Secure RTP
sRTP was first published by IETF in March 2004 as RFC 3711; it was designed to provide
encryption, message authentication, and integrity, and replay protection to RTP data in
both unicast and multicast applications.
sRTP also has a sister protocol, called Secure RTCP (sRTCP). sRTCP provides the same
security-related features to RTCP as the ones provided by sRTP to RTP. sRTP can be used
in conjunction with compressed RTP. Figure 1-8 demonstrates that an sRTP flow travels
between devices (Cisco IP phones in Figure 1-8), which are capable of sending and receiving
sRTP traffic.
20 Authorized Self-Study Guide: Cisco Voice over IP (CVOICE)
Note Using RTP header compression on any high-speed interfaces (that is, anything over
T1 speed) is not recommended. Any bandwidth savings achieved with RTP header compression
might be offset by an increase in CPU utilization on the router.
sRTP Stream
GW1
S0/0
S0/0
V GW2 V
Figure 1-8 Secure RTP Traffic Flow