Lucent Optical Management System (oms) Release
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| Partition repair
The partition repair is needed to allow management DCNs for large multi-ring networks to be designed such that single points of failure are avoided. The use of partition-repair is restricted to those cases where the current mechanisms cannot avoid a single point of failure, even though a physical backup route is available. Partition repair provides a way to enhance the robustness of the DCN by providing the capability to repair intra-area routing using connections via nodes outside the area. This is done by creating a path outside the area, between two level 2 nodes (which are provisioned to be partition capable level 2 nodes) that belong to distinct partitions of the same IS-IS area. Level 1 IS-IS PDUs and CLNP PDUs are encapsulated and transferred over the level 2 path. Note that network element types that do not support partition-repair, can exist in the “repaired” areas; however, these network element types cannot be part of the level 2 repair path (they cannot be part of the level 1 tunnel through the level 2 domain). A network element (NE) is a physical box that contains a physical piece of equipment. A network element can contain one or more nodes. A node is a logical part of the DCN and is the basic building block of the DCN. Both intermediate systems and end systems are considered to be nodes. Each node is identified by exactly one NSAP. An NSAP, or network service access point, is the address of a node. Each node has exactly one NSAP that is unique in the entire network (usually the NSAP is even globally unique). Routing and forwarding in each node of a network is done using the target NSAP. The terminology that is used in relation to partition-repair requires some explanation. A node can be partition-repair capable, partition-repair compatible, and partition-repair designated. These terms are described below: • A node is partition-repair capable if it is provisioned as such. Only possible end points of partition-repair tunnels need to be provisioned as partition-repair capable. Such possible end points must be attached level 2 nodes. (A level 2 node is attached if it can forward packets to a different area, even if the level 2 node itself is not on an area boundary). • A node is partition-repair compatible if a partition-repair path can pass through the node. No provisioning is needed or required to make a node partition repair-compatible. Many of the older network element types, are not partition-repair compatible. • A node is partition-repair designated if it is selected as such by all the other nodes in its area that are still connected to it via a level 1 path. The election is done by choosing one node from the set of still-connected nodes that are partition-repair capable. If a partition-repair designated node of a certain area learns (by listening to level 2 communication) that there is another partition repair designated node in Management communication setup concepts ................................................................................................................................................................................................................................... 365-312-875R5.2 Issue 1, March 2007 tải về 2.06 Mb. Chia sẻ với bạn bè của bạn:
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