350-501 Implementing and Operating Cisco Service Provider Network Core Technologies (350-501 SPCOR) Questions and Answers

1: graceful restart 2: IGP synchronization 3: session protection 4: targeted-hello accept

The issue of no LDP neighbor existing for 1.1.1.1 between two directly connected routers could be due to R2 not receiving any hellos from R1. In the context of LDP (Label Distribution Protocol), hellos are used for the discovery of LDP peers. They are sent periodically on each interface that LDP is enabled on to discover and maintain LDP sessions with neighbors. If R2 is not seeing any hellos from R1, it means there’s a failure in the initial step of establishing an LDP session, hence no neighbor relationship is formed.

References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide can provide more insights into the workings and troubleshooting steps for LDP protocol.

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.

Stateful (It has 1: N translation, It uses address overloading, It conservers IPv4 addresses)

Stateless (It is limited on the number of endpoints, It mandates IPv4-translatable IPv6 address allocation)

In the context of Cisco’s Implementing and Operating Service Provider Network Core Technologies, the UCS Series is typically where OpenStack components would be hosted. OpenStack is a cloud operating system that controls large pools of compute, storage, and networking resources throughout a data center, all managed through a dashboard that gives administrators control while empowering their users to provision resources through a web interface.

References: Cisco SPCOR training materials and documentation provide detailed information on the implementation and operation of service provider technologies, including the hosting of OpenStack components on the UCS Series.

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 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 direct traffic from R3 to R4 via R1, the weight attribute on R3 can be set higher for the route through R1 compared to other routes. Weight is a Cisco-specific BGP attribute that determines the preferred path when multiple routes to the same destination exist. It is local to the router on which it is configured and not advertised to other BGP peers.

References :=

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

 QPPB (QoS Policy Propagation via BGP) is a mechanism that allows the application of QoS policies using IP precedence or QoS group settings based on BGP community lists, AS paths, and prefix lists. In the context of the exhibit provided, it’s clear that QPPB is being used to apply a specific QoS policy (qos-group 10) based on AS path attributes. This aligns with option C, as it indicates that QoS policies are utilizing BGP to achieve comprehensive network coverage.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR v1.0); Cisco SPCOR Training

The difference between SNMP (Simple Network Management Protocol) and model-driven telemetry lies in their data delivery mechanisms. Telemetry allows for modeled network data to be pushed to network administrators on an as-needed basis, providing real-time insights into network performance and health. On the other hand, SNMP typically relies on polling mechanisms where network administrators request data at specific intervals. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

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.

 The configuration shown in the exhibit indicates a BGP FlowSpec policy that is configured locally on CSR1. This policy is designed to drop all traffic destined for TCP ports 80 and 443 for the IP address 10.6.5.0/24. The traffic rate is displayed as 0 bps, which suggests that the policy is not currently dropping any traffic. However, the matched and dropped statistics indicate that the policy has been active in the past, as it has matched and dropped packets.

References: This explanation is based on the principles of BGP FlowSpec configuration and operation as outlined in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) study materials. 

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.

 Both options provide a default route pointing to CE-1, allowing CE-2 to access the internet. The specific choice would depend on additional context or requirements not provided in the question.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) study materials.

The script shown in the exhibit is a REST API call that adds a user with the last name ‘CiscoTest’ to the AAA database on the server located at the IP address 192.168.201.10. This is achieved through a POST request, which is typically used to create or update resources on a server. The script specifies the user details in JSON format, which is a common data format used for API calls.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR)

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

• 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.

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.

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

• Option A corresponds to the desired configuration. It uses an access-list to permit IGMP joins for the specific multicast group 239.10.10.10 from the source 172.20.20.3.
• Options B, C, and D do not match the desired configuration. They either allow all IGMP traffic or do not specify the correct source and group addresses.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) source book

 The TTL security mechanism is used to protect a router from receiving BGP sessions that are not originated from the expected peer. It drops incoming TCP segments whose TTL value is not equal to or greater than the expected minimum value, thus helping in preventing DoS attacks that could be initiated from an unauthorized source pretending to be a legitimate BGP peer. References := Implementing and Operating Cisco Service Provider Network Core Technologies

 OSPFv3 is designed to support both IPv4 and IPv6. The message “IPv6 routing not enabled” indicates that IPv6 has not been configured on the router, but this does not prevent OSPFv3 from running for IPv4. The OSPFv3 configuration for IPv4 will still function on the interface FastEthernet0/0 as intended.

 Enabling MPLS LDP IGP Synchronization ensures that the IGP advertises a route only if there is a corresponding label binding from LDP. This synchronization helps prevent blackholing traffic when there is a direct link failure in the network. When the B-C link failed, the IGP could find an alternate path via routers E and F, but without LDP synchronization, the labels for MPLS were not available on this new path, leading to traffic loss. By enabling LDP IGP Synchronization, routers will only use paths for which a complete set of labels exists, ensuring label forwarding occurs on the alternate path.

References: The information provided is based on the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, which cover the configuration, verification, troubleshooting, and optimization of Service Provider IP network infrastructures, including MPLS LDP IGP Synchronization

 To implement a PIM-SSM (Protocol Independent Multicast - Source Specific Multicast) configuration for streaming live traffic across different domains, the network operator must ensure that IGMPv3 (Internet Group Management Protocol version 3) is enabled on R1. IGMPv3 is required for SSM because it allows the receiver to specify the source IP address of the desired traffic, which is a key feature of SSM. The operator would configure IGMPv3 on the interfaces that connect to the users who will be accessing the multicast stream. Additionally, PIM-SSM must be enabled on the router, and the multicast sources and groups must be properly defined.

References: The explanation is based on the concepts outlined in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course

YANG (Yet Another Next Generation) is a data modeling language used primarily for the configuration and state data of network elements. It is closely associated with the NETCONF (Network Configuration Protocol) for which it models configuration data. YANG provides schemas that define how data is structured and transported by NETCONF operations. It also shapes the state data of network elements, allowing for a standardized format for representing the operational state of devices. References: YANG is defined in RFCs such as RFC 6020 and RFC 7950, which outline its role in NETCONF operations and its capabilities in modeling both configuration and state data.

The REST API command shown in the exhibit is a POST request to a specific URL, indicating that it is used to submit data to be processed to a specified resource. In this case, the resource is an XML file named “Descriptions.xml”. POST requests are used when submitting data to be processed by the resource identified by the URI. The nature of the process conducted on the submitted data depends on that particular URI. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - REST API section.

In the Pipe model of MPLS QoS, the MPLS EXP bits are set by the Customer Edge (CE) device. This model allows the CE to mark the packets, and these markings are retained throughout the MPLS network until they reach the egress Provider Edge (PE) router. The PE router does not alter the MPLS EXP value, ensuring that the QoS policy applied by the customer is preserved end-to-end.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR)

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/cether/configuration/xe-3s/asr903/16-12-1/b-ce-xe-16-12- asr900/m_ce_802_1ad_900.html

The task requires the use of BGP’s well-known discretionary attribute to select the preferred path, excluding FTP prefixes from this selection process. Option B is correct because it applies a route map to incoming routes from a specific neighbor, which can be used to set attributes like local preference or AS path, or filter routes based on prefix lists or access lists.

The configuration snippet shows a route map named “ciscotest” that sets the local preference to 200 for routes matching IP address 1 (presumably defined elsewhere in an access list or prefix list). Local preference is a well-known discretionary attribute in BGP that influences path selection within an autonomous system; higher values are preferred.

References := Cisco - Implementing and Operating Cisco Service Provider Network Core Technologies

 When implementing Nonstop Routing (NSR) High Availability on an MPLS Provider Edge (PE) router, it’s important to consider that NSR generally consumes more memory and CPU resources than Nonstop Forwarding (NSF) because it needs to maintain a stateful switchover capability. Additionally, NSR requires routing protocol extensions to ensure that the state information is correctly synchronized between the active and standby routers, allowing for seamless failover without session loss. This ensures continuous packet forwarding even during a switchover event.

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.

The configuration in the exhibit shows a route policy named “ciscotest”. According to this policy, if the destination is in acl10, then the traffic will pass without any changes. However, if the destination is not in acl10 (else condition), then the local preference will be set to 300 before it passes through. This means option C is correct as it states that if traffic matches acl10, it’s allowed without any change to its local-preference; otherwise (if not matching acl10), its local-preference is set to 300.

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.

YANG (Yet Another Next Generation) is a data modeling language used to model configuration and state data of a network. It is used to define the data structure of configuration files and is widely used for network configuration and management. YANG uses containers to categorize related nodes, allowing for a hierarchical organization of the data. Types can be associated with each leaf, but they are not required. Spines are not used in YANG, and it is not a distributed model of nodes.

The correct configuration for MPLS LDP synchronization with OSPF process 1 on router R1 is to use the command mpls ldp igp sync holddown 60 under the OSPF process configuration. This ensures that the MPLS LDP synchronization is enabled and held for 60 seconds with OSPF process 1, which helps prevent black holes in MPLS networks during the convergence process by ensuring that routes are not advertised until LDP is fully operational and labels have been exchanged between adjacent routers.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco SPCOR
• Additional resources on Cisco’s Service Provider training: Cisco Service Provider Training

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

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.

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 local-as keyword is used in BGP configurations to change the local AS number that is used in the BGP OPEN message when establishing a BGP session with a specific neighbor. In this case, even though the router is configured with AS 65000, it will use AS 65112 when establishing a connection with neighbor 192.168.1.2 due to the local-as keyword configuration. References := Cisco

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13761-39.html

 To establish MPLS LDP sessions between two routers, both routers must be configured to support MPLS on the interfaces that connect them. The configuration shown for R2 includes enabling MPLS label protocol LDP and configuring interfaces Ethernet1/0 and Ethernet1/1. However, to complete the MPLS LDP session setup, R2 also needs to have MPLS enabled on the interface toward R1. This is done by entering the interface configuration mode for the relevant interface and using the mpls ip command. This command enables MPLS forwarding for IP packets on the interface, which is necessary for LDP to advertise and map labels to the IP routes.

References := The answer is based on the concepts covered in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course,

 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

IOS XE:

It uses linux-based kernel

It has a separate control plane

IOS:

It is monolithic

It shares memory space

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.

 To establish LDP peering with the loopback IP address as its Router ID, both RA and RC need to configure their LDP router IDs to use their respective loopback addresses. This is done by applying the ‘mpls ldp router-id loopback0’ command on both routers. This configuration ensures that LDP peering uses the loopback addresses, which is a requirement for the service-provider core network.

References := This explanation is based on the concepts outlined in Cisco’s Implementing and Operating Service Provider Network Core Technologies (SPCOR) course, which provides in-depth knowledge on service provider infrastructure. For further study, refer to the official Cisco documentation and training materials available on the Cisco Learning Network Store.

 RSVP (Resource Reservation Protocol) is used in MPLS Traffic Engineering (TE) tunnels to establish and maintain paths within the core network. It helps in reserving resources across an IP network and plays a crucial role in ensuring that the network can handle the traffic load efficiently, providing optimal data transfer paths while maximizing network resource utilization and quality of service. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

The Internet gateway router being connected as a PE router to the MPLS backbone is a design attribute that can be used to provide Internet access to a major customer through a separate dedicated VPN. This setup allows for efficient routing and separation of traffic, ensuring security and performance.

To collect the required traffic statistics, the network engineer must configure the router to capture specific data points. The configurations in Option A and Option D align with these requirements. Option A involves configuring the router to collect IPv4 protocol, source address, destination address, application name, interface output, IPv4 source-prefix, IPv4 destination-prefix, counter bytes, flow direction, and transport tcp-flags. Option D involves setting the cache-period timer active to 20 seconds, which aligns with the CPU limit of processing samples that are a maximum of 20 seconds long.

References := Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0

 In Cisco IOS XR, to send BGP IPv4 labels to build inter-domain Label Switched Paths (LSPs), the configuration command used is router bgp 65515 neighbor 172.16.70.23 address-family ipv4 labeled-unicast. This command specifies that the router should use the BGP labeled unicast address family for the specified neighbor, which enables the exchange of label information along with the IPv4 routing information, facilitating MPLS LSP creation for inter-domain traffic.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) training materials1.

To secure REST APIs, a network administrator should ensure that user sessions are authenticated and that the appropriate privilege level is provided for each user. This means that each API request should come with authentication credentials, and the server should validate these credentials for every request. This approach helps to maintain the stateless nature of REST APIs and ensures that only authorized users can access or modify resources. References: Best practices for securing REST APIs include using HTTPS, token-based authentication, and proper validation of input parameters to prevent common security vulnerabilities.

The configuration should include a class-map that matches the ICMP traffic destined for the web server’s IP address. This can be achieved by using an access control list (ACL) within the class-map to match the ICMP traffic. Then, a policy-map should be applied that sets the next hop to the IP address of the new security appliance. This policy-map is then applied to the appropriate interface on router R2 using the service-policy command.

References: The Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course provides detailed information on configuring class-maps and policy-maps for traffic redirection. Specifically, it covers topics related to VPLS services and DDoS protection, which are relevant to the scenario presented in the question12. The course materials and official Cisco documentation serve as the primary references for this solution.

In the context of regular expressions, the caret (^) is used to indicate the start of a string. This is a fundamental concept in pattern matching using regular expressions, where ^ matches the position at the beginning of the string.

References: This information is consistent with regular expression syntax as described in various Cisco documentation and resources related to Cisco IOS software configurations.

 In XML, a self-closing tag such as  indicates that the element does not contain any data, hence the data field is considered blank. This is a common way to represent empty elements in XML documents.

References: For further details, you can refer to XML-related sections in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) materials, which explain the structure and usage of XML in network configurations.

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

https://www.cisco.com/c/en/us/td/docs/ios/12_2sr/12_2sra/feature/guide/srtunsel.html#wp105781 5

 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.

During the traceback phase of the six-phase approach to service provider security, the action that occurs is tracing the attack flows from the attacked sections of the network toward the network edges. This phase entails identifying the source of the attack by analyzing the path that the attack traffic has taken through the network.

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.

• References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0

 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

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 requirement is for R2 to delay sending BGP updates to R5 for multicast traffic by 30 seconds. This can be achieved by configuring the advertisement interval for IPv4 multicast traffic on R2, which controls the frequency of sending BGP updates for multicast routes. References := Cisco SPCOR

Model-driven telemetry (MDT) utilizes YANG models to enable the subscription to specific data items that are streamed from network devices. This allows applications to receive near real-time updates without the need for traditional polling methods. MDT with YANG provides a more efficient and scalable way to monitor network devices by pushing updates to subscribers, which can specify the exact data they require2.

References: Configure Model-driven Telemetry on Cisco IOS-XE Devices with YANG Suite - Cisco2.

 In a multi-vendor environment with PIM-SM, the Bootstrap Router (BSR) mechanism is used for devices to dynamically learn the Rendezvous Point (RP). BSR is a protocol feature that automates the dissemination of RP information in a PIM domain. This feature allows routers to automatically discover the RP set in use, which simplifies configuration and management compared to static RP configurations or Auto-RP. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

The issue with establishing an IS-IS adjacency between the two routers stems from a mismatch in the configuration of their interfaces. Router R2’s interface is set to point-to-point, while the peer router interface is set to multipoint. For IS-IS adjacencies to form, both interfaces must be configured with the same network type. The discrepancy in the network types is preventing the adjacency from being established. To resolve this, the network operator must ensure that both interfaces are either configured as point-to-point or as multipoint. References := Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR)

In OSPF, the election of the designated router (DR) and backup designated router (BDR) is based on the OSPF network type. The network types include:

• Broadcast: This is the default network type for Ethernet interfaces. In a broadcast network, OSPF elects a DR and BDR. All other routers become DROTHERs. To prevent the election of a DR/BDR, you can configure the interface as non-broadcast (NBMA) using the ip ospf network non-broadcast command.
• Point-to-Point: This network type is used for point-to-point links (e.g., serial links). There is no DR/BDR election in point-to-point networks.
• Point-to-Multipoint: This network type is used for point-to-multipoint links (e.g., Frame Relay). There is no DR/BDR election in point-to-multipoint networks.
• Point-to-Multipoint Non-Broadcast: Similar to point-to-multipoint, but explicitly configured as non-broadcast. There is no DR/BDR election in point-to-multipoint non-broadcast networks.
• Loopback: Loopback interfaces are always treated as point-to-point.
• Virtual-Link: Used for OSPF virtual links.
• Sham-Link: Used for OSPF sham links.
• Demand Circuit: Used for demand circuits (e.g., ISDN).
• Non-Broadcast: Explicitly configured as non-broadcast. There is no DR/BDR election in non-broadcast networks.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0
• Cisco Learning Network Store - SPCOR Training

 YAML’s readability and straightforward syntax make it an ideal choice for expressing infrastructure as code, which is a core principle in both Ansible and SaltStack for automating and managing IT infrastructure.

References: For more detailed information, please refer to the official documentation for Ansible and SaltStack, as well as the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials.

When choosing between SaltStack and Chef for network automation, it is important to consider that Chef is an agent-based tool written in Ruby, while SaltStack is a Python-based module tool. This fundamental difference in language and architecture can influence the decision based on the existing environment and the team’s expertise.

References :=

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials.
• Official Cisco documentation and training resources available on the Cisco Learning Network Store.

 Transport Layer Security (TLS) is essential for securing RESTCONF communications on network devices. TLS provides a secure channel with encryption, ensuring that the data exchanged between the client and server remains private and integral. For RESTCONF to utilize TLS, it requires proper certificates for authentication. These certificates confirm the identity of the devices involved in the communication, preventing man-in-the-middle attacks and unauthorized access2.

References := Programmability Configuration Guide, Cisco IOS XE Amsterdam 17.1.x - RESTCONF Protocol2.

 mVPN (Multicast Virtual Private Network) is designed to support the efficient transport of multicast streams across a Layer 3 VPN. It enables service providers to use their existing MPLS networks to transport multicast traffic, allowing for scalable and manageable multicast delivery without requiring a separate network infrastructure. References: Implementing and Operating Cisco Service Provider Network Core Technologies

https://www.cisco.com/c/en/us/p roducts/collateral/switches/nexus-9000-series-switches/guide-c07-734107.html

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

• References:

 Router R1 is configured as a stub area with the “no-summary” option, which means it will not receive summary LSAs (Type 3) from the Area Border Router (ABR). It will only have Type 1 (Router LSAs) and Type 2 (Network LSAs) in its OSPF database for the area it belongs to. Router R2 is configured as an NSSA (Not So Stubby Area), which allows it to import AS external routes as Type-7 LSAs. These Type-7 LSAs can then be converted to Type-5 LSAs by the ABR when propagated into other areas. Therefore, R2 has Types 1, 2, and 7 LSAs in its OSPF database.

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 OSPF area types and LSA types.

 DWDM, or Dense Wavelength Division Multiplexing, uses different wavelengths of light to combine multiple optical signals. This method allows for the transmission of various data streams simultaneously over a single optical fiber. By using closely spaced wavelengths, DWDM can fit more channels onto a single fiber, significantly increasing the capacity and efficiency of fiber-optic networks.

References: The explanation is based on the information available from the web search results on DWDM, which aligns with the principles outlined in the Cisco Service Provider source book. 

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.

• Configure an IP domain name: An IP domain name is essential for generating RSA keys needed for SSH. The RSA keys are part of the crypto key configuration, which is necessary to enable SSH on the router. This step ensures that users are authenticated via the SSH protocol when accessing the network remotely.
• Configure crypto keys: The crypto keys are crucial for secure communication. The engineer should generate RSA keys using the configured IP domain name. These keys will be used for encryption and authentication during SSH sessions.

The other options (B, D, and E) are not directly related to completing the SSH configuration for secure remote access. Therefore, the correct answers are A and C.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies

 Both Chef and Puppet are configuration management platforms that aim to configure and manage servers and other IT infrastructure. They operate in the same infrastructure management space and share several similarities:

• Use a master-client architecture: Chef functions with a master-client architecture, where the server runs on the master machine, and the client runs as an agent on every client machine. Similarly, Puppet follows a similar setup.
• Manage devices or nodes to be configured: Both Chef and Puppet manage the configuration of devices or nodes within an infrastructure.
• Leverage a pull model: Both tools use a pull model, where the configuration is pulled from a central server to the managed nodes.

In this scenario, when edge routers at different regional sites are connected over a global carrier backbone, MP-eBGP must be run between routers to exchange customer VPNv4 routes. This is essential for enabling communication between customer sites located in different regions while utilizing a global carrier backbone service. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

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. (

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.

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

Option D is the correct answer because, in the context of Auto-RP, sparse-dense mode allows the router to forward Auto-RP messages. Auto-RP uses dense mode multicast groups (224.0.1.39 and 224.0.1.40) to advertise RP mapping information, so enabling sparse-dense mode on the interface ensures that it can process both types of multicast traffic. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) official course materials, which can be found here.

Application, table Description automatically generated with medium confidence

Cisco MPLS Traffic Engineering (TE) tunnels necessitate a link-state routing protocol like OSPF or IS-IS because these protocols use Shortest Path First (SPF) calculations. The tunnel endpoints leverage these SPF calculations to implement the tunnel, ensuring an efficient and optimized path through the network. This is essential for MPLS TE, which aims to optimize network resource utilization and improve traffic distribution across the network.

References: Cisco Community, Cisco Documentation

 In OSPF, for two routers to form an adjacency, they must have matching MTU sizes on their connecting interfaces. If the MTUs are mismatched, OSPF adjacency will be stuck in the EXSTART/EXCHANGE state because OSPF hello packets will not be exchanged between the routers. In this case, both routers R1 and R2 are stuck in EXCHANGE/EXSTART state due to mismatched MTU sizes as indicated in the exhibit. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco

• 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 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 configuration snippet is for model-driven telemetry on Cisco IOS XR, which involves creating a sensor-group named “cisco” and specifying a YANG model path for telemetry data collection. This configuration is used to stream telemetry data from the router, aligning with option D. References: = Implementing and Operating Cisco Service Provider Network Core Technologies course materials

To configure multi-topology IS-IS for IPv6, the router must be configured with the ipv6 router isis command under the interface configuration mode. This command enables IS-IS for IPv6 on the interface. The ipv6 router isis command is used to enable IS-IS for IPv6 on an interface. The multi-topology keyword specifies that the interface will participate in multiple topologies. The level-1 and level-2 keywords specify the IS-IS levels for which the interface will participate. In this case, we want the interface to participate in both Level 1 and Level 2 topologies, so we use both keywords. 

TI-LFA, or Topology Independent Loop-Free Alternate, is a fast-reroute mechanism that provides protection against link or node failures in a network. It guarantees a loop-free alternate path for all areas configured in OSPF, ensuring traffic can be quickly rerouted in case of a failure. This characteristic is crucial for maintaining network stability and avoiding traffic loops, which can lead to packet loss and network congestion.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) official documentation