Transcript PPP - Chakarov

Routing Fundamentals
and Subnets
Introduction to IT and
Communications Technology
CE00378-1
Content
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Describe routed protocols
List the steps of data encapsulation in an internetwork as
data is routed to Layer 3 devices
Describe connectionless and connection-oriented
delivery
Name the IP packet fields
Describe how data is routed
Compare and contrast different types of routing protocols
List and describe several metrics used by routing
protocols
List several uses for subnetting
Determine the subnet mask for a given situation
Use a subnet mask to determine the subnet ID
IP Address
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A packet of data can be sent to a particular
network by ANDing it with the network Mask
 For
a Class C Address this would be
255.255.255.0
 All of the bits which represent the network ID are
set to 1 the rest are set to 0
 When the IP address converted to binary is AND’d
with the network mask only the Network ID is
displayed
 This network address can then be used for routing
the packet to the correct interface
IP Address
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Example
IP address grouping
•All of these addresses can be represented in a routing table by the network address
•192.168.10.0
•Rather than the full 254 addresses which could be added
Routed protocol
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A routed protocol
 Is
one where it is used carry out addressing across
the network
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The most common example would be IP
Network layer devices in data flow
Decapsulate
Encapsulate
A IP Packet being transferred across a network with three routers
Router protocol stripping
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As a packet of information is transported
between two points
 The
level 1 and 2 frame information will be
stripped and replaced
 This can be done due to a different technology
being connected on the next segment of the
journey
 It may be changing the header with the address of
the next point on the route
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The IP and above layers (3 to 7) will remain the same
throughout the transport of the packet
Router protocol stripping
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Connectionless network services
•In connectionless services the packets are just transferred between devices
•No communications are agreed before sending data, all of the packets may
take different routes to the same destination based on local conditions
•Commonly referred to as Packet switched communications
Connection orientated services
•In connection orientated services, the route is worked out before communications
start
•A telephone network is an example of this
•Commonly referred to as Circuit Switched networks
Network layer fields
•The most common Network layer (Routed) protocol is IPv4 at the moment
•Below is the layout of the protocol with the additional information which needs
to be transferred with the data element
All of the field lengths are fixed except for IP Options and Padding fields
Routing metrics
•The routing metrics are the values which are used to work out the best
route between two points when offered more than one route
•Metrics can be
•Delay
•Hop Count
•Bandwidth
•Load
•Cost
•Reliability
Data encapsulation
Encapsulation
 Is
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the adding of information to the packet
Decapsulation
 Is
the removal of this information
Encapsulation
Decapsulation
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The network layer routing
•The switch will allow routing in the local LAN
•A packet of information will be forwarded out of a particular interface
based on the MAC address of the device attached to it
•Routers forward based on the IP address (Network layer) information
Layer 2 switching & layer 3 routing
ARP tables & routing tables
Router and switch feature
comparison
Routed protocol
Routing protocol
•A routing protocol is used to work out the best route based on metrics
between multiple points
Routing process
Routing tables
Routing algorithms and metrics
Interior & exterior gateway
protocols
Link-state & distance-vector
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Distance Vector protocols
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Use the distance, direction and vector to any point in the network
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RIP
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IGRP
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Distance Vector
EIGRP
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Distance Vector
Distance Vector
Link State protocols
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Send periodic updates to the network regarding the knowledge they
have
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OSPF
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Link State
IP address bit patterns
IP
Protocols are made up two parts
NETWORK ID and Host ID
Depending on the class is how many bits are represented by each part
IP Subnets
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IP Addresses are made up of
 Network
ID
 Host
ID
 Depending on the class this dictates the size of each
element.
 The host ID part though can be split again to extend
the length of the Network ID
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Example would be a Class C address by default
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Network ID is 24 bits and Host ID is 8 bits
By borrowing bits from the host id the network ID is expanded
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The disadvantage is that the number of possible hosts are
reduced hosts
Subdividing the host octets of a class C address
Subdividing the host octets of a class B address
Subdividing the host octets of a class A address
Subnetting chart (bit position and value)
Subnetting chart for a class C address (subnet mask identifier)
Subnetting
Subnetting chart
Subnet scheme
Borrowing 3 bits – therefore subnetwork addresses go up in multiples of 32
Subnetting chart
•The logical ANDing process
•This process is used to work out the network part of the IP address
for routing purposes
Calculating the subnet ID
Summary of lecture
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IP Addressing
 Routing
of these protocols
 Subnets Class C
Routing Protocols
 Serial Interfaces for WAN’s
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