Cisco Intercompany Media Engine Installation and Configuration Guide, Release 8.6(1)
Cisco ASA Configuration
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Cisco ASA Configuration

Table Of Contents

Cisco ASA Configuration

Proxy Configuration Guidelines and Limits

Proxy CLI configuration

Task Flow for Configuring Cisco Intercompany Media Engine

Configuring NAT for Cisco Intercompany Media Engine Proxy

Configuring PAT for the Cisco UCM Server

Creating Access Lists for Cisco Intercompany Media Engine Proxy

Creating the Media Termination Instance

Creating the Cisco Intercompany Media Engine Proxy

Creating Trustpoints and Generating Certificates

Creating the TLS Proxy

Enabling SIP Inspection for the Cisco Intercompany Media Engine Proxy

(Optional) Configuring TLS within the Local Enterprise

(Optional) Configuring Off Path Signaling

Proxy Configuration using ASDM

Configuring the Cisco UC-IMC Proxy by using the UC-IME Proxy Pane

Configuring the Cisco UC-IMC Proxy by using the Unified Communications Wizard


Cisco ASA Configuration


The Cisco Adaptive Security Appliance (ASA) firewall plays a key role in the security of the Cisco Intercompany Media Engine solution. This section contains information on configuring ASA using the command-line interface, as well as the ASDM, a web-based GUI application.

Proxy Configuration Guidelines and Limits

Proxy CLI configuration

Proxy Configuration using ASDM

Proxy Configuration Guidelines and Limits

Context Mode Guidelines

Supported in single context mode only.

Firewall Mode Guidelines

Supported in routed firewall mode only.

IPv6 Guidelines

Does not support IPv6 addresses.

Additional Guidelines and Limitations

Cisco Intercompany Media Engine has the following limitations:

Fax is not supported. Fax capability needs to be disabled on the SIP trunk.

Stateful failover of Cisco Unified Intercompany Media Engine is not supported. During failover, existing calls traversing the Cisco Intercompany Media Engine Proxy disconnect; however, new calls successfully traverse the proxy after the failover completes.

Having Cisco UCMs on more than one of the adaptive security appliance interfaces is not supported with the Cisco Intercompany Media Engine Proxy. Having the Cisco UCMs on one trusted interface is especially necessary in an off path deployment because the adaptive security appliance requires that you specify the listening interface for the mapping service and the Cisco UCMs must be connected on one trusted interface.

Multipart MIME is not supported.

Only existing SIP features and messages are supported.

RTCP is not supported. The adaptive security appliance drops any RTCP traffic sent from the inside interface to the outside interface. The adaptive security appliance does not convert RTCP traffic from the inside interface into SRTP traffic.

The Cisco Intercompany Media Engine Proxy configured on the adaptive security appliance creates a dynamic SIP trunk for each connection to a remote enterprise. However, you cannot configure a unique subject name for each SIP trunk. The Cisco Intercompany Media Engine Proxy can have only one subject name configured for the proxy.

Additionally, the subject DN you configure for the Cisco Intercompany Media Engine Proxy match the domain name that has been set for the local Cisco UCM.

If a service policy rule for the Cisco Intercompany Media Engine Proxy is removed (by using the no service policy command) and reconfigured, the first call traversing the adaptive security appliance will fail. The call fails over to the PSTN because the Cisco UCM does not know the connections are cleared and tries to use the recently cleared IME SIP trunk for the signaling.

To resolve this issue, you must additionally enter the clear connection all command and restart the adaptive security appliance. If the failure is due to failover, the connections from the primary adaptive security appliance are not synchronized to the standby adaptive security appliance.

After the clear connection all command is issued on an adaptive security appliance enabled with a UC-IME Proxy and the IME call fails over to the PSTN, the next IME call between an originating and terminating SCCP IP phone completes but does not have audio and is dropped after the signaling session is established.

An IME call between SCCP IP phones use the IME SIP trunk in both directions. Namely, the signaling from the calling to called party uses the IME SIP trunk. Then, the called party uses the reverse IME SIP trunk for the return signaling and media exchange. However, this connection is already cleared on the adaptive security appliance, which causes the IME call to fail.

The next IME call (the third call after the clear connection all command is issued), will be completely successful.


Note This limitation does not apply when the originating and terminating IP phones are configured with SIP.


The adaptive security appliance must be licensed and configured with enough TLS proxy sessions to handle the IME call volume. See the licensing requirements sections for TLS proxy sessions in the Cisco ASA 5500 Series Configuration Guide using the CLI.

This limitation occurs because an IME call cannot fall back to the PSTN when there are not enough TLS proxy sessions left to complete the IME call. An IME call between two SCCP IP phones requires the adaptive security appliance to use two TLS proxy sessions to successfully complete the TLS handshake.

Assume for example, the adaptive security appliance is configured to have a maximum of 100 TLS proxy sessions and IME calls between SCCP IP phones establish 101 TLS proxy sessions. In this example, the next IME call is initiated successfully by the originating SCCP IP phone but fails after the call is accepted by the terminating SCCP IP phone. The terminating IP phone rings and on answering the call, the call hangs due to an incomplete TLS handshake. The call does not fall back to the PSTN.

Proxy CLI configuration

This section contains the following topics:

Task Flow for Configuring Cisco Intercompany Media Engine

Configuring NAT for Cisco Intercompany Media Engine Proxy

Configuring PAT for the Cisco UCM Server

Creating Access Lists for Cisco Intercompany Media Engine Proxy

Creating the Media Termination Instance

Creating the Cisco Intercompany Media Engine Proxy

Creating Trustpoints and Generating Certificates

Creating the TLS Proxy

Enabling SIP Inspection for the Cisco Intercompany Media Engine Proxy

(Optional) Configuring TLS within the Local Enterprise

(Optional) Configuring Off Path Signaling

Task Flow for Configuring Cisco Intercompany Media Engine

Figure 4-1 provides an example for a basic deployment of the Cisco Intercompany Media Engine. The following tasks include command line examples based on Figure 4-1.

Figure 4-1 Example for Basic (in-line) Deployment Tasks


Note Step 1 through Step 8 apply to both basic (in-line) and off path deployments and Step 9 applies only to off path deployment.


To configure a Cisco Intercompany Media Engine for a basic deployment, perform the following tasks.


Step 1 Configure static NAT for Cisco UCM. See Configuring NAT for Cisco Intercompany Media Engine Proxy.

Or

Configure PAT for the UCM server. See Configuring PAT for the Cisco UCM Server.

Step 2 Create access lists for Cisco Intercompany Media Engine Proxy. See Creating Access Lists for Cisco Intercompany Media Engine Proxy.

Step 3 Create the media termination address instance for Cisco Intercompany Media Engine Proxy. See Creating the Media Termination Instance.

Step 4 Create the Cisco Intercompany Media Engine Proxy. See Creating the Cisco Intercompany Media Engine Proxy.

Step 5 Create trustpoints and generate certificates for the Cisco Intercompany Media Engine Proxy. See Creating Trustpoints and Generating Certificates.

Step 6 Create the TLS proxy. See Creating the TLS Proxy.

Step 7 Configure SIP inspection for the Cisco Intercompany Media Engine Proxy. See Enabling SIP Inspection for the Cisco Intercompany Media Engine Proxy.

Step 8 (Optional) Configure TLS within the enterprise. See (Optional) Configuring TLS within the Local Enterprise.

Step 9 (Optional) Configure off path signaling. See (Optional) Configuring Off Path Signaling.


Note You only perform Step 9 when you are configuring the Cisco Intercompany Media Engine Proxy in an off path deployment.



Configuring NAT for Cisco Intercompany Media Engine Proxy

To configure auto NAT, you first configure an object; then use the nat command in the object configuration mode.

The example command lines in this task are based on a basic (in-line) deployment. See Figure 4-1 for an illustration explaining the example command lines in this task.

Alternatively, you can configure PAT for the Cisco Intercompany Media Engine Proxy. See Configuring PAT for the Cisco UCM Server.

Figure 4-2 Example for Configuring NAT for a Deployment

To configure auto NAT rules for the Cisco UCM server, perform the following steps:

 
Command
Purpose

Step 1 

hostname(config)# object network name 
Examples:
hostname(config)# object network inside_to_outside

Configures a network object for the real address of Cisco UCM that you want to translate.

Step 2 

hostname(config-network-object)# host ip_address
Examples:
hostname(config-network-object)# host 192.168.10.30
hostname(config-network-object)# host 192.168.10.31

Specifies the real IP address of the Cisco UCM host for the network object.

Step 3 

(Optional)

hostname(config-network-object)# description string
Example:
hostname(config-network-object)# description "Cisco 
UCM NAT"

Provides a description of the network object.

Step 4 

hostname(config-network-object)# nat 
(inside,outside) static mapped_inline_ip
Examples:
hostname(config-network-object)# nat 
(inside,outside) static 209.165.200.227
hostname(config-network-object)# nat 
(inside,outside) static 209.165.200.228

Specifies the address translation on the network objects created in this procedure.

Where mapped_inline_ip is the outside IP address of the Cisco UCM.

What to Do Next

Create the access lists for the Cisco Intercompany Media Engine Proxy. See Creating Access Lists for Cisco Intercompany Media Engine Proxy.

Configuring PAT for the Cisco UCM Server

Perform this task as an alternative to configuring NAT for the Cisco Intercompany Media Engine Proxy.

Figure 4-3 Example for Configuring PAT for a Deployment


Note You only perform this step when NAT is not configured for the Cisco UCM server.


To configure PAT for the Cisco UCM server, perform the following steps:

 
Command
Purpose

Step 1 

hostname(config)# object network name
Examples:
hostname(config)# object network ucm-pat-config1

Configures a network object for inbound Intercompany Media Engine calls.

Step 2 

hostname(config-network-object)# host ip_address
Example:
hostname(config-network-object)# host 192.168.30

Specifies the real IP address of the Cisco UCM host for the network object.

Step 3 

(Optional)

hostname(config-network-object)# description string
Example:
hostname(config-network-object)# description "PAT 
for Inbound Calls"

Provides a description of the network object.

Step 4 

hostname(config-network-object)# nat 
(inside,outside) static mapped_inline_ip service tcp 
real_port mapped_port
Example:
hostname(config-network-object)# nat 
(inside,outside) static 209.165.200.228 service tcp 
5570 5571

Configures static PAT for inbound Intercompany Media Engine calls from the port configured on the outside network to the specified port on the inside network.

Step 5 

hostname(config-network-object)# exit

Exits from the object configuration mode.

Step 6 

hostname(config)# object network name
Examples:
hostname(config)# object network ucm-pat-config2

Configures a network object for outbound Intercompany Media Engine calls.

Step 7 

hostname(config-network-object)# subnet ip_address 
mask
Examples:
hostname(config-network-object)# host 192.168.10.0 
255.255.255.0

Specifies the subnet for the network object.

Step 8 

(Optional)

hostname(config-network-object)# description string
Example:
hostname(config-network-object)# description "PAT 
for Outbound Calls"

Provides a description of the network object.

Step 9 

hostname(config-network-object)# nat 
(inside,outside) dynamic ip_address
Example:
hostname(config-network-object)# nat 
(inside,outside) dynamic 209.165.200.228

Configures dynamic PAT for outbound Intercompany Media Engine calls that hides the inside network behind the outside interface address.

Creating Access Lists for Cisco Intercompany Media Engine Proxy

To configure access lists for the Cisco Intercompany Media Engine Proxy to reach the Cisco UCM server, perform the following steps.

The example command lines in this task are based on a basic (in-line) deployment. See Figure 4-1 for an illustration explaining the example command lines in this task.

 
Command
Purpose

Step 1 

hostname(config)# access-list id extended permit tcp 
any host ip_address eq port
Example:
hostname(config)# access-list incoming extended 
permit tcp any host 192.168.10.30 eq 5070

Adds an Access Control Entry (ACE). An access list is made up of one or more ACEs with the same access list ID. This ACE provides access control by allowing incoming access for Cisco Intercompany Media Engine connections on the specified port.

In the ip_address argument, provide the real IP address of Cisco UCM.

Step 2 

hostname(config)# access-group access-list in 
interface interface_name
Example:
hostname(config)# access-group incoming in interface 
outside

Binds the access list to an interface.

Step 3 

hostname(config)# access-list id extended permit tcp 
any host ip_address eq port
Example:
hostname(config)# access-list ime-inbound-sip 
extended permit tcp any host 192.168.10.30 eq 5070

Adds an ACE. This ACE allows the adaptive security appliance to allow inbound SIP traffic for Cisco Intercompany Media Engine. This entry is used to classify traffic for the class and policy map.

Note The port that you configure here must match the trunk settings configured on Cisco UCM. See the Cisco Unified Communications Manager documentation for information about this configuration setting.

Step 4 

hostname(config)# access-list id extended permit tcp 
ip_address mask any range range
Example:
hostname(config)# access-list ime-outbound-sip 
extended permit tcp 192.168.10.30 255.255.255.255 
any range 5000 6000

Adds an ACE. This ACE allows the adaptive security appliance to allow outbound SIP traffic for Cisco Intercompany Media Engine (in the example, any TCP traffic with source as 192.168.10.30 and destination port range between 5000 and 6000). This entry is used to classify traffic for the class and policy map.

Note Ensure that TCP traffic between Cisco UCM and the Cisco Intercompany Media Engine server does not use this port range (if that connection goes through the adaptive security appliance).

Step 5 

hostname(config)# access-list id permit tcp any host 
ip_address eq 6084
Example:
hostname(config)# access-list ime-traffic permit tcp 
any host 192.168.10.12 eq 6084

Adds an ACE. This ACE allows the adaptive security appliance to allow traffic from the Cisco Intercompany Media Engine server to remote Cisco Intercompany Media Engine servers.

Step 6 

hostname(config)# access-list id permit tcp any host 
ip_address eq 8470
Example:
hostname(config)# access-list ime-bootserver-traffic 
permit tcp any host 192.168.10.12 eq 8470

Adds an ACE. This ACE allows the adaptive security appliance to allow traffic from the Cisco Intercompany Media Engine server to the Bootstrap server for the Cisco Intercompany Media Engine.

What to Do Next

Create the media termination instance on the adaptive security appliance for the Cisco Intercompany Media Engine Proxy. See Creating the Media Termination Instance.

Creating the Media Termination Instance

Guidelines

The media termination address you configure must meet these requirements:

If you decide to configure a media-termination address on interfaces (rather than using a global interface), you must configure a media-termination address on at least two interfaces (the inside and an outside interface) before applying the service policy for the Cisco Intercompany Media Engine Proxy. Otherwise, you will receive an error message when enabling the proxy with SIP inspection.


Note Cisco recommends that you configure the media-termination address for the Cisco Intercompany Media Engine Proxy on interfaces rather than configuring a global media-termination address.


The Cisco Intercompany Media Engine Proxy can use only one type of media termination instance at a time; for example, you can configure a global media-termination address for all interfaces or configure a media-termination address for different interfaces. However, you cannot use a global media-termination address and media-termination addresses configured for each interface at the same time.

Note If you change any Cisco Intercompany Media Engine Proxy settings after you create the media-termination address for the proxy, you must reconfigure the media-termination address by using the no media-termination command, and then reconfiguring it as described in this procedure.

Procedure

Create the media termination instance to use with the Cisco Intercompany Media Engine Proxy.

The example command lines in this task are based on a basic (in-line) deployment. See Figure 4-1 for an illustration explaining the example command lines in this task.

To create the media termination instance for the Cisco Intercompany Media Engine Proxy, perform the following steps:

 
Command
Purpose

Step 1 

hostname(config)# media-termination instance_name
Example: 
hostname(config)# media-termination 
uc-ime-media-term

Creates the media termination instance that you attach to the Cisco Intercompany Media Engine Proxy.

Step 2 

hostname(config-media-termination)# address 
ip_address interface intf_name
Examples: 
hostname(config-media-termination)# address 
209.165.200.228 interface outside

Configures the media-termination address used by the outside interface of the adaptive security appliance.

The outside IP address must be a publicly routable address that is an unused IP address within the address range on that interface.

See Creating the Cisco Intercompany Media Engine Proxy for information about the UC-IME proxy settings. See Cisco ASA 5500 Series Configuration Guide using the CLI for information about the no service-policy command.

Step 3 

hostname(config-media-termination)# address 
ip_address interface intf_name
Examples: 
hostname(config-media-termination)# address 
192.168.10.3 interface inside

Configures a media termination address used by the inside interface of the adaptive security appliance.

Note The IP address must be an unused IP address within the same subnet on that interface.

Step 4 

(Optional)
hostname(config-media-termination)# rtp-min-port 
port1 rtp-maxport port2
Examples: 
hostname(config-media-termination)# rtp-min-port 
1000 rtp-maxport 2000

Configures the rtp-min-port and rtp-max-port limits for the Cisco Intercompany Media Engine Proxy. Configure the RTP port range for the media termination point when you need to scale the number of calls that the Cisco Intercompany Media Engine supports.

Where port1 specifies the minimum value for the RTP port range for the media termination point, where port1 can be a value from 1024 to 65535. By default, the value for port1 is 16384.

Where port2 specifies the maximum value for the RTP port range for the media termination point, where port2 can be a value from 1024 to 65535. By default, the value for port2 is 32767.

What To Do Next

Once you have created the media termination instance, create the Cisco Intercompany Media Engine Proxy. See Creating the Cisco Intercompany Media Engine Proxy.

Creating the Cisco Intercompany Media Engine Proxy

To create the Cisco Intercompany Media Engine Proxy, perform the following steps.

The example command lines in this task are based on a basic (in-line) deployment. See Figure 4-1 for an illustration explaining the example command lines in this task.

Note You cannot change any of the configuration settings for the Cisco Intercompany Media Engine Proxy described in this procedure when the proxy is enabled for SIP inspection. Remove the Cisco Intercompany Media Engine Proxy from SIP inspection before changing any of the settings described in this procedure.

 
Command
Purpose

Step 1 

hostname(config)# uc-ime uc_ime_name
Example:
hostname(config)# uc-ime local-ent-ime

Configures the Cisco Intercompany Media Engine Proxy.

Where uc_ime_name is the name of the Cisco Intercompany Media Engine Proxy. The name is limited to 64 characters.

Only one Cisco Intercompany Media Engine Proxy can be configured on the adaptive security appliance.

Step 2 

hostname(config-uc-ime)# media-termination 
mta_instance_name
Example:
hostname(config-uc-ime)# media-termination 
ime-media-term

Specifies the media termination instance used by the Cisco Intercompany Media Engine Proxy.

Note You must create the media termination instance before you specify it in the Cisco Intercompany Media Engine Proxy.

Where mta_instance_name is the instance_name that you created in of Creating the Media Termination Instance.

See Creating the Media Termination Instance for the steps to create the media termination instance.

Step 3 

hostname(config-uc-ime)# ucm address ip_address 
trunk-security-mode [nonsecure | secure]
Example:
hostname(config-uc-ime)# ucm address 192.168.10.30 
trunk-security-mode non-secure

Specifies the Cisco UCM server in the enterprise. You must specify the real IP address of the Cisco UCM server. Do not specify a mapped IP address for the server.

Note You must include an entry for each Cisco UCM in the cluster with Cisco Intercompany Media Engine that has a SIP trunk enabled.

Where the nonsecure and secure options specify the security mode of the Cisco UCM or cluster of Cisco UCMs.

Note Specifying secure for Cisco UCM or Cisco UCM cluster indicates that Cisco UCM or Cisco UCM cluster is initiating TLS; therefore, you must configure TLS for components. See (Optional) Configuring TLS within the Local Enterprise.

You can specify the secure option in this task or you can update it later while configuring TLS for the enterprise. See Step 11 in (Optional) Configuring TLS within the Local Enterprise.

Step 4 

hostname(config-uc-ime)# ticket epoch n password 
password
Example:
hostname(config-uc-ime)# ticket epoch 1 password 
password1234

Configures the ticket epoch and password for Cisco Intercompany Media Engine.

Where n is an integer from 1-255. The epoch contains an integer that updates each time that the password is changed. When the proxy is configured the first time and a password entered for the first time, enter 1 for the epoch integer. Each time you change the password, increment the epoch to indicate the new password. You must increment the epoch value each time your change the password.

Typically, you increment the epoch sequentially; however, the adaptive security appliance allows you to choose any value when you update the epoch.

If you change the epoch value, the current password is invalidated and you must enter a new password.

Where password contains a minimum of 10 and a maximum of 64 printable character from the US-ASCII character set. The allowed characters include 0x21 to 0x73 inclusive, and exclude the space character.

We recommend a password of at least 20 characters. Only one password can be configured at a time.

The ticket password is stored onto flash. The output of the show running-config uc-ime command displays ***** instead of the password string.

Note The epoch and password that you configure on the adaptive security appliance must match the epoch and password configured on the Cisco Intercompany Media Engine server. See the Cisco Intercompany Media Engine server documentation for information.

Step 5 

(Optional)

hostname(config-uc-ime)# fallback monitoring timer 
timer_millisec | hold-down timer timer_sec
Examples:
hostname(config-uc-ime)# fallback monitoring timer 
120
hostname(config-uc-ime)# fallback hold-down timer 30

Specifies the fallback timers for Cisco Intercompany Media Engine.

Specifying monitoring timer sets the time between which the adaptive security appliance samples the RTP packets received from the Internet. The adaptive security appliance uses the data sample to determine if fallback to the PSTN is needed for a call.

Where timer_millisec specifies the length of the monitoring timer. By default, the length is 100 milliseconds for the monitoring timer and the allowed range is 10-600 ms.

Specifying hold-down timer sets the amount of time that adaptive security appliance waits before notifying Cisco UCM whether to fall back to PSTN.

Where timer_sec specifies the length of the hold-down timer. By default, the length is 20 seconds for the hold-down timer and the allowed range is 10-360 seconds.

If you do not use this command to specify fallback timers, the adaptive security appliance uses the default settings for the fallback timers.

Step 6 

(Optional)

hostname(config-uc-ime)# fallback sensitivity-file 
file_name
Example:
hostname(config-uc-ime)# fallback sensitivity-file 
ime-fallback-sensitvity.fbs

Specifies the file to use for mid-call PSTN fallback.

Where file_name must be the name of a file on disk that includes the .fbs file extension.

The fallback file is used to determine whether the QoS of the call is poor enough for the Cisco Intercompany Media Engine to move the call to the PSTN.

What to Do Next

Install the certificate on the local entity truststore. You could also enroll the certificate with a local CA trusted by the local entity.

Creating Trustpoints and Generating Certificates

You need to generate the keypair for the certificate used by the adaptive security appliance, and configure a trustpoint to identify the certificate sent by the adaptive security appliance in the TLS handshake.

The example command lines in this task are based on a basic (in-line) deployment. See Figure 4-1 for an illustration explaining the example command lines in this task.


Note This task instructs you on how to create trustpoints for the local enterprise and the remote enterprise and how to exchange certificates between these two enterprises. This task does not provide steps for creating trustpoints and exchanging certificates between the local Cisco UCM and the local adaptive security appliance. However, if you require additional security within the local enterprise, you must perform the optional task (Optional) Configuring TLS within the Local Enterprise. Performing that task allows for secure TLS connections between the local Cisco UCM and the local adaptive security appliance. The instructions in that task describe how to create trustpoints between the local Cisco UCM and the local adaptive security appliance.


Prerequisites for Installing Certificates

To create a proxy certificate on the adaptive security appliance that is trusted by the remote entity, obtain a certificate from a trusted CA or export it from the remote enterprise adaptive security appliance.

To export the certificate from the remote enterprise, you enter the following command on the remote adaptive security appliance:

hostname(config)# crypto ca export trustpoint identity-certificate

The adaptive security appliance prompts displays the certificate in the terminal screen. Copy the certificate from the terminal screen. You will need the certificate text in Step 5 of this task.

Procedure

To create the trustpoints and generate certificates, perform the following steps:

 
Command
Purpose

Step 1 

hostname(config)# crypto key generate rsa label 
key-pair-label modulus size
Example:
hostname(config)# crypto key generate rsa label 
local-ent-key modulus 2048

On the local adaptive security appliance, creates the RSA keypair that can be used for the trustpoints. This is the keypair and trustpoint for the local entities signed certificate.

The modulus key size that you select depends on the level of security that you want to configure and on any limitations imposed by the CA from which you are obtaining the certificate. The larger the number that you select, the higher the security level will be for the certificate. Most CAs recommend 2048 for the key modulus size; however,

Note GoDaddy requires a key modulus size of 2048.

Step 2 

hostname(config)# crypto ca trustpoint trustpoint_name
Example:
hostname(config)# crypto ca trustpoint local_ent

Enters the trustpoint configuration mode for the specified trustpoint so that you can create the trustpoint for the local entity.

A trustpoint represents a CA identity and possibly a device identity, based on a certificate issued by the CA. Maximum name length is 128 characters.

Step 3 

hostname(config-ca-trustpoint)# subject-name X.500_name
Example:
hostname(config-ca-trustpoint)# subject-name 
cn=Ent-local-domain-name**

Includes the indicated subject DN in the certificate during enrollment.

Note The domain name that you enter here must match the domain name that has been set for the local Cisco UCM.
For information about how to configure the domain name for Cisco UCM, see the Cisco Unified Communications Manager documentation for information.

Step 4 

hostname(config-ca-trustpoint)# keypair keyname
Example:
hostname(config-ca-trustpoint)# keypair local-ent-key

Specifies the key pair whose public key is to be certified.

Step 5 

hostname(config-ca-trustpoint)# enroll terminal

Specifies that you will use the "copy and paste" method of enrollment with this trustpoint (also known as manual enrollment).

Step 6 

hostname(config-ca-trustpoint)# exit

Exits from the CA Trustpoint configuration mode.

Step 7 

hostname(config)# crypto ca enroll trustpoint
Example:
hostname(config)# crypto ca enroll remote-ent
%
% Start certificate enrollment ...
% The subject name in the certificate will be:  
% cn=enterpriseA
% The fully-qualified domain name in the certificate will 
@ be: ciscoasa
% Include the device serial number in the subject name? 
[yes/no]: no
Display Certificate Request to terminal? [yes/no]: yes

Starts the enrollment process with the CA.

Where trustpoint is the same as the value you entered for trustpoint_name in Step 2.

When the trustpoint is configured for manual enrollment (enroll terminal command), the adaptive security appliance writes a base-64-encoded PKCS10 certification request to the console and then displays the CLI prompt. Copy the text from the prompt.

Submit the certificate request to the CA, for example, by pasting the text displayed at the prompt into the certificate signing request enrollment page on the CA website.

When the CA returns the signed identity certificate, proceed to Step 8 in this procedure.

Step 8 

hostname(config)# crypto ca import trustpoint certificate
Example:
hostname(config)# crypto ca import remote-ent certificate

Imports the signed certificate received from the CA in response to a manual enrollment request.

Where trustpoint specifies the trustpoint you created in Step 2.

The adaptive security appliance prompts you to paste the base-64 formatted signed certificate onto the terminal.

Step 9 

hostname(config)# crypto ca authenticate trustpoint
Example:
hostname(config)# crypto ca authenticate remote-ent

Authenticates the third-party identity certificate received from the CA. The identity certificate is associated with a trustpoint created for the remote enterprise.

The adaptive security appliance prompts you to paste the base-64 formatted identity certificate from the CA onto the terminal.

What to Do Next

Create the TLS proxy for the Cisco Intercompany Media Engine. See the "Creating the TLS Proxy" section.

Creating the TLS Proxy

Because either enterprise, namely the local or remote Cisco UCM servers, can initiate the TLS handshake (unlike IP Telephony or Cisco Mobility Advantage, where only the clients initiate the TLS handshake), you must configure by-directional TLS proxy rules. Each enterprise can have an adaptive security appliance as the TLS proxy.

Create TLS proxy instances for the local and remote entity initiated connections respectively. The entity that initiates the TLS connection is in the role of "TLS client." Because the TLS proxy has a strict definition of "client" and "server" proxy, two TLS proxy instances must be defined if either of the entities could initiate the connection.

The example command lines in this task are based on a basic (in-line) deployment. See Figure 4-1 for an illustration explaining the example command lines in this task.

To create the TLS proxy, perform the following steps:

 
Command
Purpose

Step 1 

hostname(config)# tls-proxy proxy_name
Example:
hostname(config)# tls-proxy local_to_remote-ent

Creates the TLS proxy for the outbound connections.

Step 2 

hostname(config-tlsp)# client trust-point 
proxy_trustpoint 
Example:
hostname(config-tlsp)# client trust-point local-ent

For outbound connections, specifies the trustpoint and associated certificate that the adaptive security appliance uses in the TLS handshake when the adaptive security appliance assumes the role of the TLS client. The certificate must be owned by the adaptive security appliance (identity certificate).

Where proxy_trustpoint specifies the trustpoint defined by the crypto ca trustpoint command in Step 2 in "Creating Trustpoints and Generating Certificates" section.

Step 3 

hostname(config-tlsp)# client cipher-suite 
cipher_suite 
Example:
hostname(config-tlsp)# client cipher-suite 
aes128-sha1 aes256-sha1 3des-sha1 null-sha1

For outbound connections, controls the TLS handshake parameter for the cipher suite.

Where cipher_suite includes des-sha1, 3des-sha1, aes128-sha1, aes256-sha1, or null-sha1.

For client proxy (the proxy acts as a TLS client to the server), the user-defined cipher suite replaces the default cipher suite, or the one defined by the ssl encryption command. Use this command to achieve difference ciphers between the two TLS sessions. You should use AES ciphers with the Cisco UCM server.

Step 4 

hostname(config-tlsp)# exit

Exits from the TLS proxy configuration mode.

Step 5 

hostname(config)# tls-proxy proxy_name
Example:
hostname(config)# tls-proxy remote_to_local-ent

Create the TLS proxy for inbound connections.

Step 6 

hostname(config-tlsp)# server trust-point 
proxy_trustpoint
Example:
hostname(config-tlsp)# server trust-point local-ent

For inbound connections, specifies the proxy trustpoint certificate presented during TLS handshake. The certificate must be owned by the adaptive security appliance (identity certificate).

Where proxy_trustpoint specifies the trustpoint defined by the crypto ca trustpoint command in Step 2 in "Creating Trustpoints and Generating Certificates" section.

Because the TLS proxy has strict definition of client proxy and server proxy, two TLS proxy instances must be defined if either of the entities could initiate the connection.

Step 7 

hostname(config-tlsp)# client cipher-suite 
cipher_suite 
Example: 
hostname(config-tlsp)# client cipher-suite 
aes128-sha1 aes256-sha1 3des-sha1 null-sha1

For inbound connections, controls the TLS handshake parameter for the cipher suite.

Where cipher_suite includes des-sha1, 3des-sha1, aes128-sha1, aes256-sha1, or null-sha1.

Step 8 

hostname(config-tlsp)# exit

Exits from the TSL proxy configuration mode.

Step 9 

hostname(config)# ssl encryption 3des-sha1 
aes128-sha1 [algorithms]

Specifies the encryption algorithms that the SSL/TLS protocol uses. Specifying the 3des-shal and aes128-shal is required. Specifying other algorithms is optional.

Note The Cisco Intercompany Media Engine Proxy requires that you use strong encryption. You must specify this command when the proxy is licensed using a K9 license.

What to Do Next

Once you have created the TLS proxy, enable it for SIP inspection.

Enabling SIP Inspection for the Cisco Intercompany Media Engine Proxy

Enable the TLS proxy for SIP inspection and define policies for both entities that could initiate the connection.

The example command lines in this task are based on a basic (in-line) deployment. See Figure 4-1 for an illustration explaining the example command lines in this task.


Note If you want to change any Cisco Intercompany Media Engine Proxy settings after you enable SIP inspection, you must enter the no service-policy command, and then reconfigure the service policy as described in this procedure. Removing and reconfiguring the service policy does not affect existing calls; however, the first call traversing the Cisco Intercompany Media Engine Proxy will fail. Enter the clear connection command and restart the adaptive security appliance.


To enable SIP inspection for the Cisco Intercompany Media Engine Proxy, perform the following steps:

 
Command
Purpose

Step 1 

hostname(config)# class-map class_map_name
Examples:
hostname(config)# class-map ime-inbound-sip

Defines a class for the inbound Cisco Intercompany Media Engine SIP traffic.

Step 2 

hostname(config-cmap)# match access-list 
access_list_name
Examples:
hostname(config-cmap)# match access-list 
ime-inbound-sip

Identifies the SIP traffic to inspect.

Where the access_list_name is the access list you created in of the task Creating Access Lists for Cisco Intercompany Media Engine Proxy.

Step 3 

hostname(config-cmap)# exit

Exits from the class map configuration mode.

Step 4 

hostname(config)# class-map class_map_name
Examples:
hostname(config)# class-map ime-outbound-sip

Defines a class for the outbound SIP traffic from Cisco Intercompany Media Engine.

Step 5 

hostname(config)# match access-list access_list_name
Examples:
hostname(config-cmap)# match access-list 
ime-outbound-sip

Identifies which outbound SIP traffic to inspect.

Where the access_list_name is the access list you created in of the task Creating Access Lists for Cisco Intercompany Media Engine Proxy.

Step 6 

hostname(config-cmap)# exit

Exits from the class map configuration mode.

Step 7 

hostname(config)# policy-map name
Examples:
hostname(config)# policy-map ime-policy

Defines the policy map to which to attach the actions for the class of traffic.

Step 8 

hostname(config-pmap)# class classmap_name
Examples:
hostname(config-pmap)# class ime-outbound-sip

Assigns a class map to the policy map so that you can assign actions to the class map traffic.

Where classmap_name is the name of the SIP class map that you created in in this task.

Step 9 

hostname(config-pmap-c)# inspect sip [sip_map] 
uc-ime uc_ime_map tls-proxy proxy_name
Examples:
hostname(config-pmap-c)# inspect sip uc-ime 
local-ent-ime tls-proxy local_to_remote-ent

Enables the TLS proxy and Cisco Intercompany Media Engine Proxy for the specified SIP inspection session.

Step 10 

hostname(config-cmap-c)# exit

Exits from the policy map class configuration mode.

Step 11 

hostname(config-pmap)# class class_map_name
Examples:
hostname(config-pmap)# class ime-inbound-sip

Assigns a class map to the policy map so that you can assign actions to the class map traffic.

Where classmap_name is the name of the SIP class map that you created in in this task.

Step 12 

hostname(config-pmap-c)# inspect sip [sip_map] 
uc-ime uc_ime_map tls-proxy proxy_name
Examples:
hostname(config-pmap-c)# inspect sip uc-ime 
local-ent-ime tls-proxy remote_to_local-ent 

Enables the TLS proxy and Cisco Intercompany Media Engine Proxy for the specified SIP inspection session.

Step 13 

hostname(config-pmap-c)# exit

Exits from the policy map class configuration mode.

Step 14 

hostname(config-pmap)# exit

Exits from the policy map configuration mode.

Step 15 

hostname(config)# service-policy policymap_name 
global
Examples:
hostname(config)# service-policy ime-policy global

Enables the service policy for SIP inspection for all interfaces.

Where policymap_name is the name of the policy map you created in of this task.

See Creating the Cisco Intercompany Media Engine Proxy for information about the UC-IME proxy settings. See Cisco ASA 5500 Series Configuration Guide using the CLI for information about the no service-policy command.

What to Do Next

Once you have enabled the TLS proxy for SIP inspection, if necessary, configure TLS within the enterprise. See (Optional) Configuring TLS within the Local Enterprise.

(Optional) Configuring TLS within the Local Enterprise

This task is not required if TCP is allowable within the inside network.

TLS within the enterprise refers to the security status of the Cisco Intercompany Media Engine trunk as seen by the adaptive security appliance.


Note If the transport security for the Cisco Intercompany Media Engine trunk changes on Cisco UCM, it must be changed on the adaptive security appliance as well. A mismatch will result in call failure. The adaptive security appliance does not support SRTP with non-secure IME trunks. The adaptive security appliance assumes SRTP is allowed with secure trunks. So `SRTP Allowed' must be checked for IME trunks if TLS is used. The adaptive security appliance supports SRTP fallback to RTP for secure IME trunk calls.


Prerequisites

On the local Cisco UCM, download the Cisco UCM certificate. See the Cisco Unified Communications Manager documentation for information. You will need this certificate when performing Step 6 of this procedure.

Procedure

To configure TLS within the local enterprise, perform the following steps on the local adaptive security appliance:

 
Commands
Purpose

Step 1 

hostname(config)# crypto key generate rsa label 
key-pair-label 
hostname(config)# crypto ca trustpoint 
trustpoint_name
hostname(config-ca-trustpoint)# enroll self
hostname(config-ca-trustpoint)# keypair keyname
hostname(config-ca-trustpoint)# subject-name 
x.500_name
Example: 
hostname(config)# crypto key generate rsa label 
local-ent-key 
hostname(config)# crypto ca trustpoint local-asa
hostname(config-ca-trustpoint)# enroll self
hostname(config-ca-trustpoint)# keypair 
key-local-asa
hostname(config-ca-trustpoint)# subject-name 
cn=Ent-local-domain-name**., o="Example Corp" 

Creates an RSA key and trustpoint for the self-signed certificate.

Where key-pair-label is the RSA key for the local adaptive security appliance.

Where trustpoint_name is the trustpoint for the local adaptive security appliance.

Where keyname is key pair for the local adaptive security appliance.

Where x.500_name includes the X.500 distinguished name of the local adaptive security appliance; for example, cn=Ent-local-domain-name**.

Note The domain name that you enter here must match the domain name that has been set for the local Cisco UCM. For information about how to configure the domain name for Cisco UCM, see the Cisco Unified Communications Manager documentation for information.

Step 2 

hostname(config-ca-trustpoint)# exit

Exits from Trustpoint Configuration mode.

Step 3 

hostname(config)# crypto ca export trustpoint 
identity-certificate
Example: 
hostname(config)# crypto ca export local-asa 
identity-certificate

Exports the certificate you created in Step 1. The certificate contents appear on the terminal screen.

Copy the certificate from the terminal screen. This certificate enables Cisco UCM to validate the certificate that the adaptive security appliance sends in the TLS handshake.

On the local Cisco UCM, upload the certificate into the Cisco UCM trust store. See the Cisco Unified Communications Manager documentation for information.

Note The subject name you enter while uploading the certificate to the local Cisco UCM is compared with the X.509 Subject Name field entered on the SIP Trunk Security Profile on Cisco UCM. For example, "Ent-local-domain-name" was entered in Step 1 of this task; therefore, "Ent-local-domain-name" should be entered in the Cisco UCM configuration.

Step 4 

hostname(config)# crypto ca trustpoint 
trustpoint_name
hostname(config-ca-trustpoint)# enroll terminal
Example: 
hostname(config)# crypto ca trustpoint local-ent-ucm
hostname(config-ca-trustpoint)# enroll terminal

Creates a trustpoint for local Cisco UCM.

Where trustpoint_name is the trustpoint for the local Cisco UCM.

Step 5 

hostname(config-ca-trustpoint)# exit

Exits from Trustpoint Configuration mode.

Step 6 

hostname(config)# crypto ca authenticate trustpoint
Example: 
hostname(config)# crypto ca authenticate 
local-ent-ucm

Imports the certificate from local Cisco UCM.

Where trustpoint is the trustpoint for the local Cisco UCM.

Paste the certificate downloaded from the local Cisco UCM. This certificate enables the adaptive security appliance to validate the certificate that Cisco UCM sends in the TLS handshake.

Step 7 

hostname(config)# tls-proxy proxy_name
hostname(config-tlsp)# server trust-point 
proxy_trustpoint
hostname(config-tlsp)# client trust-point 
proxy_trustpoint
hostname(config-tlsp)# client cipher-suite 
aes128-sha1 aes256-sha1 3des-sha1 null-sha1
Example: 
hostname(config)# tls-proxy local_to_remote-ent
hostname(config-tlsp)# server trust-point local-asa
hostname(config-tlsp)# client trust-point local-ent 
hostname(config-tlsp)# client cipher-suite 
aes128-sha1 aes256-sha1 3des-sha1 null-sha1

Updates the TLS proxy for outbound connections.

Where proxy_name is the name you entered in Step 1 of the task Creating the TLS Proxy.

Where proxy_trustpoint for the server trust-point command is the trustpoint name for the local adaptive security appliance you entered in Step 1 of this procedure.

Where proxy_trustpoint for the client trust-point command is the name you entered in Step 2 of the task Creating Trustpoints and Generating Certificates.

Note In this step, you are creating different trustpoints for the client and the server.

Step 8 

hostname(config-tlsp)# exit

Exits from TLS Proxy Configuration mode.

Step 9 

hostname(config)# tls-proxy proxy_name
hostname(config-tlsp)# server trust-point 
proxy_trustpoint
hostname(config-tlsp)# client trust-point 
proxy_trustpoint
hostname(config-tlsp)# client cipher-suite 
aes128-sha1 aes256-sha1 3des-sha1 null-sha1
Example: 
hostname(config)# tls-proxy remote_to_local-ent
hostname(config-tlsp)# server trust-point local-ent
hostname(config-tlsp)# client trust-point local-asa
hostname(config-tlsp)# client cipher-suite 
aes128-sha1 aes256-sha1 3des-sha1 null-sha1

Updates the TLS proxy for inbound connections.

Where proxy_name is the name you entered in Step 5 of the task Creating the TLS Proxy.

Where proxy_trustpoint for the server trust-point command is the name you entered in Step 2 of the task Creating Trustpoints and Generating Certificates.

Where proxy_trustpoint for the client trust-point command is the trustpoint name for the local adaptive security appliance you entered in Step 1 of this procedure.

Step 10 

hostname(config-tlsp)# exit

Exits from TLS Proxy Configuration mode.

Step 11 

hostname(config)# uc-ime uc_ime_name
hostname(config-uc-ime)# ucm address ip_address 
trunk-security-mode secure
Example:
hostname(config)# uc-ime local-ent-ime
hostname(config-uc-ime)# ucm address 192.168.10.30 
trunk-security-mode secure

Updates the Cisco Intercompany Media Engine Proxy for trunk-security-mode.

Where uc_ime_name is the name you entered in Step 1 of the task Creating the Cisco Intercompany Media Engine Proxy.

Only perform this step if you entered nonsecure in Step 3 of the task Creating the Cisco Intercompany Media Engine Proxy.

What to Do Next

Once you have configured the TLS within the enterprise, if necessary, configure off path signaling for an off path deployment. See (Optional) Configuring Off Path Signaling.

(Optional) Configuring Off Path Signaling

Perform this task only when you are configuring the Cisco Intercompany Media Engine Proxy as part of an off path deployment. You might choose to have an off path deployment when you want to use the Cisco Intercompany Media Engine but do not want to replace your existing Internet firewall with an adaptive security appliance enabled with the Cisco Intercompany Media Engine Proxy. In an off path deployment, normal Internet facing trafficflows through the existing Internet firewall while the Cisco Intercompany Media Engine traffic flows through the adaptive security appliance enabled with the Cisco Intercompany Media Engine Proxy.

Off path signaling requires that outside IP addresses translate to an inside IP address. For the Cisco Intercompany Media Engine Proxy, the adaptive security appliance creates dynamic mappings for external addresses to the internal IP address. For inbound signaling and outbound signaling, address translation must be configured in the following ways.

For inbound signaling, the outside Cisco UCM address has to be routed to the outside interface of the adaptive security appliance. Therefore, you must configure the adaptive security appliance to translate the real Cisco UCM address to the outside address of the adaptive security appliance. The outside address of the adaptive security appliance must be routable. This ensures that the adaptive security appliance receives packets sent to the Cisco UCM.

Configuring this translation means that the source IP address of an inbound signaling packet is translated to the inside interface of the adaptive security appliance. Based the example in Figure 4-4, an inbound signaling packet from the remote adaptive security appliance:

Source
10.10.0.24

Destination
209.165.200.228

Translates to

Source
10.10.0.24

Destination
192.168.10.30


For outbound signaling, the Cisco UCM does not have an inbound packet with a translated source IP address to which it can reply when the Cisco UCM initiates a connection. To accommodate this situation, you must configure a mapping service on the adaptive security appliance. The mapping service translates the source IP address of future inbound signaling packets.

After you configure off path signaling, the adaptive security appliance mapping service listens on interface "inside" for requests. When it receives a request, it creates a dynamic mapping for the "outside" as the destination address.

Figure 4-4 Example for Configuring Off Path Signaling in an Off Path Deployment

In an off path deployment, inbound media packets and outbound media packets are routed based on the media termination address. For information about how the adaptive security appliance uses the media termination address to route media packets, see Creating the Media Termination Instance.

To configure off path signaling for the Cisco Intercompany Media Engine Proxy, perform the following steps:

 
Command
Purpose

Step 1 

hostname(config)# object network name
Example:
hostname(config)# object network outside-any

For the off path adaptive security appliance, creates a network object to represent all outside addresses.

Step 2 

hostname(config-network-object)# subnet ip_address
Example:
hostname(config-network-object)# subnet 0.0.0.0 
0.0.0.0

Specifies the IP address of the subnet.

Step 3 

hostname(config-network-object)# nat (outside, 
inside) dynamic interface

Creates a mapping for the Cisco UCM of remote enterprises.

Step 4 

hostname(config-network-object)# exit

Exits from the objects configuration mode.

Step 5 

hostname(config)# uc-ime uc_ime_name
Example:
hostname(config)# uc-ime local-ent-ime

Specifies the Cisco Intercompany Media Engine Proxy that you created in the task Creating the Cisco Intercompany Media Engine Proxy.

Where uc_ime_name is the name you specified in Step 1 of Creating the Cisco Intercompany Media Engine Proxy.

Step 6 

hostname(config-uc-ime)# mapping-service 
listening-interface interface_name [listening-port 
port] uc-ime-interface uc-ime-interface_name
Example:
hostname(config-uc-ime)# mapping-service 
listening-interface inside listening-port 8060 
uc-ime-interface outside

For the off path adaptive security appliance, adds the mapping service to the Cisco Intercompany Media Engine Proxy.

Specifies the interface and listening port for the adaptive security appliance mapping service.

You can only configure one mapping service for the Cisco Intercompany Media Engine Proxy.

Where interface_name is the name of the interface on which the adaptive security appliance listens for the mapping requests.

Where port is the TCP port on which the adaptive security appliance listens for the mapping requests. The port number must be between 1024 and 65535 to avoid conflicts with other services on the device, such as Telnet or SSH. By default, the port number is TCP 8060.

Where uc-ime-interface_name is the name of the interface that connects to the remote Cisco UCM.

Proxy Configuration using ASDM

This section contains the following sections:

Configuring the Cisco UC-IMC Proxy by using the UC-IME Proxy Pane

Configuring the Cisco UC-IMC Proxy by using the Unified Communications Wizard

Configuring the Cisco UC-IMC Proxy by using the UC-IME Proxy Pane

Use the Configure Cisco Intercompany Media Engine (UC-IME) proxy pane to add or edit a Cisco Intercompany Media Engine Proxy instance.


Note The Cisco Intercompany Media Engine Proxy does not appear as an option under the Unified Communications section of the navigation pane unless the license required for this proxy is installed on the adaptive security appliance.


Use this pane to create the proxy instance; however, for the UC-IME proxy to be fully functionally, you must complete additional tasks, such as create the required NAT statements, access lists, and MTA, set up the certificates, create the TLS Proxy, and enable SIP inspection.

Depending on whether the UC-IME proxy is deployed off path or in-line of Internet traffic, you must create the appropriate network objects with embedded NAT/PAT statements for the Cisco UCMs.

This pane is available from the Configuration > Firewall > Unified Communications > UC-IME Proxy.


Step 1 Open the Configuration > Firewall > Unified Communications > UC-IME Proxy pane.

Step 2 Check the Enable Cisco UC-IME proxy check box to enable the feature.

Step 3 In the Unified CM Servers area, enter an IP address or hostname for the Cisco Unified Communications Manager (Cisco UCM) or click the ellipsis to open a dialog and browse for an IP address or hostname.

Step 4 In the Trunk Security Mode field, click a security option. Specifying secure for Cisco UCM or Cisco UCM cluster indicates that Cisco UCM or Cisco UCM cluster is initiating TLS.

Step 5 Click Add to add the Cisco UCM for the Cisco Intercompany Media Engine Proxy. You must include an entry for each Cisco UCM in the cluster with Cisco Intercompany Media Engine that has a SIP trunk enabled.

Step 6 In the Ticket Epoch field, enter an integer from 1-255.

The epoch contains an integer that updates each time that the password is changed. When the proxy is configured the first time and a password entered for the first time, enter 1 for the epoch integer. Each time you change the password, increment the epoch to indicate the new password. You must increment the epoch value each time your change the password.

Typically, you increment the epoch sequentially; however, the adaptive security appliance allows you to choose any value when you update the epoch.

If you change the epoch value, the current password is invalidated and you must enter a new password.


Note The epoch and password that you configure in this step on the adaptive security appliance must match the epoch and password that you configure on the Cisco Intercompany Media Engine server. See the Cisco Intercompany Media Engine server documentation for information.


Step 7 In the Ticket Password field, enter a minimum of 10 printable character from the US-ASCII character set. The allowed characters include 0x21 to 0x73 inclusive, and exclude the space character. The ticket password can be up to 64 characters. Confirm the password you entered. Only one password can be configured at a time.

Step 8 Check the Apply MTA to UC-IME Link proxy check box to associate the media termination address with the Cisco Intercompany Media Engine Proxy.


Note You must create the media termination instance before you associate it with the Cisco Intercompany Media Engine Proxy. If necessary, click the Configure MTA button to configure a media termination address instance.


Step 9 If the Cisco Intercompany Media Engine Proxy is being configured as part of off path deployment, check the Enable off path address mapping service checkbox and configure the off path deployment settings:

a. From the Listening Interface field, select an adaptive security appliance interface. This is the interface on which the adaptive security appliance listens for the mapping requests.

b. In the Port field, enter a number between 1024 and 65535 as the TCP port on which the adaptive security appliance listens for the mapping requests. The port number must be 1024 or higher to avoid conflicts with other services on the device, such as Telnet or SSH. By default, the port number is TCP 8060.

c. From the UC-IME Interface field, select an interface from the list. This is the interface that the adaptive security appliance uses to connect to the remote Cisco UCM.


Note In an off path deployment any existing adaptive security appliance that you have deployed in your environment are not capable of transmitting Cisco Intercompany Media Engine traffic. Off-path signaling requires that outside addresses are translated (using NAT) to an inside IP address. The inside interface address can be used for this mapping service configuration. For the Cisco Intercompany Media Engine Proxy, the adaptive security appliance creates dynamic mappings for external addresses to the internal IP address.


Step 10 In the Fallback area, configure the fallback timer for the Cisco Intercompany Media Engine by specifying the following settings:

a. In the Fallback Sensitivity File field, enter the path to a file in flash memory that the adaptive security appliance uses for mid-call PSTN fallback. The file name that you enter must be the name of a file on disk that includes the .fbs file extension. Alternatively, click the Browse Flash button to locate and select the file from flash memory.

b. In the Call Quality Evaluation Interval field, enter a number between 10-600 (in milliseconds). This number controls the frequency at which the adaptive security appliance samples the RTP packets received from the Internet. The adaptive security appliance uses the data sample to determine if fallback to the PSTN is needed for a call. By default, the length is 100 milliseconds for the timer.

c. In the Notification Interval field, enter a number between 10-360 (in seconds). This number controls the amount of time that the adaptive security appliance waits before notifying Cisco UCM whether to fall back to PSTN. By default, the length is 20 seconds for this timer.


Note When you change the fallback timer for the Cisco Intercompany Media Engine Proxy, ASDM automatically removes the proxy from SIP inspection and then reapplies SIP inspection when the proxy is re-enabled.


Step 11 Click Apply to save the configuration changes for the Cisco Intercompany Media Engine Proxy.


Configuring the Cisco UC-IMC Proxy by using the Unified Communications Wizard

To configure the Cisco Intercompany Media Engine Proxy by using ASDM, choose Wizards > Unified Communications Wizard from the menu. The Unified Communications Wizard opens. From the first page, select the Cisco Intercompany Media Engine Proxy option under the Business-to-Business section.

The wizard automatically creates the necessary TLS proxy, then guides you through creating the Intercompany Media Engine proxy, importing and installing the required certificates, and finally enables the SIP inspection for the Intercompany Media Engine traffic automatically.

The wizard guides you through these steps to create the Cisco Intercompany Media Engine Proxy:


Step 1 Select the Intercompany Media Engine Proxy option.

Step 2 Select the topology of the Cisco Intercompany Media Engine Proxy, namely whether the adaptive security appliance is an edge firewall with all Internet traffic flowing through it or whether the adaptive security appliance is off the path of the main Internet traffic (referred to as an off path deployment).

Step 3 Specify private network settings such as the Cisco UCM IP addresses and the ticket settings.

Step 4 Specify the public network settings.

Step 5 Specify the media termination address settings of Cisco UCM.

Step 6 Configure the local-side certificate management, namely the certificates that are exchanged between the local Cisco Unified Communications Manager servers and the adaptive security appliance. The identity certificate that the wizard generates in this step needs to be installed on each Cisco Unified Communications Manager (UCM) server in the cluster with the proxy and each identity certificate from the Cisco UCMs need to be installed on the adaptive security appliance. The certificates are used by the adaptive security appliance and the Cisco UCMs to authenticate each other, respectively, during TLS handshakes. The wizard only supports self-signed certificates for this step.

Step 7 Configure the remote-side certificate management, namely the certificates that are exchanged between the remote server and the adaptive security appliance. In this step, the wizard generates a certificate signing request (CSR). After successfully generating the identity certificate request for the proxy, the wizard prompts you to save the file.

You must send the CSR text file to a certificate authority (CA), for example, by pasting the text file into the CSR enrollment page on the CA website. When the CA returns the Identity Certificate, you must install it on the adaptive security appliance. This certificate is presented to remote servers so that they can authenticate the adaptive security appliance as a trusted server.

Finally, this step of the wizard assists you in installing the root certificates of the CA from the remote servers so that the adaptive security appliance can determine that the remote servers are trusted.


The wizard completes by displaying a summary of the configuration created for Cisco Intercompany Media Engine. See the Unified Communications Wizard section in this documentation for more information.