Cruise ship sails through wireless challenges

The world’s longest cruise ship posed knotty wireless networking problems but also provided Royal Caribbean Cruises Ltd. the opportunity to pounce on iPhones, touchscreens and MPLS networking in order to deliver luxury services.
Royal Caribbean’s Oasis of the Seas houses 2,700 guest cabins and can accommodate 6,300 passengers and 2,160 crew members. The wired VoIP phone network has 4,000 extensions including one in each passenger cabin. There are 1,100 IP surveillance cameras to monitor activity aboard ship, and 370 Cisco Systems Inc.’s. plasma and LCD IP touch screen signs placed around the ship post notices of daily activities. The screens can also be used by passengers to get directions to other locations on the ship, according to Max Schmidt, associate vice president of IT and operations, and Greg Martin, network manager for the cruise line.
All that gear is complex enough without introducing a Wi-Fi network that has to function inside spaces defined by metal hulls and bulkheads that wreak havoc with wireless broadcast patterns.
“It’s a challenging environment,” Martin says.
The ship is divided into zones that can be shut off with fire doors so impermeable that closing them actually alters the effective range of some of the access points, he says. “We need additional access points for that or the wireless signals will not penetrate,” Martin says. In all, it takes more than 900 access points — all the gear is from Cisco — to supply pervasive coverage throughout the vessel.
Every cabin has wireless access, for IP phones or for Internet connectivity, and the cabin doors are heavy enough to affect wireless signals, he says. Planners first designed the wireless network based on best estimates of how signals would be affected by the materials that make up the ship. Then as they were deployed within the ship, each access point was tweaked for power and orientation to achieve full coverage, Martin says.
“It was a greenfield design, but a ship changes over time,” he says. So the wireless team visited it during construction to test out how well the access points worked on site. Sometimes the optimal location for an access point was unsuitable for architectural reasons, requiring relocation and more tweaking, he says.
“Typically we have to work around the design requirements of the ship,” he says. One challenge was that for the many types of network users — various classes of crew and passenger voice, Internet access, and data — designers thought they would need 13 different SSIDs for the network. “That’s not necessarily within the realm of best practices,” Schmidt says. They managed to get that number down to five and resorted to using multiple virtual LANs over some of them.
Cisco wireless control points impose priority for voice and video access over data, Martin says. Passengers can rent pairs of iPhones on board that are loaded with ship-specific applications. For instance, there’s a location-finding app that maps where the partner phone is so passengers can easily track traveling companions. Passengers can also rent Ekahau asset tags they attach to their children. When the children move, the tags tell an iPhone app where they’ve gone and it’s displayed on the phone’s screen.
The phones also display daily shipboard activities. The iPhones are also used for passengers’ shipboard voice communications. (The crew uses Cisco mobile VoIP phones.) If passengers want to call to shore, they can do so either on their cell phones or with the wired VoIP phones in their cabins. GSM cell calls link either directly to cell towers ashore when the ship is in range, or through a shipboard cell tower that kicks in when the ship is out of range of a cell tower on shore. The cell tower is managed by AT&T’s Wireless Maritime Services and bounces signals off satellites to reach a WMS ground station.
Passenger phone calls from their cabins travel via satellite to Royal Caribbean’s headquarters network on land, then out to the public phone network. The ship uses a 4Mbps down, 2Mbps up C-band satellite connection to reach shore. The service can burst above that, but at a premium.
“It’s managed very tightly,” Schmidt says, in order to keep costs down. “We time transmissions for applications during known downtimes in demand.” The liner also uses WAN optimization gear from Blue Coat Systems Inc. and Riverbed Technology to make more efficient use of these links. The 1,181-foot-long craft has been afloat for more than a year, but planners were busy long before that designing and testing its networking gear, Schmidt says. The work was done with a combination of Royal Caribbean staff, Cisco Services (it’s a Cisco network) and other consultants planning, staging and testing the network ashore before boxing it up for installation aboard the vessel.
“We don’t have time to do all that on site,” Martin says. All traffic runs across a routed 10Gbps MPLS backbone anchored by Cisco 6500 series switches that support a total of 27,000 gigabit Ethernet ports. MPLS as well as VLANs help impose QoS on different classes of service. The network features two data centers so if one data center goes down the other can step in. “Critical applications have an environment to fail to,” Martin says.
The network has 37 remote distribution points, each fed by more than one fiber source — the ship contains nearly 2 million feet of fiber — whose generator power is backed up by redundant UPSs that are in turn backed up by redundant UPSs, Martin says. The network is routed via MPLS to impose QoS on different classes of traffic, including passenger communications, voice, secure traffic and internal corporate data. Throughput has to be high because traffic also includes high-definition IP TV to passenger cabins.
In all, the ship has 1,100 networked IP security cameras. A person-recognition application tied to cameras mounted in ceilings of dining areas keeps a running count of how full the various restaurants are. Passengers can tap that data to figure out the best place to eat if they want to avoid crowds. At sea, the network is tended by nine crew members — an IT manager and a network manager, three passenger-support staff and four others to support back-office desktops and servers. They perform routine maintenance and troubleshoot and can call on IT staff ashore for help.
The IT crew is very loyal, Schmidt says, many of them with 10 to 20 years service to Royal Caribbean. Because the line produces new luxury ships periodically, the IT staff gets the chance to experience new technology. “It’s a very sexy product,” he says. They sign on for four to six month at sea, followed by two months off. While at sea they provide 24-hour coverage, but the actual work schedules guarantee time off. “There are guidelines for the rest time they need that are strictly enforced,” Schmidt says.
Just being aboard the ship is a reward in itself, he says. “The whole ship is a technical innovation. It’s a work of art.”

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