The Link Maintenance window is a feature of NFM-T that allows the user to perform maintenance tasks on links and nodes in a GMPLS network. The Link Maintenance window is a wizard that provides commands to set links and nodes to maintenance mode, which prevents them from being used for routing new LSPs or carrying traffic. The user can also use the Link Maintenance window to reroute existing LSPs away from the links and nodes that are in maintenance mode, either manually or automatically.  The Link Maintenance window helps the user to perform network maintenance operations without disrupting the service availability or quality 1 2 .  References :

1 : Nokia GMPLS-controlled Optical Networks Course | Nokia

2 : Nokia Network Functions Manager for Transport User Guide | 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 reservation 3 4 .  References :

3 : RFC 4829: Label Switched Path (LSP) Preemption Policies for MPLS Traffic Engineering 4

4 : MPLS Applications User Guide | Juniper Networks 5

A network with ROADM GMPLS nodes and optical transponder connections could have both L0 and L1 restoration capabilities. L0 restoration refers to the ability of the network to recover from failures at the optical layer, such as fiber cuts or node failures, by rerouting the affected LSPs to alternative paths at the same layer. L0 restoration can be achieved by using GMPLS signaling protocols, such as RSVP-TE or CR-LDP, to establish backup LSPs in advance or on demand.  L0 restoration can provide fast recovery times and high availability for optical services 3 4 . L1 restoration refers to the ability of the network to recover from failures at the sub-wavelength layer, such as transponder failures or wavelength unavailability, by rerouting the affected LSPs to alternative paths at a higher layer. L1 restoration can be achieved by using GMPLS routing protocols, such as OSPF-TE or ISIS-TE, to advertise the sub-wavelength information and availability to other nodes in the network.  L1 restoration can provide more flexibility and efficiency for sub-wavelength services 5 6 .  References :

3 : GMPLS - Nokia

4 : Generalized Multi-Protocol Label Switching - Wikipedia

5 : Sub-Wavelength Switching - Nokia

6 : Sub-Wavelength Switching in Optical Networks - IEEE Xplore

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 channel 4 .  GMPLS protocols are those that enable the control and management of different types of switching technologies, such as packet, wavelength, fiber, and time-slot switching 5 . 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 network 6 . 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

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 GMRE notify address is an IP address used to signal failures on downstream nodes upstream to the head node. The GMRE notify address is configured on each GMRE node and is used to send a Notify message to the head node when a failure occurs on a link or node along the LSP. The Notify message contains the failure information and the LSP ID. The head node can then initiate a restoration process based on the Notify message.  References  :  Nokia GMPLS-controlled Optical Networks Course | Nokia ,  GMPLS - Nokia

Tunnel Property Heritage is a feature of GMRE that allows the propagation of certain properties from higher order (HO) LSPs to lower order (LO) LSPs in a multi-layer network. These properties include cost, SRLG, and color. Cost is a metric that reflects the preference of using a certain link or path for routing. SRLG is a set of links that share a common risk of failure. Color is an attribute that can be used to group or filter LSPs based on service classes or customer profiles.  By propagating these properties from HO to LO LSPs, GMRE can ensure that the end-to-end LSPs are consistent and optimal across different layers 3 4 .  References :

3 : Nokia GMPLS-controlled Optical Networks Course | Nokia

4 : GMPLS - 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 LSP 1 2 .  References :

1 : Nokia GMPLS-controlled Optical Networks Course | Nokia

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

The GMRE functionality is guaranteed in Nokia equipment by controller redundancy. The controller is the hardware component that runs the GMPLS software and controls the switching fabric of the node. Each node has two controllers, one active and one standby, that synchronize their states and databases. If the active controller fails, the standby controller takes over and ensures the continuity of the GMRE functionality.  References  :  Nokia GMPLS-controlled Optical Networks Course | Nokia ,  1830 Photonic Service Switch (PSS) | Nokia

Automation is one of the key features of GMPLS that allows dynamic provisioning of optical transport connections between IP routers and optical network elements 2 . Automation reduces the operational time and administrative overhead required to provision new connectivity, which in turn reduces the operational expenditure (OPEX) of the network. Reducing CAPEX, providing resilience against multiple failures, and supporting multi-vendor networks are not direct benefits of automation, but rather possible outcomes of using GMPLS in general.  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