Chapter 18 Configuring the TLS Proxy for Encrypted Voice Inspection

Licensing for the TLS Proxy

Model

License Requirement1

ASA 5585-X with

Base License: 2 sessions.

SSP-20, -40, or -60

Optional licenses: 24, 50, 100, 250, 500, 750, 1000, 2000, 3000, 5000, or 10,000 sessions.2

ASA SM

Base License: 2 sessions.

 

Optional licenses: 24, 50, 100, 250, 500, 750, 1000, 2000, 3000, 5000, or 10,000 sessions.2

1.The following applications use TLS proxy sessions for their connections. Each TLS proxy session used by these applications (and only these applications) is counted against the UC license limit:

-Phone Proxy

-Presence Federation Proxy

-Encrypted Voice Inspection

Other applications that use TLS proxy sessions do not count towards the UC limit, for example, Mobility Advantage Proxy (which does not require a license) and IME (which requires a separate IME license).

Some UC applications might use multiple sessions for a connection. For example, if you configure a phone with a primary and backup Cisco Unified Communications Manager, there are 2 TLS proxy connections, so 2 UC Proxy sessions are used.

You independently set the TLS proxy limit using the Configuration > Firewall > Unified Communications > TLS Proxy pane. When you apply a UC license that is higher than the default TLS proxy limit, the security appliance automatically sets the TLS proxy limit to match the UC limit. The TLS proxy limit takes precedence over the UC license limit; if you set the TLS proxy limit to be less than the UC license, then you cannot use all of the sessions in your UC license.

Note: For license part numbers ending in “K8” (for example, licenses under 250 users), TLS proxy sessions are limited to 1000. For license part numbers ending in “K9” (for example, licenses 250 users or larger), the TLS proxy limit depends on the configuration, up to the model limit. K8 and K9 refer to whether the license is restricted for export: K8 is unrestricted, and K9 is restricted.

Note: If you clear the configuration, then the TLS proxy limit is set to the default for your model; if this default is lower than the UC license limit, then you see an error message to use the to raise the limit again (in ASDM, use the TLS Proxy pane). If you use failover and use File > Save Running Configuration to Standby Unit on the primary unit to force a configuration synchronization, the clear configure all command is generated on the secondary unit automatically, so you may see the warning message on the secondary unit. Because the configuration synchronization restores the TLS proxy limit set on the primary unit, you can ignore the warning.

You might also use SRTP encryption sessions for your connections:

-For K8 licenses, SRTP sessions are limited to 250.

-For K9 licenses, there is not limit.

Note: Only calls that require encryption/decryption for media are counted towards the SRTP limit; if passthrough is set for the call, even if both legs are SRTP, they do not count towards the limit.

2. With the 10,000-session UC license, the total combined sessions can be 10,000, but the maximum number of Phone Proxy sessions is 5000.

Table 18-1shows the default and maximum TLS session details by platform.

Table 18-1

Default and Maximum TLS Sessions on the Security Appliance

 

 

 

Security Appliance Platform

Default TLS Sessions

Maximum TLS Sessions

 

 

 

 

ASA 5505

 

10

80

 

 

 

 

ASA 5510

 

100

200

 

 

 

 

ASA 5520

 

300

1200

 

 

 

 

ASA 5540

 

1000

4500

 

 

 

 

ASA 5550

 

2000

4500

 

 

 

 

ASA 5580

 

4000

13,000

 

 

 

 

For more information about licensing, see Chapter 5, “Managing Feature Licenses,” in the general operations configuration guide.

Cisco ASA Series Firewall ASDM Configuration Guide

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Cisco Systems ASA 5545-X, ASA 5505, ASA 5555-X, ASA 5585-X, ASA 5580, ASA Services Module manual 18-5
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ASA Services Module, ASA 5555-X, ASA 5545-X, ASA 5585-X, ASA 5580 specifications

Cisco Systems has long been a leader in the field of network security, and its Adaptive Security Appliance (ASA) series is a testament to this expertise. Within the ASA lineup, models such as the ASA 5505, ASA 5580, ASA 5585-X, ASA 5545-X, and ASA 5555-X stand out for their unique features, capabilities, and technological advancements.

The Cisco ASA 5505 is designed for small businesses or branch offices. It provides essential security features such as firewall protection, flexible VPN capabilities, and intrusion prevention. The ASA 5505 supports a user-friendly interface, allowing for straightforward management. Its built-in threat detection and prevention tools provide a layered defense, and with scalability in mind, it can accommodate various expansion options as organizational needs grow.

Moving up the line, the ASA 5580 delivers greater throughput and advanced security features. This model is suited for medium to large enterprises that require robust protection against increasingly sophisticated threats. Its multi-core architecture allows it to manage high volumes of traffic seamlessly while maintaining excellent performance levels. The ASA 5580 also supports application-layer security and customizable access policies, making it highly adaptable to diverse security environments.

The ASA 5585-X further enhances Cisco's security offerings with advanced malware protection and extensive security intelligence capabilities. It incorporates next-generation firewall features, including context-aware security, and supports advanced threat detection technologies. This model is ideal for large enterprises or data centers that prioritize security while ensuring uninterrupted network performance and availability.

For enterprises requiring a balance of performance and security, the ASA 5545-X presents a compelling option. This model features scalable performance metrics, high availability, and integrated advanced threat protection. Coupled with advanced endpoint protection and detailed monitoring capabilities, the ASA 5545-X enables organizations to manage their security posture effectively.

Lastly, the ASA 5555-X blends cutting-edge technologies with strong security infrastructures. It boasts high throughput and the ability to execute deep packet inspections. Its sophisticated architecture supports threat intelligence feeds that provide real-time security updates, making it a powerful tool against modern threats.

Each of these Cisco ASA models brings specific advantages to varied environments. Their integrative capabilities enable businesses to enhance their security postures while benefiting from seamless scalability and management. As cybersecurity threats evolve, these advanced appliances play a vital role in protecting valuable digital assets.
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