Free Nokia 4A0-220 Practice Exam with Questions & Answers

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 layers34. References:

• 3: Nokia GMPLS-controlled Optical Networks Course | Nokia
• 4: 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

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 alongthe 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

A distributed control plane for GMPLS means that each router has software to run the GMPLS protocols and can modify the node’s switching fabric. This allows the routers to communicate with each other and establish Label Switched Paths (LSPs) across the network without relying on a centralized controller or network manager. A distributed control plane can improve the scalability, reliability, and efficiency of the network. References : Nokia GMPLS-controlled Optical Networks Course | Nokia, 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

Automation is one of the key features of GMPLS that allows dynamic provisioning of optical transport connections between IP routers and optical network elements2. 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

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 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 OSPF-TE protocol is an extension of the Open Shortest Path First (OSPF) protocol that is used to exchange information about the state of links in a GMPLS network. OSPF-TE advertises link attributes such as bandwidth, latency, priority, protection, or switching capabilities to other nodes in the same area. OSPF-TE enables nodes to build a Traffic Engineering Database (TED) that contains the topology and resource information of the network. OSPF-TE helps nodes to perform CSPF calculations and establish LSPs using RSVP-TE signaling. References : Open Shortest Path First - Wikipedia, Understand Open Shortest Path First (OSPF) - Design Guide, RSVP-TE and OSPF-TE extensions for GMPLS

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