With Label Distribution Protocol (LDP), a full mesh of label-switched paths (LSPs) is automatically created between all LDP-enabled routers, and these paths are reflected in the inet.3 table. LDP LSPs are set up when LDP is enabled on interfaces connecting routers in an MPLS network.

References:

• Juniper Networks documentation on LDP: Understanding LDP

https://www.juniper.net/documentation/us/en/software/junos/mpls/topics/topic-map/lsp-routers.html

In an MPLS network, the types of routers include ingress routers (where the MPLS labels are first applied), egress routers (where MPLS labels are removed), and transit routers (which switch MPLS-labeled packets through the MPLS network). Peering routers andaggregation routers are not specific types of MPLS routers; they are general network terms.

References:

• Juniper Networks documentation on MPLS: MPLS Fundamentals

In IS-IS, Level 1 routes are usually contained within the same area and Level 2 routes are used to interconnect different areas. By default, routes from Level 1 are redistributed into Level 2, and vice versa, to ensure reachability between areas.

References

• Juniper Networks Technical Documentation on IS-IS

By default, IS-IS protocol leaks routing information from a Level 1 area to a Level 2 area. However, to leak routing information from a Level 2 area to a Level 1 area, an export policy must be explicitly configured.

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

Segment routing labels can be distributed by link-state routing protocols such as IS-IS and OSPF, which have been extended to support segment routing capabilities.References:

• Segment Routing Overview, Juniper Networks Documentation
• Understanding Segment Routing with OSPF, Juniper Networks Documentation
• Understanding Segment Routing with IS-IS, Juniper Networks Documentation

In Ethernet switching, learning and aging are two fundamental concepts for maintaining a dynamic Ethernet switching table (also known as a MAC address table). Learning is the process by which switches listen for frames and learn the MAC addresses by associating them with the incoming port. Aging is the mechanism that ensures the switch updates its table by removing MAC addresses that have not been seen for a certain amount of time (aging time).

References:

• Juniper documentation on Ethernet switching: Understanding Ethernet Switching on Junos OS Devices

Wide metrics in IS-IS allow for a larger metric value than what is available with narrow metrics, which supports a maximum of 63. Wide metrics also enable an interface to advertise different metrics for Level 1 and Level 2, allowing for more flexible routing policies and greater scalability in large networks.References:

• IS-IS Wide Metrics, Juniper Networks Documentation
• Configuring IS-IS Wide Metrics, Juniper Networks Documentation

metric—Metric value. Range: 1 through 63, or 1 through 16,777,215 (if you have configured wide metrics) Default: 10 (for all interfaces except lo0), 0 (for the lo0 interface)

In Junos OS, traffic engineering extensions for OSPF, which are required for an LSP to use the OSPF link state database for path computations, are not enabled by default. They must be explicitly enabled in the OSPF configuration. Therefore, answer C is correct. Answer B is incorrect and contradicts C. The 'no-cspf' command would disable CSPF (Constrained Shortest Path First), which is used for path computations in MPLS traffic engineering, so it should not be used if you want the LSP to utilize OSPF's link state database for path computations. Therefore, answer A is incorrect. The 'policing' parameter is not relevant to enabling traffic engineering extensions in OSPF, so answer D is incorrect.

References:

• Juniper Networks documentation on OSPF and Traffic Engineering: Configuring OSPF Traffic Engineering

https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/topic-map/configuring-ospf-support-for-traffic-engineering.html

In the given exhibit, interfacege-0/0/0is configured to accept VLANs 101-120 andge-0/0/1is configured with flexible VLAN tagging, which means it can tag traffic with any VLAN ID specified. However, only VLAN 200 is explicitly mentioned forge-0/0/1.A. Traffic tagged with VLAN 101 will pass throughge-0/0/0and will egress onge-0/0/1with the same VLAN tag, because the VLAN ID is within the allowed range on both interfaces.B. VLAN 100 is not specified in the allowed VLAN range forge-0/0/0(which is 101-120),nor is it specified underge-0/0/1. Therefore, it will be dropped.References:

• Understanding VLAN Tagging, Juniper TechLibrary
• Configuring VLANs for EX Series Switches, Juniper TechLibrary