Which of the following protocols is widely used for setting up and tearing down multimedia
communication sessions such as voice and video calls over the Internet (VoIP)?
A.
LDAP
B.
ICMP
C.
UDP
D.
SIP
Explanation:
Session Initiation Protocol (SIP), designed by Henning Schulzrinne and Mark Handley in 1996, is a
signaling protocol, widely used for setting up and tearing down multimedia communication sessions
such as voice and video calls over the Internet (VoIP). Other feasible application examples include
video conferencing, streaming multimedia distribution, instant messaging, presence information and
online games. The protocol can be used for creating, modifying, and terminating two-party (unicast)
or multiparty (multicast) sessions consisting of one or several media streams. The modification can
involve changing addresses or ports, inviting more participants, adding or deleting media streams,
etc.
The SIP protocol is a TCP/IP-based Application Layer protocol. Within the OSI model, it is sometimes
placed in the session layer. SIP is designed to be independent of the underlying transport layer; it
can run on TCP, UDP, or SCTP. It is a text-based protocol, sharing many elements of the Hypertext
Transfer Protocol (HTTP), upon which it is based, allowing for easy inspection by administrators. SIP
clients typically use TCP or UDP (typically on port 5060 and/or 5061) to connect to SIP servers and
other SIP endpoints.
Answer option A is incorrect. Lightweight Directory Access Protocol (LDAP) is a protocol used to
query and modify information stored within directory services.
Answer option B is incorrect. Internet Control Message Protocol (ICMP) is an integral part of IP. It is
used to report an error in datagram processing. The Internet Protocol (IP) is used for host-to-hostdatagram service in a network. The network is configured with connecting devices called gateways.
When an error occurs in datagram processing, gateways or destination hosts report the error to the
source hosts
through the ICMP protocol. The ICMP messages are sent in various situations, such as when a
datagram cannot reach its destination, when the gateway cannot direct the host to send traffic on a
shorter route, when the gateway does not have the buffering capacity, etc.
Answer option C is incorrect. User Datagram Protocol (UDP) is often used for one-to-many
communications, using broadcast or multicast IP datagrams. Microsoft networking uses UDP for
logon, browsing, and name resolution. UDP is a connectionless and unreliable communication
protocol. It does not guarantee delivery, or verify sequencing for any datagram. UDP provides faster
transportation of data between TCP/IP hosts than TCP.
Reference:
“http://en.wikipedia.org/wiki/Session_Initiation_Protocol”