Review: Lecture 1 - Internet History

Transcription

1 Review: Lecture 1 - Internet History late 60's ARPANET, NCP 1977 first internet 1980's The Internet collection of networks communicating using the TCP/IP protocols 1

2 Review: Lecture 1 - Administration 2

3 Review: Lecture 1 - Standards TSIN02 - Internetworking Protocol specifications are entered into the so called standards track and goes through a set of maturity levels: Proposed, Draft, and Internet Standards, and Historic Internet drafts become RFCs when entered into the standards track. 3

4 Review: Lecture 2 - Network layer The network layer provides source to destination delivery of packets (across multiple networks) logical addressing routing 4

5 Review: Lecture 2 - Layer 3 Protocols ARP, RARP - converts physical addresses to logical and vice versa IP - an unreliable and connectionless datagram protocol. IPv4 vs IPv6 address space - header format fragmentation - new options security - resource allocation ICMP - a protocol for error reports and querys ICMPv6 incorporates ARP, RARP and IGMP 5

6 Review: Lecture 3 - Multicast TSIN02 - Internetworking One- to- many TV over IP Massive file distribution Many- to- many Video conferencing Many- to- one Send messages to a server with unknown IP# using a well- known multicast address. Example: locating servers (DHCP, SIP, MADCAP etc) 6

7 IGMP Internet Group Management Protocol Just for group membership communication between a host and a router Has nothing to do with multicast routing Keeps an updated list of active group listeners for each connected LAN. Simplistic network layer service. No address management, no session management, no reliable data delivery, no security support, no synchronism IGMP ICMP IP ARP RARP 7

8 IGMP versions Version 1: Just two message types: Host Membership Query Host Membership Report Version 2: Added the message type Leave Report This message is essential for decreasing zaptimes when connection only has room for one stream Version 3: Added support for source specific multicast A group is identified with a pair (S,G) where S is the sender IP# and G a normal multicast address. 8

9 Review Lecture 4 - Transport layer The transport layer provides process- to- process communication control mechanisms UDP - connectionless and unreliable transport TCP connection- oriented and reliable Stream delivery - Options Flow control - Congestion Control Error Control - Timers 9

10 Review Lecture 5 - Security Security aspects - Privacy, Authentication, Integrity and Non- repudiation Cryptography Secret (symmetric) Keys vs Public (asymmetric) Keys Hash Functions vs Digital Signatures Key Distribution IPsec, TLS, PGP, GPG, SSH Firewalls - packet filtering vs proxy Private and virtual private networks 10

11 Review: Lecture 6 - Autoconfiguration How to configure IP#, netmask and gateway? RARP BOOTP DHCP Zero- configuration of link- local addresses (i.e., no global route) an expired draft captures current behavior of Windows and Mac. DHCPv6 simplified and secure version of DHCPv4 IPv6 may use stateless address autoconfiguration Part of address constructed from hardware address. The other part from a prefix broadcast by IPv6 router 11

12 Service Discovery Two methods identified SLP Service Location Protocol Quite complex. May use a directory service DNS SRV Resource Record Create special host entries in the DNS database. Example host name:. _smtp._tcp It is unclear if these mechanisms have a future. They compete with many other protocols such as MS Active Directory, CORBA and UPnP (Universal Plug and Play) 12

13 Review: Lecture 7 - Real- time Streaming A real- time communication scenario needs to solve the following issues: Packet loss. Arrival jitter Sender/receiver synchronization Handling packet loss the TCP way might be unwanted due to that TCP leaves no firm guarantees on the delay time. Only QoS- mechanisms can solve this. Arrival jitter is solved by using a receiver buffer. Synchronization can be solved in various ways:(implicit, Global, Point- to- point) 13

14 RTP and RTCP TSIN02 - Internetworking Real- time protocol and Real- time Control Protocol works in tandem to Send one type of media to a receiver or group of receivers Convey timing information for point- to- point or global synchronization Uniquely identify a source regardless of underlying packet forwarding service (typically UDP) Convey upstream information about traffic situation in a scaleable manner (I.e., scale down control traffic when number of receivers increase) 14

15 SDP & RTSP SDP Session Description Protocol Really a data format describing associated media and how and when they will be transmitted. (E.g., multicast addresses, payload formats and port numbers) RTSP Real- time Streaming Protocol The Internet VCR Remote control protocol Works very much like HTTP. Uses SDP- data to answer DESCRIBE- requests. Fine- grained control over media. E.g. Audio and video can be referred by separate URL:s and may need separate setup to stream in synchronization. 15

16 Review Lecture 8 - Voice over IP TSIN02 - Internetworking Voice over IP requirements Signaling protocols: locate users, set up modify and tear down calls. Media transport protocols for transmission och packetised audio/video Supporting protocols for QoS, Security etc. SIP - IETF standard for session handling H ITU standard for session handling Megaco - joint venture between IETF and ITU 16

17 Review Lecture 9 - Mobile IP TSIN02 - Internetworking Home and Care- of Addresses Home and Foreign Agents Setting up communication from a foreign network discover agents register with agents transfer data Routing inefficiency MIPv4 vs MIPv6 17

18 Review Lecture 10 - SNMP TSIN02 - Internetworking A framework for managing devices in an internet. Agents and Managers A protocol for carrying management information request - response uses connectionsless services (UDP) SMI MIB 18

19 Review Lecture 11 - SCTP TSIN02 - Internetworking A new transport layer protocol connection- oriented and reliable supports multiple streams supports multihoming developed with ip telephony in mind 19

20 Review Lecture 11 - AAA TSIN02 - Internetworking Authentication Authorization Accounting (Auditing) Suggested protocol: DIAMETER 20

21 Review Lecture 12: The Future Some hot topics are: SIP Mobile IP SCTP Security Multimedia transport Ad Hoc Networking TSIN02 - Internetworking 21

22 Ad Hoc Networks TSIN02 - Internetworking Ad Hoc Networks are about building a network without one or more of the following: Routing infrastructure Server infrastructure Administrative infrastructure The protocols that are suitable in an Ad Hoc network depend on whether The network is spontaneous or planned The network is localized or distributed The participating nodes are uniform or diverse in capabilities The network will be for short or long term 22

23 Key Management in Ad hoc Networks Usually a trusted third party is part of a key management scheme. Here we cannot rely on only one node performing these tasks. Some proposed solutions are: Partially distributed certificate authority Fully distributed certificate authority Self issued certificates Secure pebblenets Demonstrative identifikation Password authenticated key exchange 23

24 Internetworking The art and science of connecting individual localarea networks (LANs) to create wide-area networks (WANs), and connecting WANs to form even larger WANs. Internetworking can be extremely complex because it generally involves connecting networks that use different protocols. Internetworking is accomplished with routers, bridges, and gateways. from the Webopedia Computer Dictionary 24