Refer to the exhibit. A large enterprise is migrating its network to use MPLS VPNs between different business divisions. Within the core, routes are shared between the routers using OSPF, and each connected linkmaintains an MPLS neighbor relationship. Which action must the migration team take so that LDP neighbor relationships are maintained if a directly-connected link goes down?
Answer(s): A
To keep LDP neighbor relationships up when the directly connected link fails, the LDP session must no longer depend on the link-local discovery on that interface. Targeted LDP establishes a TCP session to a specified peer address (typically a loopback) so the session can survive an interface failure as long as there is an alternate IP path through the OSPF core.
An ISP that provides private network services across the country has recently migrated their infrastructure to support MPLS technology. A network engineer configured mpls ip on all routers and implemented the OSPF routing protocol with TE extensions in the backbone area. The ISP wants to ensure that label exchange is performed only on MPLS-enabled interfaces that are associated with the IGP instance. Which action must the engineer take to accomplish the goal?
LDP autoconfiguration ties LDP to the IGP so that LDP is enabled only on interfaces that participate in the IGP instance. This ensures labels are exchanged only across MPLS-enabled links that are part of the routing domain, avoiding unintended LDP neighbor formation on other interfaces.
Refer to the exhibit. An engineer must update the configuration of the network with these requirements:PE routers must define labels for IS-IS learned routes in AS100. P routers must not receive LDP bindings for the external network in the IPv6 address family.Which configuration must the engineer implement to meet these requirements?
Answer(s): C
Applying global label allocation on the PE routers with the IPv4 prefix list that matches only the IS-IS core prefixes causes the PEs to allocate and advertise labels only for the internal IS-IS-learned routes in AS100.Because the external IPv6 prefixes are not included in that allocation policy, the P routers will not receive LDP bindings for the external IPv6 network.
What is the main purpose of EVPN?
Answer(s): B
EVPN provides a control-plane mechanism for scalable Layer 2 and Layer 3 VPN services, enabling multitenancy across data center and cloud networks. It uses BGP to distribute MAC and IP reachability information, delivering interoperable and highly scalable tenant segmentation over MPLS or VXLAN underlays.
Refer to the exhibit. ISP_A is a Tier-1 ISP that provides private Layer 2 and Layer 3 VPN services across theglobe using an MPLS-enabled backbone network. Routers R1, R2, R13, and R14 are PE devices. ASRs R3 and R4 and ASBRs R11 and R12 are acting as route reflectors with preconfigured next-hop-self all for all BGP neighbors. After the network experienced IGP RIB overflow with multiple routes, a network engineer is working on a more scalable network design to minimize the impact on local RIBs. The solution should be based on RFC 3107 and maintain existing QoS capabilities. Which task must the engineer perform to achieve the goal?
RFC 3107 defines carrying label information in BGP (BGP-LU). Using Unified MPLS (BGP-LU) lets the backbone forward using BGP-distributed labeled routes instead of requiring every PE/service route to be installed in the IGP on each router, which reduces IGP scale and local RIB pressure while preserving MPLS forwarding behavior and QoS handling.
What is the purpose of microsegments in the SRv6 architecture?
Answer(s): D
Microsegments in SRv6 enable multiple instructions to be encoded efficiently within the IPv6 destination address space, reducing header overhead and improving scaling. This approach enhances control-plane scalability by allowing more compact segment representation while maintaining flexible traffic steering across the network.
Refer to the exhibit. This enterprise configured MPLS within its network to connect offices that span different geographic areas, with LDP running between connected neighbors. At each office, including headquarters, the networks are running OSPF with a similar configuration. Which additional action must the engineering team take to support a more reliable connection between MPLS and OSPF?
MPLS LDP sync coordinates IGP adjacency establishment with LDP label readiness on a link. It prevents OSPF from preferring a path before LDP has completed label exchange, reducing the chance of traffic being forwarded onto an MPLS link that cannot yet label-switch packets and improving overall reliability between OSPF routing and MPLS forwarding.
What is the purpose of OSPF-TE extensions to MPLS traffic engineering functionality?
OSPF-TE extensions advertise traffic engineering attributes such as available bandwidth, link metrics, and administrative groups. These attributes are used by the headend to compute constraint-based paths (CSPF)and establish MPLS TE tunnels that satisfy defined bandwidth and policy constraints.
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