Cisco Ip Phone — Downloading Xmldefault Cnf Xml Repack
This message indicates that the Cisco IP Phone cannot find its specific configuration file on the TFTP server, so it falls back to a generic default configuration (XMLDefault.cnf.xml). The "repack" portion of the log is the critical component of this feature.
The log indicates the Forced Firmware Synchronization feature is activating. The phone is using the default configuration to forcibly downgrade or change its internal software build to match what the TFTP server dictates as the "default."
This review focuses on the common scenario where a Cisco IP phone becomes stuck or repeatedly displays "Downloading XMLDefault.cnf.xml." This typically indicates a failure in the boot sequence where the phone cannot find its specific configuration file and falls back to a default file that may be misconfigured or missing. Understanding the Boot Sequence
When a Cisco IP phone boots, it follows a specific hierarchy to obtain its configuration:
Specific Config: The phone first requests a unique configuration file named SEP based on its physical MAC address. cisco ip phone downloading xmldefault cnf xml repack
Default Fallback: If the specific file is not found on the TFTP server, the phone requests XMLDefault.cnf.xml.
Auto-Registration: This default file is primarily used for new, unprovisioned phones to learn the IP address of the Cisco Unified Communications Manager (CUCM) and download the correct firmware. Key Causes for "Downloading" Loops
If your phone is stuck in a loop or fails at this stage, it is often due to one of the following issues:
Cisco uses AES-128-CBC with a fixed key derived from the phone model (e.g., STKey for 78xx). Tools like cisco-xml-decrypt or OpenSSL can decrypt: This message indicates that the Cisco IP Phone
openssl enc -d -aes-128-cbc -K <key> -iv 0 -in XMLDefault.cnf.xml.enc -out decrypted.xml
Still stuck? Enable debug tftp events on a Cisco router acting as a helper or capture the TFTP traffic:
tcpdump -i eth0 -s 0 -w tftp.pcap port 69
Look for:
If the phone keeps re-requesting XMLDefault.cnf.xml every few seconds, the file is likely parsed and rejected. Check your CUCM version logs: RTMT > Logs > TFTP > tftp.log for XML validation errors.
Do not ignore the repack. It is a symptom, not a problem. Check these first: Still stuck
When the phone stays on the "Downloading xmldefault.cnf.xml" message for more than 2 minutes, or loops back to it after rebooting, your phone is essentially saying: “I cannot find my specific configuration, so I am using the generic one. But the generic one doesn’t have my line registration details.”
Repack steps:
| Scenario | Repacking Purpose | |----------|------------------| | Forensic analysis | Alter logging or debug flags to capture traffic | | Firmware rollback | Force older load despite security constraints | | Interoperability | Modify SIP timers for non-Cisco PBX | | Security research | Test for XML injection or buffer overflow |