Nokia 4A0-220 Nokia GMPLS-Controlled Optical Networks Exam Practice Test

 Coordination of L0 and L1 resources in case of a failure in an MRN is achieved by setting the color constraints. Color constraints are used to specify which wavelengths or timeslots can be used by a given LSP request. By setting the color constraints, the NFM-T can ensure that the L0 and L1 resources are compatible and consistent across the network. For example, if an L0 LSP request requires a specific wavelength, the NFM-T can set the color constraint to match that wavelength and assign it to the L0 LSP. Similarly, if an L1 LSP request requires a specific timeslot, the NFM-T can set the color constraint to match that timeslot and assign it to the L1 LSP. This way, the coordination of L0 and L1 resources is achieved by ensuring that the same color is used by both layers. References : Nokia GMPLS-controlled Optical Networks Course | Nokia, 3. GMPLS - Nokia

SFD is not a GMPLS protocol, but a term used in optical networks to refer to the Source Frequency Definition, which is a parameter that specifies the frequency of a wavelength channel4. GMPLS protocols are those that enable the control and management of different types of switching technologies, such as packet, wavelength, fiber, and time-slot switching5. Some examples of GMPLS protocols are OSPF-TE, RSVP-TE, and LMP. OSPF-TE is a routing protocol that advertises the topology and the link attributes of the network6. RSVP-TE is a signaling protocol that establishes, modifies, and releases LSPs. LMP is a link management protocol that verifies the connectivity and monitors the status of the links. References:

• 4: Source Frequency Definition (SFD) - ITU
• 5: Generalized Multi-Protocol Label Switching - Wikipedia
• 6: OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS) - RFC 4203
• [7]: Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource Reservation Protocol-Traffic Engineering (RSVP-TE) Extensions - RFC 3473
• [8]: Link Management Protocol (LMP) - RFC 4204

GMPLS is a protocol suite that extends the MPLS signaling and routing capabilities to control different types of switching technologies, such as optical, TDM, and packet switching1. GMPLS has several key features, such as self-discovery, fast protection, and restoration. Self-discovery allows GMPLS nodes to automatically discover their neighbors and exchange information about their capabilities and resources2. Fast protection enables GMPLS nodes to quickly switch to backup paths in case of a failure, without relying on the control plane3. Restoration allows GMPLS nodes to dynamically establish new paths in the network after a failure, using the control plane3. Resource optimization is not a key feature of GMPLS, but rather a potential benefit of using GMPLS to efficiently utilize the network resources and avoid over-provisioning. References:

• 1: Nokia GMPLS-controlled Optical Networks Course | Nokia
• 2: GMPLS - Nokia
• 3: Traffic survivability through Protection and Restoration Combined (PRC) - YouTube
• [4]: GMPLS: Architecture and Applications - Google Books

A Shared Risk Link Group (SRLG) is a set of links sharing a common resource, which affects all links in the set if the common resource fails5. These links share the same risk of failure and are therefore considered to belong to the same SRLG. For example, links sharing a common fiber are said to be in the same SRLG because a fault with the fiber might cause all links in the group to fail. SRLGs are used in MPLS and GMPLS networks to provide traffic engineering and protection/restoration mechanisms. When computing the secondary path for an LSP, it is preferable to find a path such that the secondary and primary paths do not have any links in common in case the SRLGs for the primary and secondary paths are disjoint6. This ensures that a single point of failure on a particular link does not bring down both the primary and secondary paths in the LSP. References:

• 5: Shared risk resource group - Wikipedia
• 6: Shared Risk Link Groups for MPLS | Junos OS | Juniper Networks

The GMPLS technology includes three categories of protocols: routing, signaling, and link management. Routing protocols are used to exchange information about the network topology, resources, and constraints among the nodes. Signaling protocols are used to establish, modify, and release Label Switched Paths (LSPs) across the network. Link management protocols are used to verify the connectivity and status of the links between adjacent nodes. References : Nokia GMPLS-controlled Optical Networks Course | Nokia, 3. GMPLS - Nokia

RSVP-TE Notify message is a message type defined in the RSVP-TE protocol, which is an extension of the RSVP protocol for MPLS traffic engineering. RSVP-TE Notify message is used to inform non-adjacent nodes of LSP events, such as setup, modification, or teardown. This allows the nodes to update their local state information and perform actions based on the notification. For example, a Notify message can be used to trigger a fast reroute mechanism in case of a link or node failure12. References:

• 1: RFC 3473 - Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource Reservation Protocol-Traffic Engineering (RSVP-TE) Extensions
• 2: RFC 3471 - Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description

The Feasibility File is a file that contains a set of target values for various optical impairment parameters, such as OSNR, CD, PMD, and PDL, that are used to determine whether a given LSP can be routed through the GMRE network. The Feasibility File is generated by the Network Planning Application (NPA) based on the network design and the service requirements. The Feasibility File is then loaded into the GMRE nodes and used by the GMPLS routing engine to perform feasibility checks for LSP requests. The Feasibility File ensures that the LSPs are routed in accordance with the network plan and the optical performance criteria12. References:

• 1: Nokia GMPLS-controlled Optical Networks Course | Nokia
• 2: GMPLS - Nokia

The provisioning steps that are common in both CP to plain MP networks are node creation, CPB provisioning process, node synchronization, and CPB power balance. These steps are required to create and commission the nodes, provision the cross-connect boards (CPBs), associate the links between the nodes, synchronize the network elements (NEs) with the NFM-T, and balance the power levels of the CPBs. References : Nokia GMPLS-controlled Optical Networks Course | Nokia, Nokia Advanced Optical Network Management with NFM-T Course | Nokia

To configure the Trail template in NFM-T for an Uplink board (such as 2UC400) in a network with only LI restoration capability, you need to check the Logical Link box, set the Port Type to Unterminated, uncheck the ASON Routed box, and uncheck the ASON Tunnel box. This configuration allows you to create a logical link between two Uplink boards that can be used for LI restoration. The logical link is not terminated at the Uplink board, but at the OTU board. The ASON Routed option is not needed for LI restoration, as the LSPs are established by NFM-T and not by GMPLS. The ASON Tunnel option is not applicable for Uplink boards. References : Nokia Advanced Optical Network Management with NFM-T Course | Nokia, Nokia 1830 PSS-4, PSS-8, PSS-16 and PSS-32 Platforms - NATO

 The Wait for Server Restoration (WSR) parameter in the MRN is a boolean parameter that determines whether an LI service should wait for the LO restoration or not in case of a failure.When WSR is false, the LI services do not wait for the LO restoration and restore through LI switching. This means that if an LO optical channel fails, the LI services that use that channel will switch to another available optical channel at LI layer without waiting for the LO layer to restore the failed channel. This option provides faster restoration time for LI services, but may result in suboptimal resource utilization at LO layer. When WSR is true, the LI services wait for the LO restoration and do not switch at LI layer. This means that if an LO optical channel fails, the LI services that use that channel will remain in that channel until the LO layer restores it or until a timeout occurs. This option provides optimal resource utilization at LO layer, but may result in longer restoration time for LI services. References : Nokia GMPLS-controlled Optical Networks Course | Nokia, 3. GMPLS - Nokia

The 3R resource is a type of optical regeneration resource that can be used to extend the reach of optical signals in a GMPLS-controlled optical network. The 3R resource performs three functions: reshaping, retiming, and reamplifying the optical signal. The 3R resource can be added to the Network Planning Application (NPA) in the Nokia Network Functions Manager for Transport (NFM-T) through the Constraint Wizard. The Constraint Wizard is a tool that allows the user to define various constraints and parameters for the network design, such as optical impairments, wavelength availability, protection schemes, and regeneration resources. The user can select the 3R resource from the list of available resources and specify its location, capacity, and cost. The NPA then uses this information to perform feasibility checks and path computation for the LSP requests12. References:

• 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. References:

• 1: GMPLS - Nokia
• 2: Generalized Multi-Protocol Label Switching - Wikipedia
• 3: Nokia GMPLS-controlled Optical Networks Course | Nokia