To enable advanced policy-based routing in Junos OS and activate a static route with a next-hop address in the inet.0 table within your routing instance, you should utilize RIB groups. RIB groups allow you to import routes from one routing table to another. In this scenario, the static route within the routing instance needs access to the inet.0 routes, which is facilitated by configuring a RIB group. Juniper’s documentation outlines RIB groups as a necessary component for handling instances where routes need to be shared across routing tables, thereby ensuring seamless traffic flow through specified routes. For more details, refer to the Juniper Networks Documentation on RIB Groups.

In Junos OS for SRX Series devices, when enabling advanced policy-based routing and configuring a static route with a next-hop from the inet.0 routing table, the issue arises because the static route is not being used in the routing instance. This is a common scenario when the next-hop belongs to a different routing table or instance, and the routing instance is not aware of that next-hop.

To resolve this,RIB (Routing Information Base) groupsare used. RIB groups allow routes from one routing table (RIB) to be shared or imported into another routing table. This means that the routing instance can import the necessary routes from inet.0 and make them available for the routing instance where the policy-based routing is applied.

Detailed Steps:

Configure the Static Route:First, configure the static route pointing to the next-hop in inet.0. Here’s an example:

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set routing-options static route 10.1.1.0/24 next-hop 192.168.1.1

This static route will be placed in the inet.0 routing table by default.

Create and Apply a RIB Group:To import routes from inet.0 into the routing instance, create a RIB group configuration. This will allow the static route from inet.0 to be visible within the routing instance.

Example configuration for the RIB group:

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set routing-options rib-groups RIB-GROUP import-rib inet.0

set routing-options rib-groups RIB-GROUP import-rib .inet.0

This configuration ensures that routes from inet.0 are imported into the specified routing instance.

Apply the RIB Group to the Routing Instance:Once the RIB group is configured, apply it to the appropriate routing instance:

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set routing-instances routing-options rib-group RIB-GROUP

Verify Configuration:Use the following command to verify that the static route has been imported into the routing instance:

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show route table .inet.0

The output should now display the static route imported from inet.0.

Juniper Security Reference:

RIB Groups Overview: Juniper's documentation provides detailed information on how RIB groups function and how to use them to share routes between different routing tables. This is essential for scenarios involving policy-based routing where routes from one instance (like inet.0) need to be available in another instance. Reference: Juniper Networks Documentation on RIB Groups.

By using RIB groups, you ensure that the static route from inet.0 is available in the appropriate routing instance for policy-based routing to function correctly. This avoids the need for other methods like filter-based forwarding or transparent mode, which do not address the specific issue of static route visibility across routing instances.

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The SRX Series can inspect traffic within VXLAN tunnels, providing in-depth security services across multiple layers. Adding SRX in the overlay network allows comprehensive control, leveraging advanced firewall capabilities. For more details, see Juniper EVPN-VXLAN Security.

When integrating an SRX Series device into anEVPN-VXLANsolution, it offers several security benefits:

Layer 4-7 Security Services (Answer A): The SRX can providedeep packet inspectionfor VXLAN encapsulated traffic, enhancing security by offering services such as intrusion prevention, application layer filtering, and antivirus scanning. This allows security monitoring of the encapsulated traffic at higher layers of the OSI model (Layers 4-7), which is essential for advanced threat detection.

Security in the Overlay Network (Answer C): The SRX adds security by functioning as an enterprise-grade firewall within theEVPN-VXLAN overlay. This means that traffic flowing between virtualized segments or networks can be inspected and filtered using SRX firewall rules, ensuring that the VXLAN overlay remains secure.

These features make the SRX a powerful addition for securing EVPN-VXLAN environments, providing comprehensive security for encapsulated traffic and ensuring that both the underlay and overlay networks are protected.

In this scenario, there is an issue with configuring APBR because the routing instance type may not be appropriate for handling the required routing functionality. In Juniper SRX devices,forwarding instancesare used for simple path selection but do not have full routing capabilities like virtual router instances.

To fully support advanced policy-based routing (APBR), it is recommended to use avirtual routerinstance, which provides full routing functionalities, including route tables and advanced routing protocols. Forwarding instances are limited in this respect and cannot handle the full range of routing tasks needed by APBR.

Step-by-Step Solution:

Change the Routing Instance Type:

Convert the routing instance from a forwarding instance to a virtual router instance, which supports full routing and is compatible with APBR:

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set routing-instances instance-type virtual-router

Configure the Static Routes in the Virtual Router:

After changing the instance type, ensure that all necessary routes are configured within the new virtual router instance:

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set routing-instances routing-options static route 0.0.0.0/0 next-hop

Juniper Security Reference:

Virtual Router Instances: Virtual routers are necessary for advanced routing tasks, including APBR. They provide full routing capabilities, unlike forwarding instances which are used for basic routing needs. Reference: Juniper Virtual Router Documentation.

By switching to a virtual router instance, you enable full routing functionality for APBR to work as expected.

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When using security profiles to limit system resources in Juniper logical systems:

No Resource Specification (Answer B): If a resource limit isnot specifiedfor a logical system, no specific amount of system resources is reserved for it. Instead, the logical system competes for resources along with others in the system, up to the maximum available. This allows flexible resource allocation, where logical systems can scale based on actual demand rather than predefined limits.

Multiple Logical Systems per Security Profile (Answer D): A single security profile can be applied tomultiple logical systems. This allows administrators to define resource limits once in a profile and apply it across several logical systems, simplifying management and ensuring consistency across different environments.

These principles ensure efficient and flexible use of system resources within a multi-tenant or multi-logical-system environment.

Understanding the Flow Log Output:

From the flow logs in the exhibit, we can observe the following key events:

The session creation was initiated (flow_first_create_session), but the policy searchfailed (flow_first_policy_search), which implies that no matching policy was found between the zones involved (zone trust-> zone dmz).

The packet was dropped with the reason "denied by policy." This shows that the packet was dropped either due to no matching security policy or because the default policy denies the traffic (packet dropped, denied by policy).

The line denied by policy default-policy-logical-system-00(2) indicates that the default security policy is responsible for denying the traffic, confirming that no explicit security policy was configured to allow this traffic.

Explanation of Answer A (Dropped by the default security policy):

The log message clearly states that the packet was dropped by the default security policy (default-policy-logical-system-00). In Junos, when a session is attempted between two zones and no explicit policy exists to allow the traffic, the default policy is to deny the traffic. This is a common behavior in Junos OS when a security policy does not explicitly allow traffic between zones.

Explanation of Answer D (Requires traceoptions flag of basic-datapath):

The information displayed in the log involves session creation, flow policy search, and packet dropping due to policy violations, which are all part of basic packet processing in the data path. This type of information is logged when the traceoptions flag is set tobasic-datapath. The basic-datapath traceoption provides detailed information about the forwarding process, including policy lookups and packet drops, which is precisely what we see in the exhibit.

The traceoptions flaghost-traffic(Answer C) is incorrect because host-traffic is typically used for traffic destined to or generated from the Junos device itself (e.g., SSH or SNMP traffic to the SRX device), not for traffic passing through the device.

To capture flow processing details like those shown, you need the basic-datapath traceoptions flag, which provides details about packet forwarding and policy evaluation.

Step-by-Step Configuration for Tracing (Basic-Datapath):

Enable flow traceoptions:

To capture detailed information about how traffic is being processed, including policy lookups and flow session creation, enable traceoptions for the flow.

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set security flow traceoptions file flow-log

set security flow traceoptions flag basic-datapath

Apply the configuration and commit:

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commit

View the logs:

Once enabled, you can check the trace logs for packet flows, policy lookups, and session creation details:

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show log flow-log

This log will contain information similar to the exhibit, including session creation attempts and packet drops due to security policy.

Juniper Security Reference:

Default Security Policies: Juniper SRX devices have a default security policy to deny all traffic that is not explicitly allowed by user-defined policies. This is essential for security best practices. Reference: Juniper Networks Documentation on Security Policies.

Traceoptions for Debugging Flows: Using traceoptions is crucial for debugging and understanding how traffic is handled by the SRX, particularly when issues arise from policy misconfigurations or routing. Reference: Juniper Traceoptions.

By using the basic-datapath traceoptions, you can gain insights into how the device processes traffic, including policy lookups, route lookups, and packet drops, as demonstrated in the exhibit.

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The NAT setup allows only specific external hosts to reach the internal network post-initial session, providing controlled access. Reflexive NAT preserves the source port from the original request, maintaining continuity. More on this can be found in Juniper NAT Configuration Documentation.

Looking at the NAT configuration, we observe the use ofpersistent NATwith the keywordpermit target-host. Here's a detailed breakdown:

Persistent NAT (Correct: Option B):Whenpersistent NATis configured with thepermit target-hostoption, it allows the internal host (from the 172.16.1.0/24 network) to initiate communication with an external host. After the initial session is established, only the specific external host (target host) is allowed to initiate subsequent sessions to the internal host using the reflexive address. This ensures that random external hosts cannot initiate sessions, which enhances security.

Original Destination Port Reuse (Correct: Option D):In this configuration, theinterface-based source NATuses the original destination port of the incoming session as the source port for the outbound session. This maintains port transparency for NATed traffic, which can be crucial for certain types of applications that depend on consistent port numbers.

Incorrect Options:

Option Ais incorrect because persistent NAT with target-host does not allow both internal and external hosts to initiate sessions freely. Only the specific external hostcan initiate a session after the initial session is established by the internal host.

Option Cis incorrect because only the specific external host can initiate subsequent sessions, not any random external host.

Juniper References:

Juniper NAT Documentation: Describes the behavior of persistent NAT and how target-host restrictions work for enhanced security.

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In the scenario where internal users are trying to access the company's web server via its FQDN but the DNS server resolves to a private IP, two key actions are needed:

Static NAT (Answer B): Since the internal DNS server resolves the web server to its private IP address (10.10.10.4/24), you need to configure static NAT for both the DNS server and the webserver. This will ensure that requests coming from the internet will be translated to the web server's public IP (203.0.113.4) and the DNS server’s public IP (203.0.113.2).

Example Command:

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set security nat static rule-set public-to-private from zone untrust

set security nat static rule-set public-to-private rule dns-server match destination-address 203.0.113.2/32

set security nat static rule-set public-to-private rule dns-server then static-nat-prefix 10.10.10.2/32

set security nat static rule-set public-to-private rule web-server match destination-address 203.0.113.4/32

set security nat static rule-set public-to-private rule web-server then static-nat-prefix 10.10.10.4/32

Proxy ARP (Answer D): The SRX needs to respond to ARP requests for the public IP addresses of both the DNS and webserver on the interface facing the internet (ge-0/0/3). This allows the SRX to handle requests directed at the public IPs.

Example Command:

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set interfaces ge-0/0/3 unit 0 family inet proxy-arp interface-address 203.0.113.2/32

set interfaces ge-0/0/3 unit 0 family inet proxy-arp interface-address 203.0.113.4/32

These two configurations allow external users to access the internal web server via its public IP, as resolved by the DNS server.

Logical systems on SRX Series devices allow the creation of separate virtual routers, each with its unique RPD process. This segmentation ensures that routing and security policies are isolated across different logical systems, effectively acting like independent routers within a single SRX device. For further information, see Juniper Logical Systems Documentation.

To create multiple virtual routers on a single SRX Series device, each with its own unique copy of the routing protocol daemon (RPD) process, you need to uselogical systems. Logical systems allow for the segmentation of an SRX device into multiple virtual routers, each with independent configurations, including routing instances, policies, and protocol daemons.

Explanation of Answer D (Logical System):

Alogical systemon an SRX device enables you to create multiple virtual instances of the SRX, each operating independently with its own control plane and routing processes. Each logical system gets a separate copy of the RPD process, ensuring complete isolation between virtual routers.

This is the correct solution when you need separate routing instances with their own RPD processes on the same physical device.

Configuration Example:

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set logical-systems interfaces ge-0/0/0 unit 0

set logical-systems routing-options static route 0.0.0.0/0 next-hop 192.168.1.1

Juniper Security Reference:

Logical Systems Overview: Logical systems allow for the creation of multiple virtual instances within a single SRX device, each with its own configuration and control plane. Reference: Juniper Logical Systems Documentation.

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To enable Advanced Policy-Based Routing (APBR) on SRX Series devices, three key components are necessary: filter-based forwarding, routing instances, and APBR profiles. Filter-based forwarding is utilized to direct specific traffic flows to a routing instance based on criteria set by a policy. Routing instances allow the traffic to be managed independently of the main routing table, and APBR profiles define how and when traffic should be forwarded. These elements ensure that APBR is flexible and tailored to the network’s requirements. Refer to Juniper's APBR Documentation for more details.

Advanced policy-based routing (APBR) in Juniper's SRX devices allows the selection of different paths for traffic based on policies, rather than relying purely on routing tables. To enable APBR, the following core components are required:

Filter-based Forwarding (Answer A):Filter-based forwarding (FBF) is a technique used to forward traffic based on policies rather than the default routing table. It is essential for enabling APBR, as it helps match traffic based on filters and directs it to specific routes.

Configuration Example:

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set firewall family inet filter FBF match-term source-address 192.168.1.0/24

set firewall family inet filter FBF then routing-instance custom-routing-instance

Routing Instance (Answer C):A routing instance is required to define the separate routing table used by APBR. You can create multiple routing instances and assign traffic to these instances based on policies. The traffic will then use the routes defined within the specific routing instance.

Configuration Example:

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set routing-instances custom-routing-instance instance-type forwarding

set routing-instances custom-routing-instance routing-options static route 0.0.0.0/0 next-hop 10.10.10.1

APBR Profile (Answer D):The APBR profile defines the rules and policies for advanced policy-based routing. It allows you to set up conditions such as traffic type, source/destination address, and port, and then assign actions such as redirecting traffic to specific routing instances.

Configuration Example:

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set security forwarding-options advanced-policy-based-routing profile apbr-profile match application http

set security forwarding-options advanced-policy-based-routing profile apbr-profile then routing-instance custom-routing-instance

Other Components:

Routing Options (Answer B)are not a core component of APBR, as routing options define the general behavior of the routing table and protocols. However, APBR works by overriding these default routing behaviors using policies.

Policies (Answer E)are crucial in many network configurations but are not a core component of enabling APBR. APBR specifically relies on profiles rather than standard security policies.

Juniper Security Reference:

Advanced Policy-Based Routing (APBR): Juniper’s APBR is a powerful tool that allows routing based on specific traffic characteristics rather than relying on static routing tables. APBR ensures that specific types of traffic can take alternate paths based on business or network needs. Reference: Juniper Networks APBR Documentation.

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In an ADVPN (Auto-Discovery VPN) environment with a hub-and-spoke topology, the initial communication between two spokes (Spoke-1 and Spoke-2) is always routed through the hub. Once the hub detects the communication, it facilitates the creation of a direct VPN tunnel between the spokes. Until this dynamic tunnel is established, the traffic between the spokes continues to pass through the hub.

In this scenario,Spoke-1 will route traffic through the hubinitially until the direct VPN tunnel toSpoke-2is established.

In a Juniper SRX high-availability (HA) scenario, redundancy is achieved through the use of redundancy groups. Redundancy groups are assigned to control specific functions in an active/passive setup. The HA configuration uses redundancy groups to manage failover between the two SRX nodes.

SRG0 (Services Redundancy Group 0):

Correct: Option B: SRG0 is used for control plane functions like routing engine redundancy. This group manages the Routing Engine (RE) failover and ensures that routing decisions continue seamlessly during failovers.

Correct: Option C: SRG0 is also responsible for services without control plane states. These services can include lower-level services such as packet forwarding and stateful firewall services. SRG0 handles both critical and basic functions since control plane elements are essential for network operations during failover events.

SRG1 (Services Redundancy Group 1):

SRG1, contrary to SRG0, is typically used for data plane services and does not manage control plane state. It handles services like security policies, NAT, and VPN functions but does not involve control plane redundancy.

Juniper References:

Juniper SRX HA Documentation: The role of redundancy groups in HA, detailing that SRG0 is reserved for the most crucial services, including control plane failover and basic packet forwarding.

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Explanation of Answer A (Session Reclassification):

APBR (Advanced Policy-Based Routing) requires the session to be classified based on the specified rule, which can change midstream as additional packets are processed. If the session was already established before the APBR rule took effect, the traffic may not be correctly reclassified to match the new APBR rule, leading to IDP (Intrusion Detection and Prevention) processing instead of being bypassed. This can occur especially when the session was already established before the rule change.

Explanation of Answer C (Application Services Bypass):

For APBR to work and bypass the IDP service, theapplication services bypassmust be explicitly configured. Without this configuration, the APBR rule may redirect the traffic, but the IDP service will still inspect and potentially drop the traffic. This is especially important for traffic destined for specific sites like social media platforms where bypassing IDP is desired.

Example configuration for bypassing IDP services:

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set security forwarding-options advanced-policy-based-routing profile application-services-bypass

Step-by-Step Resolution:

Reclassify the Session Midstream:

If the traffic was already being processed before the APBR rule was applied, ensure that the session is reclassified by terminating the current session or ensuring the APBR rule is applied from the start.

Command to clear the session:

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clear security flow session destination-prefix

Configure Application Services Bypass:

Ensure that the APBR rule includes the application services bypass configuration to properly bypass IDP or any other security services for traffic that should not be inspected.

Example configuration:

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set security forwarding-options advanced-policy-based-routing profile application-services-bypass

Juniper Security Reference:

Session Reclassification in APBR: APBR requires reclassification of sessions in real-time to ensure midstream packets are processed by the correct rule. This is crucial when policies change dynamically or new rules are added.

Application Services Bypass in APBR: This feature ensures that security services such as IDP are bypassed for traffic that matches specific APBR rules. This is essential for applications where performance is a priority and security inspection is not necessary.

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NAT64 requires flow-based forwarding for both IPv4 and IPv6 to ensure proper stateful inspection and address translation. Packet-based forwarding does not support the necessary stateful inspection needed for NAT64. For more on NAT64, refer to Juniper NAT64 Overview.

NAT64 allows communication between IPv6 and IPv4 devices by translating IPv6 addresses to IPv4 addresses and vice versa. On Juniper SRX devices, the device's forwarding mode is crucial in how the device processes traffic.

Flow-based forwarding mode:

Correct: Option C: For IPv4 traffic in NAT64 configurations, SRX devices should be in flow-based forwarding mode. Flow-based mode means that the device inspects traffic sessions and tracks state, which is essential for proper NAT64 operations. This mode enables the device to monitor and translate between IPv4 and IPv6 protocols dynamically while maintaining session states.

Correct: Option D: Similarly, for IPv6 traffic, the SRX device should also be in flow-based mode. Flow-based mode ensures the SRX tracks the IPv6-to-IPv4 translations properly by preserving the state of each connection, ensuring consistent NAT64 operations.

Packet-based forwarding mode:Packet-based mode is not used for NAT64 operations because it does not provide stateful inspection, which is required for NAT64 to function correctly. Hence, options A and B are incorrect.

Juniper References:

Juniper NAT64 Documentation: Discusses how NAT64 functions on SRX devices and specifies the requirement of flow-based mode for both IPv4 and IPv6 traffic when translating between these protocols.

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For ADVPN with OSPF, using a point-to-multipoint (p2mp) interface type and enabling dynamic-neighbors are crucial. This configuration allows dynamic discovery of neighbors and the establishment of tunnels. For more information, refer to Juniper ADVPN Configuration Guide.

In the ADVPN configuration, OSPF isn't functioning as expected due to the interface configuration on st0.0. Here are the adjustments needed:

Interface Type p2mp (Answer A): OSPF requires that the tunnel interface be set to p2mp (point-to-multipoint) to allow OSPF to communicate with multiple dynamic neighbors overthe ADVPN tunnels.

Command Example:

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set interfaces st0.0 family inet ospf interface-type p2mp

Dynamic Neighbors (Answer B): The dynamic neighbors statement allows OSPF to discover and communicate with dynamically established spokes in an ADVPN environment. This is essential for ADVPN to function properly since the tunnel endpoints are not static.

Command Example:

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set protocols ospf area 0.0.0.0 interface st0.0 dynamic-neighbors

These settings ensure OSPF properly functions over dynamically created ADVPN tunnels.

The Local zone represents a Layer 2 segment, which allows for traffic flows within the same zone and across other zones with proper security policies. Additionally, hosts in different zones (such as Local and Trust) can communicate when policies are defined to allow such interactions. Refer to Juniper Security Policy Documentation for detailed guidance.

From the exhibit:

IRB Interface Requirement (Answer B): To allow communication between the Trust and Untrust zones (Layer 2 and Layer 3 environments), anIRB (Integrated Routing and Bridging)interface is required. The IRB interface acts as a gateway between Layer 2 and Layer 3 domains.

Command Example:

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set interfaces irb unit 0 family inet address 10.1.1.1/24

set security zones security-zone untrust interfaces irb.0

Communication Between Local and Trust (Answer D): Hosts in the Local zone (Layer 2) can communicate with hosts in the Trust zone (Layer 3) if appropriate security policies are in place. A security policy is needed to define how traffic can flow between these zones.

Command Example:

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set security policies from-zone local to-zone trust policy allow-local-trust match source-address any destination-address any application any

set security policies from-zone local to-zone trust policy allow-local-trust then permit

These configurations ensure proper communication between zones in a mixed Layer 2 and Layer 3environment.

A virtual router instance allows for independent routing tables, which helps manage asymmetric routing issues in APBR configurations. This ensures both initial and return traffic follow the same path, resolving session issues. Further details: Juniper APBR Configuration.

The issue in the scenario stems from asymmetric routing. The SRX-1 device sends streaming traffic to ISP-B (as intended) using APBR, but the return traffic is coming back through ISP-A due to the default route. Because APBR uses forwarding instances, the traffic is dropped when it returns through a different zone.

To solve this:

Change APBR routing instance to a virtual router (Answer B): By changing the APBR routing instance to a virtual router, the SRX will maintain separate routing tables for each ISP, ensuring proper bidirectional traffic flow. Virtual routers provide independent routing tables and are ideal for ensuring traffic symmetry in multi-homed environments.

Example Command:

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set routing-instances ISP-B instance-type virtual-router

set routing-instances ISP-B routing-options static route 0.0.0.0/0 next-hop 192.0.2.1

By implementing virtual routing instances, you can resolve the asymmetry and ensure that both outbound and return traffic use the same ISP.