# Presentation: 847627

## Link and Routing Issues for Internet in SpaceOperating Missions as Nodes on the Internet(OMNI)http://ipinspace.gsfc.nasa.gov/Keith HogieComputer Sciences Corp.

**Nov. 15, 2000**

- Space Internet Workshop - 2000

## Layers Are Important

**Internet Protocol (IP) hides data-link and physical layer details from upper layer protocols**

**IP is not TCP !!!**

- Space Internet Workshop - 2000

## End-to-End Space Link Evolution

**4800BB**

**CCSDS**

**4800BB**

**1553**

**Spacecraft/**
**Balloon/**
**Field Site**

**Tracking **
**Station**

**Control Center/**
**Data Processing**

**Scientist**

**Dial-up**
**Scientist**

**CCSDS**

**Legacy**

**GW**

**IP**

**Data**

**Data**

**Data**

**Data**

**Data**

**C&**
**DH**

**CCSDS**

**Data**

- Space Internet Workshop - 2000

## Space Internet Implementation

**TDRSS**
**(White Sands)**

**Ground Stations**

**TDRSS**

**Control Center/**
**Data Distribution Facility**

**Principal**
**Investigator**

**Dial-up**
**Scientist**

**Private IP Network**

**Internet**

**Security Firewall**

**Collaborative**
**Investigator**

**RF Equip**

**Data **
**Services**
- (File &)
- (Packet)

**Ground IP **
**Routing**

**Space IP**
**Routing**

**C&DH**
- (IP addr)

**RF **

**C&DH**
- (IP addr)

**RF **

**Router**

**Inst. B**
- (IP addr)

**Inst. A**
- (IP addr)

**RF Equip**

**Data **
**Services**
- (File &)
- (Packet)

**Ground IP **
**Routing**

**Space IP**
**Routing**

**Single Address**
**Spacecraft**

**IP in **
**HDLC **
**frames**

**Multiple Address**
**Spacecraft**

**ESA**

**NASDA**

**Space Internet Implementation**

- Space Internet Workshop - 2000

## Separation of Coding and Framing

**Locate data frames**
**Error check data frames**
**Link level addressing**

**RF mod/demod**
**Up/down convert**
**Bit sync**

**Scramble/descramble**
**Randomize/derandomize**
**Convolutional encode/decode**
**Reed-Solomon encode/decode**

_**Physical Coding**_

_**Link Framing**_

- Space Internet Workshop - 2000

## Space Link Data Framing

**UoSAT-12 normally uses AX.25 (X.25 over HDLC)**
**Internet tests used standard IETF Multi-Protocol over Frame Relay (RFC 2427 over HDLC)**

**Hardware HDLC Frame**

**HDLC/Frame-Relay **
**with IETF Encapsulation**

**IP Packet**

**Link Layer**

**Flag**
**(1B)**

**Flag**
**(1B)**

**FR Hdr**
**(2B)**

**Encap Hdr**
**(2B)**

**Data**

**CRC-16**
**(2B)**

**Flag**
**(1B)**

**Link Framing**

**Flag**
**(1B)**

**Flag**
**(1B)**

**Data with bit stuffing**

**CRC-16**
**(2B)**

**Flag**
**(1B)**

**IP Packet Data**

**IP Hdr**
**(20B)**

**Network Layer**

- Space Internet Workshop - 2000

## Surrey Ground Station Modifications

**Surrey Ground Station Modifications**

**Surrey Ground Station (SSTL)**
- Installed Cisco provided router with RS-530 interface at SSTL
- Interfaced router to clock/data from SSTL transceiver
- Verified router receiving HDLC frames
- Uploaded new SCOS modules to secondary CPU onboard UoSAT

- Space Internet Workshop - 2000

## Onboard LANs

**Eventually each spacecraft instrument may be on a LAN with an IP address **
**Current LAN options being investigated**
- IEEE-1355	(1-1000 Mbps)
- IEEE-1394  	(100, 200, 400 Mbps)
- Ethernet	(10, 100, 1000, 10000 Mbps)
**Ethernet becoming major industrial LAN technology supporting real-time, deterministic environments**
- Industrial Ethernet Association -	http://www.industrialethernet.com/
- Industrial Automation Open Networking Alliance -  			http://www.iaona.com/
- GE Cisco Industrial Networks  -	http://www.gecisco.com

- Space Internet Workshop - 2000

## Network Layer

**The Internet Protocol (IP) **
- Simple datagram delivery
-  Global, end-to-end addressing with a source and destination address on each packet
**Fixed format protocol header - follow it exactly or you don’t communicate**
**IP hides the details of the data link layers from the upper layer protocols**
**Standard programming interface (Sockets) simplify programming and transportable code**

**IP is not TCP !!!**

- Space Internet Workshop - 2000

## Network Layer Issues

**Long delay communication links **
- IP is completely unaffected by delay
- IP is simply addresses on the front of your data
- IP needs no response and works fine to Pluto and beyond
**Intermittent communication links**
- IP has no concept of a “session” to be interrupted
- Each packet contains full address information
**Data priority**
- IP has a Type of Service field
- Routers support priority queuing by transport protocol and port
**Overhead**
- Lots of work on header compression due to Voice over IP and streaming video applications (RFC 2507, 2508 - 7 byte headers)

**User Data Sizes (bytes) ****	**_**100**_**	**_**500**_**	**_**1000**_**	**_**1400**_
**	****IP (20)****	****16.6%****	****3.8%****	****1.9%****	****1.4%**
**	****UDP/IP (28)****	****21.8%****	****5.3%****	****2.7%****	****1.9%**
**	****TCP/IP (40)****	****28.5%****	****7.4%****	****3.8%****	****2.7%**

- Space Internet Workshop - 2000

## Mobile IP Scenario

**Downlink data is routed normally**
**Mobile device registration with ground agents supports automatic uplink routing configuration**

- Space Internet Workshop - 2000

## Link and Network Summary

**Link and Network Summary**

**Simple network connectivity starts with changing S/C**
**Use any modulation/coding/FEC to deliver bits**
**Key issue is separation of coding from data-link framing**
**Standard framing allows wide COTS usage on ground**
**IP provides global addressing and connectivity**
**Huge amount of R&D working on applying IP to communication environments much worse than spacecraft (e.g. cell phones, cars, wristwatches, etc.)**

**OMNI - http://ipinspace.gsfc.nasa.gov/**

**IP is not TCP !!!**

- Space Internet Workshop - 2000