1. Review of Important Networking Concepts
Introductory material using Prof. Liebeherr on-line notes
Review of important networking concepts: protocol architecture, protocol layers, encapsulation, demultiplexing, network abstractions.

2. Networking Concepts Layered Architecture to reduce complexity
Encapsulation
Abstractions

3. Sending a packet from Argon to Neon

4. Sending a packet from Argon to Neon
is not on my local network.
Therefore, I need to send the packet to my
default gateway with address
is on my local network.
Therefore, I can send the packet directly.
DNS: What is the IP address of “neon.netlab.edu”?
DNS: The IP address of “neon.netlab.edu” is
ARP: What is the MAC address of ?
ARP: The MAC address of is 00:e0:f9:23:a8:20
ARP: What is the MAC address of ?
ARP: The MAC address of is 00:20:af:03:98:28
frame
frame

5. What’s a protocol? human protocols: “what’s the time?”
“I have a question”
introductions
… specific msgs sent
… specific actions taken when msgs received, or other events
network protocols:
machines rather than humans
all communication activity in Internet governed by protocols
protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt

6. What’s a protocol? Hi Hi 2:00 <file> time
a human protocol and a computer network protocol: Hi
TCP connection
req Hi
TCP connection
response
Got the
time?
Get
2:00
<file>
time
Q: Other human protocols?

7. Communications Architecture
The complexity of the communication task is reduced by using multiple protocol layers:
Each protocol is implemented independently
Each protocol is responsible for a specific subtask
Protocols are grouped in a hierarchy
A structured set of protocols is called a communications architecture or protocol suite

8. TCP/IP Protocol Suite
The TCP/IP protocol suite is the protocol architecture of the Internet
The TCP/IP suite has four layers: Application, Transport, Network, and Data Link Layer
End systems (hosts) implement all four layers. Gateways (Routers) only have the bottom two layers.

9. Functions of the Layers
Data Link Layer:
Service: Reliable transfer of frames over a link Media Access Control on a LAN
Functions: Framing, media access control, error checking
Network Layer:
Service: Move packets from source host to destination host
Functions: Routing, addressing
Transport Layer:
Service: Delivery of data between hosts
Functions: Connection establishment/termination, error control, flow control
Application Layer:
Service: Application specific (delivery of , retrieval of HTML documents, reliable transfer of file)
Functions: Application specific

10. TCP/IP Suite and OSI Reference Model
The TCP/IP protocol stack does not define the lower layers of a complete protocol stack

11. Assignment of Protocols to Layers

12. Layered Communications
An entity of a particular layer can only communicate with:
1. a peer layer entity using a common protocol (Peer Protocol)
2. adjacent layers to provide services and to receive services

13. Service Primitives
Communication services are invoked via function calls. The functions are called service primitives
N+1 Layer Entity
N+1 Layer Peer Protocol
N+1 Layer Entity
Request Delivery
Indicate Delivery
N Layer Entity
N Layer Entity

14. Service Primitives
Recall: A layer N+1 entity sees the lower layers only as a service provider
N+1 Layer Entity
N+1 Layer Peer Protocol
N+1 Layer Entity
Request Delivery
Indicate Delivery
Service Provider

15. Layers in the Example

16. Layers in the Example Send the datagram to 128.143.7.21
Send HTTP Request to neon
Establish a connection to at port 80
Open TCP connection to port 80
IP datagram is a TCP segment for port 80
Send a datagram (which contains a connection request) to
Send IP data-gram to
Send IP datagram to
Frame is an IP datagram
Frame is an IP datagram
Send the datagram to
Send the datagram to
Send Ethernet frame to 00:e0:f9:23:a8:20
Send Ethernet frame to 00:20:af:03:98:28

17. Layers and Services Service provided by TCP to HTTP:
reliable transmission of byte streams over a logical connection
Service provided by IP to TCP:
unreliable transmission of IP datagrams across an IP network
Service provided by Ethernet to IP:
transmission of a frame across an Ethernet segment
Other services:
DNS: translation between domain names and IP addresses
ARP: Translation between IP addresses and MAC addresses

18. Encapsulation & Demultiplexing
As data is moving down the protocol stack, each protocol is adding layer-specific control information

19. Encapsulation & Demultiplexing in our Example
Let us look in detail at the Ethernet frame between Argon and the Router, which contains the TCP connection request to Neon.
This is the frame in hexadecimal notation.
00e0 f923 a820 00a e c 9d bff 808f f b b e b4

20. Encapsulation & Demultiplexing

21. Encapsulation & Demultiplexing: Ethernet Header

22. Encapsulation & Demultiplexing: IP Header

23. Encapsulation & Demultiplexing: IP Header

24. Encapsulation & Demultiplexing: TCP Header
Option: maximum segment size

25. Encapsulation & Demultiplexing: TCP Header

26. Encapsulation & Demultiplexing: Application data

27. Different Views of Networking
Different Layers of the protocol stack have a different view of the network. This is HTTP’s and TCP’s view of the network.

28. Network View of IP Protocol

29. Network View of Ethernet
Ethernet’s view of the network

30. The Evolution of Internet
Introductory material.
An overview lecture that covers Internet related topics, including a definition of the Internet, an overview of its history and growth, and standardization and naming.

31. A Definition
On October 24, 1995, the FNC unanimously passed a resolution defining the term Internet.
RESOLUTION: The Federal Networking Council (FNC) agrees that the following language reflects our definition of the term "Internet". "Internet" refers to the global information system that --
(i) is logically linked together by a globally unique address space based on the Internet Protocol (IP) or its subsequent extensions/follow-ons;
(ii) is able to support communications using the Transmission Control Protocol/Internet Protocol (TCP/IP) suite or its subsequent extensions/follow-ons, and/or other IP-compatible protocols; and
(iii) provides, uses or makes accessible, either publicly or privately, high level services layered on the communications and related infrastructure described herein.

32. Internet History 1961-1972: Early packet-switching principles 1972:
1961: Kleinrock - queueing theory shows effectiveness of packet-switching
1964: Baran - packet-switching in military nets
1967: ARPAnet conceived by Advanced Research Projects Agency
1969: first ARPAnet node operational
1972:
ARPAnet demonstrated publicly
NCP (Network Control Protocol) first host-host protocol
first program
ARPAnet has 15 nodes

33. Internet History 1972-1980: Internetworking, new and proprietary nets
Cerf and Kahn’s internetworking principles:
minimalism, autonomy - no internal changes required to interconnect networks
best effort service model
stateless routers
decentralized control
define today’s Internet architecture
1970: ALOHAnet satellite network in Hawaii
1973: Metcalfe’s PhD thesis proposes Ethernet
1974: Cerf and Kahn - architecture for interconnecting networks
late70’s: proprietary architectures: DECnet, SNA, XNA
late 70’s: switching fixed length packets (ATM precursor)
1979: ARPAnet has 200 nodes

34. Internet History Late 1990’s – 2000’s:
1990, 2000’s: commercialization, the Web, new apps
Early 1990’s: ARPAnet decommissioned
1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995)
early 1990s: Web
hypertext [Bush 1945, Nelson 1960’s]
HTML, HTTP: Berners-Lee
1994: Mosaic, later Netscape
late 1990’s: commercialization of the Web
Late 1990’s – 2000’s:
more killer apps: instant messaging, P2P file sharing
network security to forefront
est. 50 million host, 100 million+ users
backbone links running at Gbps

35. Applications of the Internet
Traditional core applications: News Remote Login File Transfer
The killer application: World-Wide Web (WWW), P2P
Future applications: Videoconferencing and Telephony Multimedia Services Internet Broadcast

36. Growth of the Internet
Source: Internet Software Consortium

37. Internet Infrastructure

38. Internet Infrastructure
The infrastructure of the Internet consists of a federation of connected networks that are each independently managed (“autonomous system”)
Note: Each “autononmous system may consist of multiple IP networks
Hierarchy of network service providers
Tier-1: nation or worldwide network (US: less than 20)
Tier-2: regional networks (in US: less than 100)
Tier-3: local Internet service provider (in US: several thousand)

39. Internet Infrastructure
Location where a network (ISP, corporate network, or regional network) gets access to the Internet is called a Point-of-Presence (POP).
Locations (Tier-1 or Tier-2) networks are connected for the purpose of exchanging traffic are called peering points.
Public peering: Traffic is swapped in a specific location, called Internet exchange points (IXPs)
Private peering: Two networks establish a direct link to each other.

40. Tier-1 ISP: e.g., Sprint
Sprint US backbone network

41. Who is Who on the Internet ?
Internet Society (ISOC): Founded in 1992, an international nonprofit professional organization that provides administrative support for the Internet. Founded in 1992, ISOC is the organizational home for the standardization bodies of the Internet.
Internet Engineering Task Force (IETF): Forum that coordinates the development of new protocols and standards. Organized into working groups that are each devoted to a specific topic or protocol. Working groups document their work in reports, called Request For Comments (RFCs).
IRTF (Internet Research Task Force): The Internet Research Task Force is a composed of a number of focused, long-term and small Research Groups.
Internet Architecture Board (IAB): a technical advisory group of the Internet Society, provides oversight of the architecture for the protocols and the standardization process
The Internet Engineering Steering Group (IESG): The IESG is responsible for technical management of IETF activities and the Internet standards process. Standards. Composed of the Area Directors of the IETF working groups.

42. Internet Standardization Process
Working groups present their work i of the Internet are published as RFC (Request for Comments).
RFCs are the basis for Internet standards.
Not all RFCs become Internet Standards ! (There are >3000 RFCs and less than 70 Internet standards
A typical (but not only) way of standardization is:
Internet Drafts
RFC
Proposed Standard
Draft Standard (requires 2 working implementation)
Internet Standard (declared by IAB)

43. Assigning Identifiers for the Internet
Who gives University the domain name “netlab.edu” and who assigns it the network prefix “ /16”? Who assigns port 80 as the default port for web servers?
The functions associated with the assignment of numbers is referred to as Internet Assigned Number Authority (IANA).
Early days of the Internet: IANA functions are administered by a single person (Jon Postel).
Today:
Internet Corporation for Assigned Names and Numbers (ICANN) assumes the responsibility for the assignment of technical protocol parameters, allocation of the IP address space, management of the domain name system, and others.
Management of IP address done by Regional Internet Registries (RIRs):
APNIC (Asia Pacific Network Information Centre)
RIPE NCC (Réseaux IP Européens Network Coordination Centre)
ARIN (American Registry for Internet Numbers)
Domain names are administered by a large number of private organizations that are accredited by ICANN.

44. Summary Layered Internet architecture Reduce complexity
Higher layer views lower layer as service provider
Application layer, transport layer, network layer, and link layer