HW9.1. VoIP

(SIP)

The Session Initiation Protocol is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telephone systems, as well as mobile phone calling over LTE.

(RTCP)

RTCP provides QoS monitoring and session control

(RTP)

The Real-time Transport Protocol is a network protocol used to deliver streaming audio and video media over the internet, thereby enabling the Voice Over Internet Protocol (VoIP).

• While RTP carries the media streams (e.g., audio and video), RTCP is used to monitor transmission statistics and quality of service(QoS) and aids synchronization of multiple streams.
• RTP is one of the technical foundations of Voice over IP and in this context is often used in conjunction with a signaling protocol such as the Session Initiation Protocol (SIP) which establishes connections across the network.

HW9.2. Group-shared tree vs Source-based tree (multicast routing protocols)

Group-shared tree:

All senders send their multicast traffic using the same routing tree.

Source-based tree:

1. Each source has a different tree. (一个source 对应 一个tree)
2. A router may have to keep track of several trees for a given multicast group.
3. The multicast datagrams from a given source are routed over a specific routing tree constructed for that source.

HW9.3. Network load under unicast and multicast transmission