JN0-363 Juniper Service Provider Routing and Switching, Specialist (JNCIS-SP) Free Practice Exam Questions (2025 Updated)

In a service provider MPLS network, P routers are interior routers that are used to transit MPLS-labeled packets between edge routers but do not attach or remove MPLS labels themselves. These routers are also referred to as transit routers. They are neither ingress nor egress routers (which are typically labeled as PE routers).

https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13684-12.html#anc13

Neighbors Stuck in Exstart/Exchange State The problem occurs most frequently when you attempt to run OSPF between a Cisco router and another vendor router. The problem occurs when the maximum transmission unit (MTU) settings for neighboring router interfaces do not match. If the router with the higher MTU sends a packet larger that the MTU set on the neighboring router, the neighbor router ignores the packet. When this problem occurs, the output of the show ip ospf neighbor command displays output similar to what is shown in this figure.

A mismatched Maximum Transmission Unit (MTU) setting on OSPF interfaces can cause routers to get stuck in the ExStart state. OSPF requires that both sides of a link have the same MTU to form a full adjacency.

The exhibit shows an aggregate route configuration for the network 172.21.0.0/22, which would summarize the specific networks 172.21.0.0/24, 172.21.1.0/24, and 172.21.2.0/24. For an aggregate route to be active, it must have contributing routes in the routing table. If the route is hidden, it usually means there are no contributing routes that are active or the policy applied to the aggregate does not match any of the specific routes. Therefore, the first step in troubleshooting would be to verify that there are indeed active contributing routes for the aggregate to be valid.

The IPv6 header includes a new field that is not found in the IPv4 header, called the flow label. The flow label in IPv6 is used to identify packets that require special handling by routers for quality of service (QoS) or other reasons, allowing these packets to be handled efficiently as they move through the network.

References

Juniper Networks Technical Documentation on IPv6

IPv6 Header Fields - Juniper Networks