Networking on the International Space StationPresentation by Bradley Roach

10/09/2007

Objectives of Discussion

To highlight and discuss the following areas of the Operations Local Area Network (OPS LAN) system used to facilitate communication between laptop computers on the International Space Station.

Network Topology

Networking Protocols

Network Devices

RF Connectivity

Cabled Connectivity

Topology of OPS LAN

OPS LAN uses a Multipoint Ethernet Bus TopologyMultipoint enables the hub to send information to one or more

systems based on a specific address.

Uses IEEE 802.3 (Regular Ethernet) Uses IEEE 802.11(Wireless Ethernet)

The OPS LAN 10BASE2 cable backbone uses RG-58 coax cabling.

Uses BNC connectors and terminators.

Network Protocols Used On OPS LAN

Protocol- Collection of rules and procedures governing communication among the computers and network devices of the network.

NetBEUI (NetBIOS Extended User Interface) Very fast but non-routable Self-tuning and self-configuring Suitable for small networks such as OPS LAN Uses broadcasts to locate other computers on the network.

TCP/IP (Transmission Control Protocol / Internet Protocol) Most common network protocol in the world Routable

Network Devices Used On OPS LAN

The following network devices implemented in OPS LAN will be discussed:

File Server Various client laptops RF access points Mass Storage Device Printers Routers

File Server IBM ThinkPad 760XD

Equipped with SSC (Station Support Computer) server software load.

Uses Microsoft Windows NT Server

File server is operated from the service module of the ISS.

SSC Clients

IBM ThinkPad 760XD

Microsoft Windows 95b

During early missions, these clients communicated on the network via RF cards.

In later missions, the clients will communicate via 802.11 or 802.3

Early Communication System/Orbital Communication Adapter

Early Communication System Laptop is IBM ThinkPad 755C

Attached to a docking station to which an Orbital Communication Adaptor and Video Conferencing adapted are attached.

Primary function is to provide communication and data transfer from space to ground.

Primary printer used on OPS LAN is an Epson Color Stylus 800 which has been modified for low gravity operation

RF Connectivity

Operates in the 2.4ghz frequency band

Throughput via RF PC cards is 12MB/min;

Expected throughput is between 3.5 and 5.5 MB/Min.

To prevent RF interference and unauthorized eavesdropping, Spread Spectrum Technology is used.

•With this technology, the radio signal “hops” from frequency to frequency within a specified band(ISM 2.4000 – 2.4825) over a set time.

• Both the transmitter and the receiver know what the hopping pattern is, and are then able to decipher the information.

•Each hopping pattern is called a channel, and up to fifteen channels are available.

RF Network Adapter/Access Point

RangeLAN2 7400 PC card

This adapter is a type II pc card

Attached to the PC card is an omnidirectional dipole antenna

7520 RangeLAN2/AP-II MAC layer bridge

Connects to the coax backbone

Relays packet information from coax backbone to Laptops at a rate of 14,800 packets/sec

http://www.spaceref.com/iss/computer/iss.ops.lan.icd.pdf

http://www.spacescan.org/images/international-space-station-ctrl_65.jpg

http://www.inetdaemon.com/tutorials/lan/topology.shtml

http://newsroom.cisco.com/ts_images/cisco_10720_Internet_Router_high_res.jpg

http://www.elmundo.es/suordenador/SORnumeros/97/SOR071/imagenes/prueba.jpg

http://www.spaceref.com/news/viewnews.html?id=213

http://www.shimafukurou.jp/thinkpad/images/760xd/760xd-01.jpg