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

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. 

 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

 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

The term ‘ImpNull’ in the CLI output indicates that Label 0, also known as the “Implicit Null” label, is used for the prefix displayed. This label instructs the penultimate router in an MPLS network to pop the label before forwarding the packet to the ultimate hop, which is the egress router. Therefore, Label 0 will not be part of the MPLS label stack for packets destined for 192.168.10.10 (Option A). This process is known as Penultimate Hop Popping (PHP) and is used to optimize the forwarding process by reducing one level of lookup at the egress router (Option D).

References: For more detailed information, please refer to the MPLS section in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials.

 Egress PE NAT via a single centralized router allows L3VPN customers to access the internet. The NAT operation maintains a table that includes a field to identify the inside VRF of a translation. This is crucial for distinguishing between different customer VPNs that may use overlapping IP address spaces. By having this field, the NAT process can correctly associate each internal IP with its respective VRF and outside global IP address1. References: Centralized egress to internet, Egress PE NAT single centralized router.

Path Computation Element (Calculates paths through the network, keeps TE topology database information, sends path status updates)

Path computation Client (sends path calculation request, sends path creation request)

Path Computation Element (PCE)

Represents a software module (which can be a component or application) that enables the router to compute paths applying a set of constraints between any pair of nodes within the router’s TE topology database. PCEs are discovered through IGP.

Path Computation Client (PCC)

Represents a software module running on a router that is capable of sending and receiving path computation requests and responses to and from PCEs. The PCC is typically an LSR (Label Switching Router).

https://www.cisco.com/c/en/us/td/docs/routers/crs/softwa re/crs_r5-3/mpls/configuration/guide/b-mpls-cg53x-crs/b-mpls-cg53x-crs_chapter_0110.html#con_1279822

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.

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

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.

 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

Application, table Description automatically generated with medium confidence

 The router RA is configured with the command “ip pim ssm default”. This configuration enables Source-Specific Multicast (SSM) for the default range of 232.0.0.0/8, which is the IPv4 multicast address space reserved for SSM by IANA (Internet Assigned Numbers Authority). In SSM, data traffic is delivered to a specific group of subscribers identified by the combination of both source and multicast addresses, enhancing efficiency and security. References: Implementing and Operating Cisco Service Provider Network Core Technologies

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 requirement is to redistribute routes with a tag of 80 and IP prefixes other than 192.168.10.20/24 from Level 1 into Level 2, and also to configure route leaking from Level 2 into the Level 1 domain for routes that are tagged with only 50 or 40. Option B, “Add match ip address 152 in route-map redist1-2”, meets the first requirement as it allows all IP prefixes except for the specified one (192.168.10.20/24) to be redistributed from Level-1 to Level-2 when they have a tag of 80.

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

 In BGP, the weight attribute is the first criterion used to determine the best path. It is a Cisco-specific attribute and is not propagated in BGP updates. Weight is a numeric value, and the path with the highest weight is preferred. If weights are the same, BGP will then consider the local preference, AS path length, origin type, and other attributes in sequence.

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

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.

 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

 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

• To prevent packet loss when IGP (Interior Gateway Protocol) and LDP (Label Distribution Protocol) are not synchronized, enabling MPLS LDP IGP synchronization is crucial. This synchronization ensures that the IGP routing protocol (such as OSPF or IS-IS) waits until LDP convergence is completed before advertising labels for MPLS traffic. It helps maintain consistency between the IGP and LDP databases.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies course materials.

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

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.

The script is designed to leverage REST API calls for network configuration tasks. It uses the requests library in Python to send a PATCH request to the device with IP address 172.168.211.65. The script includes RFC 2617-based authentication, which is used for HTTP, indicating that it’s not using SSH for login. The payload of the REST API call specifies the configuration for the interface GigabitEthernet0/1 with the IP address 10.1.131.112/30. Therefore, the script is performing option B, configuring the interface via REST API calls.

References: The explanation is based on general knowledge of Python scripting for network automation and REST API interactions as typically covered in network automation sections of Cisco Service Provider courses and documentation. 

 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. 

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.

R1

key chain AUTH_ISIS

key 2

key-string C1sco!

exit

int range et0/0 , et1/0

isis authen key-chain AUTH_ISIS

ip isis

isis metric 15

Copy run start

R2

key chain AUTH_ISIS

key 2

key-string C1sco!

exit

int range et0/0 , et1/0

isis authen key-chain AUTH_ISIS

ip isis

isis metric 20

Copy run start

R3

key chain AUTH_ISIS

key 2

key-string C1sco!

exit

int range et0/0 , et1/0

isis authen key-chain AUTH_ISIS

ip isis

isis metric 25

Copy run start

?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

 In Cisco IOS XR software, the keychain management for BGP is done in the routing configuration mode. This mode allows you to configure keychain parameters such as the key identifier, cryptographic algorithm, and other related settings. The keychain is essential for authentication and secure communication between BGP peers. By configuring the keychain in the routing context, you ensure that BGP sessions use the specified keys for authentication and integrity protection1.

References:

• Implementing Keychain Management - Cisco IOS XR Routing Configuration Guide
• BGP Configuration Guide for Cisco NCS 540 Series Routers, IOS XR Release 7.8.x - Master Key Tuple Configuration

The correct configuration to reduce LDP LIB size and advertise label bindings for the /32 loopback IP space only is to use an IP prefix-list that specifies the /32 prefix length and then configure MPLS LDP to allocate labels for these prefixes. The ip prefix-list LOOPBACKS seq 5 permit 0.0.0.0/0 le 32 command creates a prefix-list named LOOPBACKS that allows any IP address with a prefix length less than or equal to 32. The mpls ldp label allocate global prefix-list LOOPBACKS command then instructs the router to allocate labels for all prefixes permitted by the LOOPBACKS prefix-list, which in this case, would be all /32 prefixes. References: The explanation is based on the concepts covered in the SPCOR course, specifically the sections on MPLS LDP configuration and optimization. For more detailed information, refer to the official Cisco SPCOR course materials and documentation available at Cisco’s official training page.

LDP session protection capability is a feature that maintains LDP bindings when a link fails, using LDP Targeted Hellos to protect LDP sessions. Without the specific exhibit, it’s not possible to determine which router has LDP session protection enabled but session hold up is not active.

References: Information about MPLS LDP Session Protection can be found in Cisco documentation, such as the Cisco IOS MPLS Configuration Guide.

The issue is occurring in OSPF stub area 100 where the Ethernet link is down between routers RX and RY due to a cut fiber, leading to dropped traffic from CE site A to the hub site. Changing the OSPF area 100 type to stub on RZ can resolve these issues. In a stub area, OSPF routers use a default route to forward traffic to destinations outside the area, reducing the size of their routing tables. This would allow traffic from CE site A to be routed through RZ when the direct link between RX and RY is down.

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

• 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

OSPFv3 is used for routing IPv6 prefixes and requires that each interface intended to participate in OSPFv3 has the protocol enabled. This involves specifying the OSPF process ID and the area ID that the interface belongs to. The process ID links the interface to a specific OSPFv3 process running on the router, and the area ID determines the area within the OSPF topology that the interface is part of. Without this configuration, the interfaces will not actively participate in OSPFv3 route advertisement or neighbor relationships12.

References :=

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials3.
• Cisco OSPFv3 configuration guides and examples

The configuration in Option C uses a route policy that checks if the MED is equal to 30 and then sets the local-preference to 70. This aligns with the requirement to prioritize routes with a MED of 30 by assigning them a higher local-preference value, which influences the BGP path selection process in favor of these routes.

References := The Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course provides insights into configuring route policies for BGP, which includes setting local-preference based on MED values

 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.

• In Cisco Unified MPLS, BGP (Border Gateway Protocol) is used to transport labels along with network layer reachability information. RFC 3107 defines BGP/MPLS IP Virtual Private Networks (VPNs) and allows BGP to carry MPLS labels, enhancing scalability and flexibility in MPLS networks.

References

1: Cisco. “Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR).” Link

 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.

MPLS TE FRR (Fast ReRoute) provides backup protection by creating a bypass LSP for each protected LSP at each point of local repair. This method allows for rapid switching to the backup path in case of a failure, minimizing traffic loss and disruption.

References :=

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

RSVP-TE Fast Reroute (FRR) is a mechanism that provides protection switching for MPLS TE LSPs. The Point of Local Repair (PLR) will prefer to use a next-hop (NHOP) backup tunnel over a next-next-hop (NNHOP) backup tunnel when both are available. This preference is due to the fact that NHOP backup tunnels can provide faster rerouting around the failure point, minimizing traffic disruption and packet loss.

References: The information is based on the RSVP-TE FRR deployment considerations from the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials.

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

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

Remember that SSM is an extension of IP multicast where datagram traffic is forwarded only from explicitly joined multicast sources to receivers. It creates source-specific multicast distribution trees without shared trees.

References:

• Cisco PIM-SSM Configuration Example
• Cisco IP Multicast: PIM Configuration 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. (

 In the context of Cisco IOS XR software, the configuration under Option D is appropriate for adding an interface to a bundle using LACP (Link Aggregation Control Protocol). The configuration specifies two Ten Gigabit Ethernet interfaces (TenGigE0/1/0/5 and TenGigE0/1/0/6) with descriptions indicating they are part of “bundle_1_link”. Both interfaces are assigned to “bundle id 1” with a load interval of 30 seconds, ensuring they are part of the same link aggregation group and share traffic load.

• Option B: Internet routing through global routing on a PE router means that the PE router performs global routing for internet traffic. This allows the PE router to handle both L3VPN traffic and internet traffic.
• Option D: Leaking internet routes from the global table into the L3VPN VRF allows the L3VPN customers to access the internet via the same MPLS backbone. The PE router imports internet routes into the L3VPN VRF, enabling internet access for VPN customers.

 When interface Gi0/0/0/2 is shut down for maintenance, the other interfaces’ states are affected based on their current configurations and roles. In this case, Gi0/0/0/0 becomes active because it is next in line to take over the traffic load, ensuring that network service remains uninterrupted. Gi0/0/0/1 remains standby as it was before the shutdown of Gi0/0/0/2.

References: The explanation can be inferred from understanding Cisco’s technology and protocols related to interface states and bundle ether configurations,

 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.

• : 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

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.

•  By setting IP precedence values (using Differentiated Services Code Point - DSCP) and configuring traffic policing, the network can enforce policies to drop or mark packets based on their priority. When traffic exceeds the specified threshold, the network can take appropriate actions.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0

The core component of MDT that describes the data streamed to a collector is the encoder. In the context of Microsoft Deployment Toolkit (MDT), the encoder is not explicitly mentioned; however, the concept aligns with the process of creating and capturing images of operating systems, which involves encoding or compiling the necessary data into a deployable image.

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

• 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

 To complete the implementation of the route map “ciscotest” for filtering routes to a BGP peer, the engineer must attach the route map to the BGP neighbor statement in the inbound direction. This will apply the specified filtering criteria to routes received from the BGP neighbor, thereby limiting access to restricted areas within the network as intended by the client. References := The Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials discuss the configuration of route maps and their application to BGP neighbors for route filtering purposes

Here is the solution:

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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.

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

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 the context of OSPF multiarea implementation, adjacency issues can arise due to network type mismatches or area boundary discrepancies. The command “ip ospf network point-to-point” is used on interface G0/1 to specify the OSPF network type as point-to-point. This configuration facilitates OSPF neighbor establishment over a direct connection between two routers, eliminating the need for a designated router (DR) or backup designated router (BDR), and resolving adjacency issues in the new area. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ iproute_ospf/configuration/xe-16/iro-xe-16-book/iro-multi-area-adj-xe.html

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)

The correct configuration to apply to the ASN 65001 border router is Option C. This configuration uses a route policy named PEER-AS65002-IN, which is applied to incoming routes from ASN 65002. The policy denies routes that have traversed 10 or more ASNs or have looped through ASN 65001. It also assigns a community value of 65001:200 to routes matching the prefix 2001:db8:aaaa::/48, which aligns with the conditions specified.

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

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)

 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)

 In IS-IS, Level 2 peers must have matching authentication settings to ensure security and integrity of the routing domain. The hello timer setting must also match to ensure that the peers can maintain a consistent adjacency state. Mismatched hello timers could lead to adjacency flaps or failure to form an adjacency.

References: The information is based on the IS-IS protocol’s use of TLVs (Type-Length-Value) which makes it highly extensible. As new features come in, they can be added to the protocol with TLVs. This includes authentication mechanisms and timer settings that ensure secure and stable adjacencies between Level 2 peers

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.

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.

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.

The correct configuration for the BGP route policy named SUBNET, as per the second set of text in the image details, is to drop traffic if the destination is in BGP. Otherwise, the MED value should be set to 400 and community (4:400) should be added. This matches Option B, which specifies these exact actions. References := The information is based on the image details provided and aligns with common BGP route policy configurations typically found in Cisco’s service provider network core technologies documentation.

 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 MPLS LSP ping is the utility that must be used to locate MPLS faults. It is specifically designed to troubleshoot Multiprotocol Label Switching (MPLS) by sending a ping through the MPLS network to verify the path and identify any issues.

References: Cisco provides a guide on MPLS Troubleshooting

R1

router ospf 10

redistribute static

int et0/0

ip ospf hello-interval 5

ip ospf dead-interval 10

ip ospf cost 15

ip ospf 10 area 0

copy run start

R2

router ospf 10

redistribute static

int et0/0

ip ospf hello-interval 5

ip ospf dead-interval 10

ip ospf cost 15

ip ospf 10 area 0

copy run start

The command PE-A(config-pmap-c)#set dscp ef is used to apply DSCP marking to the traffic matched by the class-map. DSCP marking is a part of QoS policy to prioritize traffic. The ‘ef’ (Expedited Forwarding) value is commonly used for voice traffic to ensure it receives high priority and low delay through the network.

References: For more information, refer to the QoS section in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials.

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.

 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

In this scenario, gRPC dial-out mode is being used for telemetry. The receiver with IP address 192.168.1.1 will be assigned one of the subscriptions and will manage the ASR. To configure this, the router needs to use the protocol tcp command. This ensures that telemetry data is streamed out over a TCP connection to the specified receiver. Other options (A, B, and D) are not relevant for this specific use case.

When OSPF routers establish adjacency, they must agree on the MTU size on the connecting interface. If the MTUs do not match, the routers will not form an OSPF adjacency, and the link between them will not come up. Therefore, configuring the MTUs on the interfaces to match is essential for the OSPF network to function correctly.

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

 A Virtual Network Function (VNF) role refers to a network function that is executed in software and can be deployed on a Network Functions Virtualization Infrastructure (NFVI). A firewall serves as a VNF role because it performs network functions, such as filtering traffic and security management, in software form rather than as a physical device.

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

 BGPsec enhances BGP by adding a layer of security for the AS path attribute. When BGPsec is implemented, updates from eBGP peers include a BGPsec attribute sequence with a public key hash and digital signature. This ensures the authenticity and integrity of the AS path, preventing unauthorized AS numbers from being inserted. References: = Implementing and Operating Cisco Service Provider Network Core Technologies course materials. 

 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

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)

The ttl-security hops 2 command sets the accepted Time to Live (TTL) value for BGP packets received from a neighbor. It is used to protect against BGP session hijacking by ensuring that BGP packets come from an expected number of router hops away. In this case, the command specifies that BGP packets from neighbor 2.2.2.2 must have a TTL of at least 253, which means they can only be 1 hop away (255 - 2 = 253) to be accepted.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) training material1.

To enable LDP session protection for LDP neighbors within each VRF, the engineer should configure LDP session protection within the individual VRFs. This ensures that LDP sessions are protected at the VRF level, providing security and stability for MPLS-based services. By enabling LDP session protection within each VRF, the router will take appropriate actions to protect LDP sessions against misbehaving neighbors or potential attacks. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0

 In OSPF, for two routers to establish communication, they must have the same key ID and key value on their interfaces. This ensures secure communication between the OSPF peers. The key ID and value are part of the OSPF authentication mechanism that helps in validating the identity of OSPF peers before exchanging routing information. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco SPCOR Training & Certification

• https://www.cisco.com/c/en/us/support/docs/mpls-vpns/multiprotocol-label-switching-mpls/23986-mpls-vpns-config-example.html
• https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_l3_vpns/configuration/15-mt/mp-l3-vpns-15-mt-book/mp-bgp-mpls-vpns.html

•  The PCE (Path Computation Element) communicates with the PCC (Path Computation Client) using the PCEP. PCEP is responsible for path computation and signaling in MPLS networks.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies course materials.

 The ip igmp join-group command is used on a router interface to simulate the presence of an IGMP host for a specific multicast group. By issuing the command ip igmp join-group 239.10.10.10, the router is configured to join the multicast group 239.10.10.10 and will receive multicast traffic for this group. This is useful for testing or when the router itself needs to receive the multicast stream.

References: The correct configuration for joining a multicast group is outlined in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials

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)

 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

MPLS traffic-engineering tunnels can be configured with dynamic paths or explicitly defined paths across the core network. Tunnel links inherit IGP (Interior Gateway Protocol) metrics by default unless overridden by configurations that specify explicit paths or other criteria for path selection. Dynamic path tunnels use IGP metrics and other parameters like bandwidth availability for automatic path calculation. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

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

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)