocols that transfer data from one host to another across a router are routed or routable protocols • Includes any network protocol suite that provides enough information in its network layer address to allow a router to forward it to the next device and ultimately to its destination. –IP –Internetwork Packet Exchange (IPX) –Apple Talk
  59. 59. 59 Routing Protocol • Routers use routing protocols to exchange routing tables and share routing information • Provides processes for sharing route information. • Allows routers to communicate with other routers to update and maintain the routing tables (through the transmission of routing updates). –Routing Information Protocol (RIP) –Interior Gateway Routing Protocol (IGRP): Cisco proprietary –Enhanced Interior Gateway Routing Protocol (EIGRP): Cisco proprietary –Open Shortest Path First (OSPF)
  60. 60. 60 Connected Routes Only, on R1 and R2
  61. 61. 61 Routing Protocols
  62. 62. 62 Basics of Learning Routes with Routing Protocols • Each router sends messages to other routers attached to the same subnets - The messages list all the routing information they know - Each router sends routing updates containing information about new routes - Eventually, all the routers learn all the routes • Figure shows how Routing Information Protocol (RIP) advertises and learns routes
  63. 63. 63 R1 Learns Multiple Routes for 172.16.3.0
  64. 64. 64 Using Metrics to Pick the Best Routes • A router can learn of multiple routes when there is redundancy in the network • Routing protocols determine the best route by using a metric - The metric allows a router to measure how good each competing route is and to pick the best route • RIP is a simple routing protocol that uses only hop count as its metric - The hop count metric represents how many routers sit between a router and a destination subnet
  65. 65. 65 R1 Learning One Metric 1 and One Metric 2 Route
  66. 66. 66 Other Metric Components • Cisco proprietary routing protocols such as Interior Gateway Routing Protocol (IGRP) and Enhanced Interior Gateway Routing Protocol (EIGRP) can use four metrics - Bandwidth - Delay - Link loading - Link error rate (reliability) • By default, both IGRP and EIGRP use only bandwidth and delay
  67. 67. 67 EIGRP’s Use of Constraining Bandwidth
  68. 68. 68 Routing Table • Protocol type – Type of routing protocol that created the routing table entry • Destination/ next-hop association – Tell a router that a particular destination is either directly connected to the router or that it can be reached via another router called the next hop on the way to the final destination • Routing metrics – Routing metrics are used to determine a route’s desirability • Outbound interface – Interface that the data must be sent out to reach the final destination
  69. 69. 69 Routing Tables
  70. 70. 70 Route Types • Static Routes: –Routes learned by the router when an administrator manually establishes the route. The administrator must manually update this static route entry whenever an internetwork topology requires an update, such as during a link failure. • Dynamic Routes: –Routes automatically learned by the router after an administrator configures a routing protocol that helps determine routes. Unlike static routes, as soon as the network administrator enables dynamic routing, route knowledge is automatically updated by a routing process whenever new topology information is received from routers within the internetwork.
  71. 71. 71 Dynamic Routing
  72. 72. 72 Interior Gateway Protocols (IGP) and Exterior Gateway Protocols (EGP) •16-bit number assigned by IANA
  73. 73. 73 IGP and EGP • IGPs route data within an autonomous system. –RIP, RIPv2, IGRP, EIGRP, OSPF, IS-IS • EGPs route data between autonomous systems –Border Gateway Protocol (BGP) 4
  74. 74. 74 Type of Routing Protocols • Examples of distance-vector protocols: –Routing Information Protocol (RIP) –Interior Gateway Routing Protocol (IGRP) • Examples of link-state protocols: –Open Shortest Path First (OSPF) –Intermediate System-to-Intermediate System (IS-IS) • Examples of Hybrid Protocol: –Enhanced IGRP (EIGRP)
  75. 75. Mechanics of Subnetting
  76. 76. 76 Subnetworks To create a subnet address, a network administrator borrows bits from the original host portion and designates them as the subnet field.
  77. 77. 77 Subnetworks
  78. 78. 78 Introduction to Subnetting • Host bits must are reassigned (or “borrowed”) as network bits. • The starting point is always the leftmost host bit. 3 bits borrowed allows 23 -2 or 6 subnets
  79. 79. 79 Introduction to Subnetting 5 bits borrowed allows 25 -2 or 30 subnets 12 bits borrowed allows 212 -2 or 4094 subnets
  80. 80. 80 Reasons for Subnetting • Provides addressing flexibility for the network administrator. Each LAN must have its own network or subnetwork address. • Provides broadcast containment and low-level security on the LAN. • Provides some security since access to other subnets is only available through the services of a router.
  81. 81. 81 Subnet Addresses • Internet knows your network as a whole, subnet field will become additional routing bits, routers within your organization can recognize different locations, or subnets, within the whole network
  82. 82. 82 Subnet Mask • Determines which part of an IP address is the network field and which part is the host field. • Follow these steps to determine the subnet mask: 1. Express the subnetwork IP address in binary form. 2. Replace the network and subnet portion of the address with all 1s. 3. Replace the host portion of the address with all 0s. 4. Convert the binary expression back to dotted-decimal notation. • Default Subnet Mask
  83. 83. 83 Subnet mask in decimal = 255.255.240.0 Subnet Mask
  84. 84. 84 Subnet Mask 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 1 0 0 0 0 0 0 0 =128 1 1 0 0 0 0 0 0 =192 1 1 1 0 0 0 0 0 =224 1 1 1 1 0 0 0 0 =240 1 1 1 1 1 0 0 0 =248 1 1 1 1 1 1 0 0 =252 1 1 1 1 1 1 1 0 =254 1 1 1 1 1 1 1 1 =255 Class A: 1-126 (0xxx…..) Class B: 128-191 (10xx…..) Class C: 192-223 (110xx…) First Octet:
  85. 85. 85 Four Practice Problems: Subnet Masks Listed 8 9 9
  86. 86. 86 Subnet Scheme (3 bits to the subnet field)
  87. 87. 87 Subnetting Chart • The “slash format” is a shorter way of representing the subnet mask: • /25 represents the 25 bits in the subnet mask 255.255.255.128
  88. 88. 88 Creating Subnet • Borrow at least 2 bits • At least 2 bits must remain for host numbers • Number of usable subnets: 2n – 2 where n is the number of bits borrowed • Number of usable host: 2m – 2 where m is the number of remaining bits • To determine the number of bits to be used, network designer needs to calculate how many hosts the largest subnet requires and the number of subnet. • Network administrators decide the size of subnets based on organization and growth needs.
  89. 89. 89 Four Practice Problems: Finding the Number of Subnet and Host Bits
  90. 90. 90 Subnetting Class A and B Networks • The available bits for assignment to the subnet field in a Class A address is 22 bits while a Class B address has 14 bits.
  91. 91. 91 The address 197.15.22.131 would be on the subnet 197.15.22.128. 11000101 00001111 00010110 100 00011 Network Field SN Host Field Class C address 197.15.22.131 with a subnet mask of 255.255.255.224 (3 bits borrowed) Determining Subnet Mask Size
  92. 92. 92 Calculating the Subnetwork With ANDing • ANDing is a binary process by which the router calculates the subnetwork ID for an incoming packet. 1 AND 1 = 1; 1 AND 0 = 0; 0 AND 0 = 0 • The router then uses that information to forward the packet across the correct interface. Packet Address 192.168.10.65 11000000.10101000.00001010.010 00001 Subnet Mask 255.255.255.224 11111111.11111111.11111111.111 00000 Subnetwork Address 192.168.10.64 11000000.10101000.00001010.010 00000
  93. 93. 93 Subnetting Example with AND Operation
  94. 94. 94 Broadcast Addresses
  95. 95. 95 Broadcast Addresses • Local or flooded broadcasts (255.255.255.255) are not propagated by Layer 3 internetworking device. • Broadcasts directed into a specific network are allowed and are forwarded by a Layer 3 device if configured • In Cisco IOS Release 12.0 and later, routers by default do not forward all subnets or directed broadcast.
  96. 96. 96 Cisco Academy 3 References Slide 3,5 CCNA1 9.2.1 Slide 6,8,10 CCNA1 9.2.3 Slide 9,11 CCNA1 9.2.4 Slide 17-20 CCNA1 9.2.5 Slide 24-26 CCNA1 9.2.6 Slide 31 CCNA1 9.3.2 Slide 32-33 CCNA1 9.3.5 Slide 34-37 CCNA1 9.3.6 Slide 39-42, 44-45 CCNA1 9.3.7
  97. 97. 97 Cisco Academy 3 References Slide 49,69 CCNA1 10.2.4 Slide 50 CCNA1 10.2.1 Slide 56-58 CCNA1 10.2.3 Slide 67-68 CCNA1 10.2.5 Slide 70-71 CCNA1 10.2.7 Slide 72 CCNA1 10.2.9 Slide 74-79 CCNA1 10.3.2 Slide 80-82 CCNA1 10.3.3 Slide 84-85 CCNA1 10.3.4 Slide 88-89 CCNA1 10.3.5 Slide 90-91 CCNA1 10.3.6
  98. 98. 98 Cisco Academy 4 Exploration Reference Slide 3-4 Networking Fundamentals 6.1.1 Slide 9-11 Networking Fundamentals 6.2.6-6.2.7 Slide 12-16 Networking Fundamentals 6.5.3-6.5.7 Slide 17-23 Networking Fundamentals 6.2.1 Slide 24-25 Networking Fundamentals 6.2.5 Slide 32 Networking Fundamentals 6.3.6 Slide 32-33 Networking Fundamentals 3.3.5 Slide 34-37 Networking Fundamentals 3.3.1 Slide 39-43 Networking Fundamentals 9.7.1-9.7.4 Slide 49-50 Routing Protocol and Concepts 1.4.1-1.4.4 Slide 74-93 Networking Fundamentals 6.5.1-6.5.6
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