Juniper JN0-352 Exam With Confidence Using Practice Dumps

On EX Series switches, aggregated Ethernet (ae) interfaces do not exist by default; before any ae interface can be created, referenced, or brought into service, an administrator must first reserve the desired number of aggregated Ethernet device slots by configuring set chassis aggregated-devices ethernet device-count number at the [edit chassis] hierarchy. This statement allocates the internal resources needed for that many ae interfaces to exist as valid, configurable objects; until it is committed, any interface-level configuration referencing ae0 (such as the aggregated-ether-options and family ethernet-switching stanzas shown in the exhibit) is accepted syntactically by the CLI but never actually instantiates a live ae0 device, which is exactly why show interfaces ae0.0 returns 'device ae0 not found' despite the interface appearing fully configured. Increasing the device-count to at least 1 (or higher, to cover the number of LAG bundles planned) immediately resolves this and allows ae0 to appear as an operational interface once its member links are also associated with it. This is a foundational and frequently overlooked prerequisite step in LAG deployment on Juniper switches. There is no separate licensing requirement for aggregated Ethernet functionality on EX Series switches, a reboot is not needed since the chassis statement takes effect upon commit, and the LACP mode (active versus passive) is unrelated to whether the ae interface object itself exists in the first place. Reference topics: Junos Enterprise Switching – Link Aggregation, Configuring the Aggregated Ethernet Device Count.

TLV 22, the Extended IS Reachability TLV defined in RFC 5305, is the modern and Junos-preferred mechanism for advertising a router's adjacent neighbors together with the metric associated with each link. It carries the seven-octet system ID and pseudonode number of each neighbor along with a 24-bit wide metric field, and supports an extensible set of sub-TLVs used for traffic-engineering data such as interface and neighbor IP addresses, bandwidth, and administrative groups. The original IS Reachability TLV, TLV 2, defined in the base ISO 10589 standard, carries similar neighbor and metric information but is constrained to a 6-bit narrow metric with a maximum value of 63, which is inadequate for expressing meaningful cost differentiation in modern, high-capacity enterprise and service-provider topologies; consequently, Junos deployments are commonly configured for wide-metrics-only, favoring TLV 22 over the legacy TLV 2 whenever traffic-engineering-capable or simply more granular metric representation is desired. TLV 132, the IP Interface Address TLV, only advertises the IPv4 addresses configured on the originating router's interfaces and carries no neighbor-adjacency or metric information. TLV 129, the Protocols Supported TLV, merely lists which network-layer protocols (such as IPv4 or IPv6) the originating router is capable of routing, and likewise has nothing to do with neighbor reachability or link cost. Reference topics: Junos Enterprise Routing – IS-IS, Extended IS Reachability and Wide Metrics.

OSPF's Designated Router election, as defined in RFC 2328 and implemented unchanged in Junos, is explicitly non-preemptive. Router priority is used only at the moment an election actually takes place — that is, when no DR or BDR currently exists on the segment. Once a DR and BDR have been elected and are functioning, a router with a numerically higher priority that joins the segment afterward does not trigger a new election and does not displace the incumbent DR or BDR, no matter how much higher its priority value is. In this scenario, R2 (priority 150) and R3 (priority 100) were already elected DR and BDR respectively while R1 was offline. When R1, whose priority of 200 would have made it the preferred DR had it been present during the original election, returns to the segment, it simply forms a full adjacency with the existing DR and BDR and takes on the DROther role like R4, without any re-election occurring. This design choice exists specifically to prevent unnecessary and disruptive Network LSA regeneration and adjacency churn every time a high-priority router reboots or rejoins a stable broadcast network. The only ways R1 could become DR going forward are if the current DR fails (promoting the BDR to DR and triggering a new BDR election) or if the entire segment's OSPF process is restarted, forcing a fresh election from a clean state. Reference topics: Junos Enterprise Routing – OSPF, Designated Router Election and Non-Preemption.