1、 TECHNICAL REPORT ATIS-0100031 A METHOD TO DISPLAY METRICS RELATED TO THE ROBUSTNESS OF THE UNDERSEA CABLE INFRASTRUCTURE ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertain
2、ment and communications industry. More than 200 companies actively formulate standards in ATIS Committees, covering issues including: IPTV, Cloud Services, Energy Efficiency, IP-Based and Wireless Technologies, Quality of Service, Billing and Operational Support, Emergency Services, Architectural Pl
3、atforms and Emerging Networks. In addition, numerous Incubators, Focus and Exploratory Groups address evolving industry priorities including Smart Grid, Machine-to-Machine, Connected Vehicle, IP Downloadable Security, Policy Management and Network Optimization. ATIS is the North American Organizatio
4、nal Partner for the 3rd Generation Partnership Project (3GPP), a member and major U.S. contributor to the International Telecommunication Union (ITU) Radio and Telecommunications Sectors, and a member of the Inter-American Telecommunication Commission (CITEL). ATIS is accredited by the American Nati
5、onal Standards Institute (ANSI). For more information, please visit . Notice of Disclaimer thus, they differ in makeup and capacity. Early systems, which were based on Plesiochronous Digital Hierarchy (PDH) technology, have been progressively phased out in favor of highercapacity Synchronous Digital
6、 Hierarchy (SDH) and Wave Division Multiplexing (WDM) systems, which are more resilient and have better management characteristics. All modern undersea cables use fiber-optic technology. Common components include cable landing stations, wet and dry cable segments, repeaters, terrestrial backhaul, an
7、d network management capabilities. ATIS-0100031 4 4.1 System Architectures The ITU ITU-T 41 defines eight (8) different topologies for undersea cable systems. However, for practical purposes, the majority of networks are based on four (4) different topologies: Point-to-Point Trunk and Branch Ring an
8、d Branch Festoon. Additionally, many carriers take advantage of multiple cable systems and create mesh architectures for their service network. 4.1.1 Point-to-Point Systems This configuration consists of direct submarine link between two terminal transmission equipment (TTE) located in two different
9、 terminal stations (TSs). These systems may or may not contain repeaters. Advances in fiber and transmission equipment have made it possible to reach destinations up to 500 km (approximately 300 miles) away without intermediary amplification. Originally, repeaterless systems offered cost benefits be
10、cause they did not require undersea regenerator units or power feed equipment. Now, optical amplifiers are commonly used at terminal points of repeaterless spans to boost transmitted signals or to preamplify received signals. These systems are typically 200300 km long. Repeaterless systems are used
11、among Caribbean islands, between the United Kingdom and its closest European neighbors (France, Belgium, and the Netherlands), and among British islands. Figure 1 - Topology of a Point-to-Point System 4.1.2 Trunk additionally, there are 51 cables in the planning stages between now and 2014, with 34
12、of them scheduled for later in 2012), and an increased range for repeaterless systems. The trend toward fewer cables with higher capacities is continuing. The main equipment manufacturers now have systems with 16 fibers (8 pairs) in a loosefill cable, with potential for total capacity of 10.24 Tbps
13、= 10 Gbps (Gigabit per second) x 128 WDM x 8 fiber pairs capacity. At that capacity, one undersea cable can carry approximately 160 million telephone circuits simultaneously or transfer approximately 272 digital video disks (DVDs) among continents in one (1) second. 4.3 General Risks The internation
14、al undersea cable infrastructure traverses great distances and must operate in harsh (and in some cases restrictive) environments. Consequently, undersea cables are constructed to be reliable, with the leastaccessible submerged portions designed to experience no more than three failures during a des
15、ign life of approximately 25 years. Although the infrastructure is technologically sophisticated and very reliable, certain limitations and extrinsic threats both natural and manmade can impact operations. These vulnerabilities must be understood and addressed by both service providers and customers
16、 that rely on highly resilient telecommunications to carry out critical operations. The following subclauses detail some notable risks to international telecommunications. 4.3.1 Natural Hazards Undersea cable systems can be affected by seismic activities, erosion, storm damage, undersea landslides,
17、and other geological events. Before the practice of burying cable began in the 1980s, the fault rate was 5 per 1,000 km (approximately 620 miles) of cable per year; with the burial of cable, together with increased awareness, the rate has decreased to less than 1 fault per 1,000 km per year. An exam
18、ple of a fault due to a natural hazard was an underwater earthquake in December 2006 that caused a fiber cut to six (6) undersea cable systems in the Luzon Straits. Earthquakes, though of low incidence historically, can affect multiple cables and can occur at depths that make repair operations diffi
19、cult and therefore lengthy. Newer undersea cables are equipped with oceanbottom seismographs to provide realtime monitoring of seismic activities 24 hours a day. Natural hazards can displace cables from their original positions and can cause damage over a significant length of cable. Besides making
20、for a challenging repair, such damage carries with it the risk that the quantity of cable required for the repair will exceed the spare stock held. Also, the number of ships needed to repair the multiple faults typical of damage from natural hazards may exceed the number available in the region. The
21、se circumstances, singly or in combination, may result in repair times far in excess of the norm. ATIS-0100031 9 4.3.2 Manmade Hazards Fishing, dredging, and ship anchors have been known to damage undersea cable infrastructure. For example, a December 2008 fiber-optic cable cut near Egypt attributed
22、 to an abandoned ship anchor weighing 5 or 6 tons resulted in an 80 percent loss of connectivity to Egypt. Incidents of malicious damage have also occurred, but are not of significant frequency. Careful engineering of routes and installation of cable, coupled with offshore liaison with other seabed
23、users, offers the greatest potential for further decreases in fault rates. 4.3.2.1 CableLandingStationConcentration Risk Cable landing stations are points at which the undersea cable connects to the landbased infrastructure or network. Because of limitations on the locations of undersea cable landin
24、g points (they must be away from fishing lanes and trawler operations), landing stations are generally separated by no more than 300500 km (approximately 200 or 300 miles) on any given coast. 4.3.2.2 Undersea Cable System Design Placing undersea cable systems close together can pose a significant ri
25、sk to international telecommunications. For example, an undersea earthquake near Taiwan (the Hengchun earthquake) caused an outage to six undersea cable systems in December 2006, resulting in a major degradation of telecommunications from Asia. 4.3.2.3 Component Failure note in particular the major
26、land masses that act as inter-regional interconnection points. It is in these land masses that we find hub cities and fiber-optic backhaul into that particular land mass. MSRSARCSRNSRNARIORSERNPRSPRSPRSource: Alcatel-LucentNorth Atlantic Region (NAR)North/ Baltic Sea Region (NSR)Mediterranean Sea Re
27、gion (MSR)North Pacific Region (NPR)South Atlantic Region (SAR)Indian Ocean/ Red Sea Region (IOR)South East Asia Region (SER)South Pacific Region (SPR)Caribbean Sea Region (CSR)Figure 6 - Undersea Cable Regions 5.1.2 Routes The second option for grouping cables would be to use major routes. The adva
28、ntage of using the major routes is to group together cables that provide similar services and have the potential to be used for backup routing for other cables in the same grouping. Examples of some potential routes to use would be: North America Europe North America Asia North America Caribbean / S
29、outh America Europe Middle East / Asia Europe Africa. 5.2 Factors Affecting Resiliency, Reliability, Vulnerability, the designers specify the total number of fibers that are in the cable. Additionally, the design capacity of each fiber is a factor of the number of potential wavelengths that could be
30、 carried and the bandwidth of a single wavelength. This number is typically fixed for the life of the system; however, with advances in technology, the number can change. The potential bandwidth is the capacity that could be made available if active components were configured for all fibers at all a
31、vailable bandwidths. Connectivity between Systems Systems that are co-located at a landing station or have good backhaul connectivity (i.e., terrestrial fiber between the systems), have potential to act as backup routes for each other. Thus, some number representative of potential synergy would be a
32、 valuable factor. History of Outages The historical count of outages for a system gives a good indication of the vulnerability of the system. The outage information could include number, duration, severity, cause, etc. Two values that are suggested as metrics are: o The number of outages experienced
33、 within the region or route within a specified period of time (the previous n months a suggested value for n is 12); and o The maximum number of cables that were affected by a single event (e.g., earthquake, typhoon, etc.). Availability of Repair Capabilities When an undersea cable has an outage, th
34、e repair time is typically measured in days; proximity of repair ships and spare equipment can help to minimize the outage time. Regional Susceptibility to Natural Disasters Systems are more vulnerable when placed in a location with a history of natural disasters like earthquakes. Regional Susceptib
35、ility to Man-made Outages Systems also are more vulnerable when placed in a location susceptible to external aggression, such as fishing, anchors, etc. Age of Undersea Cable or Remaining Life of Undersea Cable This factor will take into consideration the aging of technology or the remaining time tha
36、t the regions undersea cables will remain in service. Upgradability This factor would take into consideration if the capability of a system could be upgraded (e.g., upgrading capability to 10G, 40G, and 100G). 6 Selection of Parameters for Robustness It is the responsibility of the user of this Tech
37、nical Report to select a set of parameters as an input for the One-view Visualization (OVV) methodology. Based on a study of the UCI, this clause provides a list of parameters that may be considered; this list is by no means exhaustive and does not exclude the use of additional or other parameters.
38、In defining a metric to quantify the robustness of the UCI servicing a region or route, the metric should be flexible enough that it could be used generically, examining all infrastructure in a region/route, or specifically, examining the infrastructure in a region/route used by a particular service
39、 provider. At an IEEE conference in Vancouver, Canada, Omer, et al. defined a metric for resiliency examining only the traffic load and traffic capacity of the system. While this metric may be useful for the modeling described in the paper, it does not take into consideration a number of factors ass
40、ociated with the infrastructure. The proposed metrics are grouped into four categories resiliency, reliability, vulnerability, and growth potential: (i) Resiliency is the ability to adapt to an outage and restore Internet and private line services. This reflects the flexibility to adapt to changes a
41、nd the richness of intra-connectivity that leads to rapid service restoration. Resiliency is the most important factor and contains four metrics (A1 A4). (ii) Reliability is the ability of the regional undersea cable infrastructure to consistently deliver end-to-end service(s) without degradation or
42、 failure. Consideration is given to outage history, susceptibility to ATIS-0100031 13 disasters, and restoration capability. Reliability is the second most important factor and contains three metrics (A5 A7). (iii) Vulnerability is the extent to which a system will degrade when subjected to a specif
43、ied set of environmental conditions (A8 A10). (iv) Growth potential is the ability to expand capacity in a timely manner to meet increased demand. This expansion capacity reflects the near-term growth potential. Expansion capacity is likely the least important of the metrics (A11 A12). The proposed
44、set of metrics will be the following quantitative values: A1(Number of Hubs) = A scaled value of the number of landing station areas (Hub) with three or more systems landing within the same city (more is better). This metric would reflect the availability of locations for rerouting during a failure.
45、 A2= A scaled value of the average number of cable landing stations per system (more is better). When a system lands at multiple locations, the availability of synergy increases. A3= A scaled value of the number of disjoint paths in the region/route (more is better). When multiple routes are availab
46、le, the effects of a single failure are reduced (i.e., reduced chance of a single point of failure). A4= A scaled value of the average number of systems per Hub (see A1). This factor indicates whether there is an appropriate quantity and diversity of UCI systems supported at the Hubs. A5= A scaled v
47、alued related to the number of outage events per region/route within the past 36 months (less the better). This metric reflects the risks associated with the region/route. A6= A scaled value related to the maximum number of systems affected by a single event within the past 36 months (less the bette
48、r). This metric would reflect the severity of risks within the region/route. A7= A scaled valued related to the ratio of cable repair ships available in a region or for a route (more the better) to the number of paths in that region/route (see A3). Availability of repair capabilities reduces the exp
49、ected downtime if an event occurs. A8= A scaled valued related to Regional susceptibility to natural disasters. It is based on historical information) based on regional geo-seismic maps and seismic history. A9= A scaled valued related to Regional susceptibility to man-made disasters (an index of 1 to N, based on historical information from outages attributable to external aggression, such as fishing, anchors, etc.). A10= A scaled valued related to the age of the undersea cable or
