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Any Questions?. Chapter 5-Fundamentals of IP addressing and Routing. Overview of Network Layer Functions IP Addressing IP Routing IP Routing Protocols Network Layer Utilities. Do I know this?. Go through the Quiz- 5 minutes.

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chapter 5 fundamentals of ip addressing and routing
Chapter 5-Fundamentals of IP addressing and Routing
  • Overview of Network Layer Functions
  • IP Addressing
  • IP Routing
  • IP Routing Protocols
  • Network Layer Utilities
do i know this
Do I know this?

Go through the Quiz-

5 minutes

slide4
1. Which of the following are functions of OSI Layer 3 protocols?

a. Logical addressing

b. Physical addressing

c. Path selection

d. Arbitration

e. Error recovery

slide5
1. Which of the following are functions of OSI Layer 3 protocols?

a. Logical addressing

b. Physical addressing

c. Path selection

d. Arbitration

e. Error recovery

Answer: A & C

slide6
2. Imagine that PC1 needs to send some data to PC2, and PC1 and PC2 are separated by several routers. What are the largest entities that make it from PC1 to PC2?

a. Frame

b. Segment

c. Packet

d. L5 PDU

e. L3 PDU

f. L1 PDU

slide7
2. Imagine that PC1 needs to send some data to PC2, and PC1 and PC2 are separated by several routers. What are the largest entities that make it from PC1 to PC2?

a. Frame

b. Segment

c. Packet

d. L5 PDU

e. L3 PDU

f. L1 PDU

Answer: C&E

slide8
3. Imagine a network with two routers that are connected with a point-to-point HDLC serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router1, and PC2 sharing the Ethernet with Router2. When PC1 sends data to PC2, which of the following is true?

a. Router1 strips the Ethernet header and trailer off the frame received from PC1, never to be used again.

b. Router1 encapsulates the Ethernet frame inside an HDLC header and sends the frame to Router2, which extracts the Ethernet frame for forwarding to PC2.

c. Router1 strips the Ethernet header and trailer off the frame received from PC1, which is exactly re-created by R2 before forwarding data to PC2.

d. Router1 removes the Ethernet, IP, and TCP headers and rebuilds the appropriate headers before forwarding the packet to Router2.

slide9
3. Imagine a network with two routers that are connected with a point-to-point HDLC serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router1, and PC2 sharing the Ethernet with Router2. When PC1 sends data to PC2, which of the following is true?

a. Router1 strips the Ethernet header and trailer off the frame received from PC1, never to be used again.

b. Router1 encapsulates the Ethernet frame inside an HDLC header and sends the frame to Router2, which extracts the Ethernet frame for forwarding to PC2.

c. Router1 strips the Ethernet header and trailer off the frame received from PC1, which is exactly re-created by R2 before forwarding data to PC2.

d. Router1 removes the Ethernet, IP, and TCP headers and rebuilds the appropriate headers before forwarding the packet to Router2.

Answer: A

slide10
4. Which of the following are valid Class C IP addresses that can be assigned to hosts?

a. 1.1.1.1

b. 200.1.1.1

c. 128.128.128.128

d. 224.1.1.1

e. 223.223.223.255

slide11
4. Which of the following are valid Class C IP addresses that can be assigned to hosts?

a. 1.1.1.1

b. 200.1.1.1

c. 128.128.128.128

d. 224.1.1.1

e. 223.223.223.255

Answer: B

slide12
5. What is the range of values for the first octet for Class A IP networks?

a. 0 to 127

b. 0 to 126

c. 1 to 127

d. 1 to 126

e. 128 to 191

f. 128 to 192

slide13
5. What is the range of values for the first octet for Class A IP networks?

a. 0 to 127

b. 0 to 126

c. 1 to 127

d. 1 to 126

e. 128 to 191

f. 128 to 192

Answer: D

slide14
6. PC1 and PC2 are on two different Ethernets that are separated by an IP router. PC1’s

IP address is 10.1.1.1, and no subnetting is used. Which of the following addresses

could be used for PC2?

a. 10.1.1.2

b. 10.2.2.2

c. 10.200.200.1

d. 9.1.1.1

e. 225.1.1.1

f. 1.1.1.1

slide15
6. PC1 and PC2 are on two different Ethernets that are separated by an IP router. PC1’s

IP address is 10.1.1.1, and no subnetting is used. Which of the following addresses

could be used for PC2?

a. 10.1.1.2

b. 10.2.2.2

c. 10.200.200.1

d. 9.1.1.1

e. 225.1.1.1

f. 1.1.1.1

Answer: D & F

slide16
7. Each Class B network contains how many IP addresses that can be assigned to hosts?

a. 16,777,214

b. 16,777,216

c. 65,536

d. 65,534

e. 65,532

f. 32,768

g. 32,766

slide17
7. Each Class B network contains how many IP addresses that can be assigned to hosts?

a. 16,777,214

b. 16,777,216

c. 65,536

d. 65,534

e. 65,532

f. 32,768

g. 32,766

Answer: D

slide18
8. Each Class C network contains how many IP addresses that can be assigned to hosts?

a. 65,534

b. 65,532

c. 32,768

d. 32,766

e. 256

f. 254

slide19
8. Each Class C network contains how many IP addresses that can be assigned to hosts?

a. 65,534

b. 65,532

c. 32,768

d. 32,766

e. 256

f. 254

Answer: F

slide20
9. Which of the following does a router normally use when making a decision about

routing TCP/IP packets?

a. Destination MAC address

b. Source MAC address

c. Destination IP address

d. Source IP address

e. Destination MAC and IP address

slide21
9. Which of the following does a router normally use when making a decision about

routing TCP/IP packets?

a. Destination MAC address

b. Source MAC address

c. Destination IP address

d. Source IP address

e. Destination MAC and IP address

Answer: C

slide22
10. Which of the following are true about a LAN-connected TCP/IP host and its IP routing (forwarding) choices?

a. The host always sends packets to its default gateway.

b. The host sends packets to its default gateway if the destination IP address is in a different class of IP network than the host.

c. The host sends packets to its default gateway if the destination IP address is in a different subnet than the host.

d. The host sends packets to its default gateway if the destination IP address is in the same subnet as the host.

slide23
10. Which of the following are true about a LAN-connected TCP/IP host and its IP routing (forwarding) choices?

a. The host always sends packets to its default gateway.

b. The host sends packets to its default gateway if the destination IP address is in a different class of IP network than the host.

c. The host sends packets to its default gateway if the destination IP address is in a different subnet than the host.

d. The host sends packets to its default gateway if the destination IP address is in the same subnet as the host.

Answer: B & C

slide24
11. Which of the following are functions of a routing protocol?

a. Advertising known routes to neighboring routers.

b. Learning routes for subnets directly connected to the router.

c. Learning routes, and putting those routes into the routing table, for routes advertised to the router by its neighboring routers.

d. To forward IP packets based on a packet’s destination IP address.

slide25
11. Which of the following are functions of a routing protocol?

a. Advertising known routes to neighboring routers.

b. Learning routes for subnets directly connected to the router.

c. Learning routes, and putting those routes into the routing table, for routes advertised to the router by its neighboring routers.

d. To forward IP packets based on a packet’s destination IP address.

Answer: A& C

slide26
12. Which of the following protocols allows a client PC to discover the IP address of another computer based on that other computer’s name?

a. ARP

b. RARP

c. DNS

d. DHCP

slide27
12. Which of the following protocols allows a client PC to discover the IP address of another computer based on that other computer’s name?

a. ARP

b. RARP

c. DNS

d. DHCP

Answer: C

slide28
13. Which of the following protocols allows a client PC to request assignment of an IP address as well as learn its default gateway?

a. ARP

b. RARP

c. DNS

d. DHCP

slide29
13. Which of the following protocols allows a client PC to request assignment of an IP address as well as learn its default gateway?

a. ARP

b. RARP

c. DNS

d. DHCP

Answer: D

foundation topics
Foundation Topics
  • Routing: The process of forwarding packets (Layer 3 PDUs).
  • Logical addressing: Addresses that can be used regardless of the type of physical networks used, providing each device (at least) one address. Logical addressing enables the routing process to identify a packet’s source and destination.
  • Routing protocol: A protocol that aids routers by dynamically learning about the groups of addresses in the network, which in turn allows the routing (forwarding) process to work well.
  • Other utilities: The network layer also relies on other utilities. For TCP/IP, these utilities include Domain Name System (DNS), Dynamic Host Configuration Protocol (DHCP), Address Resolution Protocol (ARP), and ping.
network layer functions
Network Layer Functions
  • Although there are lots, TCP/IP is the main one
  • IP Routes data packets
  • IP is connectionless
    • If a router of host can not deliver, packet is discarded without error recovery
  • IP wants to do as little work as possible
routing
Routing
  • Figuring out the next best place to send the packet
routing1
Routing

PC1’s Logic: Sending Data to a Nearby Router

In this example, illustrated in Figure 5-1, PC1 has some data to send to PC2. Because PC2 is not on the same Ethernet as PC1, PC1 needs to send the packet to a router that is attached to the same Ethernet as PC1. The sender sends a data-link frame across the medium to the nearby router; this frame includes the packet in the data portion of the frame. That frame uses data link layer (Layer 2) addressing in the data-link header to ensure that the nearby router receives the frame.

routing2
Routing
  • R1 and R2’s Logic: Routing Data Across the Network R1 and R2 both use the same general process to route the packet. The routing table for any particular network layer protocol contains a list of network layer address groupings. Instead of a single entry in the routing table per individual destination network layer address, there is one routing table entry per group. The router compares the destination network layer address in the packet to the entries in the routing table and makes a match. This matching entry in the routing table tells this router where to forward the packet next. The words in the bubbles in Figure 5-1 point out this basic logic.
routing3
Routing
  • R3’s Logic: Delivering Data to the End Destination
  • The final router in the path, R3, uses almost the exact same logic as R1 and R2, but with one minor difference. R3 needs to forward the packet directly to PC2, not to some other router. On the surface, that difference seems insignificant. In the next section, when you read about how the network layer uses the data link layer, the significance of the difference will become obvious
network data link interaction
Network-Data Link Interaction
  • Each router forwards the PACKET
  • Each Router will create a new FRAME for the current network link
routing4
Routing
  • The process of routing forwards Layer 3 packets, also called Layer 3 protocol data units (L3 PDU), based on the destination Layer 3 address in the packet.
  • The routing process uses the data link layer to encapsulate the Layer 3 packets into Layer 2 frames for transmission across each successive data link.
layer 3 addressing
Layer 3 Addressing
  • Each computer needs one network layer address
  • Addresses are logically grouped
    • Classes
    • Networks
    • Subnets
  • Routers only need to know the grouping information
    • The network or subnet address
routing protocols
Routing Protocols
  • To make choices routers need
    • Routing table
      • Needs to know where the network is
  • Routers build the table dynamically
    • Use routing protocols
      • RIP, OSFP, IGRP, EIGRP
  • Routed protocols can use routers
    • IP
    • IPX/SPX
ip addressing overview
IP Addressing Overview
  • IP v4
  • 32 bit address
    • 4 8 bit octets
    • Dotted Decimal
    • 192.168.10.1
    • 11000000.1010100.00001010.00000001
  • Each network card need a unique address on its network
ip address grouping
IP address grouping
  • IP address are grouped by network address
  • Originally Class A, B and C networks
  • Key Ideas about network grouping
    • All IP addresses in the same group must not be separated by a router.
    • IP addresses separated by a router must be in different groups.
ip classes
IP Classes
  • Class A networks have a 1-byte-long network part. That leaves 3 bytes for the rest of the address, called the host part.
  • Class B networks have a 2-byte-long network part, leaving 2 bytes for the host portion of the address.
  • Class C networks have a 3-byte-long network part, leaving only 1 byte for the host part.
ip addresses that cannot be used
IP addresses that cannot be used
  • All 0 in the host portion
    • Network address
  • All 1 in the host portion
    • Broadcast address
ip subnetting
IP Subnetting
  • Understand the idea here
  • Learn the math later
  • Divide the larger “class” networks into smaller pieces
ip subnetting1
IP Subnetting
  • Class based address can be wasteful
ip subnetting2
IP Subnetting
  • With Subnets we can save addresses
ip subnetting3
IP Subnetting
  • With Subnetting we can “steal” some bits from the host portion
  • Allow us to redefine the Network portion of the address
  • Now we have Network, Host and Subnet
classful addressing
Classful addressing
  • Thinking of address in three parts
classless addressing
Classless addressing
  • Think of address as 2 parts
    • The routing part
    • The host part
ip routing
IP Routing
  • Host Routing
    • Step 1 If the destination IP address is in the same subnet as I am, send the packet directly to that destination host.
    • Step 2 If the destination IP address is not in the same subnet as I am, send the packet to my default gateway (a router’s Ethernet interface on the subnet).
ip routing1
IP Routing
  • Alternatively, when PC1 sends a packet to PC2 (150.150.4.10), PC1 forwards the packet to its default gateway of 150.150.1.4, which is R1’s Ethernet interface IP address according to
  • Step 2 in the host routing logic. The next section describes an example in which PC1 uses its default gateway.
routers and routing
Routers and Routing
  • Step 1 Use the data-link FCS field to ensure that the frame had no errors; if errors occurred, discard the frame.
  • Step 2 Assuming the frame was not discarded at step 1, discard the old data-link header and trailer, leaving the IP packet.
  • Step 3 Compare the IP packet’s destination IP address to the routing table, and find the route that matches the destination address. This route identifies the outgoing interface of the router, and possibly the next-hop router.
  • Step 4 Encapsulate the IP packet inside a new data-link header and trailer, appropriate for the outgoing interface, and forward the frame.
router steps
Router Steps
  • Step A PC1 sends the packet to its default gateway. PC1 first builds the IP packet, with a destination address of PC2’s IP address (150.150.4.10). PC1 needs to send the packet to R1 (PC1’s default gateway) because the destination address is on a different subnet. PC1 places the IP packet into an Ethernet frame, with a destination Ethernet address of R1’s Ethernet address. PC1 sends the frame onto the Ethernet.
router steps1
Router Steps
  • Step B R1 processes the incoming frame and forwards the packet to R2.
  • Because the incoming Ethernet frame has a destination MAC of R1’s Ethernet MAC, R1 copies the frame off the Ethernet for processing. R1 checks the frame’s FCS, and no errors have occurred (Step 1). R1 then discards the Ethernet header and trailer (Step 2). Next, R1 compares the packet’s destination address (150.150.4.10) to the routing table and finds the entry for subnet 150.150.4.0—which includes addresses 150.150.4.0 through 150.150.4.255 (Step 3). Because the destination address is in this group,
  • R2 forwards the packet outgoing interface Serial0 to next-hop router R2 (150.150.2.7) after encapsulating the packet in an HDLC frame (step 4).
router steps2
Router Steps
  • Step C R2 processes the incoming frame and forwards the packet to R3.
  • R2 repeats the same general process as R1 when R2 receives the HDLC
  • frame. R2 checks the FCS field and finds that no errors occurred (Step 1).
  • R2 then discards the HDLC header and trailer (Step 2). Next, R2 finds itsroute for subnet 150.150.4.0—which includes the address range
  • 150.150.4.0–150.150.4.255—and realizes that the packet’s destination
  • address 150.150.4.10 matches that route (Step 3). Finally, R2 sends the
  • packet out interface serial1 to next-hop router 150.150.3.1 (R3) after
  • encapsulating the packet in a Frame Relay header (Step 4).
router steps3
Router Steps
  • Step D R3 processes the incoming frame and forwards the packet to PC2.
  • Like R1 and R2, R3 checks the FCS, discards the old data-link header
  • and trailer, and matches its own route for subnet 150.150.4.0. R3’s
  • routing table entry for 150.150.4.0 shows that the outgoing interface is
  • R3’s Ethernet interface, but there is no next-hop router, because R3 is
  • connected directly to subnet 150.150.4.0. All R3 has to do is encapsulate
  • the packet inside an Ethernet header and trailer, with a destination
routing protocols1
Routing Protocols
  • Learn and fill the routing table
  • Place best route in table
  • Notice when links go down or routes are invalid and update table
    • Find another route if possible
  • Add new routes when necessary
  • Prevent Loops
routing protocol steps
Routing Protocol Steps
  • Step 1 Each router adds a route to its routing table for each subnet directly connected to the router.
  • Step 2 Each router tells its neighbors about all the routes in its routing table, including the directly connected routes and routes learned from other routers.
  • Step 3 After learning a new route from a neighbor, the router adds a route to its routing table, with the next-hop router typically being the neighbor from which the route was learned.
arp and dns
ARP and DNS
  • DNS
    • Maps names to IP addresses
    • Needed to communicate at Internet layer
  • ARP
    • Maps IP to Ethernet Addresses
    • Needed to communicate at Network Access layer
slide67
DHCP
  • IP Settings
  • IP address
  • Default Gateway
  • Subnet Mask
  • DNS Server
slide69
PING
  • Used to test connectivity
    • ICMP Echo Request and Echo Reply
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