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

 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

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

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.

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

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 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

IOS XE:

It uses linux-based kernel

It has a separate control plane

IOS:

It is monolithic

It shares memory space

• 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.

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.

The disruption in IS-IS connectivity between R1 and R2, despite the interfaces being up, suggests an issue with packet handling or MTU configuration. Action A, disabling padding for hello packets under the serial interface on R2, is necessary because excessive padding can lead to issues in processing hello packets effectively. Action C, changing the MTU to 1500 bytes on R2, addresses potential MTU mismatch issues. MTU mismatches are common problems that can interrupt connectivity in networks using routing protocols like IS-IS; ensuring both routers operate at the same MTU can resolve this issue.

References := The explanation is derived from the principles outlined in Cisco’s Implementing and Operating Cisco Service Provider Network Core Technologies, which emphasizes the importance of proper packet handling and MTU configuration for maintaining IS-IS connectivity.

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

Here is the solution:

Text Description automatically generated

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

 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.

 The error message “%CLNS-4-AUTH_FAIL: ISIS: LAN LIIH authentication failed” indicates that there is an authentication failure in the IS-IS routing protocol between routers R1 and R2. In the exhibit, it can be observed that R2 has a state of “UP” for its IS-IS neighbor relationship, while R1 is in “INIT” state. This discrepancy in states indicates an issue with the establishment of the neighbor relationship, which can be attributed to an authentication failure at both Level 1 and Level 2 PDUs as indicated by option B.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) official guide or documentation available on Cisco’s official website.

The service provider must implement a QoS configuration that includes traffic policing to enforce the contracted bandwidth limits. Option B is the correct choice because it specifies a committed information rate (CIR) of 512 kbps, which matches the customer’s contracted rate. The configuration also includes a burst size that accommodates the Tc value of 125 ms, allowing for brief periods of higher traffic without dropping packets. This setup ensures that under peak conditions, any traffic exceeding the contracted rate is either marked or dropped, thus preventing the customer from exceeding the agreed-upon bandwidth. References := For more detailed information on QoS configurations for Frame Relay networks, refer to the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, which cover the principles of traffic policing and shaping in service provider environments

 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 shown is for the head-end router of a Cisco MPLS TE tunnel with segment routing. This setup involves commands related to segment routing and MPLS traffic engineering tunnels, such as “mpls traffic-eng tunnels”, “segment-routing mpls”, and “segment-routing prefix-sid-map advertise-local”. These commands configure the head-end router to effectively create and manage TE tunnels using segment routing. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco SPCOR Training & Certification.

•  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

In this scenario, CE1 and CE2 need connectivity to the internet through the ISP connected to PE3. The most straightforward approach is to configure CE1 and CE2 with a static default route pointing to PE3 as the next-hop for internet-bound traffic. This ensures that any traffic destined for the internet will be routed directly to PE3, which is directly connected to the internet. Other options (A, B, and D) involve more complex configurations and are not necessary for this specific task. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

The configuration shown in the exhibit enables IP flow information collection on the interface gigabitethernet0/1. This setup is used for network traffic analysis, and when applied, it provides data that includes the source interface of the traffic for traceback analysis. This is useful for identifying the origin of traffic, which can be critical in situations such as security incidents or network troubleshooting.

References: The details for this configuration can be found in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course materials, which serve as a comprehensive guide for understanding and applying Cisco service provider technologies.

In an EVPN operation, the PE (Provider Edge) router determines and advertises Ethernet segment reachability by discovering remote ESIs (Ethernet Segment Identifiers) and determining their redundancy mode (all-active or single-active). This is crucial in multihoming scenarios where the PE needs to auto-discover remote PEs and the corresponding redundancy mode. In case of segment failures, PEs withdraw the routes used at this stage to trigger fast convergence by signaling a MAC mass withdrawal on remote PEs3.

References:

• Cisco, “EVPN Configuration Guide for Cisco 8000 Series Routers, IOS XR Release 7.11.x”
• Huawei, “Overview of EVPN - New IP Technologies”

 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

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

• 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.

 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.

the configuration should ensure that VRF ABC and XYZ have route targets that allow them to import routes from VRF CENTRAL, but not from each other. This can be achieved by careful manipulation of route targets and import/export policies within the VRF configurations456.

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

To inject a default route into the MP-BGP address family for a dedicated VRF, you would typically need to:

• Configure a static default route in the VRF using the ip route vrf 0.0.0.0 0.0.0.0  command.
• Redistribute the static route into BGP using the redistribute static command under the BGP VRF configuration.

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

Diagram Description automatically generated

 To achieve this, we need to apply an access control list (ACL) on PE-R9 that permits SSH traffic from the management network 192.168.0.0/16 while denying other traffic. The correct ACL configuration is as follows:

access-list 100 permit tcp 192.168.0.0 0.0.255.255 any eq 22

access-list 100 deny ip any any

• The first line permits TCP traffic from the management network to any destination with destination port 22 (SSH).
• The second line denies all other IP traffic.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0 course materials.
• Cisco Learning Network: SPCOR Training Videos
• Cisco Learning Network: Service Provider Training

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

To achieve the origination of a default route based on the condition of the application server being up, a route map policy needs to be applied. This policy should match the condition of the server’s status and then use the default-information originate command to originate the default route with the specified metric type and value on router RL.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - OSPF Route Map Policy section.

Packet loops can occur during the configuration of BIDIR-PIM if not all parts of your network support this protocol or are configured correctly for it. If some routers or switches in your network don’t understand or aren’t configured for BIDIR-PIM, they can inadvertently forward packets back into parts of the network they were already in, creating a loop. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Multicast section.

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.

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 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 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.

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.

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)

If RC is a stub router in an OSPF network, it requires a default route to be injected so that it can send traffic outside the OSPF domain. In OSPF, stub routers do not have any routes external to the OSPF domain in their routing tables. To allow these routers to reach networks outside of their OSPF domain, a default route should be injected into the stub area by the Area Border Router (ABR). This allows all routers in the stub area, including RC, to forward traffic for unknown destinations to the ABR, which then forwards it appropriately. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

The URL in the exhibit is used with REST API to send a message to the APIC (Application Policy Infrastructure Controller) to perform an operation on a managed object or class operator. In Cisco’s ACI (Application Centric Infrastructure), REST API requests are used for managing, configuring, and retrieving data from the APIC. The URL structure typically includes the IP address of the APIC and specific paths that refer to objects or classes within the ACI fabric. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

Here is the solution:

Text Description automatically generated

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.

R1

Router bgp 65515

No bgp default ipv4-unicast

Neig 2.2.2.2 remote-as 65516

Nei 2.2.2.2 update-soc loopback0

Nei 2.2.2.2 ebgp-multihop 2

Neig 2.2.2.2 pass C1sc0!

Nei 2000:cc13:cc13:2::1 remote-as 65516

Nei 2000:cc13:cc13:2::1 update-so loopback0

Nei 2000:cc13:cc13:2::1 pass C1sc0!

Nei 2000:cc13:cc13:2::1 ebgp-multihop 2

Address-family ipv4

Neig 2.2.2.2 activate

Address-family ipv6

Nei 2000:cc13:cc13:2::1 activate

Ip route 2.2.2.2 255.255.255.255 192.168.1.2

Ipv6 route 2000:cc13:cc13:2::1/128 2000:cc13:cc13:cc13::2

R2

Router bgp 65516

No bgp default ipv4-unicast

Neig 1.1.1.1 remote-as 65515

Nei 1.1.1.1 update-soc loopback0

Nei 1.1.1.1 pass C1sc0!

Nei 1.1.1.1 ebgp-multihop 2

Nei 2000:cc13:cc13:1::1 remote-as 65515

Nei 2000:cc13:cc13:1::1 update-so loopback0

Nei 2000:cc13:cc13:1::1 pass C1sc0!

Nei 2000:cc13:cc13:1::1 ebgp-multihop 2

Address-family ipv4

Neig 1.1.1.1 activate

Address-family ipv6

Nei 2000:cc13:cc13:1::1 activate

Ip route 1.1.1.1 255.255.255.255 192.168.1.1

Ipv6 route 2000:cc13:cc13:1::1/128 2000:cc13:cc13:cc13::1

 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.

 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.

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

• https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/prog/configuration/166/b_166_programmability_cg/netconf_programmability_configuration_guide.html
• https://tools.ietf.org/html/rfc6241

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

 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.

In an MPLS network, the Label Distribution Protocol (LDP) is used to distribute labels which can include segment prefixes. LDP is a protocol that automatically generates and exchanges labels between routers, allowing for the forwarding of packets along a predetermined path without the need for complex lookups in a routing table at every hop.

References: Segment Routing Overview and Migration Guidelines - Cisco1.

Flexible NetFlow improves on traditional NetFlow by providing more flexibility and efficiency in collecting and analyzing network flow data. In this specific configuration, the “mode random one-out-of-100” command is used, which means that only one out of every 100 packets is sampled. This leads to reduced CPU and memory utilization (Option A) because fewer packets are being processed. Additionally, because fewer packets are being analyzed (only one out of every 100), the number of packets to be analyzed is significantly reduced (Option D), leading to further efficiencies.

References :=

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

 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 the given scenario, to ensure that area 15 traffic from R5 to R1 prefers the route through R4, a multiarea adjacency should be implemented on the link between R2 and R4. The cost can be manipulated to make this path preferred. Multiarea adjacency allows OSPF routers to form adjacencies with routers in other areas, enabling more direct routing of traffic. By adjusting the cost of this adjacency, traffic can be directed preferentially through specific paths.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) study guide or course materials available on Cisco’s official website or learning network store.

The full separation model for Internet access and MPLS L3VPN services is chosen to enable EGP (Exterior Gateway Protocol) and IGP (Interior Gateway Protocol) to operate independently. In this model, the internet access and MPLS L3VPN services are fully separated, ensuring that the two networks do not interfere with each other’s operation. This separation enhances network security, performance, and manageability. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide

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.

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

When implementing traffic shaping on a network, the goal is to control the rate of traffic being sent into the network to avoid congestion. This is done by buffering excess packets and then scheduling them to be sent out at a steady rate.

Option A is correct because traffic shaping requires a queue with sufficient memory to buffer excess packets. When the traffic rate exceeds the configured maximum rate (shaping rate), the excess packets are temporarily stored in the queue until they can be sent out, ensuring a smooth flow of traffic without overwhelming the network1.

Option B is also correct as traffic shaping involves configuring token values in bytes. Tokens are used to represent permission to send a certain amount of data. The token bucket is filled with tokens at a steady rate, and packets can only be sent if there are enough tokens in the bucket. The token values determine the size of the bucket and the rate at which it is refilled, which in turn controls the rate of traffic1.

Option C is incorrect because packet remarking for excess traffic is not a component of traffic shaping. Packet remarking is typically used in conjunction with policing, where packets that exceed the rate limit can be remarked to a lower priority for downstream handling1.

Option D is incorrect in the context of traffic shaping. While a scheduling function is used to handle the packets that are delayed due to buffering, the scheduling itself is not part of the shaping mechanism but rather a function of the queuing system that works alongside shaping1.

Option E is incorrect as it pertains to traffic policing, not shaping. In traffic policing, packets that exceed a certain threshold are discarded or remarked, whereas shaping delays excess packets by buffering them1.

References: The information provided here is based on the Quality of Service (QoS) Configuration Guide from Cisco, which details the components and implementation of QoS, including traffic shaping1.

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

 The control plane protocol used between Cisco SD-WAN routers and vSmart controllers is the Overlay Management Protocol (OMP). OMP is a proprietary protocol of Cisco SD-WAN that facilitates the exchange of routing, policy, and management information across the network. It operates within the secure environment provided by the Datagram Transport Layer Security (DTLS) or Transport Layer Security (TLS) control connection, ensuring that the communication between the routers and controllers is encrypted and authenticated1.

References := Cisco 300-415: Cisco SD-WAN vSmart-WAN Edge Router Control Plane Protocol

 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.

• : 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

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.

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.

 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

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 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,

• 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

When implementing LDP NSF on your network, enabling NSF for the link-state routing protocol in use on the network is essential to ensure continuous forwarding of packets during a failure scenario. Additionally, enabling NSF for BGP ensures that BGP sessions are not dropped during a switchover, maintaining network stability and uptime.

 Implementing CSC VPN services for a new backbone carrier provides several benefits. Firstly, it maintains a single backbone network, which simplifies the VPN implementation to customers (A). This eliminates the need for each Level 2 carrier to create and maintain a separate backbone network, thus lowering maintenance costs and simplifying management operations. Secondly, it supports a scalable growth strategy that services multiple customers efficiently (D). The Level 1 carrier can use one backbone network to provide VPN and Internet services for multiple Level 2 carriers, increasing revenues and efficiency.

References: The benefits of implementing CSC VPN services are detailed in the Huawei IP Encyclopedia, which explains the Carrier’s Carrier (CSC) networking solution in BGP/MPLS IP VPN2.

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

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 Cisco MPLS TE forwarding adjacency feature allows a TE tunnel to be advertised into the IGP, effectively making the tunnel appear as a network link in the IGP topology. This integration helps in the optimal utilization of the TE tunnel by other routers for IP routing purposes.

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.

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.

In the given scenario, the goal is to restrict users on the network between R1 and R2 from accessing the external network through R5, while still allowing them access to all resources within the administrative domain. The correct approach is to configure an Access Control List (ACL) that permits traffic to all internal networks and denies traffic to any external address. This ACL should be applied to the R2 interface that connects to R1 in the ingress direction. By doing so, traffic originating from users between R1 and R2 destined for external networks will be blocked, while internal traffic will be allowed.

References: This explanation is derived from the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) study materials, which cover the configuration and application of ACLs in a service provider network environment.

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

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.

 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

 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,

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.

The issue described indicates that the preferred BGP path for traffic destined to 192.168.1.1/32 is not being used. By applying a route-map with a higher Local Preference (LP) on R1 for the prefix 192.168.1.1/32, the BGP path attributes can be manipulated to prefer the path through R2. Local Preference is a BGP attribute that determines the preferred exit path out of an AS. A higher Local Preference value is preferred over a lower one. Therefore, configuring the route-map High-LP with a higher Local Preference on R1’s BGP peering with R2 will influence the BGP path selection process, ensuring that traffic for 192.168.1.1/32 prefers the path R3-R2-R1 as expected.

References: The solution utilizes the BGP path selection process and the manipulation of BGP attributes, as taught in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course

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.

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

 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

PCE – 1,2,5

PCC- 3,4

To reduce network usage and minimize leave latency for users connected to VLAN 76, the configurations should focus on efficient multicast traffic management. Option A likely involves enabling IPv6 MLD snooping, which restricts multicast traffic to only the ports that have members interested in receiving the traffic, thus reducing unnecessary network usage. Option C might include configuring fast-leave processing, which allows the switch to immediately stop forwarding multicast traffic to a port when the last member of a multicast group leaves, reducing leave latency.

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

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.

 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

The configuration snippet in the exhibit shows that BGP summarization is configured with the “aggregate-address” command followed by an IP address and a subnet mask, and then the “summary-only” and “as-set” options. The IP address is 192.168.0.0, and the subnet mask is 255.255.0.0, which corresponds to a /16 prefix length (indicating that the first 16 bits of the IP address are the network portion). However, there seems to be a typo in option B as it’s not a valid IP address format; hence option A is correct with an assumption of typo error.

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

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.

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 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

• 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 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

 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