The configuration snippet shows that MPLS and LDP are configured globally but not enabled on an interface. The commands include “mpls label protocol ldp,” “mpls ldp router-id loopback 0,” and “mpls ip,” which are necessary for global settings. However, to establish LDP neighbors and exchange labels, LDP must be enabled on the specific interface where it’s needed.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR)
• Cisco SPCOR Training resources available on the Cisco Learning Network Store.

Here is the solution:

Text Description automatically generated

 The JSON script in the exhibit configures BGP with a neighbor at IP address 192.168.1.2 that resides in AS (Autonomous System) 65514. In the script,  specifies the neighbor’s IP address, and  indicates the AS number of the neighbor.

References: For more information, you can refer to the “Implementing and Operating Cisco Service Provider Network Core Technologies” training, which covers topics such as configuring, verifying, troubleshooting, and optimizing Service Provider IP network infrastructures, including BGP configurations

Router R1 establishes TCP connections that are authenticated with an MD5 password. In the context of BGP (Border Gateway Protocol), TCP is used for establishing connections, and MD5 passwords can be used for authentication to enhance security.

To prevent access from spoofed addresses to the LAN, the engineer should enable Unicast Reverse Path Forwarding (uRPF). uRPF checks the reachability of the source address in packets being forwarded, which helps mitigate issues caused by malformed or forged IP source addresses.

• Option A is correct because it enables uRPF on interface FA0/0 and verifies that the source address is reachable via the outgoing interface, which is essential when the routing is symmetric.
• Option C is also correct as it enables uRPF on interface FA0/1 and allows the source address to be reachable via any interface, accommodating environments with asymmetric routing.

References :=

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) source book and study guide.

https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k-r6-5/ip-addresses/configuration/guide/b-ip-addresses-cg-asr9000-65x/m-implementing-lpts-asr9000-crs.html

 MPLS LDP (Label Distribution Protocol) is used for label distribution in MPLS networks. When making changes to the LDP configuration, it’s essential to ensure that the changes do not disrupt existing LDP sessions. In this scenario, the network administrator implemented MPLS LDP changes on the PE-A LSR (Label Switching Router) device, and the goal is to prevent any disruption to LDP peers.

The MPLS LDP Non-Stop Routing (NSR) feature allows LDP sessions to survive control-plane switchover events without interruption. When NSR is enabled, the LDP session state information is synchronized between the active and standby control planes. If the active control plane fails, the standby control plane takes over seamlessly, and LDP sessions continue without interruption.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/msp/configuration/xe-3s/mp-ha-xe-3s-book/mp-nsr-ldp-supp.pdf

• The Forward Error Correction (FEC) field within the OTN (Optical Transport Network) signal structure is responsible for error correction. When data arrives at the receiver, the FEC field helps correct any errors that may have occurred during transmission. It enhances the reliability of optical communication by detecting and rectifying errors.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies course materials.

 The BFD (Bidirectional Forwarding Detection) interval configuration on an interface is automatically disconnected when the BFD-configured subinterface is removed. This is because BFD sessions are tied to the specific subinterface, and removing it will terminate the BFD session associated with that subinterface.

References: The information is based on the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course, which covers the configuration, verification, troubleshooting, and optimization of Service Provider IP network infrastructures, including BFD implementation

 The number 2 in the configuration “snmp-server community ciscotest ro 2” is significant because it refers to the numeric name of the Access Control List (ACL) that contains the list of SNMP managers with access to the agent. In this context, “ro” stands for read-only, meaning that SNMP managers listed in ACL 2 can only read data from the SNMP agent but cannot modify it. The ACL defines which IP addresses are allowed to access SNMP data. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

 To align with customer contract SLAs and allow 10% of interface capacity on router R3 for traffic from CE1 towards the FTP server, the network engineer must apply a policy map to R1 to reserve the remaining 10% of interface bandwidth (Option C). Additionally, applying a policy map to R3 to reserve 10% of interface bandwidth (Option D) ensures adherence to the customer’s contract SLAs while utilizing the allocated bandwidth capacity. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Quality of Service section.

In Cisco hardware, when a high bandwidth multicast stream is sent over a Multicast VPN (MVPN), a data Multicast Distribution Tree (MDT) is specifically created for that stream. This data MDT is used in addition to the default MDT, which is used for lower-bandwidth or control traffic. The purpose of the data MDT is to optimize the transmission of high-bandwidth streams through the core of the network, ensuring that the multicast traffic is only sent to those PE routers that have local receivers for the multicast group in question. This mechanism helps in efficiently using network resources and provides a scalable solution for transmitting high-bandwidth multicast streams.

References: The explanation is based on the concepts outlined in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course, which covers the configuration, verification, troubleshooting, and optimization of Service Provider IP network infrastructures, including advanced topics like MVPN and MDTs

NetFlow version 9 can report additional information such as BGP Autonomous System (AS) information due to its template-based design, which allows for flexibility and support for a wider range of IP flow information, including IPv4 and IPv6 flow information, BGP routing information, and multicast flow data.

• NetFlow provides traceback information by analyzing network traffic. To configure NetFlow for traceback, you need to set up a classification ACL (Access Control List) to identify which type of traffic will be analyzed. This allows NetFlow to focus on specific traffic flows and report relevant information. The classification ACL can be based on various criteria such as source/destination IP addresses, port numbers, or protocols. By defining the classification ACL, you ensure that only the relevant traffic is considered for NetFlow analysis.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0

The configuration shown indicates that Router 1 is set up with a route-map named “ddos” that matches traffic tagged with “tag 1”. The traffic matching this tag is then set to have a next-hop IP of 192.0.2.1 and a local preference of 150. The community is also set to “no export”, which means this route will not be advertised to external BGP peers. Since there’s no explicit deny statement in the configuration, only traffic with tag 1 and local preference of 150 will be dropped by Router 1 as per the BGP routing policy. References: Implementing and Operating Cisco Service Provider Network Core Technologies course materials. 

The network operator needs to provide connectivity between two IPv4 and IPv6 dual-stacked networks using specific assigned IPv6 space. NAT46 (Network Address Translation 46) is the appropriate technology for this scenario. It allows translation between IPv4 and IPv6 addresses, enabling communication between the dual-stack networks. NAT46 maps IPv6 addresses to IPv4 addresses and vice versa, facilitating seamless communication across different address families. References: Implementing and Operating Cisco Service Provider Network Core Technologies

• In Option A, the configuration correctly classifies and marks management protocols with DSCP AF23, which belongs to AF class 2 with low drop probability.
• Monitoring protocols are marked with DSCP AF13, aligning with AF class 1 and low drop probability.
• All other traffic is marked with a DSCP value of 0, as required.

References:

• Cisco’s official guide on Implementing and Operating Cisco Service Provider Network Core Technologies

The configuration command xconnect 192.168.0.1 12 encapsulation mpls pw-class cisco is used to set up a pseudowire connection to a remote peer at IP address 192.168.0.1 using MPLS encapsulation. The pw-class cisco refers to a pseudowire class named ‘cisco’ that defines the parameters for the MPLS pseudowire. This configuration is part of setting up Layer 2 VPNs, which are often used in service provider networks to extend services such as Ethernet, ATM, or Frame Relay over an MPLS network.

References: For more detailed information, please refer to the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, specifically the sections covering MPLS and Layer 2 VPNs.

The command “traceroute mpls ipv4 10.20.0.1/32 ttl 4” is used to trace the route that packets take to get from the source to the destination in an MPLS network, specifically for IPv4 addresses with a maximum of 4 hops (Time To Live). This command will provide information on all labels and hop-by-hop IP addresses for the specified destinations, meeting the requirements stated in the question.

References := For more detailed information, you can refer to the Implementing and Operating Cisco Service Provider Network Core Technologies training, which covers the configuration, verification, troubleshooting, and optimization of Service Provider IP network infrastructures, including MPLS operations

•  In this scenario, the network engineer is integrating several recently acquired networks into a more scalable common Unified MPLS architecture. The architecture will support end-to-end VPNv4 and VPNv6 services. The requirements include using IS-IS in Area 0 for the core layer and OSPF in Area 0 for the aggregation layers. LDP is used to distribute label bindings within each IGP domain.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0 course material

In the given architecture, if each area is running its own Interior Gateway Protocol (IGP), Border Gateway Protocol (BGP) must be used to provide an end-to-end Multiprotocol Label Switching (MPLS) Label Switched Path (LSP). This ensures that data packets can traverse through the different IGP areas seamlessly, maintaining connectivity across the entire network.

RSVP (Resource Reservation Protocol) is used with MPLS (Multiprotocol Label Switching) traffic engineering tunnels primarily to reserve bandwidth along the path of the tunnel. This ensures that sufficient resources are allocated for the traffic to meet quality of service requirements, which is crucial for maintaining the performance of critical applications that traverse the network. References := For more information on RSVP and MPLS traffic engineering, refer to the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, which provide detailed explanations on how these technologies work together to optimize network traffic1.

When there is an LSP breakage during the testing of MPLS OAM ping capabilities, the ingress MPLS router does not receive any reply because MPLS OAM ping is used to verify connectivity over Label Switched Paths (LSPs), and if an LSP is broken, the echo request will not reach the egress router, resulting in no echo reply being sent back.

1: PIM-DM 2:IGMP 3:PIM-SM 3:shared tree 4:source tree

Option B is the correct answer because it meets all the given requirements. The configuration “snmp-server community comaccess ro 10” allows read-only access for all objects to members of Access-List 10 that use the comaccess community string. The “snmp-server host ABC.com informs version 2c public” command ensures SNMP authentication failure traps are sent to SNMPv2c and then to the host using SNMPv2c with the public community string.

To redirect traffic from ASN 64501 to 10.0.0.0/8 via the primary link North_A instead of the slow backup link North_B, setting a higher local preference between North_A and South_A is required. Local preference is a BGP attribute that helps in selecting the exit point from an AS (Autonomous System). By increasing local preference for routes received on North_A, traffic will be directed through this path as it becomes more preferred. References := Cisco Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR)

The correct configuration for enabling BGP FlowSpec client function and installation of policies on all local interfaces is flowspec address-family ipv4 install interface-all local. This command configures the router to accept FlowSpec policies from a BGP peer and apply them to all local interfaces. The flowspec keyword enables the BGP FlowSpec client function, address-family ipv4 specifies the address family, and install interface-all local ensures that the policies are installed on all local interfaces. References := Implementing and Operating Cisco Service Provider Network Core Technologies course.

https://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos-policing/19645-policevsshape.html

• The configuration in Option A is used to implement URPF in loose mode on the GigabitEthernet0/1 interface.
• Loose mode allows the router to check for any route back to the source, not necessarily the best route.
• By enabling URPF, the router ensures that incoming packets have a valid return path in the routing table.
• This helps prevent IP spoofing and limits malicious traffic on the network.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies
• On-Demand E-Learning

PCE – 1,2,5

PCC- 3,4

In the context of configuring L2VPN over MPLS, the xconnect statement is essential. It specifies the peer router and virtual circuit ID, creating the connection between two customer edge routers over the service provider’s MPLS network. Without the xconnect statement, there’s no association between the attachment circuits and pseudowire, leading to the failure of the L2VPN service.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco SPCOR Training & Certification

In the context of VPLS (Virtual Private LAN Service) configuration, the engineer should perform additional configurations to enable the virtual switch instance. The correct answer is Option A, which likely involves configuring interface VLAN and associating it with xconnect vfi to establish end-to-end LAN connectivity between customer’s remote offices. This is essential for enabling VPLS, which allows geographically dispersed sites to be connected over a service provider’s network as if they were on the same local area network.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco SPCOR Training & Certification

Cisco IOS XE Software is an open and flexible operating system optimized for a variety of network infrastructures. One of its key enhancements over Cisco IOS Software is the support for symmetric multiprocessing (SMP). This allows the operating system to efficiently utilize multiple CPU cores, improving performance and scalability for network services.

References: The enhancement details are derived from the Cisco IOS XE Software overview, which highlights its capabilities and benefits over the traditional Cisco IOS Software.

 To prevent an MPLS TE Label Switched Path (LSP) from using any overseas links, an operator would use the explicit path feature. This feature allows the operator to define a specific route for the LSP to follow, which can be configured to exclude paths that traverse overseas links.

• PE-2 should import the OSPF route from the global routing table into the CUSTOMER-ABC VRF. This allows the VRF to have internet reachability.
• The configuration should include an import route-target statement under the VRF configuration on PE-2. The route target should match the one used by CE-1 to advertise the default route (0.0.0.0/0) to PE-1.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) study guide or official documentation.

In NetFlow export statistics, the BGP next hop information is not included by default. To include the BGP next hop in the export statistics, specific keywords related to BGP next hop must be configured with the version 9 NetFlow entry. This configuration allows for the measurement of network traffic on a per-BGP next hop basis, which is essential for detailed traffic analysis and accounting1. References: Configuring NetFlow BGP Next Hop Support for Accounting and Analysis - Cisco Systems1.

When implementing LDP NSF (Nonstop Forwarding) on the network, an engineer must perform the following tasks:

• Implement direct connections for LDP peers: This ensures that LDP sessions can be reestablished quickly after a switchover.
• Enable NSF for the link-state routing protocol in use on the network: This allows the routing protocol to maintain its state during a switchover, ensuring seamless operation.

The correct configuration for PE1 to connect AS 200 of the service provider with AS 100 of enterprise ABC using BGP, considering the VRF RT 100:10 is already configured, would involve setting up BGP with the correct neighbor and route distinguisher settings. Option C is likely the correct choice as it specifies the BGP neighbor to be within the enterprise ABC’s AS 100 and includes the address family configuration necessary for VRF-aware BGP sessions. References := The Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials provide detailed instructions on configuring BGP in a service provider environment, including the use of VRFs and route distinguishers. For more information, please refer to the official Cisco documentation and course materials related to SPCOR1.

The REST API script in the exhibit is used to configure a VRF (Virtual Routing and Forwarding) instance. In the script,  defines a tenant named “customer”, and  creates a VRF named “customervrf” within that tenant. A VRF allows multiple instances of a routing table to co-exist within the same router at the same time, enabling network paths to be segmented without requiring multiple routers. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide.

To influence inbound path selection when implementing BGP in a multihomed architecture, an engineer must configure a route map with the AS_PATH attribute. The AS_PATH attribute is used to manipulate the path information to make certain routes more or less attractive, thereby influencing the decision-making process for inbound traffic.

The correct action to complete the configuration for connecting two offices via an MPLS L3 VPN is option A. This involves configuring the network 172.16.10.0 and using the redistribute-internal static commands under the BGP address family for Customer_A in the global BGP configuration on R1. In an MPLS L3 VPN, the provider edge (PE) router, which is R1 in this scenario, redistributes customer routes into BGP. The PE router then advertises these routes to other PE routers within the MPLS network using MP-BGP, allowing for the establishment of the VPN.

References :=

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials and official Cisco documentation.

 In OSPF (Open Shortest Path First), the Hello interval is a critical parameter for OSPF neighbor formation. It defines the frequency at which Hello packets are sent on an OSPF interface. For two OSPF routers to become neighbors, they must have matching Hello and Dead intervals. In the provided configuration, Router 1 has a hello-interval of 1 second while Router 2 has a hello-interval of 2 seconds. Adjusting them to match will reestablish the OSPF neighbor relationship between Router 1 and Router 2. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco

 In BGP, the Local Preference attribute is used to influence the exit point from an AS (Autonomous System). A higher local preference value is preferred, and all routes received inherit the local preference value of the route that is installed in the IP routing table. So, configuring a higher local preference outbound will make specific BGP speakers as preferred exit points for customer AS. References := Cisco

 To meet the scalability and service recovery requirements, the network engineer should implement BGP PIC core functionality on routers R2 and R3 (Option A). This will enhance the convergence time during a failure. Additionally, establishing BGP connectivity between routers R1 and R4 with VPNv4 address family enabled (Option C) will facilitate MPLS services across multiple IGP domains.

References :=

• Implementing and Operating Cisco Service Provider Network Core Technologies
• On-Demand E-Learning for Implementing and Operating Cisco Service Provider Network Core Technologies

 The number “2” in the SNMP server configuration “snmp-server community ciscotest ro 2” refers to the numeric name of the Access Control List (ACL) that contains the list of SNMP managers with access to the agent. In this context, “ro” stands for read-only access, meaning that SNMP managers can only read but not modify data on the device. The ACL identified by number “2” specifies which SNMP managers are authorized to access SNMP data on this device using the community string “ciscotest”.

References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide.

 A Multi-Layer control plane, like Cisco’s nLight technology, provides an integrated approach that allows for the automatic provisioning, monitoring, and management of traffic across different network layers, from Layer 0 (optical) to Layer 3 (IP). This integration increases network agility and flexibility while improving network utilization, leading to significant cost savings and more efficient network resiliency solutions2.

References: The Economics of Cisco’s nLight Multilayer Control Plane Architecture2.

 To monitor memory consumption and buffer statistics securely on P and PE devices in an MPLS core, especially considering the high CPU usage, the engineering team should implement SNMP version 3 for its security features. Therefore, option A is correct as it specifies SNMP version 3 with authentication. Option B is also correct as it enables traps for memory buffer peak, which is essential for monitoring memory thresholds and ensuring quick response to potential issues.

To ensure that a router advertises only networks with a prefix mask length less than or equal to 21 to its BGP neighbor, the correct configuration is Option A. This involves applying a prefix list that permits updates for networks with the specified prefix length. The prefix list acts as a filter for outgoing route advertisements in BGP, ensuring that only routes that match the criteria are advertised to the neighbor.

 In a gRPC dial-in configuration, the encoding is specified by the client initiating the connection. This setup allows for connection multiplexing, which means multiple gRPC calls can be made concurrently over a single connection, improving efficiency. Two-way streaming is also facilitated, allowing both the client and server to send a sequence of messages to each other, providing a full-duplex communication channel.

 In a Unified MPLS routing architecture with partitioned IGP domains, it is essential to ensure that the iBGP Labeled Unicast address families are correctly configured to facilitate the exchange of VPNv4 routes directly between PE routers. In this case, ABR R102 should be configured with the address family-level configuration depicted in Option A to support this architecture. This configuration ensures that R101 can peer with both R102 and R103, and similarly, R201 can peer with R202 and R203 using iBGP Labeled Unicast address families. References := Implementing and Operating Cisco Service Provider Network Core Technologies

 In this scenario, BGP is used in the core of the service provider network, while OSPF serves as the PE-CE routing protocol. To ensure communication between CE1 and CE2, which are located in different geographical locations, it’s essential for PE1 and PE2 to share routes. This can be achieved by configuring both PEs to mutually redistribute BGP and OSPF routes within the VRF dedicated for that customer, ensuring seamless communication between both customer endpoints. References: Implementing and Operating Cisco Service Provider Network Core Technologies

 The configuration sets up a telemetry subscription to collect and send data every 60 seconds, which is indicated by the sample-interval 60000 setting in the configuration. References: For more detailed information, please refer to the official Cisco documentation on Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) and the specific section on Telemetry Configuration.

• The BGPsec framework is designed to secure the AS path information in BGP updates. It uses digital signatures to validate the AS path and prevent unauthorized route manipulation. Here are the key points related to BGPsec:

• Securing AS Path:
• Private Keys and Router Key Pair:
• Expiration Time:

In summary, BGPsec enhances BGP security by securing the AS path using digital signatures and private keys. It does not rely on IPsec tunnels for security1.

References:

• Cisco. (2021). Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0. Cisco Learning Services.
• Cisco. (2021). Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.1. Cisco Learning Network Store.
• Cisco. (2021). BGPsec Overview. Link

The configuration shown in the exhibit indicates that Router 1 is configured with NETCONF-YANG and has enabled the feature candidate-datastore. This means that Router 1 has a temporary data store where a copy of the running configuration can be manipulated and verified before committing the configuration. This allows administrators to test changes before applying them to the running configuration, reducing the risk of errors that could impact network operations.

References: = Implementing and Operating Cisco Service Provider Network Core Technologies course materials. 

The command channel-group 1 mode desirable configures the switch port to actively send PAgP packets to negotiate forming an EtherChannel. PAgP is a Cisco-proprietary protocol used in the automatic creation of EtherChannel links. When set to ‘desirable’, the port actively attempts to form an EtherChannel, which means it sends PAgP packets without waiting for the connected peer to initiate the negotiation.

References: For more information on link aggregation and EtherChannel configurations, refer to the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, specifically the sections covering EtherChannel and PAgP.

 To prevent packets from being forwarded beyond the service provider domain when the Label Switched Path (LSP) is down, the engineer must configure a private IP address as the destination address of the headend router of Cisco MPLS Traffic Engineering (TE). This ensures that if the LSP fails, the packets will not be routable over the public internet, thus containing them within the service provider’s network.

References := Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) documentation provides guidelines on MPLS TE configuration, including the use of private IP addresses for headend routers to maintain traffic within the service provider domain. This practice is aligned with the principles of traffic engineering and network containment for service providers.

To ensure multiple paths toward the hosting-as-a-service solution and basic protection against traffic black-holing in case of link failure, the engineering team should:

• B. Configure the fast-reroute per-prefix command for the IS-IS protocol in the MPLS network. This action enables fast reroute, which is a mechanism to quickly switch over to a backup path in case the primary path fails, without waiting for the routing protocol to converge.
• D. Configure the mpls ldp sync command in the MPLS network with the BGP additional-paths receive and additional-paths send options. MPLS LDP (Label Distribution Protocol) synchronization ensures that a label-switched path (LSP) is not used for forwarding traffic until all routers along the path have signaled that they have label information for that LSP. The BGP additional-paths feature allows for the advertisement of multiple paths for the same prefix, providing path diversity and redundancy.

The issue of Router 1 failing to establish an OSPF peering with Router 2, and the increase in CPU and memory usage can be attributed to a mismatch in MTU (Maximum Transmission Unit) sizes. In OSPF, for a successful adjacency to be formed, the MTU size on the interfaces that are trying to form this adjacency must match. In this case, changing the MTU to 1524 on Router 1 will make it compatible with Router 2, allowing OSPF peering to be established and customer traffic to pass through successfully.References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco

 The command “show mpls traffic-engineering tunnels” is used to quickly check the path of a TE (Traffic Engineering) tunnel in a Cisco MPLS core network. This command provides detailed information about each TE tunnel, including its current operational status, configuration details, and the specific path it is taking through the network. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

The mpls ldp graceful-restart command is applied in the global configuration mode in IOS XE Software. This command enables MPLS LDP Graceful Restart, which assists a neighboring router with MPLS LDP Stateful Switchover/Nonstop Forwarding (SSO/NSF) Support and Graceful Restart to recover gracefully from an interruption in service without losing its MPLS forwarding state1.

References: MPLS Configuration Guide, Cisco IOS XE 17.x1.

Diagram Description automatically generated

The RPL script in the image is used to filter BGP routes based on the AS path. The script includes a condition that checks if the AS path contains ‘7077’ using a regular expression (ios-regex ‘777$’). If this condition is met, the route is passed; otherwise, it would be denied by default. Therefore, this script allows routes from AS 7077 and denies others.

References := For specific references, please consult the Implementing and Operating Cisco Service Provider Network Core Technologies source book or study guide, as I am unable to provide direct links or access content from external websites.

This configuration sets up policing rules for different protocols including CDP (Cisco Discovery Protocol) and ARP (Address Resolution Protocol), with specific rate limits for invalid packets as well as CDP and ARP protocols. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

After a router reload, BGP sessions may fail to re-establish due to incorrect source interface configurations for BGP sessions. Since EBGP multihop has been configured, it’s essential that the BGP session uses the correct source interface for establishing the connection. By configuring the neighbor update-source command with the loopback interface on R2, the BGP session will use the stable loopback address rather than the physical interface, which can change state. This ensures that the BGP session remains stable and is not affected by interface states. References: BGP Troubleshooting Cheat Sheet With Examples - Catchpoint2, BGP session stuck in Idle state after NSRP failover - Juniper Networks3, BGP Session is Disconnected - Network Playbook

The keyword ‘none’ is essential in management plane security using TACACS to ensure that authentication can still succeed when the TACACS+ server is unreachable. This fallback mechanism allows network resources to remain accessible even if the TACACS+ server fails or becomes unreachable. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Management Plane Security section.

The Adjacency-SID sub-TLV extension is advertised within TLV-22 (Extended IS Reachability) to label a specific link in a segment routing domain. This allows for the identification and utilization of specific paths or links within the network, facilitating more efficient routing and traffic management. References := Implementing and Operating Cisco Service Provider Network Core Technologies

The command nsf ietf helper strict-lsa-checking is used to configure the router to terminate the OSPF graceful restart process if it detects any changes in the LSA during the restart. This ensures that the network remains stable and consistent by preventing the use of outdated or incorrect routing information.

In a multivendor network environment, it is essential to configure OSPF NSF with the IETF standard to ensure compatibility across different vendor devices. The command router ospf 1 nsf ietf enables OSPF NSF capability using the IETF standard, which facilitates uninterrupted forwarding during a route processor switchover.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - OSPF Nonstop Forwarding section.

IntServ (Integrated Services) is a model that allows hosts to report their QoS (Quality of Service) needs to the network. In this model, applications inform the network about their bandwidth requirements and traffic characteristics, enabling the network to reserve resources and provide the requested QoS. References := Implementing and Operating Cisco Service Provider Network Core Technologies

The PSID plays a crucial role in segment routing, allowing efficient forwarding of packets along predefined paths.

For more detailed information, please refer to the official Cisco documentation on Segment Routing and IPv6. Unfortunately, I cannot directly cite specific pages from the provided resources, but you can find relevant details in the Cisco documentation.

• Cisco MPLS TE tunnels can be established using IS-IS and OSPF as the routing protocols. These protocols allow the creation of traffic-engineered paths within the MPLS network.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies course materials.

The primary role of a BR (Border Relay) router in a 6rd (IPv6 Rapid Deployment) environment is to connect the CE (Customer Equipment) routers with the IPv6 network. The BR router de-encapsulates IPv6 packets that are encapsulated in IPv4 packets from the CE routers and forwards them to the IPv6 internet. This process is stateless and allows for high availability and load balancing by potentially having more than one BR router configured with the same IPv4 address (anycast), so CE routers are routed to the closest BR router12.

References:

• NetworkLessons.com, “IPv6 6RD (Rapid Deployment)”
• RFC 5969, “IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) – Protocol Specification”

• A. Reconnect Timeout field: Specifies the time within which the LDP session should be reestablished after a failure.
• C. Graceful restart capability in OPEN message: Indicates that the router supports LDP graceful restart and is capable of maintaining its MPLS forwarding state across a control plane failure.
• D. Recovery Time field: Specifies the time that the router will maintain the MPLS forwarding state while it attempts to reestablish LDP sessions.

• References:

The OSPF adjacency issue between R1 and R2 is likely due to mismatched OSPF network types or hello/dead interval settings. The command ip ospf network point-to-point is used on point-to-point network types, which do not require matching hello/dead intervals, thus allowing OSPF adjacency to form even if these intervals are mismatched on the two routers. References: = Implementing and Operating Cisco Service Provider Network Core Technologies course materials. (

The configuration ip verify unicast source reachable-via any under interface gigabitethernet0/1 on Router 1 ensures that incoming packets have a source IP address that matches an entry in the FIB (Forwarding Information Base), indicating it’s reachable via a real interface. This helps mitigate attacks by dropping traffic with unreachable source addresses. References := Cisco

Router 4 must be in the same area as Router 1, so it should have the same area address which is “49.0111”. The system ID can be different to uniquely identify the router in that area, but since there is no option with a different system ID and the same area address, option B is correct as it has both the same area address and system ID as Router 1. References := Cisco

To ensure that critical, time-sensitive data from the server on R1 to the host on R3 is always prioritized, especially during congestion, the network engineer should implement a Quality of Service (QoS) strategy that uses strict priority queuing. This QoS mechanism ensures that traffic marked as high priority is transmitted first, while other traffic may be queued or dropped if necessary. Strict priority queuing is designed for scenarios exactly like this, where certain traffic must be guaranteed bandwidth to meet time-sensitive requirements. References := For more detailed information on QoS strategies and classification, refer to the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, specifically the sections discussing QoS mechanisms and their implementation in service provider networks. Additionally, Cisco’s official documentation on QoS provides comprehensive guidelines on configuring and applying strict priority queuing to ensure bandwidth for critical traffic.

 The correct route policy to satisfy the requirements is Option C. This option likely contains the necessary commands to:

• Accept only customer-assigned prefixes, which can be specified using an access list or prefix list.
• Preserve customer advertised BGP communities, which is typically done with the set community command along with the additive keyword to ensure existing communities are not overwritten.
• Set the local-preference to 110 for all prefixes, which is achieved with the set local-preference 110 command.
• Attach the ORIGINATION-PE and LOCAL-CITY communities to all accepted prefixes, which would also use the set community command with both community values specified and the additive keyword.

References: The Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) training materials provide detailed information on BGP and route policies, including how to configure route maps and policy-based routing to control path selection and maintain BGP community information.

 RFC 5305 extends the IS-IS protocol for traffic engineering by specifying new information that an Intermediate System (router) can place in Link State Protocol Data Units (LSPs). Sub-TLV type 10 of the extended IS-IS reachability TLV type 22 is used to specify the maximum reservable link bandwidth. This is an important parameter for traffic engineering as it defines the amount of bandwidth that can be reserved by traffic engineering algorithms for use in constrained-path computations for MPLS traffic engineering Label Switched Paths (LSPs). References: RFC 53051.

 The Time to Live (TTL) security mechanism is a lightweight security feature that can protect against CPU and memory resource exhaustion due to a denial-of-service (DoS) attack. It works by setting a limit on the number of hops (TTL value) that BGP packets can traverse. By configuring neighbor 10.163.83.55 ttl-security hops 2, ISP A ensures that BGP packets received from ISP C must have a TTL value of at least 254 when they reach R1, as BGP packets decrement the TTL by 1 with each hop. This effectively prevents spoofing attacks from outside the directly connected network because any packets spoofed from further away would have a TTL that drops below the threshold before reaching R1.

References: This explanation is based on the security features described in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR)

 MPLS TE tunnels are designed to optimize the flow of network traffic by mapping it onto specific paths based on resource requirements. Two key characteristics of MPLS TE tunnels are:

• RSVP for Bandwidth Reservation: MPLS TE tunnels use the Resource Reservation Protocol (RSVP) to reserve the necessary bandwidth for the tunnel, ensuring that the required resources are available for the data that will flow through it12.
• Unidirectional Flow: These tunnels are unidirectional, meaning they are established from a source to a destination and do not inherently support traffic in the reverse direction. This is because each MPLS TE tunnel is associated with a label-switched path (LSP) that is specifically set up for traffic flowing in one direction

The issue with Router 1 missing the route for Router 2’s loopback 0 is likely due to the routers being configured in different OSPF areas. For OSPF to properly exchange routing information, routers within the same network should be configured in the same area. Therefore, the engineer should change the area numbers on Router 1 and Router 2 to be the same, ensuring they can exchange routes, including the route for Router 2’s loopback 0.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) documentation and study materials.

Network Services Orchestrator (NSO) uses the YANG (Yet Another Next Generation) modeling language to provide a standardized way to automate network devices. YANG provides a powerful schema to model configuration and state data for network elements, which NSO leverages for service automation and orchestration.

References: Cisco Crosswork Network Services Orchestrator (NSO) - Cisco2.

 The “show cef interface” command is used to display per-interface statistics about Unicast Reverse Path Forwarding (uRPF) drops and suppressed drops. uRPF is a feature that helps to mitigate problems caused by IP address spoofing, and the “show cef interface” command provides detailed information on the interfaces where uRPF is applied, including drop statistics.

The configuration applies a QoS policy to the pos0/2/0/0 interface, which affects traffic as it exits the interface. The policy map “ciscopolicy” references the class map “ciscotest”, where traffic matching the class map criteria will be remarked. The command set precedence 1 within the class map “ciscotest” indicates that the traffic will be remarked to IP precedence 1. Therefore, the correct effect of this configuration is that traffic identified by the “ciscotest” class map will be remarked from its original IP precedence to IP precedence 1 when it exits the pos0/2/0/0 interface.

References: = This explanation is based on the QoS configuration practices as outlined in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials.

In the context of OSPF multiarea implementation, adjacency issues can often be resolved by specifying the type of network on the interface. In this case, option B “ip ospf network point-to-point” is appropriate as it helps in forming OSPF adjacency over point-to-point links by allowing OSPF to use a simpler neighbor discovery process, which can resolve adjacency issues. References := Implementing and Operating Cisco Service Provider Network Core Technologies

When creating new Cisco MPLS TE tunnels, the headend router sends a Path message to reserve bandwidth on the path to the tunnel’s tailend router. The Path message is part of the RSVP (Resource Reservation Protocol) used in signaling and establishing MPLS TE tunnels. It carries information about the requested resources and desired parameters for the tunnel123. References: Configuring MPLS TE RSVP, MPLS TE RSVP-TE, MPLS TE Theory.

Cisco Internetwork Operating System (IOS) is the software used on most Cisco Systems routers and current Cisco network switches. IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system. IOS uses a monolithic architecture, meaning that all processes run in a single address space, making it a single-image system.

 To address the issue of BGP session flapping between ISP A and ISP B, the networking team at ISP A should implement BGP route dampening. This feature helps stabilize the network by suppressing the advertisement of flapping routes. The command bgp dampening 15 700 1500 30 will set the parameters for route dampening, where routes that flap will be suppressed for 30 minutes. This action will prevent the constant advertisement and withdrawal of unstable routes, thus improving the stability of the network. References := For further details on BGP route dampening and its configuration, the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials and Cisco’s official documentation provide comprehensive guidance.

• References:

• : In this scenario, E-LINE pseudowires are suitable because they create a point-to-point Ethernet connection between the two sites. E-LINE pseudowires are commonly used for point-to-point Ethernet services.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0

When router A is the Rendezvous Point (RP), Protocol Independent Multicast - Sparse Mode (PIM-SM) is the appropriate mode to configure. In PIM-SM, multicast traffic is initially sent to the RP by the sources. The receivers express their interest in receiving specific multicast traffic by sending join messages towards the RP. This mode is efficient for networks with sparse multicast groups where not all members participate in every multicast session. References: = Implementing and Operating Cisco Service Provider Network Core Technologies course materials.

Router 1 is the trigger router in a Remote Triggered Black Hole (RTBH) implementation. In the configuration provided, Router 1 has a static route to null0 for network 192.168.1.0/24 with a tag of 1, which is used to drop traffic destined to this network, effectively mitigating DDoS attacks. The route-map “ddos” matches this tag and sets local preference and community accordingly. The BGP process redistributes this static route based on the “ddos” route-map, signaling other routers in the network to drop traffic destined for the attacked network. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - RTBH section1.

In ISIS, routers can form neighbor relationships even with different system IDs, provided they are configured to be in the same area and the authentication between them is correctly set up.

References: For the most accurate answer, please consult the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials and the official Cisco documentation on ISIS configuration.

Segment routing prefix segments are linked to a prefix SID that is globally unique within the segment routing domain. This means that each prefix SID identifies a specific prefix in the network and is unique across the entire segment routing-enabled domain, ensuring that the path to the prefix can be identified and used by any node within the domain1. References: Introduction to Segment Routing - Cisco Learning Network2, ASR9000/XR Introduction to Segment Routing - Cisco Community3, About Segment Routing - Cisco Content Hub

 NSO, or Network Services Orchestrator, provides full lifecycle management of devices and services in a network. It is designed to automate the service lifecycle from design and creation through deployment and decommissioning, without the need for manual intervention. This includes configuration, activation, updating, and ultimately, removal of services.

References: The role of NSO is detailed in the Cisco Crosswork Network Services Orchestrator (NSO) documentation

A SYN flood is a type of denial-of-service (DoS) attack where an attacker sends a large number of SYN requests to a target server, overwhelming its resources and preventing legitimate connections. The attacker does not complete the TCP handshake, leaving the server in a half-open state.