November 2006

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Definition of the Internet

• Network of networks– millions of smaller domestic, academic, business, and

government networks– Uses TCP/IP protocol suite

• Carries various information and services, such as electronic mail, online chat, file transfer, documents of the World Wide Web.

• Internet and the World Wide Web are not synonymous:– the Internet is a collection of interconnected computer networks,

linked by telecommunication media– the Web is a collection of interconnected documents, linked by

hyperlinks and URLs.

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Common Protocols allow Coexistence

• Internet can be used as:– an underlying technology for some components of the GTS in special

conditions

– as a backup to the GTS

– as a complement to the GTS

Communication Component

Function

GTS Delivery of time critical communication for weather, water and climate operations

Internet Communication for less critical requirements and possibly for large volumes of data

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Telecommunication Options

BROADCASTNETWORK

GTS

INTERNET

CENTER B

OTHER NON-GTS LINKS

CENTER A

INTERNET

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VPN Concept

VPN CLIENT

VPN SERVER

INTERNET

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Virtual Private Networks (VPN)

Create the equivalent of a dedicated private link using the Internet as a connection media

CENTER A

PUBLIC SUBNET

GTS

INTERNET

WORKSTATION 1

WORKSTATION 2

WAFS RECEIVER

DIGITAL VIDEO BROADCAST

RECEIVER

INTERNAL ROUTER / FIREWALL

MESSAGE SWITCHING SERVER

1

MESSAGE SWITCHING SERVER

2

ACCESS DEVICE ROUTER / FIREWALL

VPN INTERFACE

DMZ SUBNET

INTERNAL PROTECTED

SUBNET

OTHER SYSTEMS

ACCESS DEVICE ROUTER / FIREWALL

FIREWALL

LINK PROVIDED BY TELECOM SUPPLIER

LINK PROVIDED BY INTERNET SUPPLIER

WEB PORTAL / SERVER 1

WEB PORTAL / SERVER 2

TYPICAL VPN OVER INTERNET CONNECTIONAND

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WIS VPN Pilot Project in Regions II and V (as of Sept 2006)

Hong Kong

India

Iran

Korea

Oman

Saudi Arabia

Vietnam

Australia

Brunei

Malaysia

New Zealand

China

Soon established VPN-link with Japan

Established VPN-linkwith Japan

Japan

Singapore

10Mbps (max)

2Mbps

4Mbps

512Kbps

2Mbps

1Mbps

100Mbps (max)

3Mbps

2Mbps

2Mbps

1MbpsInternet

100Mbps (max)

100Mbps (max)

256Mbps (min)- 　　440Mbps

(max)

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File Transfers and FTP servers

• Uses File Transfer Protocol

• Can be used for dissemination or exchange of bulk meteorological data through Internet, GTS or other local/wide area networks

• Recommended for predefined users

• Efficient data exchange protocol

• Good for both push and pull configurations

• File Naming is important – see Man 386 Att II.15

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FTP Server Implementation

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Electronic Mail

• Uses the Simple Mail Transfer Protocol (SMTP)• Complementary method of data input into the GTS

– Should not be used to replace GTS data exchanges for mission critical components

– Usually can not guarantee real time data delivery– Requires sites to collect messages (some examples: Washington, New

Zealand, Tokyo, Beijing)– Requires a strong quality control at the collecting center as the collected

messages often contain several typing or format mistakes• Mostly a push mechanism• May be used for notification (for example that a file is available for

delivery while the file itself is placed on an FTP server)• Excellent general communication tool• Important entry point for virusses, worms and Trojan Horses• Must deal with SPAM problem

– Spamming is the abuse of electronic messaging systems to send unsolicited, undesired bulk messages

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Email Implementation

CENTER A

PUBLIC SUBNET

GTS

INTERNET

WORKSTATION 1

WORKSTATION 2

WAFS RECEIVER

DIGITAL VIDEO BROADCAST

RECEIVER

INTERNAL ROUTER / FIREWALL

MESSAGE SWITCHING SERVER

1

MESSAGE SWITCHING SERVER

2

ACCESS DEVICE ROUTER / FIREWALL

VPN INTERFACE

DMZ SUBNET

INTERNAL PROTECTED

SUBNET

EMAILSERVER

ACCESS DEVICE ROUTER / FIREWALL

FIREWALL

LINK PROVIDED BY TELECOM SUPPLIER

LINK PROVIDED BY INTERNET SUPPLIER

WEB PORTAL / SERVER 1

WEB PORTAL / SERVER 2

TYPICAL EMAIL SERVER EXCHANGES

VIRUS & SPAM

FILTERS

TYPICAL EMAIL USER EXCHANGES

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Web Servers

• Based primarily on Hyper Text Transfer Protocol (HTTP)• Used to make available various data and reports, available to users

who request the information by downloading the various « web pages » (pull mechanism)

• Offers an intuitive approach to presentation of data and links between data elements

• Allows complex scripts and data management tools to be added• Requires permanent connection to the Internet• Requires careful and significant planning and maintenance

– Weather data is updated very often

– Demand for weather data can be very high

– In large sites can become very complex

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Web Server Implementation

CENTER A

PUBLIC SUBNET

GTS

INTERNET

WORKSTATION 1

WORKSTATION 2

WAFS RECEIVER

DIGITAL VIDEO BROADCAST

RECEIVER

INTERNAL ROUTER / FIREWALL

MESSAGE SWITCHING SERVER

1

MESSAGE SWITCHING SERVER

2

ACCESS DEVICE ROUTER / FIREWALL

VPN INTERFACE

DMZ SUBNET

INTERNAL PROTECTED

SUBNET

OTHER SYSTEMS

ACCESS DEVICE ROUTER / FIREWALL

FIREWALL

LINK PROVIDED BY TELECOM SUPPLIER

LINK PROVIDED BY INTERNET SUPPLIER

WEB PORTAL / SERVER 1

WEB PORTAL / SERVER 2

TYPICAL WEB SERVER ACCESS

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Important Documents

http://www.wmo.int/web/www/documents.html

• Manual 386, Attachment II.15 – Use of TCP/IP on the GTS (Revision 3, Sept 2006)

• Guide on Information Technology Security (Sept 2006)• Guide on Internet Practices (Sept 2006)• Guide on use of FTP and FTP servers at WWW centres

(Sept 2006)• Guidance on IPSec-based VPNs over the Internet (April

2004)