Juniper JN0-649 Enterprise Routing and Switching Professional (JNCIP-ENT) Exam Practice Test

Dynamic VLAN assignment using 802.1X authentication relies on vendor-specific attributes (VSAs) to assign VLANs dynamically based on the authentication results. The modes that support using VSAs for dynamic VLAN assignment are:

Single-Secure Supplicant Mode: This mode supports a single secure client on a port and can use VSAs to dynamically assign VLANs based on the authentication result.

Multiple Supplicant Mode: This mode supports multiple clients on a single port, each with its own authentication session, and can use VSAs to dynamically assign VLANs.

References:

The Juniper documentation and configuration guides discuss the capabilities of these modes in supporting dynamic VLAN assignment through VSAs. Specific configuration examples and guidelines can be found in the documents:

Useful Juniper Commands.txt

Tech Ops Managed Router Juniper Install Guide

# Example of enabling single-secure supplicant mode

set protocols dot1x authenticator interface ge-0/0/1.0 supplicant multiple

# Example of enabling multiple supplicant mode

set protocols dot1x authenticator interface ge-0/0/1.0 supplicant multiple

Step 1: Identify the requirements for interface-level authentication.

Ensure only corporate devices can connect using their MAC addresses.

Centralized server handles authentication.

Step 2: Evaluate authentication methods.

MAC RADIUS: Uses MAC addresses for authentication via a centralized RADIUS server.

Captive Portal: Typically used for guest access, not suitable for restricting to corporate devices.

802.1X with single-secure supplicant mode: Ensures only one device per port, but requires certificates or credentials, not just MAC addresses.

802.1X with multiple supplicant mode: Allows multiple devices per port, still requires certificates or credentials.

Step 3: Select the appropriate method.

MAC RADIUS: Satisfies the requirement of using MAC addresses for device authentication via a centralized server.

References:

Juniper authentication configuration and best practices​​​​.

Commands for configuring MAC RADIUS: set protocols dot1x authenticator interface mac-radius, set access radius-server ​​​​.

For Multiple Spanning Tree Protocol (MSTP) to operate correctly, all switches in the same region must have the same VLAN to instance mapping, revision level, and configuration name. These parameters ensure that all switches interpret the MSTP configuration consistently.

References:

MSTP Configuration Guide, Juniper Networks

- Configure the local routing device so that it appears to be overloaded. You might do this when you want the routing device to participate in OSPF routing, but do not want it to be used for transit traffic. - Traffic destined to directly attached interfaces continues to reach the routing device. - When configured, the transit interface metrics are set to the maximum value of 65535. https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/ref/statement/overload-edit-protocols-ospf.html

https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/topic-map/configuring-ospf-route-control.html#id-understanding-ospf-overload-function

The address range 232.0.0.0/8 is reserved for Source-Specific Multicast (SSM). This range is specifically allocated for SSM where data is sent from a specific source to the receivers.

References:

Source-Specific Multicast (SSM) Overview, RFC 4607

 Captive Portal Functionality:

Captive portals are used to enforce user authentication by redirecting web browser requests to a login page until authentication is successful.

 Operation:

When a user connects to the network, their HTTP requests are intercepted and redirected to the captive portal login page. This process continues until the user provides valid credentials.

 Implementation:

Juniper Configuration:

shell

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set security authentication-web redirect-url "http:// "

set security zones security-zone interfaces host-inbound-traffic system-services http

set security zones security-zone interfaces host-inbound-traffic system-services https

set access profile captive-portal

This configuration ensures that all HTTP/HTTPS traffic is redirected to the specified captive portal for authentication.

 References:

Detailed configuration and operation are documented in "Tech Ops Managed Router Juniper Install Guide" and related documents​​​​.

The leaf node is not configured for the family evpn NLRI (D):

The exhibit shows that there is an unsupported capability NP error for AFI 1, SAFI 70. This indicates that the leaf node is not configured to support the EVPN (Ethernet VPN) address family.

References:

The BGP configuration and troubleshooting details can be found in "Juniper Commands.pdf" and related EVPN configuration documents​​​​.

When video packets are being dropped, and the network is configured to use the expedited-forwarding forwarding class, it typically indicates that the scheduler assigned to this class does not have sufficient bandwidth to handle the traffic. Adjusting the scheduler to allocate more bandwidth to the expedited-forwarding class will ensure that video packets are transmitted without being dropped.

Steps:

Identify the scheduler map: First, identify the scheduler map that is applied to the interfaces. This can be done using the following command:

shell

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show configuration class-of-service scheduler-maps

Adjust the scheduler: Modify the scheduler for the expedited-forwarding forwarding class to support a higher transmit rate. You can edit the scheduler configuration to increase the bandwidth allocated.

Example:

shell

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set class-of-service schedulers expedited-forwarding transmit-rate percent 30

Apply the configuration: Apply the modified scheduler to the interfaces using the following commands:

shell

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set class-of-service interfaces ge-0/0/0 scheduler-map

set class-of-service interfaces ge-0/0/1 scheduler-map

commit

References:

Useful Juniper Commands.txt

Tech Ops Managed Router Juniper Install Guide

Single supplicant mode authenticates only the first end device that connects to an authenticator port. All other end devices connecting to the authenticator port after the first has connected successfully, whether they are 802.1X-enabled or not, are permitted access to the port without further authentication. If the first authenticated end device logs out, all other end devices are locked out until an end device authenticates. Single-secure supplicant mode authenticates only one end device to connect to an authenticator port. No other end device can connect to the authenticator port until the first logs out

In the given scenario, the connection between DC1 and DC2 is routed through a Layer 3 network. This indicates that the devices connecting the two data centers must be capable of performing Layer 3 routing to ensure that traffic can be properly forwarded across the network. Additionally, the use of VXLAN suggests that Integrated Routing and Bridging (IRB) functionality is required to enable communication between Layer 2 networks over the Layer 3 infrastructure.

The border devices (QFX10002) must handle Layer 3 routing to manage IP traffic between the data centers.

IRB functionality is necessary for routing between VLANs, allowing VXLAN to carry Layer 2 traffic across the Layer 3 network.

References:

The diagrams indicate the use of VXLAN for Layer 2 extension over a Layer 3 network.

The need for IRB is suggested by the presence of routed interfaces (IRB1 and IRB2) in the data center diagrams.

The "Tech Ops Managed Router Juniper Install Guide" provides insights into the Layer 3 routing capabilities and configurations necessary for such setups​​​​.

OSPF Protocol Basics:

OSPF (Open Shortest Path First) is a link-state routing protocol.

Routers exchange LSAs (Link-State Advertisements) to share topology information.

LSA Acknowledgment Mechanism:

OSPF uses a reliable mechanism to ensure LSAs are received.

When a router sends an LSA to a neighbor, it expects an acknowledgment (ACK).

If an ACK is not received within a certain period, the router will retransmit the LSA.

Acknowledgment Process:

LSAs are sent over OSPF's reliable transport, which ensures delivery through acknowledgments.

This mechanism helps to maintain consistent and up-to-date topology databases across routers.

References:

OSPF RFC 2328

Understanding OSPF Operations

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 BGP neighbor can advertise EVPN related routes.

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

D. The BGP neighbor cannot advertise L3 VPN related routes.

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.

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​​​​.

Understanding the Problem:

The requirement is to provide Layer 2 connectivity between campus sites using Ethernet switches through a metro Ethernet service provider who is using Q-in-Q tagging.

Design Considerations:

VXLAN Implementation:

VXLAN (Virtual Extensible LAN) can be used to extend Layer 2 networks over Layer 3 networks. It is often used to provide scalability and flexibility in modern data center networks. In this case, VXLAN could be used to encapsulate Layer 2 frames within UDP packets, allowing them to be transported over the service provider’s network.

S-Tag Configuration:

Q-in-Q tagging, also known as 802.1ad, involves an outer tag (S-Tag) and an inner tag (C-Tag). The service provider network uses the S-Tag to identify and segregate customer traffic. Therefore, each campus switch must have the correct S-Tag (300 in this case) configured to ensure the service provider can correctly handle and route the traffic.

References:

Juniper Networks: Understanding VXLAN

Configuring Q-in-Q Tagging

The correct sequence for BGP active route selection when BGP multipath or multihop are not configured is as follows:

Higher local preference: Routes with a higher local preference are preferred.

Shortest AS path: Routes with the shortest AS path are preferred.

Lower origin code: Routes with lower origin code (IGP < EGP < Incomplete) are preferred.

Lowest router ID: Routes with the lowest router ID are preferred.

Lowest peer address: Routes with the lowest peer address are preferred.

References:

Standard BGP route selection criteria as outlined in network routing protocols.

Documentation from "Useful Juniper Commands.txt" and "Juniper Commands.pdf" which include detailed BGP operational commands and preferences​​​​.

Area-1 has no external connections. However, Area-1 has static route (172.16.31.0/24) that are not internal OSPF route. You can limit the external route advertisements to the area and advertise the static routes by designating the area an NSSA. In an NSSA, the ASBR (vMX1) generates NSSA external (Type 7) LSAs and floods them into the NSSA, where they are contained. Type-7 LSAs allow an NSSA to support the presence of ASBR and their corresponding external routing information. The ABR (vMX2) converts Type-7 LSAs into Type-5 External LSAs and leaks them to the other areas, but external routes from other areas are not advertised within the NSSA. An admin should check this and change it https://www.packetswitch.co.uk/configuring-junos-ospf-stub-and-nssa-areas/ https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/ref/statement/nssa-edit-protocols-ospf.html