Cisco Systems ASA 5555-X, ASA 5505, ASA 5545-X manual Optional Configuring Off Path Signaling, 21-30

Chapter 21 Configuring Cisco Intercompany Media Engine Proxy

Configuring Cisco Intercompany Media Engine Proxy

(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 ASA enabled with the Cisco Intercompany Media Engine Proxy.

In an off path deployment, the existing firewall that you have deployed in your environment is not capable of transmitting Cisco Intercompany Media Engine traffic.

Off path signaling requires that outside IP addresses translate 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 ASA creates dynamic mappings for external addresses to the internal IP address; therefore, using the dynamic NAT configuration on outbound calls, Cisco UCM sends SIP traffic to this internal IP address, and the ASA uses that mapping to determine the real destination on inbound calls. The static NAT or PAT mapping is used for inbound calls in an off path configuration.

Figure 21-9 Example for Configuring Off Path Signaling in an Off Path Deployment

Local Enterprise		OUTSIDE 0.0.0.0 0.0.0.0
Local Cisco UCM	192.168.10.1		ip_address:port
	ASA inside interface
M	192.168.10.1
192.168.10.30
	TCP	TLS	Internet
Corporate
Network	Local ASA	Outside Cisco UCM address		Remote ASA
IP		209.165.200.228		10.10.0.24
				766
IP	IP
				248

After you configure off path signaling, the ASA mapping service listens on interface “inside” for requests. When it receives a request, it creates a dynamic mapping for the “outside” as the destination interface.

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	For the off path ASA, creates a network object to
	Example:		represent all outside addresses.
	hostname(config)# object network	outside-any
Step 2	hostname(config-network-object)#	subnet ip_address	Specifies the IP address of the subnet.
	Example:
	hostname(config-network-object)#	subnet 0.0.0.0
	0.0.0.0
Step 3	hostname(config-network-object)#	nat	Creates a mapping for the Cisco UCM of remote
	(outside,inside) dynamic interface inside		enterprises.
Step 4	hostname(config-network-object)#	exit	Exits from the objects configuration mode.

Cisco ASA Series Firewall ASDM Configuration Guide

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