4A0-220 Exam Dumps and Practice Questions

The Commissioning File in GMRE nodes is a file with target values that determine whether a given LSP is possible. The Commissioning File contains parameters such as power, OSNR, Q-factor, and dispersion that are used to evaluate the feasibility of an LSP request. The Commissioning File is generated by the Network Planning Application (NPA) based on the network design and optical impairments. The Commissioning File is uploaded to each GMRE node and is used by the CSPF algorithm to find a suitable path for the LSP.Reference:Nokia GMPLS-controlled Optical Networks Course | Nokia,Network Planning Application (NPA) | Nokia

Preemption is a mechanism that allows a higher priority LSP to tear down an existing lower priority LSP in order to obtain the required resources for its establishment. Preemption can occur when there is not enough bandwidth or other resources available on a link or node to accommodate a new LSP request. In this case, the node can select one or more lower priority LSPs that are using the resources and send them a PathErr message with a Preempt error code. This causes the lower priority LSPs to be terminated and release their resources.The node can then allocate the resources to the higher priority LSP and send a Resv message to confirm its reservation34.Reference:

3: RFC 4829: Label Switched Path (LSP) Preemption Policies for MPLS Traffic Engineering4

4: MPLS Applications User Guide | Juniper Networks5

Quality of Service (QoS) in GMPLS is the ability to set constraints such as latency and priority for different kinds of services. This means that GMPLS can allocate network resources according to the specific requirements of each service, such as voice, video, or data. For example, a voice service may need low latency and high priority, while a data service may need high bandwidth and low priority. GMPLS can use Traffic Engineering (TE) extensions to OSPF and RSVP protocols to advertise and reserve network resources based on QoS parameters.Reference: [Nokia GMPLS-controlled Optical Networks Course | Nokia], [Quality of Service - Nokia]

The SNC state with an uppercase ''N'' means that the resource is currently using the nominal resource assigned to it. As explained in the previous question, a nominal resource is the default or preferred resource that is assigned to an LSP when it is created. If an LSP is using the nominal resource on a TE-link, it means that the LSP has not been rerouted or switched due to any failure or constraint violation.In this case, the SNC state of the resource will be ''N'', indicating that it is in use by an LSP12.Reference:

1: Nokia GMPLS-controlled Optical Networks Course | Nokia

2: Nokia Network Functions Manager for Transport User Guide | Nokia

GMPLS-enabled nodes use routing protocols, such as OSPF-TE or ISIS-TE, to exchange information about the topology and the state of the links in the network12.This information includes the link attributes, such as bandwidth, wavelength, protection, and shared risk link groups (SRLGs)3. The state of each link indicates whether it is up or down, available or reserved, and so on. This information is used by GMPLS-enabled nodes to compute feasible paths for LSPs and to avoid routing loops or conflicts. The bandwidth and the frequency of each client path are not present in every GMPLS-enabled node, but only in the ingress and egress nodes that initiate and terminate the LSPs. The list of LSPs created in the entire network is also not present in every GMPLS-enabled node, but only in the nodes that are involved in the LSPs or that maintain a global view of the network.Reference:

1: GMPLS - Nokia

2: Generalized Multi-Protocol Label Switching - Wikipedia

3: Nokia GMPLS-controlled Optical Networks Course | Nokia