nanog mailing list archives

RE: Vonage complains about VoIP-blocking


From: Nathan Allen Stratton <nathan () robotics net>
Date: Tue, 15 Feb 2005 17:18:14 -0500 (EST)


On Tue, 15 Feb 2005, Jay Hennigan wrote:

Vonage devices initiate an outbound TFTP connection back to Vonage to
snarf their configs on initial connection and also (presumably) on reboot.

Many, many VoIP devices do this, including Cisco phones in all major
flavors.  If an ISP is blocking TFTP originated by its customers at the
border, this will cause numerous problems with many VoIP devices as
well as numerous other things where a customer needs to initiate a TFTP
session over the Internet.

Filtering customer-initiated TFTP will cause problems with many legitimate
applications and devices.

Most devices have moved to http config, sipura, snom, panasonic, etc. We
moved away from tftp because of a lot of NAT and blocking issues. As far
as SIP, I don't see it as a major problem since you can use any port.


<>
Nathan Stratton                                   BroadVoice, Inc.
nathan at robotics.net                                 Talk IS Cheap
http://www.robotics.net                           http://www.broadvoice.com


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