The main purpose of this MIB is to define the statistics
information for Session Border Controller application. The 
statistics are mainly of two types - Call statistics and 
Media statistics. The calls can further be categorized as SIP 
calls and H.248 calls.

This MIB categorizes the statistics information into following
four types:
1. Global call statistics - Represents the global call related
   statistics like call rates, media flows, signaling flows
   etc.

2. Periodic statistics - Represents the SBC call statistics 
   information for a particular time interval like current 5 
   minutes, previous 5 minutes, current 15 minutes, previous 15
   minutes, current hour and previous hour.

3. Per flow statistics - Represents the SBC media flow 
   statistics. These are media statistics for each of the
   current ongoing call flow.

4. H.248 statistics - Represents the H.248 call related 
   statistics information when H.248 controller is associated
   with SBC.

The Session Border Controller (SBC) enables direct IP-to-IP
interconnect between multiple administrative domains for
session-based services providing protocol inter-working,
security, and admission control and management. The SBC is a
voice over IP (VoIP) device that sits on the border of a 
network and controls call admission to that network. 

The primary purpose of an SBC is to protect the interior of the
network from excessive call load and malicious traffic.
Additional functions provided by the SBC include media bridging
and billing services. 


GLOSSARY
SBC: Session Border Controller

CSB: CISCO Session Border Controller

CAC: Call Admission Control - protects voice traffic from the
negative effects of other voice traffic and to keep excess
voice traffic off the network. It is used to prevent congestion
in Voice traffic. It is used in the Call Setup phase.

RTP: Real Time Transport Protocol - defines a standardized
packet format for delivering audio and video over the Internet.

RTCP: Real Time Control Protocol - It is a sister protocol of
the Real-time Transport Protocol (RTP). RTCP provides
out-of-band control information for an RTP flow. It partners
RTP in the delivery and packaging of multimedia data, but does
not transport any data itself. It is used periodically to
transmit control packets to participants in a streaming
multimedia session.

VMG: Virtual Media Gateway - introduced to bridge between
different transmission technologies and to add service to
end-user connections. Its architecture separates control and
connectivity functions into physically separate network layers.

VPN: Virtual Private Network - It is a communications network
tunneled through another network, and dedicated for a specific
network.

Gate Id - Context Identifiers assigned uniquely to a SIP/H.248
call flows.

Flow Pair Id: Stream Identifiers assigned uniquely to a
SIP/H.248 call flows.

Adjacency: An adjacency contains the system information to be
transmitted to next HOP.

REFERENCES
1. CISCO Session Border Controller Documents and FAQ
http://zed.cisco.com/confluence/display/SBC/SBC