Subnet Design and IP Addressing

Transcription

1 Subnet Design and IP Addressing Asst. Prof. Chaiporn Jaikaeo, Ph.D. Computer Engineering Department Kasetsart University, Bangkok, Thailand Adapted from the notes by Lami Kaya and lecture slides from Anan Phonphoem 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved. The McGraw-Hill Companies, Inc.

2 Outline IP Address CIDR 2

3 Internet Addresses Internet protocol must hide physical network details Application doesn t care about physical Need address to communicate without knowing underlying network of each other Address should be Unique Uniform addressing scheme Independent to physical networks 3

4 Internet Model Revisited sender router router receiver Application Application Transport Transport Network Network Network Network Data Link D.L. D.L. D.L. D.L. Data Link Physical P.L. P.L. P.L. P.L. Physical Transmission medium 4

5 Network Layer Revisited Data Network 1 1.1, 1.2, 6.1, 5.7,... are logical addresses R1 6.1 Network R2 Router Network 3 R Network 5

6 IP Addressing Scheme Unique 32-bit binary number (4 bytes) Assigned to each network interface Used for identify host and communicate Two-level hierarchical address prefix (network ID) assigned globally suffix (Node/host ID) assigned locally Address must be coordinated globally Network ID Prefix Host ID Suffix 6

7 Internet Classes Traditional addressing scheme Classful Addressing 7

8 IP Address Classes A 50% B 25% C 12.5% E D 9

9 No. of Networks / Hosts 10

10 IP address in decimal notation x x x x x x x x = 11 11

11 Class ranges of Internet Address 13

12 IP address in decimal notation 14

13 Class A example 15

14 Class C example 16

15 Network Address 17

16 Internet Example Network and Host addresses 18

17 A Network with Two Levels of Hierarchy Network -> Host 19

18 A Network with Three Levels of Hierarchy Network -> Subnet -> Host 20

19 Addresses with and without Subnetting 21

20 Classful Subnet Masks Class Binary Dotted-Decimal CIDR Notation A /8 B /16 C /24 22

21 Subnet Masks 23

22 Example: Subnet Mask Find the network ID of each of the following hosts with specified subnet masks: IP: Mask: IP: Mask: IP: Mask: IP: Mask:

23 Outline IP Address CIDR 25

24 Classless Inter-Domain Routing CIDR - Classless Inter-Domain Routing Introduced in 1993 to replace classful network design in the Internet To slow the growth of routing tables on routers To help slow the rapid exhaustion of IPv4 addresses No longer restrict network addresses as one or more 8-bit groups 26

25 CIDR Notation Specifies mask with prefix size More convenient than binary representation Example: NetID: Subnet Mask: CIDR notation: /16 27

26 CIDR Host Address 28

27 Example: CIDR Notation Convert mask to corresponding prefix size Convert prefix size to corresponding mask /8 /12 /16 /20 /28 29

28 Example: CIDR Notation Find the network ID of each of the following hosts with specified prefix size: IP: /24 IP: /18 30

29 Special IP Addresses Network Address all hosts = 0; e.g /16 Directed Broadcast Address Broadcast to a specified network all hosts = 1; e.g /16 Limited Broadcast Address Broadcast to local network all 1; e.g This computer Address all 0; e.g Loopback Address /8 127.x.x.x 31

30 Loopback Addresses Allow programmers to test the program logic quickly without needing two computers and without sending packets across a network During loopback testing no packets ever leave a computer the IP software forwards packets from one application to another The loopback address never appears in a packet traveling across a network 32

31 Loopback Addresses โปร เซส A Process A Process B Outgoing packet from Loopback to Process / TCP/UDP IP Data Link Physical Loopback Interface Incoming packet to Loopback Interface Other Addresses 33

32 Directed Broadcast Address Use for sending to all nodes in class range Class A broadcast example: Class B broadcast example: Class C broadcast example:

33 Special IP Address 35

34 Example: Subnet Design You are given an IP address block /24 You want to divide this block into subnets Subnet A to serve 28 hosts Subnet B to serve 40 hosts Subnet C to serve 70 hosts List the designed subnets with the following information (1) subnet ID, (2) mask, (3) first usable address, (4) last usable address, (5) directed broadcast address 36

35 Example: Subnet Design Design subnetting scheme Original /24 block (256 addrs) Subnet C (70 hosts) Subnet A (28 hosts) Subnet B (40 hosts) /25 block (128 addrs) /26 block (64 addrs) /26 block (64 addrs) 37

36 Example: Subnet Design Create summary table Subnet SubNet ID Subnet Mask First Host IP Last Host IP Broadcast Addr C A B