PDF 350-501 Study Guide

The OSPF neighbor relationship is not establishing due to a mismatch in MTU (Maximum Transmission Unit) settings on the interfaces of PE-A and PE-B routers. On PE-A, there is no MTU configuration under the interface FastEthernet0/0, which means it is using the default MTU setting. However, on PE-B, the MTU is explicitly set to 1400 bytes with “ip mtu 1400” command under interface FastEthernet0/0. OSPF requires that both ends of a point-to-point link have matching MTU sizes to form a neighbor relationship; otherwise, OSPF adjacency will not be established.

References:

• Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco SPCOR Resources

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

• NetFlow provides traceback information by analyzing network traffic. To configure NetFlow for traceback, you need to set up a classification ACL (Access Control List) to identify which type of traffic will be analyzed. This allows NetFlow to focus on specific traffic flows and report relevant information. The classification ACL can be based on various criteria such as source/destination IP addresses, port numbers, or protocols. By defining the classification ACL, you ensure that only the relevant traffic is considered for NetFlow analysis.
• References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.0

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.