part 1 ipv4 and subnetting. announcements and outline assessment 1 results: range: 66 – 112...
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Announcements and OutlineAssessment 1 Results:Range: 66 – 112Average: 859 students did extra credit
Curve3 MC Questions (6 pts)3pts on Essay Questions
IPv4• Review of packet formats and addressing• Assigning Addresses
• Public vs. Private
• Dotted decimal notation
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D D+ C- C C+ B- B B+ A- A0
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IPv6 Addressing
IPv4 uses 4 byte addresses: Total of 4 billion possible addresses IP addresses often assigned in (large) groups
• Giving out many numbers at a time• IPv4 address space has been used up quickly
IPv6 uses 16 byte addresses: 3.2 x 1038 addresses, 320 undecillion Little chance this address space will ever be used up
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Types of Addresses
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• Application Layer Address
• Network Layer Address
• Data Link Layer Address
Network Layer
Data Link Layer
Application Layer
Transport Layer
7© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
IP Addressing Structure The dotted decimal structure of a binary IP address and
label its parts
8© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
IP Addressing Structure The general role of 8-bit binary in network addressing
and convert 8-bit binary to decimal
6.1.1.1
IPv4 Addresses
4 byte (32 bit) addresses Strings of 32 binary bits
Dotted decimal notation Used to make IP addresses easier to understand for
human readers Breaks the address into four bytes and writes the digital
equivalent for each byte
Example: 128.192.56.1
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1 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 1
IP Addresses (dotted decimal notation)
Examples
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11000000 10101000 00000001 00000101
192 . 168 . 1 5
Converting from binary to decimal
128(2^7)
64(2^6)
32(2^5)
16(2^4)
8(2^3)
4(2^2)
2(2^1)
1 (2^0)
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In decimal, this number is:
• Use the same template as before• Add the place values corresponding to the
locations that have 1 in the number• E.g.: 11100011
Converting from binary to decimal
128 64 32 16 8 4 2 1
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You should be comfortable working with binary numbers with up to 8 bits e.g.: 10011011
• This number is equal to:
• Largest possible number with 8 digits?
Converting from binary to decimal
Try converting the following numbers to decimal 10000110
11001000
11110000
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128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
Converting from decimal to binary
128 64 32 16 8 4 2 1
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• Used to compute subnet sizes, broadcast addresses etc.– You should be comfortable with binary numbers with up
to 8 digits
• One technique is to fill-in-the-blanks– Start with template below– Place 1 in the leftmost-possible position– Subtract place-value and repeat until subtraction yields
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IP addresses – structure
• IP addresses are not assigned at random like MAC addresses– Or even on first-come-first-serve basis
• The first few address bits define the organization to which the address belongs– Remaining bits are unique to the computer (host) within
the organization
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Assigning Addresses - Network Classes (IPv4)
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https://www.arin.net/knowledge/address_filters.html
Public and Private IP Addresses
The use of these addresses need not be unique among outside networks. Hosts that do not require access to the Internet at large may make unrestricted use of private addresses.
The private address blocks are:• 10.0.0.0 to 10.255.255.255 (10.0.0.0 /8)• 172.16.0.0 to 172.31.255.255 (172.16.0.0 /12)• 192.168.0.0 to 192.168.255.255 (192.168.0.0 /16)
Does UNCW use the private address blocks within their network?
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24© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Introducing NAT and PAT
NAT is designed to conserve IP addresses and enable networks to use private IP addresses on internal networks.
These private, internal addresses are translated to routable, public addresses.
IPv4 addresses are almost depleted.
NAT/PAT has allowed IPv4 to be the predominant network protocol