| 12.1 |  | Advanced Protocols |
| 12.1.7 |  | Skinny fixup configuration |

| In software versions 6.0 and higher, the PIX Security Appliance application supports the Skinny Client Control Protocol (SCCP) that is used by Cisco IP phones for VoIP call signaling. This can create issues because the Skinny protocol operates by dynamically opening pinholes for media sessions and Network Address Translation (NAT) that has embedded IP addresses. SCCP supports IP telephony and can coexist in an H.323 environment. An application layer ensures that all SCCP signaling and media packets can traverse the PIX Security Appliance and interoperate with H.323 terminals. Functionally, the support of SCCP by PIX Security Appliance means that an IP phone and a Cisco Call Manager can now be placed on separate sides of the PIX Security Appliance.

Figure illustrates the communication that takes place across the PIX Security Appliance when SCCP is used to communicate between IP phones and a Call Manager or Call Manager cluster. Skinny Fixup Control Protocol configuration is discussed further in the Command Reference associated with this section.

| Lab Activity Lab Exercise: Configure and Test Advanced Protocol Handling on the Cisco PIX Security Appliance In this lab exercise, students will complete the following tasks:

- Display the fixup protocol configurations
- Change the fixup protocol configurations
- Test the outbound FTP fixup protocol
- Test the inbound FTP fixup protocol

Set the fixup protocols to the default settings