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TURN Traversal Using Relays around NAT: An Easy-to-Understand Explanation of the Key Technology for NAT Traversal
NAT (Network Address Translation) is a common technology used in networking to enable multiple devices to share a single public IP address. While NAT is effective in conserving IPv4 addresses, it poses challenges for certain types of network communication, especially peer-to-peer communication.
In a peer-to-peer communication scenario, the peers involved often face the issue of not being able to establish a direct connection due to NAT. This is where the technology of TURN Traversal Using Relays around NAT comes into play.
What is TURN Traversal Using Relays around NAT?
TURN, which stands for Traversal Using Relays around NAT, is a protocol that allows devices behind NAT to establish peer-to-peer communication by relaying their data through a third-party server, known as a TURN server. The TURN server acts as a mediator between the two peers, facilitating the traversal of NAT boundaries.
TURN is particularly useful when other NAT traversal techniques, such as UPnP or STUN, are not feasible or effective. It enables devices behind restrictive NAT environments, including symmetric NAT, to initiate direct communication with other devices.
How does TURN Traversal Using Relays around NAT work?
When a device behind a NAT wants to establish communication with another device, the following steps occur using TURN:
1. Discovery Phase: The initiating device sends a request to the TURN server, which acts as a relay. This request is often accompanied by a message indicating the intended destination.
2. Allocation Phase: The TURN server assigns a relayed address to the initiating device. This relayed address will be used as the communication endpoint for the other devices.
3. Connection Phase: The initiating device shares the relayed address with the desired device, allowing the two devices to establish a communication channel through the TURN server. The TURN server relays the data between the peers until the direct connection is established.
It’s important to note that TURN traversal introduces an additional hop in the communication path, which may lead to increased latency. However, this trade-off is often necessary for enabling communication in NAT-restricted environments.
In conclusion, TURN Traversal Using Relays around NAT is a vital technology for enabling peer-to-peer communication in networks with NAT restrictions. By relaying data through a server, devices behind NAT can establish direct communication channels with each other, thus overcoming the limitations imposed by NAT.
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