JN0-649 Practice Questions

A modified deficit round-robin (MDRR) scheduler is defined by the following three variables:

Priority (A):

Priority determines the importance of the queue, influencing the order in which packets are serviced. Higher priority queues are serviced before lower priority queues.

Transmit rate (C):

The transmit rate controls the amount of bandwidth allocated to each queue. It determines how quickly packets from a queue can be transmitted.

Buffer size (E):

Buffer size defines the amount of memory allocated to each queue for storing packets before they are transmitted. Larger buffer sizes can accommodate more packets but may introduce more latency.

References:

Detailed information on MDRR and its variables can be found in Juniper's QoS configuration guides and related networking documents​​​​.

Reviewing MST Configuration:

The configuration shown in the exhibit indicates MST (Multiple Spanning Tree) configuration for DS-1 and DS-2 switches.

For DS-1:

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mstp {

configuration-name Region-1;

revision-level 1;

interface ge-0/0/8;

interface ge-0/0/9;

interface ge-0/0/10;

interface ge-0/0/12;

msti 1 {

bridge-priority 4k;

vlan 10-19;

}

msti 2 {

bridge-priority 8k;

vlan 20-29;

}

}

For DS-2:

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mstp {

configuration-name Region-1;

revision-level 1;

interface ge-0/0/8;

interface ge-0/0/9;

interface ge-0/0/10;

interface ge-0/0/12;

msti 1 {

bridge-priority 8k;

vlan 10-19;

}

}

Understanding Bridge Priority:

In MSTP, the switch with the lowest bridge priority becomes the root bridge for the respective MST instance.

For MSTI 1:

DS-1 bridge-priority is 4k (4096)

DS-2 bridge-priority is 8k (8192)

Thus, DS-1 will be the root bridge for MSTI 1.

For MSTI 2:

DS-1 bridge-priority is 8k (8192)

DS-2 does not participate in MSTI 2.

Thus, DS-1 will be the root bridge for MSTI 2.

Analyzing VLAN Assignments:

DS-1 MSTI 1: VLANs 10-19, priority 4k

DS-1 MSTI 2: VLANs 20-29, priority 8k

DS-2 MSTI 1: VLANs 10-19, priority 8k

DS-2 does not have MSTI 2 configuration.

Conclusion:

DS-1 is the root bridge for MSTI 1 (C)

DS-2 does not participate in MSTI 2 (eliminates A)

DS-1 is the root bridge for MSTI 2 (D)

DS-2 is not the root bridge for MSTI 1 (eliminates B)

References:

Configuration snippets

Understanding of MSTP priorities and root bridge election

When troubleshooting an EVPN-VXLAN IP fabric loop, the following steps are crucial:

Issue the show route table bgp.evpn.0 command on Leaf2 and verify that Type 4 routes are present: Type 4 routes indicate EVPN Ethernet Segment routes, which are essential for detecting and mitigating loops.

Issue the show route table bgp.evpn.0 command on Leaf2 and verify that Type 3 routes are present: Type 3 routes (Inclusive Multicast Ethernet Tag routes) ensure that multicast and broadcast traffic is properly handled, helping identify and troubleshoot loop issues.

References:

The commands for verifying BGP EVPN routes are standard in troubleshooting EVPN-VXLAN fabrics.

Documentation from "Useful Juniper Commands.txt" and "Juniper Commands.pdf" which provide command references for verifying EVPN route types​​​​.

Reviewing POE Interface Information:

The exhibit shows the output of show poe interface and show poe controller commands.

The show poe interface command provides information about the PoE (Power over Ethernet) status on each interface.

Maximum Wattage Allocation:

The show poe controller output indicates that the maximum power available is 100 watts:

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Controller Maximum Power consumption Guard Management Status Lldp

index power band

0 100.00W 22.40W 10W Class AT_MODE Disabled

Thus, statement A is correct.

Power Consumption and Interface Priority:

The interface ge-0/0/11 has a high priority with a max power of 25.4W and current consumption of 11.4W:

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ge-0/0/11 Enabled ON 25.4W(L) High 11.4W 4

Given its high priority, ge-0/0/11 will continue to receive power even if the total power consumption exceeds 90 watts, as high-priority interfaces are less likely to be powered off when resources are low.

POE Status on Interfaces:

The ge-0/0/0 interface is shown as Enabled OFF, indicating PoE is not currently enabled.

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ge-0/0/0 Enabled OFF 15.4W Low 0.0W not-applicable

PoE+ Support:

The ge-0/0/10 interface has a power class of 4, which indicates support for PoE+.

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ge-0/0/10 Enabled ON 25.4W(L) Low 11.0W 4

References:

Exhibit output for show poe interface

Understanding PoE and PoE+ classes and priorities

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 understand what routes the BGP neighbor can and cannot advertise, we need to analyze the output provided in the exhibit. Here are the key points from the BGP neighbor configuration:

Address Families Configured:

The neighbor has the EVPN (Ethernet VPN) address family configured.

There is no indication of L3 VPN (Layer 3 Virtual Private Network) address family configuration in the provided output.

Advertised NLRI (Network Layer Reachability Information):

The output shows that the BGP neighbor advertises EVPN NLRI and does not have configurations to advertise L3 VPN NLRI.

Session Details:

The BGP session is established and in sync with the EVPN address family.

Based on these observations, the correct statements about the BGP neighbor's capabilities are:

C.  

The exhibit confirms that the EVPN address family is configured and EVPN NLRI is advertised.

D.  

There is no configuration or NLRI for L3 VPN in the exhibit, indicating that L3 VPN routes cannot be advertised by this neighbor.

References:

Useful Juniper Commands.txt

Tech Ops Managed Router Juniper Install Guide

In summary, the BGP neighbor in the exhibit can advertise EVPN routes but cannot advertise L3 VPN routes based on the provided configuration and session details.