计算机网络,全英文

计算机网络

是非题 1.In computer networking jargon, the computers connected to the Internet are referred to as end systems, including servers , routers, mobile computers.

2.One of the attractive features of DSL and HFC is that the services are always on。

3.HTTP/1.1 uses inpersistent HTTP with pipelining.

4.UDP socket is identified by two-tuple: dest IP address, dest port number.

5.The IPv6 addresses space is 264.

6.ARP translates computer name to network-layer address.

7.HTTP uses reliably transfer email message from client to server, port number is 52.

8.Link Layer Services include Error Detection, full-duplex etc.

9.Star topology popular through mid 90s, Now bus topology prevails.

10.FTP,SMTP,POP3 and IMAP run on top of TCP rather than UDP.

11.With the SR protocol ,it is possible for the sender to receive an ACK for a packet that falls outside of its current window.

12.With GBN, it is possible for the sender to receive an ACK for a packet that falls outside of its current window. 13.Ethernet frames can carry more than 1500 bytes of data ,whereas frames for some wide-area links can carry no mare than 576 bytes.

14.Ipv6 allows for fragmentation at routers and IP header to be extended,but Ipv4 not.

15.For TDM, the time domain is segmented into four circuits; each circuit is assigned the same dedicated slot in the revolving TDM frames. The transmission rate of the frame is equal to the frame rate multiplied by the number of bits in a slot.

16.Most packet switches use store and forward transmission at the inputs to the links. Store-and-forward transmission means that the switch must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.

计算机网络,全英文

17.If a network employs virtual circuits, then the network's switches must maintain the ongoing connections. Specifically, each time a new connection is established connection entry must be added to the switch's VC number translation table; and each time a connection is released, an entry must be removed from the table.

名词解释：写英文全称和汉语全称

DNS Domain Name System 域名系统

FDM Frequency Division Multiplexing 频分多路复用

SMTP Simple Mail Transfer Protocol 简单邮件传输协议

TCP Transport Control Protocol 传输控制协议

RIP Routing Information Protocol 路由信息协议

ARP Address Resolution Protocol 地址解析协议

CSMA/CD Carrier Sense multiple Access/ Collision Detection 带有碰撞检测的载波侦听多点访问

MIME Multipurpose Internet Mail Extensions 多用途英特网邮件扩充协议

填空题

1.DNScvoked by an application to obtain the canonical hostname for a supplied alias hostname as well as the（IP address）of the host。

2.Two approaches toward congestion control are （end-to-end congestion control）and （network assisted congestion control）

3.The most fundamental responsibility of UDP and TCP is to extend IP's delivery service, extending host-to-host delivery to process-to-process delivery is called （transport layer multiplexing 多路传输、复用）and（demultiplexing多路分解 ）

4.Four types of OSPF routers（internal routers ） （boundary routers）（areas border routers） （backbone routers）

5.（filtering）(过滤、筛选)is the ability to determine whether a frame should be forwarded to an interface or should just be dropped.When the frame should be forwarded, （forwarding）（转发、运输）is the ability to determine which of the interfaces the frame should be directed to. These are done with a （switch table）.

计算机网络,全英文

6.Two generic forms of pipelined（流水线） protocols are （Go-back-N）and (selective repeat ).

7.(flow control)means that sender won’t overflow receiver’s buffer by transmitting too much, too fast. ( congestion control)is used to prevent too many hosts from sending too much data too fast for network to handle.

8.Moving packets from router’s input to appropriate router output is called (forwarding). Determining route taken by packets from source to dest is called ( routing).

( RIP) and (OSPF ) are two routing protocols have been used for routing within an autonomous system in the internet.

9.In practice, algorithms with global state information are referred to as (link state)algorithm,since the algorithm must be aware of the cost of each link in the network. The decentralized routing algorithm is called (distance vertor ) algorithm,because each node maintain a vector of estimates of the costs to all other nodes in the network.

10.Each IP node (Host, Router) on LAN has ARP table, ARP Table includes three parts: ( IP address),( MAC address)and TTL.

11.Any multiple access protocol belongs to one of the three categories: (channel partitioning protocol),(Random Access )and taking-turns protocols.

12.A switch has the property of building its table automatically, dynamically and autonomously -- without anyintervention from a network administrator or from a configuration protocol. In other words, switches are （self-learning / plug and play）。

13.Data which an application wants to send and passed onto the transport layer are called（application-layer message ）。Data generated by the transport layer and encapsulates application-layer message with transport layer header are called（transport-layer segments）。Data encapsulated transport-layer segment with a network-layer header are called（datagram）。 Data ncapsulated network-layer datagram with a link-layer header are called（frame）。

14.Three predominent architectures used in modern network applications are （client/server），（peer-to-peer），（Hybrid of client/server and peer-to peer）。

15.There are two fundamental approaches to build a network core: (circuit switching)and ( packet switching).

16.Access networks can be classified into three categories: ( residential access network),( institutional access network), mobile access networks.

17.Internet standards are developed by ( Internet Telecommunication Union), the Internet documents are called ( FTP files).

计算机网络,全英文

18.What services might a network application need from a transport protocol? We can broadly classify an application's service requirements along three dimensions: (data loss), (band width), and timing.

19.The TCP service model includes a ( connect-oriented service) and a (realiab data transfer service). When an application invokes TCP for its transport protocol, the application receives both of these services from TCP.

20.FTP uses two parallel TCP connections to transfer a file, （control connection）is used for sending control information between the two hosts, such as user identification, password, commands to change remote directory, and commands to "put" and "get" files.（data connection）is used to actually send a file.

21.At the receiving end, the transport layer can then examine this field to determine the receiving process, and then direct the segment to that process. This job of delivering the data in a transport-layer segment to the correct application process is called（demultiplexing）. The job of gathering data at the source host from different application processes, enveloping the data with header information to create segments, and passing the segments to the network layer is called（multiplexing）.

22.There are two types of network links , a ( point-to-point) link consists of a single sender at one end of the link and a single receiver at the other end of the link. A (broadcast)link can have multiple sending and receiving nodes all connected to the same, single,shared channel.

选择题

1.（ C）is reliable data transfer over channels with errors and loss。

A) rdt1.0 B)rdt2.0

C) rdt3.0 D)rdt2.1

2.In the following four types of delays ,( C) is uncertain 。

A)processing delay B) transmission delay

C) queuing delay D) propogation delay

3.Application that uses either TCP or UDP is ( A)。

A) Streaming multimedia B) Electronic mail

C)File transfer D)Web

4.( C) is called sliding-window protocol.。

A)SR protocol B)ARQ protocol

C)Go-Back-N protocol D)Alternating-bit protocol

计算机网络,全英文

5.During the period of encapsulation at the sending host，the network layer takes data

from transport-layer and appends network-layer header information，creating a network-layer （ C）。

A) message B)segment

C) datagram D)frame

6.The time required to examine the packet’s header and determine where to direct the packet is the part of the ( A)。

A）nodal processing B）queuing

C) transmission D) propagation

7.Which application runs over TCP rather than UDP? ( A)

A) file transfer B)streaming multimedia

C) DNS D)internet telephony

8.（ A ）are responsible for com, org, net, edu, etc.

A) Top-level domain (TLD) servers B) Authoritative DNS servers

C) Local Name Server D）Root name servers

9.The Internet's address assignment strategy is known as ( B )。

A)longest prefix matching rule B)CIDR(Classless Interdomain Routing)

C)classful addressing D)address aggregation

10.( D ) translates network-layer address to link-layer address。

A) DNS B) IGMP

C)MPLS D) ARP

简答：

1.What are some characteristics of TCP?

Full-duplex data Connection-oriented Flow control congestion control point-to-point Piplined send&receive buffer Reliable in-order byte stream

2.Why is it said that FTP sends control information "out of band"?

FTP use two parallel TCP connection:one connection for sending control connection and another Connection for actually transferring file.

Because the control information is not sent over the same connection that the file is send over . FTP sends control information out of band;

http://www.77cn.com.cnpare and contrast Link state algorithms and Distance-vector routing

计算机网络,全英文

Link state :computes the least-cost path between source and destination using complete global knowledge about network

Distance-vector routing :the calculation of the least-cost path is carried out in an iterative,distributed,manner. A node only knows the neighbour to witch it should forward a packet in order to reach given destination along the least-cost path ,and the cost of that path from Itself to the destination.

4.What are the principle characteristics of the connection-oriented service and connectionless service?

1\ two end system first: "hand shake"before send

Application data:

Provides reliable data transfer

Provides flow control

Provides congestion control

2\ no handshaking

No guarantees of reliable data transfer

No flow control or congestion control

5.Suppose A sends two TCP segments back-to-back to B. The first segment has sequence number 90; the second has sequence number 110.

a) How much data is the first segment? 20 bytes

b) Suppose that the first segment is lost, but the second segment arrives at B. In the acknowledgement that B sends to A, what will be the acknowledgment number?90

6.Describe why an application developer may choose to run its application over UDP rather than TCP.

An application may not wants its application use TCP'S congestion ,which can throttle the application's sending rate at times of congestion and choose to run their application on UDP because want to avoid TCP's congestion .

Also ,some application do not need the reliable data transfer provided by TCP;

7.Consider sending a 3000 byte datagram into a link that has a MTU of 500 bytes. Suppose the original datagram is stamped with the identification number 422. How many fragments are generated? What are their characteristics?

计算：

1.Consider the queueing delay in a router buffer (preceding an outbound link). Suppose all packets are L bits, the transmission rate is R bps and that N packets arrive to the buffer every LN/R seconds. Find the average queueing delay of a packet。

计算机网络,全英文

2.Consider three LANs interconnected by two routers, as shown in the diagram below.

a) Redraw the diagram to include adapters. shown in Figure 2

Assign IP addresses to all of the interfaces. For LAN 1 use addresses of the form 111.111.111.xxx ; for LAN 2 uses addresses of the form 122.222.222.xxx ; and for LAN 3 use addresses of the form 133.333.333.xxx .

Assign LAN addresses to all of the adapters.

b) Consider sending an IP datagram from host A to host F. Suppose all the ARP tables are up-to-date。Write all the steps as done for the single-router 。

3.This elementary problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts, Hosts A and B, connected by a single link of rate R bps. Suppose that the two hosts are separted by m meters, and suppose the propagation speed along the link is s meters/sec. Host A is to send a packet of size L bits to Host

B.

a) Express the propagation delay and the transmission time of the packet。

b) Suppose s=2.5*108, L=100bits and R=28 kbps. Find the distance m so that dprop equals dtrans.

4.ＣＲＣ计算

5.最长前缀匹配表，应用最长前缀匹配表规则转发分组，见幻灯片