IP Addressing Part 2

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24 Οκτ 2013 (πριν από 3 χρόνια και 7 μήνες)

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IP Addressing


Part 2


MIS 4700


Advanced Networking

Dr. Garrett



1

Vanishing IP Address Space


Mid
-
1990s experts began to predict that the
Internet would “run out” of available IP addresses


Address space saving techniques


Classless Inter
-
Domain Routing (CIDR)


Trade in existing IP network addresses ($)


RFC 1918 private IP addresses range


Network Address Translation (NAT) lets networks use
private IP addresses internally and maps them to public
IP address externally

2

Understanding Basic Binary Arithmetic


Binary equivalents


0000 (0), 0001 (1), 0010 (2), 0011 (3)


0100 (4), 0101 (5), 0110 (6), 0111 (7)


1000 (8), 1001 (9), 1010 (10), 1011 (11)


1100 (12), 1101 (13), 1110 (14), 1111 (15)


Converting decimal to binary


Division or subtraction methods


Converting binary to decimal


Add powers of 2 for each bit placement

3

Understanding Basic Binary Arithmetic
(cont.)


High
-
Order bit patterns


Left most bits of an octet


11000000


Low
-
Order bit patterns


Right most bits of an octet


00000011

4

IP Networks, Subnets, And Masks


Class A, B, and C default masks


a mask is a special bit pattern that identifies the network
portion of an IP address


network prefix


extended


network prefix


IP subnets and
supernets


Network addresses are further subdivided beyond their
defaults with subnet masks “stealing bits” from the host
portion, this is called
subnetting


Supernetting

combines contiguous network addresses

5

IP Networks, Subnets, And Masks (cont.)


Calculating subnet masks


2
b



2 = (the number of usable subnets)


Constant
-
Length Subnet Mask (CLSM)


Subnetting

into multiple equal segments


Each subnet includes the same number of stations


Variable
-
Length Subnet Mask (VLSM)


Subnetting

into multiple unequal segments


Each subnet may not have the same number of stations


Calculating
supernets


Supernets

“steal” bits from the network portion of an
IP address to “lend” those bits to the host

6

Classless Inter
-
Domain Routing (CIDR)


Ignores the traditional A, B, and C class designations
for IP addresses


Allows IP addresses from Class A, B, or C to be
combined as a larger address space


CIDR limitations:


Network address must be contiguous


Routers in the routing domain must understand CIDR
notation

7

Public Versus Private IP Addresses


Private IP addresses:


RFC 1918 designates specific addresses for use as private
IP addresses


Private IP addresses are not routed across the public
Internet


Public IP addresses:


Used when identifying servers or services that must be
accessible to the Internet


Assigned to routers, proxy servers, firewalls, web servers,
e
-
mail servers, FTP servers, and news servers

8

Private Address Ranges


9

Managing Access To IP Address Information


IP security


Private IP addresses and NAT


Proxy server


Reverse proxy

10

Obtaining Public IP Addresses


Public IP addresses issued by ISPs


ICANN manages all


IP
-
related addresses


Protocol numbers


well
-
known port addresses


assigns MAC layer addresses


www.icann.org

11

IP Addressing Schemes


The Network space


Number of physical locations


Number of network devices at each location


Amount of broadcast traffic at each location


IP network is a broadcast domain


Routing (instead of bridging) is done to prevent unnecessary
broadcasts from clogging expensive WAN circuits
2


Availability of IP addresses

12

IP Addressing Schemes (cont.)


The Network space (cont.)


Delay caused by routing from one network to another


Size of the routing tables


Time required for the network to “converge”


Route aggregation or summary addresses


The Host space


Assign IP addresses based function (.1
-
.6 network
devices)(.9
-
.14 servers)

13