Scientists test wider use of IP

The 140-foot Coast Guard icebreaking tug Neah Bay has a low-pressure-air bubbler system that forces air between the hull and the ice to ease passage. The Neah Bay helped NASA test Mobile IP.

The Internet Protocol revolutionized communications on Earth, and NASA scientists think it could bypass proprietary interfaces to tie together vast arrays of Earth and space devices.

'IP in space is something that is going to fly,' said Phillip Paulsen, project manager for space Internet technologies at NASA's Glenn Research Center in Cleveland.

Before IP takes off, however, it has to be redesigned for use beyond stationary computers and contained networks.

In November, NASA Glenn demonstrated a router implementation of the Mobile IP protocol from Cisco Systems Inc. of San Jose, Calif., connecting to the Coast Guard icebreaker Neah Bay on Lake Erie.

Why use a ship to test a technology intended for space?

'It's incredibly expensive to test in space,' Paulsen said. 'A ship at sea has many of the same needs as a satellite.'

It's a long way from Lake Erie to the space shuttle, but the mobile router test demonstrated that IP services can be delivered to a subnet remote from the home network.

IP in space not only would standardize interfaces but could enable new services, such as letting Earth-bound scientists run their own experiments in orbit.

Glenn began the work in the mid-1990s at the request of the satellite industry, which wanted to overcome latency problems that stall IP communications. With that worked out, the next problem was how a router in space could roam between connections while keeping the same IP address.

Wait a minute, Mr. Postman

The Internet Engineering Task Force defined how nodes can change their point of attachment without changing address. A mobile node'a computer or router'retains its IP address from its home network address space but receives an 'in care of' address from an agent on a router in a foreign network. The mobile node sends the 'in care of' address to the agent on its home network.

When the home agent receives IP traffic for a mobile node, it encapsulates and forwards the packets to the foreign agent. The foreign agent strips off the capsules and sends the packets to the mobile node.

The Mobile Router feature of Mobile IP uses a tunnel within a tunnel. Traffic to individual devices behind the mobile router is encapsulated, then encapsulated again with the router's 'in care of' address. The foreign agent strips off the outer capsule and sends the packets to the router, which strips the second capsule and sends the packets to the destination device.

In theory, Mobile Router reduces overhead when an entire network or subnet is mobile because only the router has to register with a foreign agent and receive an address. 'The complexity is hidden behind the router,' Paulsen said.

Easier said than accomplished

In practice, that can be difficult to pull off, said David Steward, a Verizon Federal Network Services engineer working at Glenn.

'It's simple but not necessarily easy,' Steward said. 'There's an awful lot of encapsulation, so trying to figure out why something is not coming back can be complex.'

And then there's encryption. 'Once you start thinking of security it gets fairly complicated,' Steward said.

Cisco incorporated Mobile Router code in its IOS operating software for a small, two-card router delivering 100 Mbps'a good fit for NASA satellites. The router company came to Glenn two years ago to validate that the router would work in the real world'and out of this world.

NASA 'offered our mobile lab to test the device,' Paulsen said. The truck-mounted platform included antennas, a generator, four Mobile IP routers, two bridges, a delay simulator, six wireless bridges and multiple workstations. NASA Glenn scientists and Verizon worked with Cisco, Lockheed Martin Corp. and Analex Corp. of Alexandria, Va., to put the router through its paces.

Then it was time to move offshore.

The mobile test bed had used an IEEE 802.11b wireless link to the Internet. But the icebreaker could not access the WLAN offshore, so it used a commercial satellite link from Globalstar LP of San Jose, Calif., instead.

Globalstar's ground station for the Great Lakes area is in Canada, which added to the Coast Guard's security concerns, already piqued by the wireless and commercial satellite links to the vessel.

A hardware encryption device from Western DataCom Co. of Cleveland eased security concerns. The device, about the same size as the small mobile router, is under National Security Agency evaluation for the High Assurance IP Encryption standard. If it passes muster, it will be one of the first HAIPE-compliant products.

The final demonstration in November drew more than 100 observers from Defense Department, law enforcement and intelligence agencies. The two-way webcast between the Neah Bay and a shore station demonstrated e-mail, Web browsing, voice over IP, File Transfer Protocol, Secure Shell and Telnet services.

Performance was limited only by the encryption device, which 'doesn't have the performance of the router,' Paulsen said. Over the wireless link, the Neah Bay achieved 1.5-Mbps T1 rates, and 56 Kbps over the satellite connection.

Because the ship now has no Internet connection while at sea, 'for them, 56K is wonderful,' Paulsen said.

The demo went so well that the Coast Guard is considering mobile routing for cutters to be acquired under its $12 billion Integrated Deepwater System program.

Mobile computing with static IP addresses is attractive for military, law enforcement and emergency response applications. But Paulsen wants first to get the hardware and software flight-qualified for a shuttle or space station test.

'That's my primary goal now'to get this gear into space and prove that it works,' he said.

About the Author

William Jackson is a Maryland-based freelance writer.


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