Cisco Small Business SPA2102 Administration Manual page 232

Troubleshooting
Cisco Small Business ATA Administration Guide
4. Add a STUN server to allow traversal of UDP packets through the NAT device.
On the SIP tab of the administration web server, set
enter the IP address of the STUN server in
STUN (Simple Traversal of UDP through NATs) is a protocol defined by RFC
3489, that allows a client behind a NAT device to find out its public address, the
type of NAT it is behind, and the port associated on the Internet connection
with a particular local port. This information is used to set up UDP
communication between two hosts that are both behind NAT routers. Open
source STUN software can be obtained at the following website:
http://www.voip-info.org/wiki-Open+Source+VOIP+Software
STUN does not work with a symmetric NAT router. Enable debug through
NOTE
syslog (see FAQ#10), and set
indicate whether you have symmetric NAT or not.
STUN Enable
STUN Server
STUN Test Enable
to yes. The messages
C
to yes, and
.
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