Parameters that are considered and computed for ASON rerouting


To achieve dynamic rerouting for optical-layer ASON services and ensure service transmission quality, optical parameters must be considered, such as OSNR, CD, and PMD. In addition, they need to be included in service routing constraints.

Other related questions:
Rerouting policy when ASON network resources are insufficient
Rerouting policy when ASON network resources are insufficient: When the resource of a link is insufficient, the VC4 service will be rerouted to a different link until there is no idle resources.

Whether optical-layer ASON services are rerouted after an OBU board is removed and re-inserted
Question: If frontline engineers remove an OBU board from the OSN 6800 V100R007C02SPC200 in the optical-layer ASON network, and the corresponding FIU board does not report any alarms, will ASON services on the FIU board be rerouted? The OMS_TEL_DOWN alarm is generated on the TE link xxx as follows: OMS_TEL_DOWN CR start 2013-11-18 14:29:30+05:30 None NSA TEL Node=,TE LinkID=0x8;,Sub-shelf=0,Board=2,Port=1,Error=0x2; Answer: In versions earlier than V100R007C00, after an OBU board is removed, ASON services on the corresponding FIU board are not rerouted. Since V100R007C00, the offline alarms of an OBU board are transferred to the corresponding FIU board. As a result, ASON services on the FIU board are rerouted. In conclusion, after an OBU board is removed from OSN 6800 V100R007C02SPC200, ASON services are rerouted. Suggestion and conclusion: By default, in versions earlier than V100R007C00, optical-layer ASON services are rerouted on the condition that the FIU board reports the MUT_LOS or BD_STATUS alarm. Since V100R007C00, optical-layer ASON services are also rerouted on the condition that boards on the line dimension report the BD_STATUS alarm. These boards can be OA boards, and multiplexer/demultiplexer boards.

Rerouting rules of Huawei WDM/OTN ASON systems
Through traffic engineering, a WDM/OTN ASON network has various rerouting constrains: 1. Constraints on explicit network resources: explicit nodes, links, wavelengths, and channels 2. Constraints on excluded network resources: excluded nodes and links 3. Limitation on the quantity of nodes (or hops) traversed by a strict route or service 4. Limitation on the reach of an optical fiber carrying services, loading sharing mode, SRLGs, and associated services 5. Combinations of the preceding constraints

Precautions for setting rerouting trigger conditions on an ASON network
Rerouting trigger conditions are determined based on the number of available network resources and service importance. If there are sufficient resources or protected services are important, you can select the policy of triggering rerouting when any LSP fails. In this way, 1+1 protection is retained for services under SNCP protection or optical-layer associated services, and quick switching can be achieved upon a fault. Even if a rerouting failure occurs, the failure can be detected in a timely manner. If there are insufficient resources or the protected services are less important, you can select the policy of rerouting when both LSPs fail. In this way, the 1+1 protection provided for the services can survive only one fault. When both LSPs fail and service rerouting is triggered, the service will be interrupted for a short time (depending on the rerouting time), or be interrupted for a long time if rerouting fails.

Method used to select routing policies on an ASON network
Various rerouting policies are provided on an ASON network and are selected based on the available system resources. When the resources are sufficient, diamond services can be used. As resources are continuously consumed, a user may have to select copper services to ensure that sufficient resources are provided for diamond services. Copper services are rarely used. Generally, only temporary services are configured as copper services.

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