JN0-363 Exam Dumps - Juniper JNCIS-SP Questions and Answers

Segment routing is a source routing paradigm that allows a source router to define the path that a packet will take through the network by assigning an ordered list of segments—identifiers that specify a forwarding path for the packet through the network. Segment Routing can be implemented over an MPLS architecture or with IPv6 (SRv6).

A. Segment routing does not require a full mesh of adjacencies or state per transit path in the network, which is often the case with conventional MPLS signaling protocols like RSVP-TE. It leverages the existing IGP topology for forwarding without the need to maintain a state for each LSP (Label Switched Path), hence requiring very little resources to maintain.

B. In segment routing, labels (or segments) are distributed via IGP routing protocols like OSPF or IS-IS with extensions to carry segment routing information. These protocols are enhanced with Segment Routing extensions to distribute labels. For example, OSPFv2 is extended with Segment Routing extensions defined in RFC 8665.

C. This statement is not entirely correct. While it is true that segment routing does not require the maintenance of a state for each path (LSP), the concept of "segment routing adjacencies" is a mischaracterization. Segment routing leverages the existing adjacencies formed by the underlying IGP.

D. Label assignments in segment routing are not advertised through LDP (Label Distribution Protocol) updates. Segment routing does away with LDP and instead uses IGP extensions to distribute labels.

References:

• Juniper Networks documentation on Segment Routing: Segment Routing Overview
• Juniper Networks technical documentation providing guidance on configuring OSPF with Segment Routing extensions.
• IETF RFC 8665: OSPF Extension for Segment Routing.

By default, the router that originally sourced the route into BGP places its peer address into the attribute field. The next-hop value is then typically changed when the route is transmitted across external gGP (EBGP) links. Internal BGP (IBGP) peers do not alter the next-hop value between themselves.

B. By default, the next-hop value is changed when a route is passed from an EBGP peer to another EBGP peer.C. By default, the next-hop value is retained when a route is advertised across IBGP links.References:

• BGP Next Hop Attribute, Juniper TechLibrary
• Understanding BGP Next-Hop Selection, Juniper TechLibrary

You can see area 0.0.0.1 set for one interface and area 0.0.0.0 for the other interface. This means the router communicates in the backbone and area 1, thus it is an ABR.

Default hello timer and dead intervals are configured

hello-interval—Specifies the length of time, in seconds, before the routing device sends a hello packet out of an interface. By default, the routing device sends hello packets every 10 seconds. The range is from 1 through 255 seconds.

dead-interval—Specifies the length of time, in seconds, that the routing device waits before declaring that a neighboring routing device is unavailable. This is an interval during which the routing device receives no hello packets from the neighbor. By default, the routing device waits 40 seconds (four times the hello interval). The range is 1 through 65,535 seconds.

https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/topic-map/configuring-ospf-timers.html#:~:text=The%20hello%20interval%20and%20the,devices%20on%20a%20shared%20network .

C. The R2 device is shown as having interfaces in two different OSPF areas (Area 0 and another area not specified), which makes it an Area Border Router (ABR).D. The OSPF hello and dead intervals are set to their default values of 10 and 40 seconds, respectively.References:

• Understanding OSPF Areas and ABRs, Juniper TechLibrary
• OSPF Configuration Guide, Juniper TechLibrary

The policy statement shown in the exhibit has a term that specifiesload-balance per-packet, which indicates that per-packet load balancing is being used. This means that the routing device will distribute packets out multiple paths on a per-packet basis, rather than on a per-flow (per-destination or per-source-destination pair) basis.

References:

• Juniper Networks documentation on Load Balancing: Load Balancing Overview

A Level 1 router can become adjacent with the Level 1 and Level 1-2 (L1/L2) router. A Level 2 router can become adjacent with Level 2 or Level 1-2 (L1/L2) router. There is no adjacency between L1 only and L2 only router. HOWEVER: If two routers are in different areas, they can only form a Level 2 adjacency. As such, two routers in different areas can NOT form a Level 1 adjacency. If you want two routers to form a Level 1 adjacency, they have to be in the same area.

IS-IS (Intermediate System to Intermediate System) operates at two levels: Level 1 and Level 2. Level 1 routers are only aware of their own area's topology, while Level 2 routershave knowledge of the topology across areas. A Level 1 router cannot form an adjacency with a Level 2 router unless the Level 2 router is also operating as a Level 1 router (Level 1-2 router). Level 2 routers can form adjacencies regardless of their area IDs because Level 2 operates at the domain level and is used to interconnect different IS-IS areas.

References

• Juniper Networks Technical Documentation on IS-IS
• IS-IS Levels and Areas Explanation - Juniper Networks