The Service Provider Professional (JNCIP-SP) (JN0-664)

The vrf-target statement is used in routing-instances to define route-target communities for VPN route import and export policies .

vrf-target export → Controls which route targets (RTs) are added to advertised routes (used when sending routes to remote PEs).

vrf-target import → Controls which VPN routes are accepted into the VRF (used when receiving routes from remote PEs).

Option A (Correct):

In IS-IS, the  Designated Intermediate System (DIS)  is elected based on the  highest configured priority  (as defined in Junos OS).

If priorities are equal, the router with the  highest MAC address  becomes the DIS.

A priority value of  10  will always override a lower priority (e.g., 1).

Type 1: When Type value is 1, the Administrator field is 4-bytes and Assigned Number field is 2-bytes. The Administrator field should be set to the IP address (public IP addresses should be used). The Assigned Number field contains a number from a numbering space that is administered by the enterprise to which the IP address has been assigned by the appropriate authority.

In a PIM Sparse Mode (PIM-SM) domain , Anycast RP is used for load balancing and redundancy by configuring multiple RPs with the same IP address. However, for active multicast sources to be shared between RPs , an additional mechanism is needed since PIM-SM does not automatically synchronize sources between RPs.

Evaluating the Answer Choices

Option A: " Configure MSDP on each RP router. " ✅

Multicast Source Discovery Protocol (MSDP) is required in an Anycast RP setup to share active source information between RPs.

MSDP allows RPs to exchange source-active (SA) messages , ensuring that multicast receivers in different regions can still receive traffic from sources registered with different RPs.

Juniper Documentation confirms that MSDP is used to synchronize active sources across multiple RPs in an Anycast RP deployment.

✅ This is a correct answer.

Option B: " Configure anycast PIM with the rp-set statement on each RP router. " ✅

Anycast PIM allows multiple RPs to share the same IP address, and the rp-set statement is used to define the set of Anycast RPs.

This enables receivers and sources to register with the closest RP .

However, Anycast PIM alone does not share active source information between RPs ; MSDP is still needed for that.

The combination of Anycast PIM (rp-set) and MSDP is the correct approach.

✅ This is a correct answer.

PIM sparse mode (PIM-SM) is a multicast routing protocol that uses a pull model to deliver multicast traffic. In PIM-SM, routers with receivers send join messages to their upstream neighbors toward a rendezvous point (RP) or a source-specific tree (SPT). The RP or SPT acts as the root of a shared distribution tree for a multicast group. Traffic is only forwarded to routers that request to join the distribution tree by sending join messages. PIM-SM does not flood traffic to all routers or prune routers without receivers, as PIM dense mode does.

The OSPF cost is carried in the LSAs that are exchanged within an OSPF area. When a router calculates the cost to a destination it uses the cost of the exit interface of each router in the path to the destination.

To determine the correct answer, let ' s analyze the BGP path selection process and identify which attribute would be considered next in this scenario.

Background on BGP Path Selection

When multiple paths to the same destination are received via BGP, the router uses a step-by-step process to select the best path. The order of attributes considered is as follows (simplified for this scenario):

Highest Local Preference : The path with the highest local preference is preferred.

Shortest AS Path : The path with the shortest AS path length is preferred.

Lowest Origin Code : Paths with an origin code of IGP are preferred over EGP , and EGP is preferred over Incomplete .

Lowest MED (Multi-Exit Discriminator) : If the first three attributes are identical, the path with the lowest MED value is preferred.

eBGP over iBGP : eBGP paths are preferred over iBGP paths.

IGP Metric to Next Hop : The path with the lowest IGP metric to the next-hop router is preferred.

Router ID : If all else is equal, the path from the router with the lowest Router ID is preferred.

Peer IP Address : As a last tiebreaker, the path from the peer with the lowest IP address is preferred.

Scenario Analysis

In this scenario:

You are receiving the 203.0.113.0/24 network via EBGP from two different autonomous systems ( AS 64500 and AS 64501 ).

Both advertisements have identical local-preference values , AS-path lengths , and BGP origin codes .

Given that the first three attributes in the BGP path selection process are identical, the next attribute to consider is the MED (Multi-Exit Discriminator) value.

Analysis of the Options

Option A: Router ID

Incorrect : The Router ID is considered much later in the BGP path selection process, only after other attributes like MED and IGP metric have been evaluated. Since MED is still relevant here, Router ID is not the next attribute to consider.

Option B: MED value

Correct : The MED value is used to influence inbound traffic from neighboring ASes. When local preference, AS path length, and origin code are identical, the path with the lowest MED value is preferred. This makes MED the next attribute to consider in this scenario.

Option C: Peer IP Address

Incorrect : The peer IP address is a tiebreaker used only at the very end of the BGP path selection process, after all other attributes have been evaluated. It is not relevant here because MED has not yet been considered.

Option D: IGP Metric

Incorrect : The IGP metric to the next-hop router is considered after MED. Since MED is still relevant in this scenario, IGP metric is not the next attribute to evaluate.

Final Answer

The correct answer is:

B. MED value

Summary

When local preference, AS path length, and origin code are identical, the MED value is the next attribute considered in the BGP path selection process.

MED is used to influence how traffic enters your AS from neighboring ASes.

When a Juniper device receives a packet on an interface with both a Behavior Aggregate (BA) classifier and a Multifield (MF) classifier , Junos OS follows a specific processing order to apply Class of Service (CoS).

Understanding the Classifiers in Junos CoS

1️ ⃣ Behavior Aggregate (BA) Classifier

Uses packet headers (DSCP, IP precedence, or MPLS EXP bits) to classify traffic into forwarding classes.

Applied at the ingress interface.

Example: A packet with DSCP 46 (Expedited Forwarding) is mapped to a high-priority queue .

2️ ⃣ Multifield (MF) Classifier

Uses match conditions (like source/destination IP, port numbers, protocol types) to classify traffic.

Typically used for more granular classification beyond what BA can provide.

Junos Processing Order:

???? When both BA and MF classifiers are configured on an interface, Junos first applies the BA classifier, then the MF classifier.

???? MF classifier can override the BA classification if necessary.

Evaluating the Answer Choices

✅ B. The packet will be processed by the BA classifier first, then the MF classifier.

Correct , because Junos first applies BA classification based on DSCP/MPLS EXP bits.

After BA classification, the MF classifier is applied , which can refine or override the BA classification.

❌ A. The packet will be discarded.

Incorrect , because classification does not drop packets unless explicitly configured with a filter or policing action.

❌ C. The packet will be forwarded with no classification changes.

Incorrect , because both classifiers are applied in a specific order, meaning classification changes will occur.

❌ D. The packet will be processed by the MF classifier first, then the BA classifier.

Incorrect , because BA classification is always applied first , followed by MF classification.

Final Answer: ✅ B. The packet will be processed by the BA classifier first, then the MF classifier.

???? Official Juniper Reference:

" When both BA and MF classifiers are applied on an interface, Junos OS first classifies packets using the BA classifier before applying the MF classifier. "

To allow Site 1 to access three VLANs that are located in Site 2 and Site 3, you need to configure three L2VPN routing instances on PE-1, one for each VLAN. Each L2VPN routing instance will have a different VLAN ID and a different VNI for VXLAN encapsulation. Each L2VPN routing instance will also have a different vrf-target export value to identify which VPN routes belong to which VLAN. This way, PE-1 can forward traffic from Site 1 to Site 2 and Site 3 based on the VLAN tags and VNIs.