 Technology Overview :

Q-in-Q (802.1ad) , also known as VLAN stacking, allows multiple VLAN tags to be inserted into a single frame. This enables the carrying of multiple VLANs across a single backbone, preserving the original VLAN tags across different network segments.

 Application in Scenario :

By using Q-in-Q, the existing VLANs of the acquired company can be encapsulated within a single VLAN tag. This technique is highly efficient for carrying VLANs across a corporate backbone without altering the existing addressing scheme and with minimal configuration changes.

 Configuration Example :

Juniper Configuration :

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set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan-id 100

set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan-id-list 100-200

set interfaces ge-0/0/2 unit 0 family ethernet-switching vlan-id 300

set interfaces ge-0/0/2 unit 0 family ethernet-switching vlan-id-list 300-400

This setup ensures that VLANs 100-200 on interface ge-0/0/1 and VLANs 300-400 on interface ge-0/0/2 are bundled together, achieving the desired encapsulation.

 References :

Detailed configuration and benefits are documented in the " network-mgmt.pdf " file, which outlines the necessary steps and considerations for deploying Q-in-Q​​.

Understanding EVPN Route Types:

EVPN routes facilitate Layer 2 and Layer 3 connectivity across data centers.

Layer 2 and Layer 3 Connectivity:

For Layer 3 connectivity across data centers, where Layer 2 does not extend, IP prefixes need to be communicated.

Type 5 Routes:

Type 5 (IP Prefix Route):

Used to distribute IP prefixes between data centers.

Ensures that Layer 3 connectivity is established without extending Layer 2 domains.

References:

Juniper EVPN Type 5 Routes

Configuring EVPN for Data Center Interconnect

Understanding 802.1X Authentication:

802.1X is a network access control protocol that restricts access until the device or user is authenticated.

Guest VLAN Configuration:

When hosts fail authentication, they need to be placed in a separate VLAN to provide limited network access.

server-reject-vlan Command:

This command configures a VLAN for unauthenticated devices.

Ensures that devices that fail authentication are placed in a designated guest VLAN.

Configuration Example:

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set protocols dot1x authenticator interface ge-0/0/1.0 server-reject-vlan guest-vlan

References:

Juniper 802.1X Authentication Configuration Guide

Juniper Guest VLAN Configuration

Multitenancy with Routing Instances:

In a multitenant network, different tenants are isolated using routing instances.

Each routing instance can have its own routing table and policies.

BGP and Load Balancing:

BGP (Border Gateway Protocol) is often used for interconnecting different autonomous systems or for internal routing.

Load balancing in BGP can be achieved using the multipath feature, which allows the installation of multiple paths to the same destination in the routing table.

Additionally, configuring per-packet load balancing ensures that traffic is distributed across multiple paths more granularly.

Configuring Multipath in BGP:

Hierarchy Considerations: The multipath option must be configured at appropriate hierarchies to ensure it applies to the correct scope (either globally or within a specific routing instance).

Detailed Configuration:

Statement C: Configure a load-balance per-packet policy and apply it at the [edit routing-options forwarding-table] hierarchy.

Correct : Configuring a load-balance per-packet policy ensures that packets are distributed evenly across multiple paths. This is crucial for achieving effective load balancing.

Configuration Example:

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set routing-options forwarding-table export load-balance-per-packet

Policy Definition Example:

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set policy-options policy-statement load-balance-per-packet term 1 then load-balance per-packet

Statement D: Configure the multipath option at the [edit routing-instances < instance-name > routing-options] hierarchy.

Correct : Configuring multipath within a routing instance ensures that the load balancing feature is applied specifically to that instance, which is crucial in a multitenant environment.

Configuration Example:

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set routing-instances < instance-name > routing-options multipath

References:

Useful Juniper Commands

Juniper Routing Instances and Multipath Configuration

These configurations ensure that load balancing is achieved within each routing instance, leveraging both per-packet load balancing and the multipath feature in Junos OS for BGP. By configuring at the forwarding-table and routing-instance levels, you ensure the load balancing behavior is correctly applied to achieve the desired network performance and redundancy.

Understanding Multicast Listener Registration Protocols:

Multicast listener registration protocols are used to manage multicast group memberships on a network.

They allow devices to join or leave multicast groups dynamically.

Protocols Supported by Junos:

MLD (Multicast Listener Discovery):

Used for IPv6 multicast group management. It is the IPv6 equivalent of IGMP.

MLD allows routers to discover multicast listeners on a network.

IGMP (Internet Group Management Protocol):

Used for IPv4 multicast group management.

IGMP enables hosts to join and leave multicast groups and allows routers to manage multicast group memberships.

Verification and Configuration in Junos:

MLD and IGMP are supported on Juniper devices running the Junos operating system.

Configuration examples:

IGMP:

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set protocols igmp interface ge-0/0/1.0

MLD:

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set protocols mld interface ge-0/0/1.0

References:

Juniper IGMP Configuration Guide

Juniper MLD Configuration Guide

From the provided IS-IS adjacency outputs:

R1 is configured to participate in both Level 1 and Level 2 (A): This is indicated by the adjacency states for both Level 1 and Level 2 on the R1 interfaces.

R2 is configured to participate in Level 2 only (D): This is shown by the adjacency state for Level 2 only on the R2 interfaces.

References:

The IS-IS adjacency outputs indicate the state and levels of participation for each router.

Configuration and command references from " Example configs for VMRCAXP01W.txt " and other documents provide context for understanding IS-IS states and levels​​​​​​.

To ensure that each host is placed on a separate VLAN when using an unmanaged switch between the hosts and the EX Series switch:

Configure an input firewall filter on interface ge-0/0/3 to match the source MAC or IP address of the hosts to assign the VLANs:

By configuring an input firewall filter, you can match the source MAC or IP address of incoming traffic and assign the appropriate VLAN based on these criteria.

This method ensures that even though the switch between hosts and EX Series is unmanaged, VLAN assignments are still properly enforced at the EX Series switch.

Configuration Example:

set firewall family ethernet-switching filter VLAN-assignment term VLAN100 from source-mac-address xx:xx:xx:xx:xx:xx

set firewall family ethernet-switching filter VLAN-assignment term VLAN100 then vlan-assignment vlan 100

set firewall family ethernet-switching filter VLAN-assignment term VLAN200 from source-mac-address yy:yy:yy:yy:yy:yy

set firewall family ethernet-switching filter VLAN-assignment term VLAN200 then vlan-assignment vlan 200

set firewall family ethernet-switching filter VLAN-assignment term VLAN300 from source-mac-address zz:zz:zz:zz:zz:zz

set firewall family ethernet-switching filter VLAN-assignment term VLAN300 then vlan-assignment vlan 300

set interfaces ge-0/0/3 unit 0 family ethernet-switching filter input VLAN-assignment

References:

The command references from " Useful Juniper Commands.txt " and network configuration guides provide details on firewall filters and VLAN assignments​​.

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 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