/mcpSent: INVITE sip:1001@14.50.228.63:5060 SIP/2.0 Via: SIP/2.0/UDP 10.50.228.61:5060;branch=z9hG4bK3C7CD Remote-Party-ID: "5001" sip:5001@10.50.228.61;party=calling;screen=yes;privacy=off From: "5001" sip:5001@10.50.228.61;tag=34C458-D6 Contact: sip:5001@168.117.64.94
Special Notes Protocol Signaling and Media Binding All Signaling protocols allow administrators the ability to bind the signaling to a specific interface. By default, a gateway without a static defined binding, then the gateway sources the signaling for a call from the physical interface the packet traverses. With binding on a dial-peer, the packet features source headers, messaging, and packets from the specified interface, but the actual packet still routes over the physical interface. Dial-peer binding always supersedes voice class tenant and global voice service voip binding with Session Initiation Protocol (SIP). Many times administrators bind signaling to a loopback. This being a logical interface means no packets traverse this interface. In order to perform packet captures, the capture must be performed on a physical interface. The command show ip cef <remote-ip> displays the physical interface a packet utilize to route to the destination / remote IP even if the configuration is bound to a virtual interface. Media and signaling binding do not always need to be the same IP. If an administrator needs to bind to a specific interface for signaling to / from a CUCM but the audio / media between the phone and the gateway can need to bind to another interface. Configuration Example This example shows a dial-peer bound to loopback 1 and it receives a call from CUCM.
Even though the media and signaling (control) are bound to loopback 1 the show ip cef command shows