CCNP Service Provider 350-501 Exam Questions and Answers PDF

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.

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

In a multivendor network environment, it is essential to configure OSPF NSF with the IETF standard to ensure compatibility across different vendor devices. The command router ospf 1 nsf ietf enables OSPF NSF capability using the IETF standard, which facilitates uninterrupted forwarding during a route processor switchover.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - OSPF Nonstop Forwarding section.

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

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