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Interworking Services in SIP
Published in Radhika Ranjan Roy, Handbook on Session Initiation Protocol, 2018
The primary purpose of the STUN protocol is to discover the presence and types of NATs and firewalls between them, and the public IP network including Internet for the applications like SIP. In addition, applications such as SIP can determine the public IP addresses allocated to them by the NAT. However, STUN, as its name implies, only works with NATs such as full-cone NATs that use UDP transport protocols, and also cannot work with symmetric NATs thereby raising security concerns. The STUN functional entity, for example, implemented in a stand-alone server, must have the public IP address. Figure 14.15 shows an example of STUN server configuration that can be used in the SIP network by the SIP functional entities (e.g., UAs and proxies) to be aware of the STUN as the STUN client/server.
Generic Capability Attribute Negotiations in SDP
Published in Radhika Ranjan Roy, Handbook of SDP for Multimedia Session Negotiations, 2018
Interactive Connectivity Establishment (ICE) (RFC 5245, see Section 3.2) provides a mechanism for verifying connectivity between two endpoints by sending STUN messages directly between the media endpoints. The basic ICE specification (RFC 5245) is defined only to support UDP-based connectivity; however, it allows extensions to support other transport protocols, such as TCP, which is specified in RFC 6544. ICE defines a new "a=candidate" attribute, which, among other things, indicates the possible transport protocol(s) to use and then associates a priority with each of them. The most preferred transport protocol that *successfully* verifies connectivity will end up being used.
Site Interconnection
Published in Cheng Sheng, Jie Bai, Qi Sun, Software-Defined Wide Area Network Architectures and Technologies, 2021
SD-WAN involves the following NAT traversal scenarios: Connection between the CPE and the SDN controllerA management channel is established between the CPE and the SDN controller. The SDN controller is assigned a public IP address, and the CPE proactively sends a connection request to the public IP address of the SDN controller. In this case, we can assume that NAT traversal has been implemented between the CPE and the SDN controller.Connection between CPEsInter-site traffic is transmitted over the data channel established between CPEs. In this case, a peer-to-peer (P2P) connection is established between CPEs. If a P2P connection needs to be established between a CPE deployed on the private network behind the NAT device and another CPE, especially between CPEs at two sites deployed on the private network behind the NAT device, NAT traversal is required.STUN can be used to implement NAT traversal in such scenarios. In related standards, STUN is positioned as a tool for implementing NAT traversal and is used by a terminal to check the IP address and port allocated by a NAT device to the terminal itself, as well as connectivity between two terminals.STUN is a client-server network protocol. The server is deployed on a public network and has a public IP address, while the client is deployed on a private network behind the NAT device. In SD-WAN, the SDN controller or RR functions as the STUN server, and a CPE functions as the STUN client. Figure 5.43 shows the STUN connection established between a CPE (STUN client) and the SDN controller (STUN server).
Comparison of QoS optimisation techniques in adaptive smart device peer-to-peer overlay networks
Published in International Journal of Parallel, Emergent and Distributed Systems, 2021
Ananda Maiti, Andrew Maxwell, Alexander Kist
NDCs are used to create Content delivery networks. For content delivery, a number of replication servers can be installed in geographically diverse locations to minimize latency with respect to geographical location [14]. NDCs allow saving considerable energy, still maintaining required scalability. Such systems are more spread apart geographically than conventional data centers and are often larger in numbers to make up for their lower performance. In the context of establishing an end-to-end connection between users, NDCs may play a role in relaying data as well as in addressing communication issues such as firewalls. Traversal Using Relays around NAT (TURN) [15] protocol uses this principle to operate. A significant impact of protocols like Interactive Connectivity Establishment [16] (ICE), STUN, and TURN protocols on delays in operation of Peer-to-Peer Session Initiation Protocol is presented in [17]. These factors further necessitate correct positioning of the relay NDC servers. The following sections describes several ways to choose the optimal positions of the nodes in the network architecture.