Can an interface be shut down on the Symantec SSL Visibility Appliance (SSLVA) to prevent routing loops or asymmetric routing?

Products

• SV-3800

Issue/Introduction

The question regarding the ability to shut down an interface on the Symantec SSL Visibility Appliance (SSLVA) for preventing routing loops or asymmetric routing is clear. See the clarification in the solution section of this article, for how this can be approached:

Environment

SSLV 4.5/5.x

Resolution

Interface Management on SSLVA

The Symantec SSL Visibility Appliance does not provide a direct option in the GUI or CLI to administratively shut down an interface, similar to how one might disable an interface on a router or switch.

However, there are a few alternatives to achieve similar outcomes, depending on your requirements and use case.

Options to Prevent Asymmetric Routing or Loops

1. Use Monitoring and Failover Mechanisms

• SSLVA supports interface monitoring and failover capabilities. You can configure monitoring for specific interfaces, and if an issue (like packet loss) is detected, the SSLVA can redirect traffic to an alternate interface or stop passing traffic on the failed path.
• This is managed under Configuration > Monitoring in the SSLVA GUI.

Steps:

• Define a monitoring profile for the interfaces.
• Enable interface failover based on the health status of monitored links.

2. Implement Link State Propagation (LSP)

• SSLVA supports Link State Propagation, where the status of an interface can be propagated to connected devices. If the SSLVA detects an interface failure, it can propagate that failure state upstream to the load balancer (LB).
• The load balancer can then switch traffic away from the affected path.

Steps:

• Enable LSP on the relevant interfaces in the SSLVA settings.
• Verify that the load balancer supports and responds to link state propagation.

3. Control Traffic with Policy-Based Routing

• If you need to dynamically reroute traffic during issues, policy-based routing (PBR) can be configured to control which SSLVA interface is used based on conditions.
• PBR rules can help ensure that traffic is only sent through active paths.

4. Disable the Interface at the Switch

• Since SSLVA interfaces cannot be "shut down" directly, you can manage this by administratively shutting down the corresponding interface on the connected switch.

• For example:

  interface GigabitEthernet0/1 shutdown

• This prevents traffic from reaching the SSLVA on the specific path and avoids routing loops.

5. Dynamic Routing Protocols with Health Detection

• If your network supports dynamic routing (e.g., OSPF or BGP), you can integrate the SSLVA interfaces into the routing process:
  • If a particular SSLVA path becomes unavailable, the dynamic routing protocol can automatically withdraw the route and redirect traffic.

So, while the SSLVA does not allow you to shut down an interface directly, you can mitigate the risk of routing loops or asymmetric routing by:

1. Leveraging interface monitoring and failover features.
2. Using Link State Propagation to signal failures to the load balancer.
3. Shutting down interfaces at the switch level.
4. Exploring policy-based routing or dynamic routing mechanisms for failover control.