Telecommunications Essentials

Chapter 8The Internet & IP Infrastructure

Internet Basics

Time to reach 50,000,000 peopleTelephone – 74 yearsInternet – 4 years

ARPA – 1969 – develops a distributed data networkBomb resistant networkShared computing resourcesDeveloping LANs, paging systems, satellite networks

1980 – TCP/IPCisco

Internet Organizations

No one is in chargeISOC

An international non-profit organizationOversees the IETF (designs standards through consensus)

Registry organizationsARIN, APNIC, RIPE NCC, IANA, ICANN

Internet Structure

An ad hoc internetwork of networksUses the IP protocol suiteUses routers to move packets between networksRouters operate at OSI Layer 3Routers know the address of network segments and the various interconnecting paths

Internet Protocols - IP

Defines the datagram (packet)ConnectionlessOperates at OSI layer 3Handles packet forwarding, addressing, error notificationSegments the data to 1500 byte chunks (64000 bytes is allowed but never used)

Internet Protocols - UDP

Adds application multiplexing & checksum to IP Used for multicasting & VoIPNo error correction (the application must provide error correction)

Internet Protocols - TCP

TCP – Assigns packet and port numbers

Connection orientedOperates at OSI layer 4Sets up virtual circuits, flow control, ACK, retransmission

Port Numbers

1 – 65,535Assigned to user sessionsSocket = port number + IP address

Identify server applications21 – FTP25 – E-mail80 – Web servers

Firewalls can use port numbers & IP addresses to control information flow

Other Internet Protocols

ICMP - Used by operating systems to send error messages. Ping - sends ICMP Echo Request to determine delayIGMP - Manages the membership of Internet Protocol multicast groupsARP & RARP – maps between IP and MAC addresses

Network (Routing) Protocols

Used to connect to the service providerSLIP, PPP

Interior - used within autonomous systemsOSPF

Exterior - used between autonomous systems (service providers)

BGP

Routing Protocols

Distance Vector – each router sends a copy of its routing table to its neighbor

RIP, IXP, RTMP,IGRP

Link State – shares information regarding numbers of hops, line speed, traffic, cost, etc.

OSPF, IS-IS, NLSPMore reliable, easier to debug, less network traffic

ISP Terminology

POP – Point of presenceGigaPOPNAP – Network access pointIXP – Internet exchange pointMAE – Metropolitan exchange areaBackbone NetworkNSP – Network service providerTier 1, Tier 2, Tier 3

IPv4 Addressing

32 Bits long2 Parts – Network ID and host ID5 Classes

Class A – very large networks (126)Class B – medium sized networks (16,384)Class C – small to mid size business (2,097,152 each of which can have 254 hosts)Class D – multicast or mboneClass E – experimental

CIDR – Allows blocks of addresses to be grouped together in routing tables

IPv6 Addressing

128 bits long 2 Parts - 64 bits network ID, 64 bits host IDUses hexadecimal notationAdvantages• Improved routing efficiency• QoS capabilities• Better security mechanisms

Deployment• Not widely used in the US•Required in Japan & far east (3G wireless phones)

Moonv6 largest multivendor IPv6 network

DNS & TLD

Translates host names to IP addressesLocal name server – in a company or ISPDomain name resolvers – local computers duplicating root domain serversRoot domain servers - 13

IP QoSPresent System

• Best Effort – no guarantees

QoS Parameters:• Latency• Jitter• Loss• Sequencing• Errors

Needed for real-time traffic• VoIP• Video• Interactive applications

QoS Mechanisms• Classification (different kinds of packets)• Conditioning (traffic shaping)• Queue management (RED)• Queue scheduling (prioritizing)

Queuing Mechanisms• Fair queuing• Weighted fair queuing• Weighted round robin• Deficit round robin

IP QoS

DiffServ – Differentiated services• Header flags set hop behaviors• Defines latency, and jitter

IntServ - Integrated services• Uses RSVP to reserve bandwidth• Not practical on the internet• RSVP-TE used on MPLS

NSIS – Next steps in signaling