Collaborating GloballyCollaborating Globally

… … and going via Space too!and going via Space too!… … and going via Space too!and going via Space too!

The network is about The network is about peoplepeople

• Want to connect people.Want to connect people.

• People exchange information in a People exchange information in a wide range of wayswide range of ways

• Methods depend on personalitiesMethods depend on personalities

• Networking technology determines Networking technology determines capabilitiescapabilities

The first collaborative The first collaborative network toolnetwork tool

• E-mail!E-mail!– Simple exchange via a very simple set Simple exchange via a very simple set

of protocolsof protocols

– Many different ways of moving e-mail Many different ways of moving e-mail around for different kinds of networkin. around for different kinds of networkin. SMTP used a lot for internet.SMTP used a lot for internet.

– Different ways to read mail. From Different ways to read mail. From Netscape to your phone!Netscape to your phone!

E-mail ain’t so sadE-mail ain’t so sad

• Modern versions support attachmentsModern versions support attachments

• Flexible way of exchanging informationFlexible way of exchanging information

• Delivered asynchronously -- bridges across Delivered asynchronously -- bridges across space space and and time.time.

• Delivery can work over very old technologies, Delivery can work over very old technologies, like HF radio, or over the latest space like HF radio, or over the latest space communication systems.communication systems.

• Interplanetary mailboxes!Interplanetary mailboxes!

How e-mail worksHow e-mail works

• Mail clientMail client– Connects to a mail delivery server and delivers Connects to a mail delivery server and delivers

e-mail, often using Simple Mail Transfer Protocol.e-mail, often using Simple Mail Transfer Protocol.

– Reads mail from a mailbox server, often using Reads mail from a mailbox server, often using POP3 or IMAP.POP3 or IMAP.

• Mail deliveryMail delivery– Protocol using Mail Transfer Agents to move mail Protocol using Mail Transfer Agents to move mail

from one place to another.from one place to another.

Text messengingText messenging

• Simple version of e-mail conceptsSimple version of e-mail concepts

• Often one way, without a mailbox to Often one way, without a mailbox to review on the remote serverreview on the remote server

• Also light, easy to implementAlso light, easy to implement

• Great for short communication, Great for short communication, emergencies, dates!emergencies, dates!

Text chattingText chatting

• Also old! Comes from BITNET and other old Also old! Comes from BITNET and other old systems, including HF bulletin boards!systems, including HF bulletin boards!

• Based on delivery of messages to a server, Based on delivery of messages to a server, and then out to one or more users.and then out to one or more users.

• Can be simply peer-to-peer, like ICQ, Can be simply peer-to-peer, like ICQ, Messenger, Yahoo.Messenger, Yahoo.

• Can be complex, interserver, like IRC, MUDs, Can be complex, interserver, like IRC, MUDs, MOOs.MOOs.

Next-Gen text chattingNext-Gen text chatting

• CellphonesCellphones

• PDAsPDAs

• Pocket PCPocket PC

• Blackberry devicesBlackberry devices

• You name it!You name it!

• It’s social!It’s social!

Sharing files - the big Sharing files - the big needneed

• If you need to work, you often need If you need to work, you often need to share large amounts of content. to share large amounts of content.

• The previous tools often make that a The previous tools often make that a little tough, though possible.little tough, though possible.

• Need to structure anything complex.Need to structure anything complex.– Windows, Apple file sharing is local, Windows, Apple file sharing is local,

unless you go VPN.unless you go VPN.

File transfer systemsFile transfer systems

• The Web! Basically one big file transfer The Web! Basically one big file transfer system, with a nice front end. Invented system, with a nice front end. Invented for black hole physicists!for black hole physicists!

• File Transfer Protocol: the Internet’s File Transfer Protocol: the Internet’s standard file transfer process. Comes in standard file transfer process. Comes in secure versions.secure versions.

• NFS: exporting a file system via the NFS: exporting a file system via the Internet.Internet.

Other file transferOther file transfer

• CVS - more for sharing text-based CVS - more for sharing text-based content or software source code.content or software source code.

• ICQ file transfer - synchronousICQ file transfer - synchronous

• Netmeeting file transfer - dittoNetmeeting file transfer - ditto

• And so on!And so on!

• Napster!Napster!

WhiteboardingWhiteboarding

Whiteboarding and Whiteboarding and application sharingapplication sharing

• Highly synchronous forms of Highly synchronous forms of communication. Allows one to communication. Allows one to communicate the same way as you communicate the same way as you would in a classroom.would in a classroom.

• Also can share programs, build Also can share programs, build solutions, at the same time.solutions, at the same time.

• Not used as much as it could be.Not used as much as it could be.

Whiteboarding for the Whiteboarding for the worldworld

• Traditionally high-bandwidth, big Traditionally high-bandwidth, big computerscomputers

• PolyLAB has systems that run on PolyLAB has systems that run on handheld computers.handheld computers.

• Important for disaster response.Important for disaster response.

• Great for science work, and problem Great for science work, and problem diagnosis in the field.diagnosis in the field.

VideoconferencingVideoconferencing

Videoconferencing Videoconferencing technologytechnology

• Peer to Peer or server based.Peer to Peer or server based.

• Netmeeting, one to one or many to many Netmeeting, one to one or many to many (if you buy the expensive version). Low (if you buy the expensive version). Low resolution.resolution.

• Multicast Backbone: video transmission Multicast Backbone: video transmission based on UDP “multicasting”. High speed, based on UDP “multicasting”. High speed, resolution. Expensive infrastructure.resolution. Expensive infrastructure.

Telephones, TelephonyTelephones, Telephony

• Phone is a pretty good collaborative tool!Phone is a pretty good collaborative tool!

• Can now have telephony over IP: Can now have telephony over IP: Netphone, dialpad, and so on.Netphone, dialpad, and so on.

• Can have voice over IP without the Can have voice over IP without the telephone bit: Netmeeting, multicast telephone bit: Netmeeting, multicast backbone audio.backbone audio.

• Convergence!Convergence!

Web applicationsWeb applications

• Can have Java and other applications on Can have Java and other applications on web pageweb page

• Can provide chatting services, file Can provide chatting services, file sharingsharing

• Forms/Java/Javascript can provide Forms/Java/Javascript can provide interactive access to database systems.interactive access to database systems.

• Increasingly interactive.Increasingly interactive.

Other collaborationsOther collaborations• TeleLearning: you collaborate with your TeleLearning: you collaborate with your

teachersteachers

• TeleMedicine: you collaborate with your TeleMedicine: you collaborate with your doctordoctor

• TeleSurgery: your doctor collaborates with TeleSurgery: your doctor collaborates with your internal organs!your internal organs!

• Remote control: you control robots, access Remote control: you control robots, access remote data, and so on.remote data, and so on.

Space!!!!!!!!!!Space!!!!!!!!!!• Communicate via a spacecraft, from one Communicate via a spacecraft, from one

point on Earth to another.point on Earth to another.– Can have spacecraft in low Earth orbit. Needs Can have spacecraft in low Earth orbit. Needs

LOTS of them, and they move in the sky.LOTS of them, and they move in the sky.

– Can have spacecraft in geosynchronous Earth Can have spacecraft in geosynchronous Earth orbit: Only need a few, and they don’t move.orbit: Only need a few, and they don’t move.

• Works just like wireless networking. Works just like wireless networking. Convert packets to radio signals.Convert packets to radio signals.

Space networkingSpace networking

• Can send normal telephone signals over the Can send normal telephone signals over the satellite link.satellite link.

• Can use TDMA-type systems to put phone Can use TDMA-type systems to put phone and data, and other services over the and data, and other services over the satellite link.satellite link.

• Can use equipment to send ATM and IP Can use equipment to send ATM and IP networking directly over the link.networking directly over the link.

• Can message across the link.Can message across the link.

The problems with TCP/IPThe problems with TCP/IP

• TCP/IP waits for signals to come back TCP/IP waits for signals to come back to decide if packets are being lost.to decide if packets are being lost.

• Waits a certain amount of time - time Waits a certain amount of time - time designed for standard networks.designed for standard networks.

• Assumes any problems with lost Assumes any problems with lost packets are due to congestion (too packets are due to congestion (too many packets), and slows down!many packets), and slows down!

Bandwidth-delay product Bandwidth-delay product problemproblem

• If a computer stores If a computer stores B B bits, and has to wait bits, and has to wait TT seconds to hear back, it can only transmitseconds to hear back, it can only transmit B B bits bits every every TT seconds, so max data rate is seconds, so max data rate is R=B/T. R=B/T. B=R*T.B=R*T.

• Most Windows and Apple boxes are set to Most Windows and Apple boxes are set to B=8,192 B=8,192 bytes = 65,536 bits = 64 Kb.bytes = 65,536 bits = 64 Kb.

• Average internet connection, Average internet connection, T = 1/8 T = 1/8 second.second.

• Max data rate = 512 Kbps! ASDL?Max data rate = 512 Kbps! ASDL?

Going geosynchronousGoing geosynchronous

• Round trip time from geosynchronous Round trip time from geosynchronous Earth orbit (GEO) is Earth orbit (GEO) is T = 1/2 second.T = 1/2 second.

• Max data rate, per connection, on normal Max data rate, per connection, on normal computer = 128 Kbps!computer = 128 Kbps!

• Independent of how fast the connection Independent of how fast the connection is (can be 10 Mbps).is (can be 10 Mbps).

• Only a property of TCP/IP.Only a property of TCP/IP.

SolutionsSolutions• Not use TCP/IP -- UDP for video is used a lot, even on Not use TCP/IP -- UDP for video is used a lot, even on

the Internet.the Internet.

• Advanced space protocols being discussed.Advanced space protocols being discussed.

• Can retune the computer -- edit the registry on Can retune the computer -- edit the registry on WindowsWindows– Change BChange B

– Change other parameters to keep data rate up.Change other parameters to keep data rate up.

• Changes need to be on both ends!Changes need to be on both ends!

IssuesIssues

• Need bigger computers to have larger Need bigger computers to have larger buffersbuffers

• Need somebody to retune machines. Who Need somebody to retune machines. Who does it in remote communities?does it in remote communities?

• Retuning reduces performance of local Retuning reduces performance of local networks.networks.

• Different bandwidth needs different buffer Different bandwidth needs different buffer sizes. Needs an expert.sizes. Needs an expert.