1、 TECHNICAL REPORT ATIS-0100033 MULTI-LAYER COORDINATION IN ALL-IP NETWORKS ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertainment and communications industry. More than 200
2、 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 Platforms and Emerging Networks. In addition, num
3、erous Incubators, Focus and Exploratory Groups address evolving industry priorities including Smart Grid, Machine-to-Machine, Networked Car, IP Downloadable Security, Policy Management and Network Optimization. ATIS is the North American Organizational Partner for the 3rd Generation Partnership Proj
4、ect (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 National Standards Institute (ANSI). For more informati
5、on, please visit . Notice of Disclaimer Loss of Frame (LoF); and Alarm Indication Signal (AIS). IP Layer Alarms: Link Down alarm that is triggered following a delay exceeding 100 ms on the optical layer. Softswitch Layer Alarms: SCTP Path Switchover alarm that is triggered following a delay exceedin
6、g 6s on a single softswitch plane. SCTP Link Failure alarm that is triggered following a delay exceeding 7.5s on the dual softswitch planes. Dual-plane is used in softswitch network for higher reliability. In the event a plane fails, the traffic on the plane can failover to the other plane. Priority
7、Priority: This failure will have high priority. A fiber cut could potentially result in loss of service to a large number of customers. Action/Follow-UpAction & Follow-Up: (i) Immediately fix the fiber cut by switching traffic to the protection fiber. Document detailed report of the incident. ATIS-0
8、100033 12 IP Bearer Net.er NOptical Transport Net. Softswitch Net.CableCutOTURecei ve no lightShut off Laser100msLinkdownSCTP Pat h SwitchoverDevice Failure and Ser vi ce Do w nLOS LOF AISLinkDow nSCTP Pat h Sw it choverSCTP Link FailureTrigger condition alarm Protection mechanismOptical layer prote
9、ctionRout e r e-convergenceInterruption beyond 6sfor single planeInterruption beyond 7.5sfor dual planesEven tInsert PRBS or all 1 downwardLegend: AIS = Alarm Indication Signal LOF = Loss of Frame LOS = Loss of Signal OTU =Optical Transport Unit PRBS = Pseudo Random Bit Signal SCTP = Stream Control
10、Transmission Protocol Figure 5 - An Example of Alarm-Flow following a cable-cut in a multi-layer network (ii) The alarms will escalate in time through the different layers of the network as shown in Figure 5, if the problem remains unsolved. To ensure coordination amongst the different layers in All
11、-IP networks the hold-off timers shall be synchronized. Otherwise, in the event of a failure, this lack of coordination between the layers can lead to race conditions. Different network layers will resort to simultaneous restoration activity that lead to route flapping and network instability and other undesired behavior. Furthermore, prevent future incidents by adopting suitable best practices Nrsc-1993, Nrsc-1996, and Nrsc-1997 and adopting steps to prevent their recurrence in Fcc-Nrc, Nrsc-1996, and Nrsc-1997.
