SSCA SDP Protocol 3

Question 1

What does the 'm=' line in SDP specify?

Accepted Answer

Media type, port, transport protocol, and payload type list

Answer

The m= line defines the media type (audio/video), port, transport protocol (e.g., RTP/AVP), and the list of payload format numbers.

Question 2

Which SDP attribute is used to carry SIP session-level bandwidth information for RTCP?

Accepted Answer

b=RS and b=RR

Answer

b=RS (RTCP sender bandwidth) and b=RR (RTCP receiver bandwidth) specify the bandwidth allocated for RTCP streams.

Question 3

In SDP, what is the role of the 'a=fmtp' attribute?

Accepted Answer

Provides format-specific parameters for a payload type

Answer

The a=fmtp attribute conveys additional codec-specific parameters not covered by a=rtpmap, such as packetization-mode for H.264.

Question 4

What is a 'session-level' SDP attribute as opposed to a 'media-level' attribute?

Accepted Answer

An attribute that applies to the entire session unless overridden at the media level

Answer

Session-level attributes appear before any m= line and apply globally, but can be overridden by attributes within individual m= sections.

Question 5

Which transport protocol value in the m= line indicates secure RTP (SRTP)?

Accepted Answer

RTP/SAVP

Answer

RTP/SAVP (Secure Audio/Video Profile) in the m= line indicates that SRTP is to be used for media transport.

(SSCA) Sip School Certified Associate Practice Test