Download - Session Border Contoller
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IMS Training
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What is an SBC? Session Border Controller is an element regularly used
VoIP networks, whose role is to control the signallingbetween service providers network and access (customers)network, and also between two different VoIP providers;
Session: communication between two points session (e.g.call) is controlled by SBC
Border: it is deployed at the edge of the VoIP network(border demarcation point)
Controller: it controls communications (once again) provides access control, measurements, data conversion,modification of signalling messages, etc
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Position of SBC in VoIP networks
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Lets take a closer look to SBCs function
Security- protects the network (and devices inside)
Prevents DoS, DDoS attacks
Topology hiding
Encryption of signaling (TLS, IPSec)
Encryption of media (SRTP)
Connectivity- allow different parts of the network to communicate
through the use of a variety of techniques NAT traversal
SIP normalization via SIP message and header manipulation (SMM)
IPv4 to IPv6 interworking
Protocol translations between SIP, SIP-I, H.323
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Quality of service QoS
Traffic policing
Resource allocation
Rate limiting
Call admission control
ToS/DSCP bit setting
RegulatorySBC can optionally provide regulatoryrequierements
emergency calls prioritization
lawful interception
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Media services DTMF relay and interworking
Media transcoding
Tones and announcements
Data and fax interworking Support for voice and video calls
Statistics and billing information
Since all sessions that pass through the edge of the network passthrough the SBC, it is a natural point to gather statistics and usagebased information on these sessions
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Rolesof SBC Depending of the position where SBC is deployed, it can take different
roles
SBC can be configured for more than one role at the same time
Roles of SBC in access part of the network: A-ALG/P-CSCF
IWF
SPDF
Role of SBC between two different networks:
IBCF
IWF
SPDF
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3GPP Network Architecture for Fixed
Access
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A-ALG/P-CSCF
Forwarding of the SIP REGISTER request received fromthe UE to an entry point determined using the home domain
name, as provided by the UE Forwarding of SIP messages received from the UE to
the SIP server (for example S-CSCF)
Forwarding of the SIP request or response to the UE
Generation of Accounting Charging Records (ACRs).
SIP message compression/decompression
Acting as an ALG by changing the appropriate SIP/SDPparameters
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IWF Typically, IWF is used for translation between H.323 and SIP
standard
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IBCF Controlling transport plane functions
Supporting functions to allow the establishment of communicationbetween SIP applications in disparate address realms
Providing network configuration hiding to restrict the subsequentinformation from being passed outside of an operator's network:
exact number of S-CSCFs, capabilities of S-CSCFs, or capacity of thenetwork, and so on
Screening of SIP signaling information based on source, destination,and operator policy
Generation of Accounting Charging Records (ACRs)
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SDPF
Service Policy Decision Function (Tispan architecture only)
Checks if the request information received from the AF isconsistent with the policy rules defined in the SPDF
Authorizes the requested resources for the AF session
Requests resources of the A-RACF/C-RACF
Requests one or more services from the BGF
Hides the details of the RACS from the AF
Hides the details of the transport layer from the AF
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Media Proxy Similar to SBC, which acts as a signalling proxy (in a signalling
plane), Media Proxy (MP) operates in the media plane
Together with SBC forms an SBG (Session Border Gateway) SBC and MP communicate via standardized Ia interface, through
H.248 protocol
Relation between SBC and MP, is much like MGC and MGW
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SBG in an access network
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Thank you for your attention!
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