Transcript Document

IP Based Network Concepts
&
Overview
Faculty of Network Planning
ALTTC, Ghaziabad.
1
Introduction
Standalone computers.
Computers in a network.
Different applications/services between
computers: e-mail, File Transfer, Remote
Login,
Web
Surfing,
Network
Management, chatting, playing games
etc.
2
Introduction
To
achieve
interworking
between
computers & other devices like servers,
routers etc the computer is made to work
in a hierarchical manner ie it is to work as
a layered model. Each layer doing certain
functionalities & offering services to its
upper layer.
3
Introduction
International Standard Organisation (ISO) devised a 7
layered model called Open System Interconnection (OSI
model)
APPLICATION
APPLICATION
PRESENTATION
PRESENTATION
SESSION
SESSION
TRANSPORT
TRANSPORT
NETWORK
NETWORK
DATA LINK
DATA LINK
PHYSICAL
PHYSICAL
A
B
4
Introduction
Each computer has this OSI model
embedded in it.
Whenever any computer wants to
communicate with any other computer or
entity it will adopt a set of rules
agreeable to all the computers & entities
in the network. This set of rules is called
Protocol. Each layer communicates with
its peer layer using a protocol before
actual data transfer takes place.
5
Introduction
So we require a stack of protocol called
Protocol Suite to effect communication
between computers in a network.
Different protocol suites are available
like:
(a) AppleTalk
(d) TCP/IP
(b) OSI
(e) DECnet
(c) IPX/SPX
(f) XNS
6
IP Protocols
Internet or IP technology over the years has
emerged as the most prominent data
communication technology.
TCP/IP protocol has become de-facto data
comm standard throughout the world.
It can carry even voice/video also over IP
protocol and in turn has started challenging the
complete monopoly of TDM technology in voice
communication.
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TCP/IP and OSI
OSI is made of seven layers.
TCP/IP protocol is made of five layers.
APPLICATION
PRESENTATION
APPLICATION
SESSION
OSI Model
TRANSPORT
TRANSPORT
NETWORK
NETWORK
DATA LINK
DATA LINK
PHYSICAL
PHYSICAL
TCP/IP Model
8
TCP/IP Protocol Suite
A
T
N
D
FTP
SMTP
TELNET
HTTP
TFTP
NFS
SNMP
DNS
TCP
ICMP IGMP
UDP
IP
ARP
RARP
Ethernet, Token Ring, FDDI, HDLC, FR, PPP, ATM
Protocols defined by the underlying networks
P
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Data Encapsulation
Application
Data
TCP Header
TPT Layer
Data
TCP Segment
UDP Header
Data
UDP Message
NW Layer
IP Header
TCP-UDP
Data
IP Datagram
Data Link
Frame Head
IP Header
TCP-UDP
Data
Trailer
Frame
10
TCP Header
Octet +0
Octet +1
Octet +2
Octet +3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
SOURCE PORT
DESTINATION PORT
SEQUENCE NUMBER
ACKNOWLEDGEMENT NUMBER
HELEN
UAP RS F
RCSSYI
GKHT NN
CHECKSUM
WINDOW SIZE
URGENT POINTER
OPTIONS AND PADDING
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UDP Header
Octet +0
Octet +1
Octet +2
Octet +3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
SOURCE PORT
DESTINATION PORT
MESSAGE LENGTH
CHECKSUM
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IP Header
Octet +0
Octet +1
Octet +2
Octet +3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
VER
HLEN
TOS
IDENTIFICATION
TIME TO LIVE
PROTOCOL
TOTAL LENGTH
DM
FF
FRAGMENT OFFSET
HEADER CHECKSUM
SOURCE ADDRESS OF HOST
DESTINATION ADDRESS OF HOST
OPTIONS
PADDING
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Internet Control Message
Protocol
Internet Control Message Protocol is a
mechanism used by hosts and routers to send
notification of datagram problems back to the
sender.
Sends error messages only to the source and
not to intermediate routers.
Sole function is to report problems, not to
correct them.
ICMP (Ping- Packet Internet Gropher) uses
echo/reply to test whether a destination is
reachable and responding.
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Address Resolution Protocol
Address Resolution Protocol is used to translate
32 bits IP addresses to 48 bits Ethernet
addresses.
A host’s physical address is determined by
broadcasting its IP address to all machines.
The machine with matching IP address, in
broadcast message, sends its hardware address
to the machine originating broadcast.
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ARP Operation
Give me MAC address of 129.1.1.4
Here is my MAC address
129.1.1.1
ARP
Response
Accepted
129.1.1.4
Request
Ignored
129.1.1.2
Request
Ignored
That’s
Me
129.1.1.3
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Reverse Address Resolution Protocol
Reverse Address Resolution Protocol is
used to get the 32 bits Source IP
address, knowing the 48 bits Hardware
address.
It is reverse of ARP, hence named
Reverse Address Resolution Protocol.
A diskless workstation broadcasts RARPRequest to find its IP Address at the time
of boot up.
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RARP Operation
Give me my IP address
RARP Response
Diskless
work
station
RARP
Server
08-00-39-00-2F-AB
223.1.2.1
08-00-39-00-2F-C3 223.1.2.2
223.1.2.3
08-00-10-99-AC-54
08-00-5A-21-A7-22
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IPv4 Address
32 Bits
Network
8
Bits
8
Bits
172 . 16
Host
8
Bits
8
Bits
. 122 . 204
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NAT (Network Address Translation)
•Private addressing
•Public IP Addressing
•Address translation
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IPv4 Address Classes
Class-A:
N
H
H
H
Class-B:
N
N
H
H
Class-C:
N
N
N
H
Class-D:
For Multicast
Class-E:
For Research
Present day Internet does not use Class full addressing, Instead
Classless addressing is used.
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IPV6
IP version 4 has got 32 bit IP addressing
scheme.
With the explosive growth of Internet there is a
severe shortage of IP addresses as every host
on internet should have an IP address.
To overcome the shortage of IPV4 IP addresses
IPV6 has been designed which has 128 bit IP
addressing scheme.
To implement IPV6 in the network all IPV4
network elements are to be replaced with IPV6
devices as they are directly not compatible.
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Segment - A segment is any portion of a network
that is separated, by a switch, bridge or router, from
other parts of the network.
Network Interface Card (NIC) - Every computer
(and most other devices) is connected to a network
through a NIC. This is usually an Ethernet card
(normally 10 or 100 Mbps) that is plugged into a
slot on the computer's motherboard.
Media Access Control (MAC) address - This is
the physical address of any device -- such as the
NIC -- on the network. MAC address is made up of
two equal parts (6 bytes long). The first 3 bytes
identify the company that made the NIC and the
second 3 bytes are the serial number of the NIC
itself.
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HUB vs SWITCH
A vital difference between a hub and a switch
is that all the nodes connected to a hub share
the bandwidth among themselves, while a
device connected to a switch port has the full
bandwidth all to itself.
For example, if 10 nodes are communicating
using a hub on a 10-Mbps network, then each
node may only get a portion of the 10 Mbps if
other nodes on the hub want to communicate
as well. But with a switch, each node could
possibly communicate at the full 10 Mbps.
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LAN Switch
Most switches operate at the Data layer (Layer 2)
but some incorporate features of a router and
operate at the Network layer (Layer 3) as well.
Router: When a router receives a packet, it looks at
the Layer 3 source and destination addresses to
determine the path the packet should take.
Standard Switch: This relies on the MAC addresses
to determine the source and destination of a packet,
which is Layer 2 (Data) networking.
Layer 2 vs. Layer 3 switch: L3 switches have
optimized hardware to pass data as fast as Layer 2
switches, yet they make decisions on how to
transmit traffic at Layer 3, just like a router.
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Router
Router is a layer 3 device which can look into
the destination IP address of an IP packet and
with the help of its routing table it can forward
the packet to appropriate direction.
Routers have many interfaces to connect LANs
and WANs.
Routers can build their routing table
automatically with the help of various routing
protocols.
Routers share their information with their
neighboring routers to build routing tables.
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Routers
Internet can be considered as thousands
of routers connected with each other in
criss-cross manner.
Routers can be deployed by a carrier in
the core to create the backbone and the
customers routers get connected to the
backbone.
Customer’s routers act as gateway for
their network.
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Static - Dynamic Routing
Static/Non Adaptive
Choice of route is computed in advance, off
line, and downloaded to the router when
network is booted.
Dynamic/Adaptive
Routing decisions change to reflect the
changes in topology and/or traffic.
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Static Routing
Routes to destinations are set up
manually.
Network reachability is not dependent on
the existence and state of the network.
Route may be up or down but static
routes will remain in the routing tables
and traffic would still be sent towards the
route.
Not suitable for large networks.
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Default Routing
When a router receives a packet and its table
does not contain the network number indicated
in the packet, it is forwarded to default router.
The default router, too, may have a default
route.
If there is no route or default route at any
stage, the router will send a control message
(through ICMP) to the originating station.
30
Dynamic Routing
Routes are learnt via an internal or external
routing protocols.
Network reachability is dependent on the
existence and state of the network.
If a router is down, its entry will be deleted
from the routing table and traffic to that will
not be forwarded.
Used to enable routers to build their own
routing tables and make appropriate
decisions.
31
Routing Protocol
It is a language a router speaks with
other routers to share information about
the reachability and status of the
network.
Provides mechanisms for sharing routing
information.
Allows the routers to communicate with
other routers to update and maintain
routing tables.
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Routing Protocol
Routing Protocol messages do not carry
end user traffic from network to network.
Routing Protocol uses the routed protocol
( e.g. IP)to pass information between
routers.
RIP & OSPF are routing protocols.
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Radius Server

RAS Support for RADIUS authentication and RADIUS Accounting

Irrespective of mode of access (such as Dial-up Internet access,outsourced remote access
,managed VPNs, Broadband etc),it will manage the Authentication of all users/customers- both
locally and via proxy RADIUS- and deliver the appropriate level of service to each customer.

RADIUS will support interfacing with LDAP based authentication, billing and Provisioning
systems.

It will include advanced proxy RADIUS support.It will be able to act as a proxy target server,
and can forward proxy requests to other RADIUS servers.

It will load balance authentication requests between several SQL or LDAP databases, to
eliminate the risk of a single point failure, and increase performance on busy networks.

The RADIUS will generate CDRs for the Billing system and the CDRs will contain the following
information
 The calling IP address allotted by the RADIUS
 Start Time and Date
 End Time and Date
 Volume of data transmitted and port type.
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LDAP (Directory Server)
Light weight Directory Access Protocol
 The Directory Server shall support unlimited number of read
only consumers for authentication queries.
 The Directory Server shall support Class of Service and Role
based mechanism.
 The
Directory Server shall support Storage of Digital
Certificates.
 The LDAP and RADIUS will be able to handle a customer base
of 8 Lakhs assuming a concurrency rate of 40% .
 The authentication will not take more than 1 sec under the full
load.
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Remote Access Server (RAS)
RAS is a device which allows a customer to
access internet through his telephone line by
dialing an access code.
RAS is an interface between PSTN and Internet.
Before allowing the access RAS authenticates
the dial up user with the help of RADIUS sever.
RAS is having circuit switched interface with
PSTN and packet switched interface with
Internet.
36
Remote Access Server (RAS)
Internet Node
RAS
PSTN
E1s or PRI
V
Router
Modem
Internet
LAN Switch
37
Domain Name System (DNS)
DNS is a mechanism which translates
host name to IP address in Internet
All the network elements in Internet
understand only IP address. To reach a
site host name is to be converted to IP
address.
DNS servers in the Internet search IP
address of these host names.
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Domain Name System (DNS)
DNS Server
What is the IP Address of
www.Yahoo.com
What is the IP Address of
www.Yahoo.com
DNS Server
Internet
User traffic
www.yahoo.com , IP address
is 210.212.90.15
www.yahoo.com , IP address
is 210.212.90.15
yahoo.com
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