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
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