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

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

 For OSPF, the subnet mask must match between two devices on the same network segment to form an adjacency, as it defines the network’s address range. The hello timer setting is crucial for the OSPF Hello protocol, which is used for neighbor discovery and maintaining neighbor relationships. Finally, the area number must be the same because OSPF uses areas to define a hierarchy within the network, and routers within the same area share routing information.

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.

https://community.cisco.com/t5/mpls/cisco-xr-rpl-destination-vs-destination-prefix/td-p/4587693

For encrypted authentication on Router 1, the correct action is to configure an SNMP user with an authentication password and associate it with a group. Option B includes the use of MD5 authentication, which provides the required security for message confidentiality.

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 exhibit shows a snippet of configuration for a router using OSPF (Open Shortest Path First) protocol along with segment-routing MPLS (Multiprotocol Label Switching) and segment-routing forwarding MPLS.

In the context of Cisco Service Provider Network Core Technologies, segment routing is designed to be highly scalable, flexible, and allows for simplified traffic engineering and management across network domains.

Once the initial setup is done (as shown in the exhibit), segment routing can operate without any additional configuration. The segment-routing MPLS and segment-routing forwarding MPLS commands are sufficient for the operation of segment routing.

MPLS LSP ping is a utility for locating faults within an MPLS network, specifically for Label Switched Paths (LSPs). It helps in verifying the LSPs in the MPLS network. The utility sends echo requests to the destination, and if the path is complete, echo replies are received. References := Cisco

When a prefix list is applied to a BGP neighbor, it filters routes based on the specified conditions. In this scenario, the prefix list is designed to permit prefixes that are equal to or longer than /17 but shorter than or equal to /19. Therefore:

A: 192.168.0.0/19 is denied because it falls outside the specified range.

D: 192.168.0.0/16 is denied as it is shorter than the minimum length of /17.

E: 192.168.0.0/16 is permitted because it is the exact prefix specified in the prefix list, and the ge and le modifiers apply to more specific routes derived from this prefix. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco official courseware.

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

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.

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

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.

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

In a multicampus network that supports video streaming, the engineer should configure the network to use IGMPv3. IGMPv3 is the version of IGMP that supports Source-Specific Multicast (SSM). SSM allows the receiver to specify the source of the multicast stream, which is particularly useful for video streaming applications. By using SSM, the network can efficiently deliver the video content from the specified source to the receivers without unnecessary traffic from other sources. References := Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.01.

 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

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

B. Configure the fast-reroute per-prefix command for the IS-IS protocol in the MPLS network. This action enables fast reroute, which is a mechanism to quickly switch over to a backup path in case the primary path fails, without waiting for the routing protocol to converge.

D. Configure the mpls ldp sync command in the MPLS network with the BGP additional-paths receive and additional-paths send options. MPLS LDP (Label Distribution Protocol) synchronization ensures that a label-switched path (LSP) is not used for forwarding traffic until all routers along the path have signaled that they have label information for that LSP. The BGP additional-paths feature allows for the advertisement of multiple paths for the same prefix, providing path diversity and redundancy.

 The 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.

The configuration in Option C correctly sets up the interfaces for VLAN tag translation. On interface GigabitEthernet2, the command rewrite ingress tag translate 1-to-1 dot1q 21 changes the incoming VLAN tag from 12 to 21. Conversely, on interface GigabitEthernet3, the command rewrite egress tag translate 1-to-1 dot1q 12 changes the outgoing VLAN tag from 21 to 12. This setup ensures that traffic flowing from R1 to R2 and vice versa has the correct VLAN tags as required.

 The issue described involves packets being dropped when sent from the application server to the access site. Since OSPF and BGP peerings are confirmed to be operational, the problem likely lies within the route advertisement. Allowing 172.16.20.1 in the BGP advertisement on R3 by adjusting the route-map will likely resolve the issue, ensuring that traffic destined for 172.16.20.1 is not being inadvertently filtered or blocked.

 The configuration in the exhibit shows the implementation of Nonstop Forwarding (NSF) with OSPF. NSF is used to minimize the downtime of neighbor relationships during a Route Processor (RP) switchover. The nsf command enables NSF, and ietf specifies the use of the IETF standard for graceful restart in OSPF. The restart interval 90 sets the time, in seconds, within which the restarting router should complete its restart, helping to maintain uninterrupted forwarding despite the switchover.

Area 10 should receive inter-area routes and support mutual redistribution with the extranet but not receive the default route (::/0). This requirement does not align with any of the stub or NSSA configurations, as these would restrict the type of routes received.

Area 11 should only receive the default route from the ABR and not support external route redistribution or advertise inter-area routes. Configuring Area 11 as an NSSA (Not So Stubby Area) with the no-summary option on R7 and as NSSA on XR31 would prevent inter-area routes from being advertised into Area 11. Additionally, the default-information-originate command on R7 would generate a default route into Area 11, fulfilling the requirement.

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.

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

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

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.

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.

 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.

Best – 50.50.50.2

2nd Best – 40.40.40.2

3rd Best – 20.20.20.2

44th Best – 30.30.30.2

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.

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.

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 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.

The configuration snippet indicates a BGP setup where the neighbor 192.168.1.2 is defined, but not activated for the IPv4 address family. To complete the configuration and allow the exchange of IPv4 routes, the neighbor must be activated under the IPv4 address family. This is done by adding the command address-family ipv4 unicast followed by neighbor 192.168.1.2 activate in the BGP configuration mode.

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

To establish LDP sessions between the PE and P routers, you need to enable communication over TCP port 646 for T-LDP hello messages.

T-LDP (Targeted LDP) uses TCP port 646 for session establishment.

Example configuration:

interface GigabitEthernet0/0

mpls ldp discovery targeted-hello accept

 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

 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.

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.

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.

 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.

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.

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

 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.

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.

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

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

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

Option A is correct because it enables uRPF on interface FA0/0 and verifies that the source address is reachable via the outgoing interface, which is essential when the routing is symmetric.

Option C is also correct as it enables uRPF on interface FA0/1 and allows the source address to be reachable via any interface, accommodating environments with asymmetric routing.

References :=

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

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

RSVP tear messages are used to clear the PATH or RESERVATION states on a router instantaneously, which enables the reuse of resources on the router for other requests. This is essential in MPLS Traffic Engineering where efficient resource management is crucial for maintaining network performance and stability.

The configuration in Option A is correct for enabling dial-out telemetry streams using gRPC on devices with TLS disabled.

It uses model-driven telemetry (MDT), which is a new method of monitoring network devices. Unlike traditional methods that pull data from the device, MDT pushes data from the device to the collector.

In this configuration:

Telemetry is model-driven.

It specifies a destination group with an IP address and port number where the telemetry data will be sent.

The encoding is self-describing-gpb (Google Protocol Buffers).

The protocol used is TCP.

This setup ensures that telemetry data is sent to the specified collector without requiring TLS encryption.

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

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

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

The task requires the engineer to configure a route map that permits all unmatched routes during router redistribution within BGP. The correct action is to remove the implicit deny entry at the end of the route map, as indicated in Option C. By default, route maps have an implicit deny at the end, meaning that if a route doesn’t match any of the permit or deny statements in the route map, it will be denied. Removing this implicit deny entry ensures that all unmatched routes are permitted. References := Implementing and Operating Cisco Service Provider Network Core Technologies

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

 BSR (Bootstrap Router) is used in PIM-SM networks to automate the distribution of group-to-RP mappings. In this scenario where devices need to dynamically learn about Rendezvous Points (RPs), BSR would be appropriate as it allows routers to automatically discover RP candidates and convey that information throughout the PIM domain. References := Cisco

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

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.

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

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

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.

Cisco MPLS TE uses OSPF extensions to allow for optimized transit between a headend router and a destination router by utilizing Opaque LSAs. Opaque LSAs allow for the calculation and establishment of unidirectional tunnels that are set according to the network constraint. The tunnels are built bidirectionally by utilizing Router LSAs, which share router link advertisements to each router within the MPLS environment. ASBR Summary LSAs are also used to share OSPF domain information so that the two routers know how to reach each other during tunnel setup. Furthermore, Network LSAs are used to share RSVP information which is necessary for setting up the tunnel between the two routers.

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.

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.

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.

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.

 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

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

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

 To ensure that traffic for the prefix 192.168.1.1/32 travels via the alternate path R6-R5, a route-map with a higher local preference should be applied inbound on R3 for neighbor R6. This will make the path through R6-R5 more preferable, thus meeting the requirement. References := Implementing and Operating Cisco Service Provider Network Core Technologies

Using verbose knob in above command will list all the hops as below: R1#traceroute mpls multipath ipv4 10.1.5.5 255.255.255.255 verbose https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/multiprotocol-label-switching-mpls/200097-MPLS-LSP-Multipath-Trace.html

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

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

In Cisco’s path selection process, the weight attribute is the first criterion for selecting a path. It is a Cisco-specific parameter, local to the router, and it is not propagated in routing updates. The path with the highest weight is preferred. Therefore, configuring a high weight on the peer to ASN 4567 will make Router R1 prefer this path for all outbound traffic directed towards ASN 4567. References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco SPCOR Training & Certification

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

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.

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

 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 MPLS Layer 3 VPNs, shared services such as Internet access can be provided through the use of a shared services VRF (Virtual Routing and Forwarding). The customer VRF uses route targets to import routes from the shared services VRF, which contains the routes to the Internet. This allows the customer sites to access the Internet without compromising the isolation of their private networks. References: The concept of shared services VRF and the use of route targets for importing and exporting routes are common practices in MPLS VPN implementations.

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

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.

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

References :=

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

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

Securing AS Path:

BGPsec ensures the integrity of the AS path by allowing routers to sign BGP updates using their private keys.

When a router originates a BGP route, it signs the AS path information with its private key.

Other routers can verify the signature using the corresponding public key.

This prevents malicious AS path modifications and ensures the authenticity of the advertised route.

Private Keys and Router Key Pair:

BGPsec relies on cryptographic keys for signing and verifying BGP updates.

Each router has a router key pair consisting of a private key and a corresponding public key.

The private key is kept confidential and is used for signing route updates.

The public key is distributed to other routers for verification.

Expiration Time:

Unlike regular BGP updates, BGPsec does not assign an expiration time (TTL) to route advertisements.

The absence of an expiration time ensures that the signed AS path remains valid until explicitly withdrawn.

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

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

 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.

 The multicast implementation shown in the exhibit indicates that R2 is elected as the RP (Rendezvous Point) for the domain. This is inferred from the configuration commands which show R2 set up as a Bootstrap Router (BSR) candidate. In PIM-SM (Protocol Independent Multicast Sparse Mode), the BSR is responsible for announcing the RP-set to all routers in the PIM domain, and since R2 is the only BSR candidate, it effectively becomes the RP by default unless there are other configurations not shown in the exhibit.

 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

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

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

The available PHY modes to implement an IOS XR Gigabit Ethernet interface are MAN (Metropolitan Area Network) and WAN (Wide Area Network). References:

Cisco IOS XR Software Configuration Guide

Cisco ASR 9000 Series Aggregation Services Routers Interface and Hardware Component Configuration Guide

Hr40wan - 10 Gigabit Ethernet WAN PHY Controller Commands on Cisco IOS XR

10-Gigabit Ethernet WAN PHY Controller Commands 

Model-driven telemetry (MDT) in a service provider environment uses a push model to send data to network monitoring tools. This method is beneficial because it allows for the streaming of data from network devices to monitoring tools in real-time, using reliable transport mechanisms. This approach is more efficient than traditional polling methods like SNMP, as it can provide faster and more granular data updates, which is crucial for maintaining network performance and reliability123.

The configuration in Option A is used to implement URPF in loose mode on the GigabitEthernet0/1 interface.

Loose mode allows the router to check for any route back to the source, not necessarily the best route.

By enabling URPF, the router ensures that incoming packets have a valid return path in the routing table.

This helps prevent IP spoofing and limits malicious traffic on the network.