Complete 350-501 Cisco Materials

 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.

The primary role of a BR (Border Relay) router in a 6rd (IPv6 Rapid Deployment) environment is to connect the CE (Customer Equipment) routers with the IPv6 network. The BR router de-encapsulates IPv6 packets that are encapsulated in IPv4 packets from the CE routers and forwards them to the IPv6 internet. This process is stateless and allows for high availability and load balancing by potentially having more than one BR router configured with the same IPv4 address (anycast), so CE routers are routed to the closest BR router12.

The configuration snippet shows that MPLS and LDP are configured globally but not enabled on an interface. The commands include “mpls label protocol ldp,” “mpls ldp router-id loopback 0,” and “mpls ip,” which are necessary for global settings. However, to establish LDP neighbors and exchange labels, LDP must be enabled on the specific interface where it’s needed.

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.