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

The diagram you provided shows two routers, Router A and Router B, with MPLS labels between them. In the context of segment routing with MPLS, each router advertises a set of SIDs (Segment Identifiers). These SIDs can be node SIDs, which are associatedwith the router itself, or adjacency SIDs, which are associated with the links between routers.

Given the information from the exhibit:

• Router A has a Router ID of 10.1.1.1 and is associated with the MPLS label 11.
• Router B has a Router ID of 10.1.1.2 and is associated with the MPLS label 12.

The adjacency SID in segment routing is used to identify a specific adjacency between two routers. In this case, the question is asking for the adjacency SID that Router B advertises to Router A. This would be the label that Router B tells Router A to use to send packets directly to Router B over their shared adjacency.

So, the adjacency SID that Router B advertises would be associated with the link that Router A would use to send traffic to Router B, which is labeled with the number 12 in the exhibit.

Therefore, the answer to the question is:

D. 12

This is the label that packets would carry when being sent from Router A to Router B to identify the specific adjacency between the two routers in the context of segment routing.

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

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

To verify the status of the tunnel from R1, you would issue a ping from the source address that is assigned to R1's end of the tunnel. In the exhibit, we can see that the tunnel interface (gre-0/0/0.0) has the IP address 198.51.100.1 on R1. Therefore, to test the tunnel's status, you should ping the IP address at the other end of the tunnel (which is likely the address on User B's interface or another interface on R2) from R1's tunnel source address.

References:

• Juniper Networks documentation on GRE: GRE Interface Configuration

To test connectivity to a server from within a specific routing instance, you use thepingcommand along with therouting-instanceoption to specify the routing instance from which you are pinging. This is necessary because the routing table associated withvr3is separate from the main routing table, and you must explicitly tell the device to use thevr3routing table to reach the server.

References:

• Juniper Networks documentation on Routing Instances: Routing Instances Overview

To configure OSPFv3 (the version of OSPF that supports IPv6), you would use theset protocols ospf3command with the appropriate area and interface. OSPFv3 requires a 32-bit router ID just like OSPFv2, which is typically an IPv4 address. OSPF does not use a 128-bit router ID, so answer D is incorrect.

References:

• Juniper Networks documentation on OSPFv3: OSPFv3 Overview

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

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

In the OSPF routing table output, prefixes are marked with different route types. An external prefix injected into OSPF is marked as 'Ext' (External) followed by a number that indicates whether it's an E1 or E2 route. The prefix 172.18.1.0/24 is marked as Ext2, which indicates that it is an external route that has been redistributed into OSPF from another routing protocol or static configuration.

References

• Juniper Networks Technical Documentation on OSPF

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

IS-IS is a link-state routing protocol that uses a Shortest Path First (SPF) algorithm to create a topology map of the network. It floods link-state advertisements (LSAs) to all nodes within the network area to ensure each node has a consistent view of the network topology.

References

• Juniper Networks Technical Documentation on IS-IS
• Understanding IS-IS - Juniper Networks

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

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 MPLS, multiple paths can be merged if they share the same egress router. In the given scenario, traffic from Network 1 to Network 3 and Network 4 can be engineered to follow the same label-switched path (LSP) within the MPLS network until they reach the last common point before diverging to their respective destinations.

As for R3 performing label operations, in a typical MPLS network, intermediate routers (like R3) perform label swapping. They replace the incoming label with a new label before forwarding the packet along the LSP. A label pop operation is typically performed by the egress router in the case of an ultimate hop pop (UHP), where it removes the MPLS label before delivering the packet to the final destination outside the MPLS domain.

References

• Juniper Networks Technical Documentation on MPLS
• Understanding MPLS Label Operations (Swap, Push, and Pop) - Juniper Networks

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

IPv6 link-local addresses are automatically generated for each interface and have a prefix of fe80::/10. The interface's MAC address is typically used as part of the process to create the Interface Identifier (IID) in the link-local address, following the EUI-64 format.

References

• Juniper Networks Technical Documentation on IPv6
• IPv6 Interface Addresses - Juniper Networks

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

Referring to the configuration in the exhibit, R1 is set to export the 3rd_Policy to the neighbor at 192.168.1.5. Since 3rd_Policy permits the 10.200.3.0/24 prefix, only that prefix will be advertised to the neighbor.References:

• BGP Policies, Juniper Networks Documentation
• Policy Framework, Juniper Networks Documentation

only 10.200.3.0/24 will be advertised. The neighbor export overrides anything at the group level and protocol level. Policies aren't additive, you can't apply all three at the same time. What if one of them rejected a prefix while the other accepted the same one? You need one to override the other

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

The exhibit shows the configuration of a virtual switch calledsw-1with two VLANs defined within it:vlan_1with VLAN ID 1 andvlan_2with VLAN ID 2. To add interfacexe-1/0/5to the virtual switch, the interface must be associated with one of these VLANs. Since the interface is already configured withvlan-id 2, it implies that it is intended to be part ofvlan_2within the virtual switchsw-1. Therefore, the correct answer is to add interfacexe-1/0/5to thevlan_2bridge domain under thesw-1routing instance.

References:

• Juniper documentation on virtual switches: Junos OS Routing Instances Overview

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://zartmann.dk/sr-intro/

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

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

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

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