ITU-T / ATIS Workshop
“Next Generation Technology and Standardization”
Las Vegas, 19-20 March 2006
Session Border Control – The
ATIS Perspective
Thomas Helmes
PMTS - Verizon
ITU-T
Overview & Definitions (1)
o
In the context of Session/Border Control, we
make two critical classes of distinctions:
1. Session/Border Control vs. Session/Border
Controller
2. Carrier VoIP Peering Needs vs Carrier’s
Internal S/BC Functional Architecture Needs
ITU-T
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006
Overview & Definitions (2)
1. Session/Border Control:
•
Session Border Control - The activities & actions of a collection
of network signaling & bearer/media functions deployed within a
VoIP carrier’s network which assist in interfacing with other
carriers and/or end users by providing security, call processing &
traffic management capabilities, e.g.: Firewalls, NATs, call
admission, policing, etc.
2. Session/Border Controller:
•
Specific vendor implementations (network elements) consisting
of various subsets & supersets of the Session Border Control
functions
ITU-T
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006
Overview & Definitions (3)
1. Carrier VoIP Peering:
•
In the context of Peering, the only relevant aspects of a
carrier’s S/BC deployment are those functions/actions visible to
the peer carrier across the interface.
2. Carrier’s Internal Functional Architecture:
•
The specific mechanisms, placements & physical packaging of
the various S/BC functions within a carrier’s network are solely
an issue internal to that carrier.
•
However, we agree there is value in establishing core
requirements on S/BC functions in order to:
1.
2.
ITU-T
Facilitate network element interoperability, and
Ensure that these functions act in the same way, regardless of
where/how they are implemented in the various providers’
networks.
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006
ATIS VoIP Peering Reference Model
(Note that this reference model is not concerned with the internal details
of the providers’ networks, or the manner in which S/BC functionality is
internally implemented and distributed)
VoIP NNI
IP Phone
CRFE
(future)
CRFE
Wireless
Provider
A CCFE
VoIP
CCFE Provider
B
VoIP
Wireless
BFE
SS7
PSTN
BFE
IP Phone
MG
MG
CCFE: Call Control FE
BFE: Bearer FE
CRFE: Call Routing FE
SS7
Bearer (RTP/IP)
Signal (SIP)
ITU-T
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006
PSTN
IMS Architecture – 3GPP
(Note that S/BCs are not explicitly identified (at least not yet)
Application Service
Layer
AS
Signaling and Control
Layer
HSS
ISC
Cx
Other IP
Networks
Dh
Sh,Si
Cx
SLF
Gq
Dx
Dx
Mm
S-CSCF
Mi
Mr
BGCF
I-CSCF
Mg
Mj
MRFC
Bearer Transport
Layer
Mw
Mp
MRFP
PDF
Mw
MGCF SGW
F
Gq
P-CSCF
Mn
Gm
IMS-MGW
Customer Premises Equipment
UE
ITU-T
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006
Current ATIS Functional Architecture and Interfaces
(Note that S/BC functional entities are explicitly identified)
Rr/Ro
IMS Core functions
SIP
H.248
DIAMETER
Other
SCIM
MRB
Sh
AS
HSS
Charging Function
Dh
ISC
Cx
Mw
S-CSCF
Mr
Mw
Mi
Mg
Dx
Cx
Rf/Ro
IWF
I-CSCF
Ib
Mi
BGCF
Mw/Mk/Mm
P-CSCF
P-
Gm
MGCF
SGF
SGW
Mp
MS
PSTN
GW
Access
SBC
A-BGF
MRFP
Ic
Id
Interconnect
SBC
T-MGF
MGW
ITU-T
PSTN/ISDN
PSTN
If
MRFC
IBCF
SEG
Mj
UE
Ia
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006
I-BGF
Other IP Networks
Mw
SLF
Discussion
o
ATIS Viewpoint:
1.
2.
3.
“S/BC” is not a functional entity itself.
“S/BC” is really just a cooperating set of functions or
functionalities distributed amongst one or more alreadyidentified FEs (e.g., P-CSCF).
A useful approach is to consider S/BC as a “functional group”
spanning a number of already-existing FEs. (A functional group
does not necessarily map to a single physical entity.)
4.
o
Working Document PTSC-SAC-2006-079 contains the ATIS
Baseline text for the currently-agreed S/BC functions.
It is essential to adopt a consistent view across SDOs as
to terminology and the “proper” level of granularity to
utilize in discussing S/BCs.
ITU-T
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006
Summary
o
Distinguishing between Session/Border Control and
Session/Border Controllers is necessary and useful.
o
The distinction between carrier peering needs and a
carrier’s internal network architecture needs must be
kept in mind – this implies some differences in
treatments in standards’ reference models, etc.
o
The “correct” functional representation of these socalled “S/BCs needs to be resolved consistently across
SDOs, in order to progress NGN standardization work.
ITU-T
ITU-T / ATIS Workshop “Next Generation Technology and
Standardization“
Las Vegas, 19-20 March 2006