# Presentation: 391491

## Space-BasedIP Testing UsingCOTS Equipment

**Will Ivancic - NASA GRC**
**Terry Bell - Lockheed Martin Global Telecommunications **
**Dan Shell - Cisco System**

## Space-Based IP TestingAgenda

**Goals**
**Network Topology**
**Network Setup**
**STS Interfaces and Links**
**Test Results**
**Conclusions**
**Recommendations**

## Cisco/GRC Goals

**Could we tie COTS interfaces into STS system without expensive modifications.**
**Demonstrate use of COTS data networking equipment and protocols with STS and/or ISS **_***with delay***_** (600 msec in each link).**
**Demonstrate applications such as VOIP, IPTV, Telnet, Wireless LANs.**

## MCC Goals ?

**Can a COTS router replace the OCA now.**
**- OCA lost 3 cards on the ground due to          lightening strike.**
**- Replacement may take up to 18 months**
**- Running with no spares**

## ESTL Goals

**Ensure that all communications fully functions at the guaranteed BER, 1E-5. **
**- NASA certainly needs to do this if that is the truly an operational point.**
**Determine why something doesn’t work (?) **

## Network Topology with Delay

**Ground **

**128 kbps**

**STS **
**Connections**

**2 Mbps**

**S0/Tx**

**S0/Rx**

**STS **
**Connections**

**S1/Rx**

**S1/Tx**

**Space**

## Network Topology without Delay

**Ground **

**128 kbps**

**STS **
**Connections**

**2 Mbps**

**S0/Tx**

**S0/Rx**

**STS **
**Connections**

**S1/Rx**

**S1/Tx**

**Space**

## Network Setup

**RS-449 to STS Cabling (with and without delay units)**
**Static  Routes on simplex links**
**DCE to DTE Clocking**
**Use “no keep-alive” on simplex links **
**Use “ignore-dcd” on DTE interface (be sure cables are connected first!)**
**Set “clock rate” on DCE interfaces**

## Network Setup

**Use NRZI encoding. It solved all zeros, all ones and phase ambiguity problems.**
**Use HDLC framing**
**Use the “transmit” command on the receiving interface to transmit on the sending interface.  **
**int S1(Rx) **
**transmit int S0(Tx)**

## STS Links

***ALL***** links guaranteed to 1E-5 (even the FEC encoded link)**
**- Nobody could (would?) tell us **
**what the guaranteed S/N is.**
**Nominal is Near-Error-Free**

## STS Links

**Channel 2 FM and channel 3 FM are straight BPSK, no coding, no phase ambiguity resolution, no scrambling.**
**Channel 3 PM is implemented as 5 parallel 10 Mbps convolutional encoders/decoders with an over guaranteed BER of 1E-5 after FEC.**

## Slide 12

## Forward Link

**Forward Link**

**Ground**
**Portion**

**Space **
**Portion**

## Return Link (Space Portion)

## Return Link (Ground Portion)

## Preliminary Test Results(All testing was with 1.2 sec RTT)

**TCP works fine error free (12+Mbyte file) using:**
** ****ttcp -t -l1440 -b300,000 10.0.2.54 < file **
**TCP does not work efficiently with 1E-6 over 1.2 sec delay (Obviously)**
**UDP packet transfers worked fine 2 Mbps error-free**
**UDP lost 70% at 1E-6 (why???)**
**- TCP did not show this phenomena **

## Preliminary Test Results(All testing was with 1.2 sec RTT)

**VOIP work fine error free**
**VOIP appeared to work even at 1E-5 including call setup (This was a very limited test.)**
**Telnet work even at 1E-6**

## Preliminary Test Results(All testing was with 1.2 sec RTT)

**Used browser to control the Aironet wireless access point over the link.**
**- Worked error free, didn’t try with errors.**
**We tried IPTV briefly, but ran out of time.  IPTV would have demonstrated multicast over simplex links.**
**- We can try this back at GRC.**

## Conclusions

**IP will work over long delays (1.2 sec RTT) on near error free links.  **
**- No news here. We tested this may times in the lab with even greater delays.**
**VOIP with G729.R8 compression appears to be very error tolerant.**

## Recommendations

**Use COTS standard interfaces such as RS422.**
**Provide duplex links if possible**
**- At least one duplex link (even a low rate link) enable UDLR.  Then one doesn’t have to do static routing and all the other goofy commands.**
**Fix the radio link - only once.**

## Did You Know?

**Service Module of the International Space Station (the Russian Module) uses the following:**
**- Ethernet LAN running 100Base-TX**
**- Cabletron SmartSwitch router**
**- Module is wired with shielded cat-5 type cable**
**- 3Com 3C589D, or Intel Pro/100 PCMCIA Ethernet cards**
**- Using VPN's**
**- All of the module's flight control systems as well as the operational and payload data systems are connected to the same LAN**