Reference11r1:Concept ICE
Applies To
This information applies to
- all innovaphone devices from V11
Overview
ICE is a protocol for finding and selecting a working network path between two media endpoints. The basic idea is that each endpoint discovers all its addresses that could be used to receive media. Those candidates are sent to the other endpoint. Then all combinations of local and remote candidates are tested. The best working combination is used for the actual media stream. If there is no working combination, the call can be disconnected.
ICE is designed to solve the following problems:
- NAT traversal
- If an endpoint is behind NAT, ICE creates a NAT mapping using STUN. Even if both sides are behind NAT, ICE can successfully establish a connection.
- Avoid no media / one-way media
- Only network paths are chosen for media that work in both directions. So there is no risk of one-way media. If there is no appropriate path, the call can be disconnected automatically.
- IPv4 and IPv6
- ICE also selects the IP version that is supported by both endpoints. This is good news for migrating from IPv4 to IPv6 because there is no extra configuration change to be done if more and more endpoints support IPv6.
Configuration
Activation
From v11 ICE is the default call establishment mechanism, so it does not have to be activated. However if needed it can be deactivated using an interop config option.
config add H323 /ice-disabled config add SIP /ice-disabled config add SIPS /ice-disabled config add TSIP /ice-disabled config add TSIPS /ice-disabled
STUN
The STUN server is used for gathering server reflexive candidates. The server configuration is a string in one of the following formats:
- a single DNS name and an optional port (e.g.
stun.example.com:1234). - a comma separated list of one or two IP addresses and optional ports (e.g.
172.16.13.1:1234,172.16.13.2).
The STUN server string can be configured at the following places:
- For many boxes using the DHCP Server (on page IP4/ETHx/DHCP-Server)
- For an individual box (on page IP4/General/STUN)
- For an individual registration (as part of the configuration of the registration)
If it is configured in more than one place, the more specific one is used. For example the configuration at the registration overwrites the DHCP config.
Tracing
Activation
Traces for debugging ICE can be activated at the signalling module. The trace flags are also available on the debug.xml page.
config add H323 /ice-trace on config add SIP /ice-trace on config add SIPS /ice-trace on config add TSIP /ice-trace on config add TSIPS /ice-trace on