Free Practice Questions for Juniper JN0-649 Exam

Enabling LLDP-MED:

LLDP-MED (Link Layer Discovery Protocol - Media Endpoint Discovery) is an extension of LLDP specifically for VoIP devices.

It allows network devices to advertise and receive configuration information, such as VLAN IDs, from the network switch.

Voice VLAN Feature:

The voice VLAN feature on switches is designed to simplify the deployment of VoIP by automatically placing voice traffic on a designated VLAN.

Configuring the appropriate access interfaces and VLAN ID for voice traffic ensures that voice packets are prioritized and properly segmented from other types of traffic.

Configuration Steps:

Enable LLDP-MED on the appropriate access interfaces:

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set protocols lldp-med interface ge-0/0/0

Enable the voice VLAN feature and specify the VLAN ID:

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set ethernet-switching-options voip interface ge-0/0/0 vlan voice

set ethernet-switching-options voip interface ge-0/0/0 forwarding-class assured-forwarding

References:

Juniper documentation on LLDP-MED

Juniper EX Series switch configuration guide for voice VLAN

To ensure proper functioning within an MST (Multiple Spanning Tree) region, the following parameters must match across all switches:

Revision number:

The revision number identifies the version of the MST configuration. All switches within the same MST region must have the same revision number to ensure consistency.

MSTI-to-VLAN mapping:

The MSTI (Multiple Spanning Tree Instance) to VLAN mapping must be identical on all switches. This mapping ensures that each VLAN is assigned to the correct spanning tree instance.

Configuration name:

The configuration name (or region name) must be the same across all switches. This name uniquely identifies the MST region and must be consistent to ensure switches recognize they are part of the same region.

References:

The MSTP configuration requirements are detailed in Juniper network configuration guides and standards documents on MSTP​​​​.

When MVRP is enabled, the protocol manages VLAN registration dynamically. In forbidden mode, VLANs are neither registered nor declared on the interface, meaning it prevents VLANs from being learned or propagated.

References:

Juniper Networks Configuration Guide on MVRP

Step 1: Check the error messages in the log.

The log messages indicate:

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Dec 22 19:22:29 router rpd[7394]: bgp_process_open:4185: NOTIFICATION sent to 192.168.1.4 (Internal AS 65000): code 2 (Open Message Error) subcode 2 (bad peer AS number), Reason: peer 192.168.1.4 (Internal AS 65000) claims 65100, 65000 configured

Dec 22 19:22:33 router rpd[7394]: bgp_pp_recv:4788: NOTIFICATION sent to 192.168.1.4+56714 (proto): code 2 (Open Message Error) subcode 2 (bad peer AS number), Reason: no group for 192.168.1.4+56714 (proto) from AS 65100 found (peer as mismatch) in master

Step 2: Interpret the messages.

The first message indicates that a BGP NOTIFICATION was sent to 192.168.1.4 due to an "Open Message Error" with a "bad peer AS number" because peer 192.168.1.4 claims AS 65100, but 65000 is configured.

The second message reiterates that the peer AS number 65100 does not match the configured AS 65000, causing a mismatch.

Step 3: Understand the MD5 key error.

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Dec 22 19:23:29 router kernel: tcp_auth_ok: Packet from 192.168.1.5:64047 missing MD5 digest

Dec 22 19:23:30 router kernel: tcp_auth_ok: Packet from 192.168.1.6:56201 missing MD5 digest

These lines indicate that packets from 192.168.1.5 and 192.168.1.6 are missing the MD5 digest, suggesting a potential MD5 key misconfiguration.

Step 4: Validate the answers.

Option B: The 192.168.1.5 peer has a misconfigured MD5 key. This is correct because the logs show that packets from 192.168.1.5 are missing the MD5 digest.

Option D: The 192.168.1.4 peer has a misconfigured autonomous system number. This is correct because the logs indicate that 192.168.1.4 claims AS 65100, while the router is configured for AS 65000.

References:

Document on useful Juniper commands for troubleshooting BGP and understanding log messages​​​​.

Commands for checking BGP logs: show log messages | match notification, show bgp summary, show configuration protocols bgp​​​​.

Based on the provided configuration, let's analyze each term to determine the correct forwarding class and acceptance of traffic:

Term 1:

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term 1 {

from {

protocol udp;

port [ 16000 16002 ];

}

then {

loss-priority high;

forwarding-class voice;

}

}

This term specifies that UDP traffic on ports 16000 and 16002 is assigned a high loss priority and placed in the "voice" forwarding class. The action does not include an explicit "accept;" statement, but traffic matching this term will be forwarded according to the specified forwarding class and priority.

Term 2:

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term 2 {

from {

protocol tcp;

port 4423;

}

then {

loss-priority low;

forwarding-class best-effort;

accept;

}

}

This term specifies that TCP traffic on port 4423 is assigned a low loss priority and placed in the "best-effort" forwarding class. It explicitly includes an "accept;" statement, meaning this traffic will be accepted and processed according to these parameters.

Term 3:

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term 3 {

from {

protocol tcp;

port [ 22 80 443 ];

}

then {

forwarding-class af;

}

}

This term specifies that TCP traffic on ports 22 (default SSH port), 80 (HTTP), and 443 (HTTPS) will be placed in the "af" forwarding class. There is no explicit "accept;" statement here, but the traffic matching this term will be forwarded according to the specified forwarding class.

Term 4:

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term 4 {

then {

forwarding-class best-effort;

accept;

}

}

This term applies to any traffic that does not match the previous terms. Such traffic will be placed in the "best-effort" forwarding class and explicitly accepted.

Statement A: "SSH traffic using the default port will be placed in the af forwarding class and accepted."

Correct. Term 3 matches TCP traffic on port 22 (default SSH port) and assigns it to the "af" forwarding class. Although "accept" is not explicitly stated, the traffic is forwarded based on this class.

Statement B: "SSH traffic using the default port will be placed in the best-effort forwarding class and accepted."

Incorrect. The default SSH port (22) matches Term 3, which places it in the "af" forwarding class, not "best-effort."

Statement C: "UDP traffic using the 16000 port will be placed in the voice forwarding class and accepted."

Correct. Term 1 matches UDP traffic on port 16000 and places it in the "voice" forwarding class. Although "accept" is not explicitly stated, the traffic is processed based on the forwarding class and priority.

Statement D: "UDP traffic using the 16000 port will be placed in the best-effort forwarding class and accepted."

Incorrect. UDP traffic on port 16000 matches Term 1, which places it in the "voice" forwarding class, not "best-effort."

Juniper Networks Configuration Guidelines and Command References

Detailed command references from the uploaded files, particularly those related to firewall and CoS configurations​​​​​​​​​​​​​​.

Analysis:References:

Understanding the Configuration:

The provided configuration and output snippets show how traffic is classified and assigned to different forwarding classes based on the IP precedence values.

The inet-precedence classifier maps specific IP precedence values to forwarding classes with associated loss priorities.

Review of Classifiers:

IP Precedence Value 100:

The IP precedence value 100 in binary is represented as 100 (binary for 4).

Matching with Classifiers:

According to the configuration shown in the exhibit:

classifiers {

inet-precedence cos;

}

The classifier cos maps the following:

forwarding-class expedited-forwarding;

loss-priority low code-points 100;

Conclusion:

The IP precedence value 100 matches the expedited-forwarding forwarding class with low loss-priority as per the configuration.

B - because only one next hop in forwarding table C- becuse TTL=1 limiting bgp connection to be established only over loopbacks interface https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/multihop-sessions.html Use the multihop statement to alter the default use of the neighbor 's physical address. In addition, you can also specify a time-to-live (TTL) value in the BGP packets to control how far they propagate. We use a TTL value of 1 to ensure that the session cannot be established across any other backdoor links in the network.

"Secondary interfaces are supported for LAN interfaces (the primary interface can be a LAN interface, but any secondary interfaces are treated as point-to-point unnumbered links over the LAN). In this scenario, you must ensure that there are only two routing devices on the LAN or that there are only two routing devices on the LAN that have secondary interfaces configured for a specific OSPF area." [https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/topic-map/configuring-ospf-areas.html#id-example-configuring-multiarea-adjacency-for-ospf]