This document discusses the role of Diameter signaling controllers in mobile networks. Diameter controllers help address challenges around scalability, interoperability, overload, and security for Diameter signaling, which is used for subscriber authentication, authorization, location updates, and session quality of service and charging in LTE and IMS networks. Diameter signaling controllers provide routing, traffic control, security, and interworking functions to help service providers manage Diameter interfaces across vendors and networks.

1. Diameter
Solutions
Miguel Tenorio
mtenorio@acmepacket.com

2. 2

3. IP comms network control
– complex & challenging
 All-IP networks are built differently
 SIP - control communication sessions
- voice, video, IM, presence, … LTE
&
IMS
 Diameter - exchange 2G/3G
&
PSTN
subscriber authentication, SIP
authorization, location; SS7
session QoS & charging
Diameter
 Exploding signaling traffic
 Moving beyond voice
- UC, RCS messaging, collaboration
 Extreme mobile data
 Mobile device proliferation
– smartphones, tablets, M2M
 Increased mobility and roaming

4. The Next Gen Signaling Core
Diameter SIP core
servers I/S-CSCF
HSS, OCS, PCRF
Roaming IP Peering
partners
Routing
I-SBC partners
IPX carriers
IP
DSC Wholesale transit
Routing
TDM
Roaming hubs MGCF IPX carriers
Diameter IMS NGN
clients edge edge
MME, PDN GW, SBC, C5 SS,
GGSN, CSCF, AS P-CSCF S-MSC
Internet LTE 3G DSL/Cable/
FTTx
4

5. Diameter roles in LTE & IMS
Attachment/registration Mobility
Authentication & Authentication &
authorization location updates
Data and voice sessions Roaming
QoS & charging AAA, charging & QoS

6. Diameter Interfaces in LTE and IMS
IMS Sh
Ro Cx Diameter Pain Points
Rf e2  Scalability and
Complexity
Rx
EPC S9  Interoperability
Gy/
Gz Other Challenges
Gx S6a service  Overload and
Gx S6a
providers
Congestion
 Security
S6d
6

7. Messy mesh of signaling –
unscalable, unsecure, unmanagable
Visited
Home
service
provider
service
provider

8. Introducing
Diameter Signaling Controllers
 All Diameter interfaces & applications
• Authentication Service provider
• Location/mobility HSS, OCS, IPX/
• QoS PCRF nodes roaming
• Charging hub
• LTE data and VoLTE roaming
 Provides critical signaling controls
MME, PDN Visited
• Security service
GW, GGSN,
• Traffic & congestion control CSCF, AS provider
• Interoperability & mediation
• Routing & aggregation
• Reporting & analysis
• Fulfill key standards DSCs enable successful
• RFC 3588 Diameter agent transition to LTE & IMS
• 3GPP Diameter Routing Agent (DRA)
• Lowers total cost of ownership
• 3GPP Subscriber Location Function (SLF)
• GSMA Diameter Edge Agent (DEA) • Accelerates time to market
• Mitigates risk
Oct. 2012 Acme Packet | www.acmepacket.com

9. DSCs ensure service availability &
reliability, lower TCO
Visited Home
service provider Multivendor service provider
interoperability
Simplified
routing & config
Congestion &
overload control
Security
Signaling
performance
scalability
Service
visibility

10. Diameter signaling controllers are
intermediaries in Diameter transactions
Clients
Agent
Servers
Request
Request
Response
Clients Agents Servers
request info or send parse, manipulate store info, process
updated info to and route Diameter or respond to
Diameter servers messages as they requests from
flow from client to clients
server and server
to client

11. Diameter Signaling Controllers are
different from STPs
 Diameter lacks congestion management and
resource allocation provided by SS7
– Similar to the ISUP to SIP paradigm shift
– Same challenges in Signaling Control for Diameter
and SIP
– Routing logic MUST be based on flexible criteria
 Security for Diameter signaling is key
– Hardware based encryption and Access Control
– DoS protection
– rate limiting and Overload Control
 Diameter Signaling Adaptations will be required
– Diameter AVP manipulations to normalize vendor
implementations
– IP and transport layer interworking
Diameter is an IP Signaling Protocol
11
Acme Packet confidential

12. SS7 vs. Diameter networks
MAP S6, S9, S13, e.g.
Gx,Gy,Gz
CAP Cx,Dx,Sh,Dh
subscrip,on
ID
INAP Rx,Ro,Rf,
Des,na,on
TCAP Diameter realm
SCCP Global
Title
SCTP
MTP OPC/DPC
IP
 different layers carry address information
02/03/12 Acme Packet | Product Overview 12

13. Two Types of DSCs:
Core and Edge OTT/
Cloud
• Voice roaming IPX
• Data roaming MNO
Edge • Services
federation
MNO
Service provider
HSS, OCS, PCRF
• Aggregation & nodes
routing
Core • OCS proxy
• HSS/AAA proxy
• PCRF proxy
MME, PDN GW,
GGSN, CSCF, AS
13

14. Core Diameter routing solution
 Core DSC requirements
 Universal Diameter agent Central node for
 Online charging (OCS) – Gy, Rf, Ro all Diameter signaling
 QoS / policy (PCRF) – Gx, Rx
Server
 Subscriber profile/AAA (HSS) – nodes
S6a, S6b, S6d, Swm
 3GPP DRA and SLF functions
 Connection aggregation, routing
& load balancing Client
 Overload control nodes
 Layer 3-5 interworking
 Reporting and analysis
 Benefits
 Streamlined and scalable network 3G LTE
 Improved network resiliency
 Lower total cost of ownership
 Faster time to market
 Enhanced visibility and manageability
14

15. VoLTE and Data Roaming Solution
 Comprehensive SIP and Diameter control across roaming ecosystem
 Edge DSC – DRA and GSMA DEA functions: S6a & S9 interfaces
 Access SBC – Visited P-CSCF
 Interconnect SBC – I-BCF/TrGW and IPX Proxy
 Potects Diameter and SIP borders – service availability
 Maximize service reach – end-to-end interworking
 Cost effective scalability – lower TCO
Visited Home
IPX
LTE SIP Data LTE
RTP Diameter
15

16. DSC requirements checklist
 Comprehensive & programmable interworking
 Flexible, dynamic Diameter routing
 Overload and congestion controls
 Signaling security
 Multi-vendor, end-to-end
 centralized monitoring and KPI reporting
 High-performance, reliable, highly available
platforms

17. Security requirements
Challenge:
 Ensure service availability for LTE and IMS
services that depend upon Diameter signaling
Requirements:
 DoS protection
 Avoid resource starvation
 Prevent Diameter overloads
 Diameter fuzzing protection
 Topology hiding
 Block IMSI ranges
 Encryption of Diameter messages

18. Traffic Control requirements
Challenges:
 Maximize utilization of network resources
 Monitor network element availability and
perform workarounds when necessary
Requirements:
 Transaction rate policing by agent
or group
 Monitor upstream and downstream agent
availability
 Diameter load balancing to external nodes
 Fine grained policy-based routing and
rejection
 Agent failure detection and route-around
 Active-Active redundancy

19. Routing requirements
Challenge:
 Complexity of Diameter routing while scaling network
 Route to hundreds of internal and external elements
Requirements:
 IMSI to HSS resolution
 Route to correct home MNO
 Preferred network selection
 PCRF binding
 Internal diameter aggregation
 Flexible routing
 Message rejection /forwarding

20. Interoperability requirements
Challenges
 Diameter interoperability in multi-vendor
environments
 Diameter implementations may not have
compatible AVPs
 Multiple IP networks for transport with
differing address schemes
 Diameter implementation running over
different transport protocols
Requirements
 Diameter signaling normalization
 Transport layer interworking
 IP address interworking
 Broad standards compliance

21. Conclusions
 Diameter & SIP signaling underpin all services
in LTE and IMS
 Assuring interoperability and service availability/reliability
as network scales are signaling pain points
 Diameter signaling controllers addresses these challenges
for multiple use cases – core, interconnect, federated
services

22. Thank You
Learn more at
www.acmepacket.com/diameter