由不同的國家當起點做ping, Traceout
我們可以reconstruct整個網路的拓蹼

domain name 跟 ip address 的關係?
1.知道ip, 知道此主機位置 (空間地理位置)
2.domain name則不然, 就算.jp .ca亦不代表其地理位置
可利用domain name查詢其IP, 知道IP後再透過NeoTrace查詢其地理位置, 同時也可利用whois查詢其相關單位

about期末專題:
最難的是server/client之間protocol的設計, 跟其AP有關
client request <-> server response
跟據其AP特性, 哪些事情應該在client/server做?

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1.電腦網路上data&voice兩種資料共存
2.distance between CPUs: 越近速度越快
使用protocol來做區分
LAN: OSI layer 1&2
WAN: OSI layer 1~3

ISO releases OSI Model and protocols => 用來解釋網路運作的原理

ISP
1.NSP: network service provider (ex:中華電信 => 網路提供者)
2.PSP: platform service provider (ex:GOOGLE, Microsoft => 平台提供者)
3.ASP: application service provider (ex:自己架站 => 服務提供者)

Networking Devices
End user devices | Network devices
PC,Printer,MAC,Server Hub,Repeater(1)
Bridge,Switch(2)
Router(3)
Network Cloud
Computing center, Data center

Network Topology:
<Physical>
Bus / Ring / Star / Extended Star / Hierarchical / Mesh

Network Protocols:
上層跟下層的協定?
對等層的協定?
L,M,N : Layers in our model of computer communications
Msource,Mdestination : Peer layers
-> Peer to peer communication
M layer Protocol : The rules by which Msource communication with Mdestination

每一層都有固定的interface
每一層的資料都有固定的同一層解析
一層一層加上header, 傳送至對方時, 對方在一層一層解開header

Storage-Area Networks(SANS)
data 是寫到 storage area, 再透過 Network access

Virtual Private Networks(VPNs)
結合LAN與LAN

Intranet and Extranet VPN

頻寬(Bandwidth)的問題:
limited by physics and technology
not free
requirements are growing at a rapid rate

bps,kbps,Mbps,Gbps,Tbps

Bandwidth Throughput:
Throughput <= Digital Bandwidth of a Medium
wait time? time out(too long or too short)?