Transcript Real time Services

Real-Time Service (RTS)
Introduction
Barry Sweeney, Ph.D.
703-676-2282
[email protected]
September 2007
1
Agenda
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Legacy Voice and Video Technologies
IP RTS Technologies
IP RTS Information Assurance
IP RTS Quality of Service
Future Technologies
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Legacy Voice and Video Technologies
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History
Standards
Development Model
Cost Model
3
Legacy Voice and Video Technology
Overview (History)
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The first commercial end instruments (EIs)
were offered by Bell Telephone in 1877
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Long haul was provided by Western Union
Business service cost $40.00/yr and Residential
service cost $20.00/yr
By 1877 over 600 EIs were deployed and
Central Office Exchanges were built to
handle the switching of calls
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COs is still the term used today
4
Legacy Voice and Video Technology
Overview (History Cont.)
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As the number of EIs increased it became more cost
effective to provide the switching at the customer
locations
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Customer site centralized switches became known as
Private Branch Exchanges (PBXs) and provide:
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Call routing
Basic call features (call hold, call transfer, call waiting, etc.)
Conference calling
Call Detail Records (Billing Information)
EIs still belonged to the Telco and were rented to the
customer resulting in the name Customer Premise
Equipment (CPE)
PBXs connect to the PSTN via End Offices (EOs)
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See next slide
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Legacy Voice and Video Technology
Overview (History Cont.)
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As the size of the network increased PBXs were serviced by
more power switches called End Offices (EOs)
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Lowest level of a PSTN switch
Also known as Class 5 switches
Typically include the PBX functions, but are more powerful with
increased functions
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Network management
More robust feature set (release to pivot, conferencing, etc.)
Test capabilities (i.e., line tests)
Timing
As the number of EOs increased, Tandem Switches were created
to link the EOs’ together
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Also known as Class 4 switches
Do not service EIs
Sometimes combined with an EO and called a Multifunction Switch
(MFS)
6
Legacy Voice and Video Technology
Overview (Standards)
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Numbering Plan
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In US we use the North American Numbering Plan
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Bellcore Generic Requirements
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Requirements that a TDM switch vendor must meet to ensure
interoperability
International Telecommunications Union (ITU)
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Country Code (North America is 0015)
Area Code (703)
Central Office Exchange (676)
Port and Circuit ID (2282)
My Phone Number at work is 703-676-2282
Developed by Telcordia Technologies (formerly Bell Labs)
CODECs (G.711, G.729, H.264, etc.)
Physical Transmission Requirements (H.320, Q.931, etc.)
Telephone Quality (P.800, P.862, P.1010, etc.)
Over the last 30 years interoperability issues resulting from
implementation of TDM standards have been largely resolved
7
Legacy Voice and Video Technology
Overview (Development Model)
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Single Physical Appliance
Proprietary Operating System
Proprietary (protected) Application
20 year depreciation model
Only external interfaces were standardized
Closed network management network
Signaling and Bearer typically travel same path
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Bearer in B channel and Signaling in D channel of a PRI
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23B + D = 24 channels in a PRI
CAS and SS7 are in-band signaling protocols
8
Legacy Voice and Video Technology
Overview (Cost Model)
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Historically, the Telcos have generated revenue by charging for
every minute a session is active
 Call Detail Records in the EO maintain a record of the sessions
Modem data connections were treated as single voice sessions
Call hold times averaged 5 minutes in the pre Internet days
 Increase in Internet related calls impacted voice traffic
engineering
Each voice session was exactly 64 kbps of bandwidth or 1 DS0
on a T1 circuit
 Video and ISDN muxed together multiple DS0s
TDM switch was typically most expensive element
 Sometimes in Millions of dollars including OA&M
9
IP RTS Technologies
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RTS Technology Overview
VoIP
Video over IP
Standards
Signaling, Bearer, and Network Management
Characteristics
Development Model
Cost Model
10
IP RTS Technologies (Overview)
Aggregate Service Class
Granular Service Class
Examples
Control
Network Control and Signaling
Routing and QoS signaling
User Signaling
RTS Signaling
Short Message
Inelastic/Real-time
Services
Preferred Elastic
Elastic
Safety Critical Applications
Voice
IP Telephony
Video
Interactive Video Conferencing and
Broadcast Video
Low Latency Data
Instant Messaging (IM) and User
Authentication
High Throughput Data
Imagery
Multimedia Streaming
Video and Audio Streaming, Multimedia
Conferencing
Operations, Administration and
Maintenance (OA&M)
SNMP, Trap and Syslog Files, Audit and
Accounting Records
Default/Best Effort
E-mail, Web browsing, Document
transfers
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IP RTS Technologies (VoIP)
Traditional Digital TDM Voice Transmission
Analog
Voice
Digital
Analog/Digital
Samples
Converter
Analog
Voice
Digital
Analog/Digital
Samples
Converter
Digital
Network
Digital Digital/Analog
Samples
Converter
Analog
Voice
Voice over IP Transmission
Encoder
De-Jitter Buffer
RTP
Packetizer
RTP
De-Packetizer
UDP
UDP
IP
IP
Link
Link
Physical
Analog
Voice
Decoder
Digital/Analog
Converter
Physical
IP
Network
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IP RTS Technologies
(Legacy Video Technologies (H.320 Video))
Analog
Video
Analog/Digital
Converter
Digital
Frame
Color
Transformation
Re-sampling
Capture Subsystem
H.261/H.263 Formatted Frame
H.261/H.263 Compressed
Encoder
Frame
Digital
Network
H.261/H.263
Encoder
Uncompressed Frame
Color
Transformation
Re-sampling
Modified Frame
for Display
Display Subsystem
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IP RTS Technologies (H.323/SIP Video)
Analog
Video
Analog/Digital
Converter
Digital
Frame
Color
Transformation
Re-sampling
Capture Subsystem
H.261/H.263 Formatted Frame
H.261/H.263 Compressed
Encoder
Frame
RTP
Packetizer
RTP
De-Packetizer
UDP
UDP
IP
IP
Link
Link
Physical
Physical
De-Jitter
Buffer
IP
Network
H.261/H.263
Encoder
Uncompressed
Frame
Color
Transformation
Re-sampling
Display Subsystem
Modified Frame
for Display
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IP RTS Technologies (Standards)
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Combination of Legacy Standards and New Standards
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North American Numbering Plan
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Bellcore Generic Requirements
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For interfacing to legacy PSTN systems
International Telecommunications Union (ITU)
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E.164 is the primary approach taken today
May be replaced by concept known as ENUM – RFC 2916
CODECs (G.711, G.729, H.264, etc.)
Signaling
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Session Initiation Protocol (SIP) - RFC 3261
ITU H.323
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Bearer
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Aggregation of several H.series standards
Real-time Transport Protocol (RTP) – RFC 3550
Network Management
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Simple Network Management Protocol (SNMP) – RFC 3414
Secure Shell (SSHv2) – RFC 4251
Hyper Text Transport Protocol over Secure Socket Layer (SSL) (HTTPS) –
RFC 2818
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IP RTS Technologies (Development
Model)
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Distributed Systems
 Multiple appliances with different functionalities
Typically multivendor
 Call Control Agent (CCA) from Vendor A
 LAN from Vendor B
 TDM Switch from Vendor C
 Firewall from Vendor D
Off-the Shelf Operating System (Windows, Unix, LINUX, etc.)
Proprietary (protected) Application
5 – 10 year depreciation model
Only external interfaces are standardized
Open and Closed network management networks
Signaling and Bearer typically travel different paths
 See next slide
16
IP RTS Technologies (Signaling, Bearer,
and Network Management Characteristics)
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Signaling is hierarchical
Bearer does not necessarily take the same
path as signaling
Network Management traffic is often in-band
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IP RTS Technologies (End-to-End Functional
Components)
WAN or Core Network
Trusted Relationships Required
Among All Appliances
Edge or Business
NM/PBNM
•Control to SS,
CCA, & Routers
LCC
• Session Control and Signaling (SCS)
• State of Local LAN Sessions
• State of Local Access Layer Sessions
• Local Access Bandwidth Used
• Local Access Bandwidth Available
• Directs CCA SCS to Modify Resources
• Network Management
• Local Directory Services
• Media Gateway Controller
• Appliance Authentication and IA Services
• EI & User Authentication and Authorization
• User Features and Services
Softswitch (SS)
• Session Control and Signaling (SCS)
• State of RTS WAN Sessions
• Access Layer SLA Enforcer
• Process Input from Closed Loop System
• SLA Performance Monitoring
• Directs SS SCS to modify resources
• CCA
• Signaling Gateway
• Media Gateway Controller
• Global Directory Services
• Network Management
• Appliance Authentication and IA Services
Media Gateway
RTS Aware Firewall & CER
• Traffic Conditioning
• Bandwidth Management
• PHB
• Topology Hiding
• Opening and Closing “Pinholes”
Media Gateway
PER
NM
Signaling
Bearer
Converged
LAN
SS & LCC/ASAC
End Instrument
• Signaling Client
• COS Packet
Marking
• CCA Authentication
• User Interface
Router Control
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IP RTS Technologies (IP End-to-End Session)
PRI/SS7
Signaling
Bearer
SS
SS
MFS
MFS
PRI
PRI
IP Core
PER
PER
Enclave A
Enclave B
CER
CER
PRI
PRI
CCA
EO
CCA
EO
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Phone A
IP RTS Technologies (Cost Model)
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Flat rate for RTS services
Voice bandwidth based on 92 Kbps per voice
session
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102 Kbps for IPv6 voice sessions
Video bandwidth based on 500 Kbps per traditional
384 Kbps video session
SLAs are typically data centric
Typically LAN is most expensive element due to
reliability requirements
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99.999% reliable
Power backup is often a considerable cost
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IP RTS Information Assurance
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IA Architecture Approach
Methods for Assessing Risk
IA Architecture Considerations
Example RTS IA Architecture
Example RTS LAN
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IP RTS Information Assurance
(Information Assurance Process)
Document
IA Threats
Additional IA
Requirements
Develop
Generic CMs
Industry and
User
Community
Develop
IA
Architecture
Specify
IA
Requirements
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IP RTS Information Assurance
(Risk Assessment Method)
NOTE: Score = Impact X Likelihood
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Likelihood of Successful Attack
ETSI TISPAN/TIPHON Risk Assessment Model
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IP RTS Information Assurance
(IA Architecture Considerations)
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Physical Security
RTS Appliance Security Architecture
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RTS Component Interactions
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VLANs
Segmentation
Network Management
RTS Protocol Architecture
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Generic in respect to vendor solutions
User roles
Hardened Operating Systems
Auditing
Application level security
Redundant Systems
Signaling
Transport
Network Management
Firewalls and NATs
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IP RTS Information Assurance
(Example RTS IAMedia
Architecture)
Gateway
PRI/CAS
End Instrument
Only Standardized
Protocols
Proprietary Protocols
Allowed
PSTN
Data
Firewall
SIP(TLS)
Switch
H.248/MGCP/MEGACO(IPSec)
End Instrument
Protocol (IA Protocol)
Protocol (IA Protocol)
IP WAN
Customer
Router
Customer
Edge Router
CA/PKI
Server
RTS Firewall
Switch
LDAPv3/HTTPS
RTS NM
Services
RTS IA &
Profile
Services
RTS
Signaling
Services
CCA
Local
Directory
Services
RTS User
Feature &
Services
SIP(TLS)
SS
NMS
SNMPv3/SSH/TLS1.0(SSL3.1)
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IP RTS QoS
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Call Control Budgets
DiffServ
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Per Hop Behaviors
Explicit Congestion Notification
RSVP
Bandwidth Brokers
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IP RTS QoS (Call Control Budgets)
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Current RTS Architectures primarily use Call Control
Agents (CCAs) as the mechanism for avoiding
congestion
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Each site is assigned a predefined budget
Each call is allocated against budget
When budget is full CCA blocks the call and plays a trunk
busy signal
CCA is typically operated by the business (replaces PBX)
Softswitch polices the CCA to ensure that the CCA
stays within its subscribed budget
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Softswitch is owned by the TELCO (augments EO and
Tandem Switch)
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IP RTS QoS (DiffServ)
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Differentiated Services (DS) is an architecture for indicating a traffic
class in the IP header (RFC 2474)
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6 bit field in IP header (allows 64 markings)
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Marking is performed by layer 3 traffic conditioners or by end instrument
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May also be used for traffic shaping or policing
Voice is typically placed in the Expedited Forwarding Queue (RFC
2598) along with the User Signaling (i.e., SIP, H.323, H.248, etc.)
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EF queue is served before all other queues are served in accordance with its
allocation
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Marking may be based on incoming port, IP address, protocol, VLAN tag, etc.
Marking used by routers to discriminate between different classes of traffic
by placing packets into different queues (also known as Per Hop Behaviors
(PHBs))
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Markings are called DiffServ Code Points
The router checks to see if any packets are in the EF queue before it services the
other queues
All packets in EF queue are treated equally
Video is usually placed in the Assured Forwarding Queue (RFC 2597)
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AF queues have 3 drop probabilities
AF queues are typically served in a Weighted Round Robin (WRR) approach
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IP RTS QoS (ECN)
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Explicit Congestion Notification (ECN) is a mechanism for signaling in
the IP header or the RTP header the relative congestion experienced in
the IP network
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Documented in two Internet Drafts
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2 bit field indicates whether congestion exists or when congestion thresholds
are met
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Bits 6 & 7 in the DS field when found in IP header
2 bits between the version and the RTP sequence number in the RTP header
Each router in the bearer path that may experience congestion must
participate
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“RTP Payload Format for ECN Probing draft-alexander-rtp-payload-for-ecnprobing-02.txt”
“Admission Control Use Case for Real-time ECN draft-alexander-rtecnadmission-control-use-case-00.txt”
Requires the marking of every packet
Some IA concerns are associated with attacks that change the bits to
indicate congestion is occurring when none is actually occurring
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Reverse attack can be detected by sending probes preset to indicate
congestion
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IP RTS Technologies (ECN Flow)
Signaling
Bearer
PRI/SS7
SS
SS
MFS
MFS
PRI
PRI
IP Core
PER
PER
Enclave A
Enclave B
CER
CER
ECN Bits Set
ECN Updates
PRI
PRI
CCA
EO
CCA
EO
ECN Updates
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Phone A
IP RTS QoS (RSVP)
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RSVP is an acronym for Resource Reservation Protocol (RFCs 2205 &
2208)
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RSVP is typically used as a bandwidth reservation mechanism executed on
a session-by-session basis
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Reservation is evaluated on a hop-by-hop basis
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Sophisticated mechanism for efficiently utilizing network resources
Requires CCA to interact with routers
Aggregated RSVP was developed to deal with scalability issues (RFC 3175)
SIP with Preconditions is designed to check with RSVP to ensure resources
are available prior to establishing a session
Currently, RSVP is typically considered by industry to be a Cisco
approach
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Each path is allocated a budget and reservations are decremented against the
budget
Juniper MPLS-TE RSVP implementation conflicts with Cisco RSVP
implementation
Juniper does not implement RSVP for individual sessions
RSVP is deemed by some to be a IA risk due to the unregulated fields
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Allows for possibility of a covert channel
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IP RTS Technologies (RSVP)
Signaling
Bearer
RSVP
Precondition
PRI/SS7
SS
SS
MFS
MFS
PRI
PRI
IP Core
PER
PER
Enclave A
Enclave B
CER
CER
SIP With
Preconditions
PRI
PRI
CCA
EO
CCA
EO
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Phone A
IP RTS QoS (Bandwidth Broker)
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Requires a centralized server to know status of RTS
network
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CCAs provide status to centralized server on current
counts
Routers provide bandwidth utilization on each circuit and
routing table/MPLS paths
Bandwidth Broker (BB) periodically calculates
budgets for each CCA and updates CCA
Does not conform easily to commercial model where
enclaves have contractual budgets, which are
managed at the enclave level
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IP RTS Technologies (Bandwidth Broker)
CCA Budgets
PRI/SS7
Routing Tables
and Queue
Congestion
SS
SS
MFS
MFS
PRI
PRI
IP Core
PER
PER
Enclave A
Enclave B
Bandwidth
Broker
CER
CER
SIP With
Preconditions
PRI
PRI
CCA
EO
CCA
EO
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Phone A
Future Technologies
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IMS
Unified Communications
Wireless Expansions
IPv6 Mobility
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Future Technologies (IMS)
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IP Multimedia Subsystem
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Vision was to introduce Internet services over GPRS
(General Packet Radio Service)
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An architectural framework for delivering IP multimedia to
mobile users.
Developed by 3rd Generation Partnership Project (3GPP)
An attempt to develop mobile wireless beyond the Global
System for Mobile (GSM) standard
Medium speed data transfers
SIP is an important protocol in the IMS architecture
Many vendors market IMS capabilities
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Future Technologies (Unified
Communications)
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Unified Communications
 A new buzzword indicating the use of IP to deliver multimedia
services
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Typically focused on wireline users
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Some capabilities are targeted at wireless users
Types of multimedia services provided include:
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Google search shows that Nortel, Cisco, Avaya, and Microsoft market
Unified Communications
Instant Messaging
E-mail
Voice
Video
Whiteboard
At this time, most vendor solutions are not interoperable
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Future Technologies (Wireless Expansion)
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Wireless is becoming more predominant in every facet of
telecommunications
 Wireless LANs to support mobile users within a campus LAN is
becoming more predominant
 PDAs use continues to expand
Increased use of mobile phones to replace traditional desktop
phones and residential phones
 Significant threat to traditional telecom companies due to change
in business model
Recent FCC decision to auction wireless spectrum allowing open
network
 Allows users to connect to any service
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Google, Yahoo, Skype, etc.
SIP allows users of multiple extension phone to subscribe to
multiple carriers
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Future Technologies (IPv6 Mobility)
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IPv6 allows nodes to move around the Internet, but be reachable
using their “home” IP address
 Involves the concept of a “home agent”
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Mobile node registers with home agent
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Typically a router
Home agent forwards all traffic destined to “home” IP address to the
temporary “mobile” IP address
Relies on Internet QoS to ensure that quality is acceptable
Can cause issues with CCA budget since bearer traffic affects
remote nodes access bandwidth budget while the remote CCA is
unaware that the mobile node is generating traffic
Relies on VPN or secure IA architecture to ensure that mobile
node does not introduce risk to “home” network
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Questions
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