Title: Layering and the TCP/IP protocol Suite
1Layering and the TCP/IP protocol Suite
- The TCP/IP Protocol only contains 5 Layers in its
networking Model - The Layers Are
- Physical -gt 1 in OSI
- Network Interface -gt 2 in OSI
- Internet -gt 3 in OSI (loosely)
- Transport -gt 4 in OSI
- Application -gt 5, 6, 7 in the OSI Model
2Internet Protocol Addresses (IP)
- The IP standard (IPV4) states that each host on a
network will contain a unique 32 bit number. - This number is known as the IP address of the
host. - Both the Senders IP address and the Receivers IP
address are sent in each packet over the internet.
3IP Address Hierarchy
- Each IP is divided into two parts
- Network Number (prefix)
- Host ID (suffix)
- Prefix or network numbers are granted globally
- The hierarchy guarantees two important
properties. - Each computer can have a Unique ID
- Each suffix can be granted locally without global
coordination.
4IP address Classes
- Network numbers can be further divided into
different classes. - Choosing large prefixes provided large number of
network numbers but small number of host IDs - Choosing small prefixes provided a small number
of network numbers but a large number of Host IDs
5IP address Classes (Continued)
- Designers compromised with providing different
classes of numbers for each network. - Depending on the class, determines the size of
the network number (ID) - The first four bits of an address determine the
class. - This determines how the address is divided into
prefixes and suffixes.
6IP address Classes (Continued)
- IP Classes are
- A, B and C (primary classes)
- D (used for multicasting)
- E (used for future use)
- Classes use octet boundaries
- A (the network number is the first octet of the
address and the host ID is the last three octets) - B (the network number is the first two octets and
the host ID is the last two) - C (the network number is the first three octets
and the host ID is the last octet of the address)
7IP address Classes (Continued)
- Classes can be determined from the address itself
and there for are considered to be self
identifying - Most computer hardware can examine bits faster
than comparing integers. - The first four bits are extracted and compared to
determine the class or network the address
belongs. - Speeds up routing of IP addresses by sorting
traffic according to their intended network.
8IP address Classes (Continued)
Although difficult for us to understand,
computers can distinguish the class of a network
by examining the first four bits of an address
9Dotted Notation
- Dotted notation is used to display the IP address
for people. - Binary numbers are translated into four numbers
separated by a decimal point. - Each number is called an octet and each number
can range from 0 to 255.
10Classes and Dotted Notation
- Determining the Network Class by examining the
first octet of an IP Address - Class A network ID, the first octet will range
between 0 and 127 - Class B network ID, the first octet will range
between 128 to 191 - Class C network ID, the first octet will range
between 192 through 223
11Classes and Dotted Notation (Continued)
As you can see, each network class can be divided
according To the value of the first octet
12The Division of IP Addresses
- Class A
- Max number of Network IDs 128
- Max Number of Hosts IDs per network 16777216
- Class B
- Max number of Network IDs 16384
- Max number of Hosts IDs per network 65536
- Class C
- Max number of Network IDs 2097152
- Max number of Host IDs per network 256
13Authority for IP Addresses
- Internet Assigned Number Authority governs the
issuing of Network Addresses to ISPs. - ISPs (Internet Service Providers) provide clients
with available network IDs. - Network administrators of the clients will
determine the assignment of Host IDs on each
network.
14Subnets
- Network numbers can be logically divided into sub
networks. - This divides the host numbers among different
subnets and network traffic is routed on each sub
net. - This benefits the network by
- Dividing network traffic of IP addresses in a
particular part of a network according to traffic
patterns - Unused Host IDs from a network can be reclaimed
and redistributed to other clients.
15Address Masks
- Are used to mask the traffic intended for a
particular subnet. - This is accomplished by applying the AND
function to the Mask and the IP address. - This will provide the means of abstracting the
network ID, and the host ID from the IP address.
- EXAMPLE subnet mask 255.255.255.0 will pull out
the network ID for a Class C network - 255.255.0.0 will pull out the network ID for a
Class B network. - Routers can then just compare the network numbers
in their tables and route them accordingly.
16CIDR Notation
- Used by people to denote the prefix (network
number) and the subnet mask. - Uses the network number followed by the mask
(denoting the number of bits). - For example for the class B network
- 130.14.0.0/16
- This shows the network number is 130.14 and the
mask for this network is 255.255.0.0 (16 bits or
2 Bytes) - Makes it easier for people to understand the
networks and their corresponding masks - Increasing the number of bits on a network can
divide classes into many subnets providing
additional addresses for more clients.
17Special IP Addresses
- Network Addresses Host 0 is reserved to denote
the number of the network and is never assigned
to a computer. - Broadcast Addresses A host address (ID) that
contains all 1s is reserved for broadcasts only. - Limited Broadcasts Used only on the local
network 255.255.255.255 is reserved when
computers boot up on a network.
18Special IP Addresses (Continued)
- This Computer 0.0.0.0 when booting a computer
may request IP and network information. In this
case the address of 0.0.0.0 refers to the
computer booting up. - Local Loop back
- 127.0.0.1 is used by programmers to test
client/server applications. - Both client and server software are run on one
machine and communicate with each other without
sending out a packet on the network.
19Routers and the IP Addressing Principle
- Routers are assigned IP addresses as well
- Routers usually have host ID of 1 for each
network it is attached. - This is not the case all of the time.
- In all the router IPs are reserved by the system
Administrator and are never given to other hosts
on a network. - The IP address of a router is often defined as
the networks Gateway.
20Multi-Homed Hosts
- A computer that connects to multiple networks is
called a Multi-Homed computer. - Often used to increase reliability
- Can also improve performance by avoiding routers
when sending messages onto a network.