Problem Description:
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MGCP gateway not able to register to CUCM, where a "Check-point Firewall" is between the CUCM and the Gateway.
Analysis:
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Call-flow:
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IP-PHONE>>CUCM>>>(CHECK-POINT/FW) / MGCP>>>>>GW>>PRI>>PSTN
The endpoint (PRI) on the CUCM show’s as registered.
While on the gateway, shows the following:
Cisco.ca#sh ccm-manager
MGCP Domain Name: Cisco.ca
Priority Status Host
============================================================
Primary Registering with CM 122.192.180.18
First Backup Backup Ready 122.192.180.19
Second Backup None
From the packet capture taken from the CUCM we see that he source port changes to 10000 on the Check-point sent to the CUCM:
This is a known bug on checkpoint which is related to sk102049:
https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk102049
Checkpoint does not recognize RSIP message from CUCM as a valid protocol. Configuring the protocol to MGCP on the firewall rule will fix the issue.
Resolution:
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Work with Checkpoint team to fix the issue. They should not be modifying the source port from 2427 to 10000.