JN0-363 Exam Dumps : Service Provider Routing and Switching, Specialist (JNCIS-SP)

The "ultimate-hop-popping" term refers to the action taken by the penultimate router in an LSP to remove the MPLS label before delivering the packet to the ultimate router,which is not desired here. Configuring the "explicit-null" statement causes the penultimate router to replace the top label with a label that has a value of 0, which instructs the ultimate router to perform a label lookup and preserve the label switching for the entire LSP.

References:

• Juniper Networks documentation on MPLS: MPLS Applications User Guide for Routing Devices

In segment routing, SIDs (Segment Identifiers) are used to identify different types of segments that can be traversed. A node SID represents an instruction to route a packet to a particular node, and an adjacency SID represents an instruction to route a packet over a specific link or adjacency between two nodes.

References

• Juniper Networks Technical Documentation on Segment Routing

In MPLS (Multiprotocol Label Switching) networks, routers use label switching to forward packets. The first router at the edge of the MPLS network (R1) will perform a lookup in the mpls.0 table to determine the label to attach to the packet as it enters the MPLS network. This label informs the next routers in the MPLS network (like R2) on how to forward the packet. Internal MPLS routers, like R2, also perform lookups in their mpls.0 table to determine how to switch the packet toward its destination (label swapping). The inet.3 table is used for resolving next-hop information for labeled routes, but it's the mpls.0 table that is used for label switching decisions.

References:

• Juniper Networks documentation on MPLS: MPLS Applications User Guide for Routing Devices