一些数据.ppt

一些数据,从1978年到2007年，通信业年业务收入一直保持两位数增长并一直领先于GDP增幅。业务总量和业务收入年同比增长率均保持了两位数，年收入规模从7.3亿元扩张到7280亿元，年均增长率达到26.9% 7887年，电信业务收入年平均增长率达到21.1%, 7.3 亿- 41.1亿 8897年，电信业务收入年复合增长率达到42.2%, 59.6亿 1421.3亿 9807年，电信业务收入年平均增长率达到16.6%, 1828.4亿 7280亿 2007年，电信业务收入增长11.2%, GDP增速13.0% 2008年，电信业务收入增长9.0%, GDP增速6.6% 2009年上半年，电信业务收入增长2.3%，不到GDP的1/3 电信业的转型 话务运营阶段 转型阶段 信息运营阶段,1,机会在哪里？,3G与宽带！ 2009年上半年，电信运营商资本开支投向主要是3G、传输网(光传输)、和宽带(FTTx) 3G 中国移动计划2009年底前3G覆盖238个城市，2011年覆盖所有地级市 中国联通3G网络覆盖城市已由年初计划的284个扩大到年内的335个，2010年将近一步扩大覆盖面 宽带业务具有高ARPU值，现金流稳定的特征 宽带提速 有线宽带和无线宽带的融合发展和无缝连接,2,Network layer in practice: IP and atm,The TCP/IP protocol suite,4,Transmission Control Protocol / Internet Protocol Developed by DARPA to connect universities and research labs,Telnet, FTP, email etc,TCP, UDP,IP, ICMP, IGMP,Device drivers, interface cards,TCP: Transmission Control Protocol UDP: User Datagram Protocol IP: Internet Protocol,The Internet Layered model,Internetworking with TCP/IP,5,application,transport,IP,Data link and lower layer,application,transport,IP,Data link and lower layer,IP,Ethernet,Token ring,Token ring,Ethernet,Ethernet,IP protocol,IP protocol,TCP/UDP protocol,FTP, HTTP, SMTP,The TCP/IP suite,6,PING,telnet & rlogin,FTP,SMTP,X,Trace route,DNS,TFTP,BOOTP,SNMP,RPC,TCP,UDP,ICMP,IP,IGMP,DATA LINK,ARP,RARP,Internet sub-layer,A sub-layer between the transport and network layers is required when various incompatible networks are joined together This sub-layer is used at gateways between the different networks In the internet this function is accomplished using the Internet Protocol (IP),7,IP,DLC Layer Link 1,DLC Layer Link 1,DLC Layer Link 1,On a gateway connecting different types of networks, IP is the protocol to realize inter-operability,IP addresses,32 bit address written as four decimal numbers One per byte of address (202.120.39.134) IP Address classes,8,8,32,16,32,16,32,Class A Address,Class B Address,Class C Address,16,32,Class D Address, (For multicast only),IPv4 address classes,9,Routing a packet in the network,10,1,2,1,2,3,1,3,2,1,2,3,4,1,2,3,1,2,3,4,IP router architecture,3 generations of IP routers,Bus based router,Bus based router with dist. routing,Switch-based router with multi. Forwarding eng.,Host name,Each host has a unique name Domain name system (DNS): a distributed database that provides a mapping between IP addresses and host names E.g., 202.120.39.134 FRONT.SJTU.EDU.CN,13,Internet standards,Internet Engineering Task Force (IETF) Development on near term internet standards Open body Meets 3 times a year Request For Comments (RFCs) Official internet standards Available from IETF web page: http:/www.ietf.org/,14,The Internet protocol (IP),Routing packets across the network Unreliable service Best effort delivery Recovery from lost packet must be done at higher layers Connectionless Packets are delivered independently Can arrive out of order Re-ordering must be done at higher layers Current version V4, IPv4 Future IPv6,15,IP header,16,Note that the minimum header size is 20 bytes, or 160 bits,IP header,17,Dynamic Host Configuration (DHCP),Automated method for assigning network numbers IP addresses, default routers Computer contact DHCP server at Boot-up time Server assigns IP address Allows sharing of address space More efficient use of address space Adds scalability Addresses are “leased” for some time Not permanently assigned,18,Address Resolution Protocol (ARP),The role of the IP routing is to deliver the packet to its destination subnet To the last hop router Addressing inside a subnet, or a LAN, is based on local addresses, such as Ethernet addresses ARP provides a mapping between IP addresses and LAN addresses RARP provides mapping from LAN addresses to IP addresses Both accomplished by sending out a broadcast message An ARP cache is maintained at each node with recent mappings to avoid frequent address resolution (for better performance),19,ARP at source subnet,20,R1,(4) I am here at 00-01-21-32-32-32,(3) Hi all Where is my lovely router R1?,Computer S is configured to have a default router R1 S wants to send a message to D, and D is outside of the same LAN S sends an ARP request for Ethernet Address of R1 R1 sends ARP responds to S S sends the message to R1 with Ethernet addressing R1 routes the packet to the next hop in the internet and the message will be subsequently routed further toward D,ARP at destination subnet,21,R2,(3) Hi all I got a message for 202.120.39.134. Where is he?,(4) Hi R2 I am here at 00-01-01-11-AB-ED,An IP packet is delivered by the network from its source subnet to router R2. Router R2 realizes that the packet has reached its destination subnet by comparing the destination address in the IP packet and its local interface configurations (subnet address and mask) Router R2 sends an ARP request on the interface to the subnet Destination node D responses to the request Packet is delivered to D with Ethernet addressing,Routing in the multi-AS Internet,The Internet is divided into sub-networks, each under the control of a single authority known as an Autonomous Systems (AS) Routing algorithms are divided into two categories Interior protocols (within an AS) Exterior protocols (between ASs) Interior protocols use shortest path algorithms Distance vector proto. Based on Bellman-Ford Link state proto. Based on Dijkstras algorithm Exterior protocols route packets across ASs Issue: no single cost metric, policy routing, etc Hierarchical routing based on “peering” agreements Example: Exterior Gateway Protocol (EGP) and Border Gateway Protocols (BGP),22,Border Gateway Protocol (BGP),Routing between Autonomous systems Find a path (no optimality) to destination (AS) Path must satisfy policy criteria,23,AS corporation,AS Large service provider,AS Large service provider,AS Small ISP,AS corporation,AS corporation,AS Small ISP,AS Small ISP,Transit AS,Multi-homed AS (No transit traffic),Stub AS,BGP overview,BGP speaker one per AS Establishes (TCP) sessions with other “speakers” to exchange reachability information Border “gateways” routers that interface between ASs BGP advertises complete paths to destination AS Avoid loop problems Enable policy decisions (e.g. avoid certain ASs) AS numbers centrally assigned 16 bit numbers for transit ASs,24,128.64.3 128.61.2,192.12.2,Path to 128.64.2: (AS-144, AS-367),AS - 12,AS - 144,AS - 367,AS - 298,Relationship between ASs,ISP “tiers” Tier-1 ISPs provide global reachability Tier-2 ISPs regional/country Tier-3 ISPs local Provider-customer relationship (transit) Smaller ASs purchase internet access from larger ones Peering ISPs of similar size are “peers” and forward each others traffic at no charge Paid peering: a small ISP may purchase the right to peer with a larger provider Policy issue Which route would an ISP advertise?,25,Tier-1 ISP,Tier-2 ISP,Tier-1 ISP,Tier-2 ISP,Tier-3 ISP,IPv6,Effort started in 1991 as IPng Motivation Need to increase IP address space Support for real-time applications QoS Security, mobility and auto-configuration Major changes Increased address space (128bit) Support for QoS via Flow Label field Simplified header Security Transition to IPv6 Cannot be done at once; must support co-existance Dual-stack: routers run both IPv4 and IPv6 Tunneling: IPv6 packets carried in payload of IPv4 packets, or vice versa,26,QoS in the Internet,Quality of Service parameters Dropped packets Delay Jitter Out-of-order delivery Error Applications that require QoS Multimedia streaming IPTV IP telephony, or VoIP Video conferencing Online game Remote control ,27,QoS mechanisms,IntServ: integrated services best-effort service, real-time service, and controlled link sharing Resource reserved prior to data transfer Resource released after transfer completes,28,request,grant,QoS mechanisms (cont.),DiffServ: differentiated services Tagging on ingress edge node Un-tagging on egress edge node Routed/processed in network according to the tag/label Realizes service differentiation through per-hop behavior (PHB),29,DiffServ and MPLS,30,MPLS: Multi-Protocol Label Switching,ATM - Asynchronous Transfer Mode,1980s effort by the phone companies to develop an integrated network standard (B-ISDN) that can support voice, data, video, etc. ATM uses small (53 Bytes) fixed size packets called “cells” Why cells? Cell switching has properties of both packet and circuit switching Easier to implement high speed switches Why 53 bytes? Small cells are good for voice traffic (limit sampling delays) For 64Kbps voice it takes 6 ms to fill a cell with data ATM networks are connection oriented Virtual circuits,31,ATM Reference Architecture,Upper layers Applications TCP/IP ATM adaptation layer Similar to transport layer Provides interface between upper layers and ATM Break messages into cells and reassemble ATM layer Cell switching Congestion control Physical layer ATM designed for SONET Synchronous optical network TDMA transmission scheme with 125 s frames,32,ATM Cell format,33,VPI/VCI,34,ATM cell switches,35,ATM summary,ATM is mostly used as a “core” network technology ATM Advantages Ability to provide QoS Ability to do traffic management Fast cell switching using relatively short VC numbers ATM disadvantages It not IP -most everything was design for TCP/IP Its not naturally an end-to-end protocol Does not work well in heterogeneous environment Was not design to inter-operate with other protocols Not a good match for certain physical media (e.g., wireless) Many of the benefits of ATM can be “borrowed” by IP Cell switching core routers Label switching mechanisms,36,Project #1,Try to identify at least 3 applications that use plaint text password/identification method Use Wireshark to capture the plaint text password Write a report to describe the problem Due date: Oct. 28,37,