Transcript TCP/IP Subnetting
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TCP/IP Subnetting
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TCP/IP Cheat Sheet
IP Addresses • • My localhost -> 192.168.5.201
www.yahoo.com
-> 87.248.113.14
IP Addresses • Every IP Address has a node portion and a network portion IP Address: 192.168.5.201
Network Portion:
192.168.5
.201
Node Portion: 192.168.5.
201
Subnet Mask •The subnet mask tells us which part of an IP address is the node portion vs. the network portion •An IP address without a subnet mask is meaningless IP Address: 192.168.5.201
Subnet Mask: 255.255.255.0
--------------------------------------------------- Network ID: 192.168.5.0
Binary ANDing • AND is a mathematical operator just like + (plus) and – (minus) • 1 + 1 = 2 • 1 AND 1 = 1
AND Truth Table A | B | A AND B -------------------------------------- FALSE | FALSE | FALSE FALSE TRUE TRUE | | | TRUE FALSE TRUE | | | FALSE FALSE TRUE
AND Truth Table A B A AND B ---------------------------- 0 0 0 0 1 1 1 0 1 0 0 1
AND Truth Table 0 AND 0 = 0 0 AND 1 = 0 1 AND 0 = 0 1 AND 1 = 1
Man vs Machine • Human readable dotted decimal notation
192.168.5.201
– Each number represents an “Octet” or 8 bits • What the computer sees:
Subnet Mask and ANDing • IP: • Subnet: 192.168.5.201
255.255.255.0 AND
TCP/IP Cheat Sheet: The Rules • The Subnet/network address is always hidden behind the 1s in the mask IP: 11000000.10101000.00000101
.11001001
Subnet: 11111111.11111111.11111111.00000000
---------------------------------------------- 11000000.10101000.00000101
.00000000
TCP/IP Cheat Sheet: The Rules • The Host/Node address is always hidden behind the 0s in the mask IP: 11000000.10101000.00000101.
11001001 Subnet: 11111111.11111111.11111111.
00000000 ---------------------------------------------- 11000000.10101000.00000101.00000000
TCP/IP Cheat Sheet: The Rules (Except in special cases) • The all-1s and all-0s
subnet
addresses are invalid (but NOT in CIDR) Ex.
Network ID 192.168.1.0 Subnet Mask 255.255.255.128 ->
11111111
.
11111111
.
11111111
.
1
0000000 0s hide the host address These bits belong to the Big IP in the Sky (we can’t change These are them) 1s hide the Breaks the rule! (
1
the bits 0000000 except in CIDR )
TCP/IP Cheat Sheet: The Rules Ex.
(Except in special cases) • The all-1s and all-0s
host
addresses are invalid (Always) IP Address: Subnet Mask: IP Address: Subnet Mask: 192.168.1.
0
255.255.255.0
OR 192.168.1.
255
255.255.255.0
Reason Behind the Rule • The all zeros host address is the same as the network ID Ex.
IP: Subnet: 192.168.1.0
255.255.255.0
--------------------------------------- Network ID: 192.168.1.0
• The all ones host address is reserved for the broadcast address
Practice Problems • 1 AND 1 • 1 AND 0 • 0 AND 1 • 0 AND 0 • 1111 AND 1010 • 0000 AND 1010 • 110101 AND 1101110
Practice Problems • 110010b to Decimal • 137d to Binary