Transcript Internet and IP infrastructure

Internet and IP infrastructure
Internet basics
• ARPANET – Advanced Research Project Agency Network developed by US DoD
Advanced Research Project Agency introduced in 1969.
• World’s first packet-switched network
• ARPA renamed as Defense Advanced Research Project Agency (DARPA) and
started working on packet-switched as well as LANs, paging and satellite networks
• Internet Protocol (IP) was created in 1973 to support an open-architecture
network protocol to communicate between the disparate networks via gateways
– routers
• Internet Assigned Numbers Authority (IANA) – currently operated as Internet
Corporation for Assigned Names and Numbers (ICANN) oversees IP address
allocation, DNS, root zone management, protocol and port numbers
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Organizations for managing the Internet
• Internet Society (ISOC) – focuses on Internet standards, education
and policy
• Internet Engineering Task Force (IETF) – a community of network
designers, operators and vendors to create the technical standards
through consensus
• Internet Assigned Numbers Authority (IANA) – for assigned names
and numbers
Organizations for
managing the Internet
• Regional Internet Registries (RIR) – Registration
of IP addresses is managed by 5 RIRs
• ARIN – American Registry for Internet
Numbers for North America
• APNIC – Asia-Pacific Network Information
Centre for Asia Pacific region
• RIPE NCC – Reseaux IP European Network
Coordination Center for Europe, Central Asia
and Middle East
• LACNIC – Latin American and Caribbean
Internet Address Registry
• AfriNIC – African Network Information
Centre for Africa
Internet and how it works
• An internetwork composed of a collection of networks,
routers, gateways, servers and clients linked by a set of
telecommunication protocols – the IP family.
• Client – a set of computers that receives services
from servers
• Server – a computer or software program that
provides services to network users or Web services to
internet users.
• Intranets – internal networks connecting site-to-site
LAN interconnections through WAN
• Extranet – connections between partnering
organizations using IP
• Router – the main process that a host uses to deliver
packets from one network to other.
The Internet and PSTN
• Internet
• Internet uses packet switching which fragments data into packets and does
not require any dedicated connection
• Each packet travelled through different routes and reassembled at the
destination
• PSTN
• PSTN uses circuit switching which requires dedicated circuit setup and taken
down for each call
• This allows PSTN charging based on minutes
• PSTN is reliable
host
host
HTTP message
HTTP
HTTP
TCP segment
TCP
TCP
router
IP
Ethernet
interface
IP packet
router
IP packet
IP
Ethernet
interface
IP
SONET
interface
SONET
interface
IP packet
Ethernet
interface
IP
Ethernet
interface
Internet Protocol
• Protocols are formal description of messages to be exchanged and of rules
to be followed in order for two or more systems to exchange information in
a manner that the parties will understand
• The set of Internet’s Protocols are
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IP – Internet Protocol
TCP – Transmission Control Protocol
UDP – User Datagram Protocol
SCTP – Stream Control Transmission Protocol
DCCP – Datagram Congestion Control Protocol
ICMP – Internet Control Message Protocol
IGMP – Internet Group Management Protocol
ARP – Address Resolution Protocol
RARP – Reverse Address Resolution Protocol
IP
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IP defines the format and basic unit of data transfer which is known as packet or
datagram
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Datagram has 4 entities
• Data/payload
• Protocol (TCP/UDP)
• IP
• Layer 2 (L2) PDU
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IP provides routines to route, to store or forward data among hosts.
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IP services include
• Host addressing
• Error notification
• Fragmentation and reassembly
• Routing
• Packet timeout
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Maximum IP packet sizes are 1500 bytes
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IP protocol is connectionless, best effort service
TCP
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The most common Layer 4 protocol
TCP segments data into packets and give a sequence number to each
Sequence numbers are used to reassemble the packets at destination for reliable data delivery
TCP also ensures data delivery to the right application by assigning port number within the range
of 1 to 65,535
Port number resides in the TCP header and is assigned to user sessions and server applications
The combination of a port number and IP address is called socket
Numbers between 1 to 1023 are reserved for well-known server applications (port 80 for Web
server, port 21 for FTP)
TCP is responsible for
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Virtual circuit setup
Flow control
Error control
Retransmission
UDP
• Transport Layer (L4) protocol
• Provides end-to-end, connectionless, unreliable datagram service
• Suitable for query/response application, multicasting, VoIP
• UDP has minimum delay, but unreliable as it does not support
retransmission
• UDP does not provide error correction and sequenced delivery,
instead the application under way has to incorporate such services
• In order to avoid the connection setup and retransmission overhead
of TCP, UDP is preferable for multimedia applications
SCTP and DCCP
• SCTP and DCCP are Layer 4 protocols
• SCTP is introduced
• to overcome the limitation of TCP for transport of signaling messages and
VoIP networks, Stream Control Transmission Protocol is introduced
• Applications such as telephone signaling over IP, multimedia Web browsing,
video over IP, IPTV are supported by SCTP
• DCCP supports
• Congestion control for unreliable dataflow
• unreliable transport with acknowledgement, reliable handshake, negotiation
of features and congestion control
ICMP and IGMP
• Internet Control Messaging Protocol (ICMP)
• Layer 3 protocol
• Best effort delivery of messages over IP header
• Provides error-handling, error control and network congestions
• Internet Group Management Protocol (IGMP)
• Layer 3 protocol
• Designed to allow Internet hosts to participate in multicasting IP traffic –
formatting, addressing and encapsulation
ARP and RARP
• Address Resolution Protocol
• Layer 3 protocol
• Resolves the IP address of a node to physical address (MAC address) from
mapping table
• Reverse Address Resolution Protocol
• Rediscovers physical address to logical address (MAC to IP address
conversion) by broadcasting its physical address
• A node within the LAN answers with IP address
Routing Protocols
• Allows routers to communicate with each other
• Computes various metrics to compute the destination path efficiently
• Distance
• Cost
• Routing protocols are
• RIP (Routing Information Protocol)
• IGP (Interior Gateway Protocol)
• OSPF (Open Shortest Path First)
• EGP (Exterior Gateway Protocol)
• BGP (Border Gateway Protocol)
Internet addressing and
address resolution
• Each host in the Internet is assigned a unique 32-bit IP address to
route the packets to destination
• Bits in IP address indicate the network/subnetwork number
and the host
• The host portion is examined after the packet reaches to
destination network
• Information flow in a network can be
• Unicast – serves one-to-one communication such as server
to host
• Multicast – serves one-to-many communication such as a
videoconferencing between three remote locations which
uses only one IP connection and multicast addresses
• Anycast – point-to-point flow of packet between a client and
the nearest destination
IPv4 addressing
• IP address has two parts – network address and host
address
• Classful IP addressing – addressing to the boundary of 8bits
• Classless Interdomain Routing (CIDR) – address are
assigned as per ISPs and hosts instead of 8-bit octates
• Class A – 126 networks with 16,777,214 hosts
• Class B – 16384 networks with 65,534 hosts
• Class C – 2,097,152 networks with 254 hosts
• Class D – reserves for multicast
• Class E – reserved for experimental purposes