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Cisco ASA 5500 Series Configuration Guide using the CLI
Chapter3 Managing Feature Licenses
Supported Feature Licenses Per Model
UC Phone Proxy sessions 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 toward 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 tls-proxy maximum-sessions command or
in ASDM, using the Configuration > Firewall > Unified Communications > TLS Proxy pane.
To view the limits of your model, enter the tls-proxy maximum-sessions ? command. When you
apply a UC license that is higher than the default TLS proxy limit, the ASA 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 TLSproxy 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.
If you clear the configuration (using the clear configure all command, for example), 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 tls-proxy maximum-sessions
command to raise the limit again (in ASDM, use the TLS Proxy pane). If you use failover
and enter the write standby command or in ASDM, 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 toward the SRTP
limit; if passthrough is set for the call, even if both legs are SRTP, they do not count toward
the limit.
VPN Load Balancing VPN load balancing requires a Strong Encryption (3DES/AES) License.
Table3-15 License Notes (continued)
License Notes