Juniper JN0-363 Service Provider Routing and Switching, Specialist (JNCIS-SP) Exam Practice Test

static route with a next-hop of next-table pointing to the appropriate routing table which contains more accurate information rib-groups to mirror routing information from one route-table to another. However, in many cases, in order to make this work, interface-routes also need to be mirrored. RIB Group policy can be used to constrain the routing information instance-import and instance-export statements configured within the individual routing-instances to leak routes from one table to another. Again, policy can be used here to constrain the routing information. This method is more straightforward than the rib-group method A final approach is to use physical interfaces or logical-tunnels to stitch routing-instances and use a routing protocol or static routes across this connection between the two routing-instances.

To share routes between two routing instances on a Junos device, you can configure an instance import policy in one or both instances to import routes from the other instance. Alternatively, a RIB (Routing Information Base) group can be used to share routes between instances.References:

• Routing Instances Overview, Juniper Networks Documentation
• RIB Groups Configuration Guide, Juniper Networks Documentation

In OSPF, an Area Border Router (ABR) that connects to a Not-So-Stubby Area (NSSA) will convert the Type 7 LSAs generated by an NSSA Autonomous System Boundary Router (ASBR) into Type 5 LSAs to advertise them into the OSPF backbone area (Area 0). Type 7 LSAs are specific to NSSAs and are used to advertise external routes within the NSSA.

References:

• Juniper Networks documentation on OSPF: OSPF Areas and LSA Types Explained

The AS path is a BGP attribute that lists the autonomous systems (AS) that routing information has passed through to get to a destination. It is used to detect and prevent routing loops by checking if the router's own AS number is in the path.

References:

• Juniper Networks documentation on BGP: BGP Attributes and Policy

The exhibit shows that the BGP session state is "Active," which generally indicates that the router is trying to establish a BGP session but has not received a response. One common cause for this issue is that there is no route to the BGP neighbor's address. Since the routers are using internal BGP (iBGP) and they are in the same AS, the AS number does not need to be unique, and anext-hop selfpolicy is not strictly required for iBGP. Therouter-idis usually automatically determined and does not need to be explicitly set.

References:

• Juniper Networks documentation on BGP: Troubleshooting BGP

To influence ISP C to prefer the path through R2 for the 172.20.0.0/16 network, R2 should make its path less preferable to ISP B by prepending its AS number multiple times. This makes the path through R2 appear longer and less desirable to ISP C, which would receive these updates from ISP B. AS path length is a well-known attribute in BGP and is used to determine the best path; paths with a longer AS path are considered less preferable.

References:

• Juniper Networks documentation on BGP: BGP Path Selection and Configuration

Junos devices learn about MAC addresses by examining the source MAC address of frames received on an interface and then storing these MAC addresses in the MAC address table (also known as the forwarding database) along with the interface on which the traffic was received.References:

• Understanding Learning and Forwarding, Juniper TechLibrary
• MAC Address Table Processing, 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

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

Graceful Routing Engine Switchover (GRES) and Nonstop Active Routing (NSR) are two features used in Junos OS to provide high availability. GRES allows for the stateful failover of the Routing Engine, and NSR allows for the continuation of packet forwarding and protocol states during a Routing Engine switchover. These technologies ensure that peer nodes are not alerted during a switchover. VRRP and ISSU serve different purposes and do not apply to this specific requirement.

References:

• Juniper Networks documentation on High Availability: High Availability Features

https://www.catchpoint.com/bgp-monitoring/bgp-attributes

BGP Attribute Categories

There are four categories of BGP attributes:

Well-known mandatory:Recognized by all BGP peers, passed to all peers, and present in all Update messages. Well-known mandatory attributes include:- Next-hop- Origin- AS PATH

Well-known discretionary:Recognized by all routers, passed to all peers, and optionally included in the Update message. Well-known discretionary attributes include:- Local Preference- Atomic Aggregate

Optional transitive:Possibly recognized by BGP routers and passed to BGP peers. Optional transitive attributes are marked as partial when not recognized. Optional transitive attributes include:- Aggregator- Community

Optional non-transitive:Possibly recognized by BGP routers but not passed to peers. Optional non-transitive attributes include:- Multi-exit discriminator (MED)- Originator ID- Cluster-ID

The three well-known mandatory BGP attributes that must be present in every BGP update message are:

• Next Hop: Indicates the next hop IP address to reach the advertising BGP peer.
• Origin: Indicates how the route was originated, whether it was via IGP, EGP, or incomplete.
• AS Path: Lists the autonomous systems that the update has traversed.

References

• Juniper Networks Technical Documentation on BGP Attributes

To create connections between routing instances on the same Junos device and route between them, you can use logical tunnel interfaces, which are virtual interfaces that can be used to route traffic between instances without the need for physical connectivity. Additionally, loopback interfaces, which represent the device itself, can be used to route traffic between routing instances as they are always up and can be reached within the device.

References

• Juniper Networks Technical Documentation on Routing Instances
• Juniper Networks Technical Documentation on Logical Tunnel Interfaces

The Segment Routing Global Block (SRGB) defines a range of MPLS labels reserved for segment routing. With an SRGB starting label of 10,000 and an index range of 500, the first usable label is indeed 10,001 because label 10,000 is typically reserved and not usedfor forwarding. The last usable label would be 10,499 because the range includes 500 labels starting from 10,001.

References:

• Juniper Networks documentation on Segment Routing: Segment Routing Overview

Theshow bgp neighborcommand in Junos OS provides a detailed description of each BGP session, including session state, options configured, and counters for messages sent and received. This is the command you would use to see a detailed list of all established BGP sessions.

References:

• Juniper Networks documentation on BGP: BGP Commands

On a Junos device, trunk ports are configured to receive and transmit tagged traffic only, while access ports are configured to receive and transmit untagged traffic.References:

• Understanding Access and Trunk Interfaces, Juniper Networks Documentation
• VLANs and Trunking, Juniper Networks Documentation

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

Thenext-hop-self-policypolicy is used to alter the next-hop attribute of BGP routes. When you apply it as an export policy to an external BGP (eBGP) group, it changes the next-hop attribute of the routes being advertised to eBGP neighbors so that the next-hop IP address is the IP address of the router itself. This ensures that the eBGP neighbors use the local router as the next hop to reach these routes.

References

• Juniper Networks Technical Documentation on BGP Policies

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 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

To influence the path taken through an autonomous system, the Multi-Exit Discriminator (MED) attribute can be used. By setting a lower MED on R2 for routes advertised toR1 and R3, it will make the path through R2 to the 203.0.113.0/24 network more preferable.References:

• Understanding BGP Path Selection, Juniper TechLibrary
• BGP Attributes and Path Selection, Juniper TechLibrary

Upon a link failure in an RSVP-signaled LSP, the router upstream of the failure (R2) sends a PathTear message upstream to the ingress router (R1), and the router downstream of the failure (R3) sends a ResvTear message downstream to the egress router (R4). These messages signal the failure and initiate tear down of the LSP state in the respective directions.References:

• RSVP-TE Overview, Juniper Networks Documentation
• Understanding RSVP Signal Failures, Juniper Networks Documentation

tunnel-end-point name {

ipv4 {

source-address 10.255.1.1;

destination-address 10.255.2.0/25;

}

gre {

key 9;

}

}

https://www.juniper.net/documentation/us/en/software/junos/routing-policy/topics/ref/statement/tunnel-end-point-edit-firewall.html

Theipandgrinterface types are used as endpoints for various tunneling protocols.ipis a generic term that can refer to any IP-based tunnel, whilegrspecifically refers to Generic Routing Encapsulation (GRE) tunnel interfaces in Junos.

References:

• Juniper Networks documentation on Interface Types: Interface Types and Their Default Properties

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

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

https://www.juniper.net/documentation/us/en/software/junos/static-routing/topics/ref/statement/qualified-next-hop-edit-routing-options.html

https://www.juniper.net/documentation/us/en/software/junos/static-routing/topics/topic-map/static-route-prefer-qualified-next-hop.html: Qualified next hops allow you to associate one or more properties with a particular next-hop address. You can set an overall preference for a particular static route and then specify a different preference for the qualified next hop. For example, suppose two next-hop addresses (10.10.10.10 and 10.10.10.7) are associated with the static route 192.168.47.5/32. A general preference is assigned to the entire static route, and then a different preference is assigned to only the qualified next-hop address 10.10.10.7. For example:

The qualified-next-hop statement with a static route is used to specify multiple next hops for a static route with different preferences (priorities). This allows for more granular control over the path selection process in the event that the primary next hop becomes unreachable.References:

• Static Routes Overview, Juniper Networks Documentation
• Example: Configuring Qualified Next Hop, Juniper Networks Documentation

The FE80::/10 prefix is reserved for IPv6 link-local addresses. These addresses are auto-configured on all IPv6-enabled interfaces and can be used for communication within the local link (subnet) only.

References

• Juniper Networks Technical Documentation on IPv6 Addressing