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Slide 1Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Distribution of Numbering Information in Distribution of Numbering Information in Interconnected Circuit and Packet Switched NetworksInterconnected Circuit and Packet Switched Networks
Distribution of Numbering Information in Distribution of Numbering Information in Interconnected Circuit and Packet Switched NetworksInterconnected Circuit and Packet Switched Networks
Nicklas [email protected]
Networking LaboratoryHelsinki University of Technology
P.O. Box 3000, 02015 HUT, Finland
Master’s Thesis: HUT, Networking Laboratory, Espoo, 2002Supervisor: Prof. Raimo Kantola
Presentation: S-38.360 Research Seminar, 25.2.2002
Slide 2Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
1. Background (Number portability, TRIP, ENUM)2. Motivation and goals3. Architecture4. The CTRIP protocol5. Scenario based on TRIP/CTRIP6. CTRIP and TRIP attributes7. Numbering gateway8. Results9. Conclusions
Agenda
AgendaAgendaAgendaAgenda
Slide 3Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
TRIP (Telephony Routing over IP)• IETF protocol, still at draft stage• Inter-domain protocol between Internet Telephony Administrative Domains (ITAD)• Distributes routing information between location servers
• Information about gateways and the numbers reachable through them• Routes to gateways and signaling servers
• Interdomain distribution modeled after BGP-4• Gateway selection driven by policies• Intra-domain synchronization based on SCSP and OSPF• Information transported as attributes of the UPDATE message• Expandable
Locates the most suitable gateway for a given call
BackgroundBackgroundBackgroundBackground
Slide 4Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
ENUM (tElephone NUmbering Mapping)• RFC 2916• Maps E.164 numbers into Uniform Resource Identifiers (URI)• The URIs represent different ways to contact a host
• SIP, H.323, TEL, email, ...• Uses the Domain Name System (DNS)
• E.164 number rewritten as a domain name:
• Provides simple number portability
Locates a terminal with a given E.164 number on the IP network
+358-9-4515303-> 3.0.3.5.1.5.4.9.8.5.3.e164.arpa
BackgroundBackgroundBackgroundBackground
Slide 5Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Number portability• Change service provider, location or service type without changing telephone number• Implemented with IN (Intelligent Network)• Separate directory numbers and routing numbers• Number portability required for IP networks• Number portability between SCN and IP network
• Operator may move subscribers to its IP telephony network
Increasing management burden• More services• More service providers• SCN and IP network with several signaling protocols
BackgroundBackgroundBackgroundBackground
Slide 6Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
MotivationMotivationMotivationMotivation
• SCN and IP telephony networks will co-exist• Management is becoming more complex due to
• IP telephony• number portability• increasing number of services• increasing number of operators• new mobile networks
• Number portability is required between SCN and IP networks• Media conversions in gateways should be avoided• TRIP routes are currently configured manually• Gateway selection for calls SCN IP is still done manually• The information in IN, TRIP and ENUM must be kept synchronized• Automatic routing based on policies instead of static routes
A routing protocol is required
Slide 7Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
GoalGoalGoalGoal
Main goal: To examine how a routing protocol can be utilized for distribution of numbering information in an interconnected SCN and IP network
The TRIP protocol selected as basis
In the thesis:• The architecture for distribution of numbering information is developed• A new protocol named CTRIP (Circuit Telephony Routing Information Protocol) is developed as a counterpart to TRIP• The numbering gateway is defined• Scenarios and applications are examined
Slide 8Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Application-layer routingApplication-layer routingApplication-layer routingApplication-layer routing
SS
Gateway
Application layer
Network layer SS SS
Routing numbersIP-addresses
E.164 Directory numbers
34.65.43.2
54.75.43.7
124.65.3.32
98734232147.12.6.125
98734532
97798234
9872346
358-9-4514563
358-9-4321253
358-9-2315532
Slide 9Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
IP-networkITAD
IP-networkITAD
SCN networkCTAD
SCN networkCTAD
CTRIP node(SDF, switch, ...)
TRIP node(location server)
Reference architectureReference architectureReference architectureReference architecture
External peer
Internal peer
External peer
TRIPCTRIP
CTRIP node(SDF, switch, ...)
TRIP node(location server)
Numbering gateway
Numbering gateway
Slide 10Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
CTRIPCTRIPCTRIPCTRIP
CTRIP (Circuit Telephony Routing Information Protocol)• Counterpart of TRIP for the SCN• Similar protocol as TRIP, new attributes added
Purpose• Inter-domain distribution between networks
• Routes are formed based on the policies of the network• Aggregation to reduce information amount and to hide topology details
• Intra-domain synchronization within the networks• All routing databases in a domain contain identical information
• Provides automatic selection of gateways between IP and SCN• Collects information about the SCN for distribution with TRIP
Slide 11Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
SS1 SS2
TAD 2 (IP)
TAD 5 (SCN)
TAD 3 (SCN)
TAD 1 (IP)
TAD 4 (SCN)
RP1
RP2
RP3
RP5 RP4
RP6
GW1
GW2
CTRIP
TRIP TRIPTRIP
CTRIP
CTRIPN G
N G
Protocol connectionsProtocol connectionsProtocol connectionsProtocol connections
Slide 12Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
SS1 SS2
TAD 2 (IP)
TAD 5 (SCN)
TAD 3 (SCN)
TAD 1 (IP)
TAD 4 (SCN)
RP1
RP2
RP3
RP5
987: SS2 {(2,IP),(3,SCN)}987: SS2 {(2,IP),(3,SCN)}
987: GW2 {(3,SCN)}987: GW2 {(3,SCN)}
987: RP6 {(1,IP),(2,IP), (3,SCN)}987: RP5 {(5,SCN),(3,SCN)}
987: RP6 {(1,IP),(2,IP), (3,SCN)}987: RP5 {(5,SCN),(3,SCN)} 987: RP3
{(3,SCN)}987: RP3 {(3,SCN)}
987xxxxx
RP4
GW2
Routes formed by TRIP/CTRIPRoutes formed by TRIP/CTRIPRoutes formed by TRIP/CTRIPRoutes formed by TRIP/CTRIP
CTRIP
TRIP TRIPTRIP
CTRIP
CTRIP
RP6N G
N G
GW1
Slide 13Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Route selectionRoute selectionRoute selectionRoute selection
Selection performed by policy functions• Defined for each network (TAD)• Calculates a preference value based on the attributes• Highest preference route for each prefix selected
Selection based on attributes• The operators on the path• Number of intermediate network• The type of the intermediate networks (SCN/IP)
• Used to minimize numbers of media conversions• The signaling protocols on the path• Properties and capabilities of the gateways• Cost• New attributes can be added
Slide 14Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Name Description
Withdrawn routes List of telephone numbers that are no longer available.
Reachable routes List of reachable telephone numbers.
Next hop server The IP address of the next hop signaling server.
Advertisement path The path that the route advertisement has traveled. Loop avoidance.
Routed path Path for signaling.
Atomic aggregate Indicates that the path can contain networks not included in Routed Path.
Local preference The intra-domain preference of the route.
Multi exit disc The inter-domain preference of the route if several links are used.
Communities For grouping destinations in groups with similar properties.
Domain topology For advertising the ITAD topology to other servers in the same ITAD.
Converted route Indicates that the Application Protocol has been converted.
TRIP attributesTRIP attributesTRIP attributesTRIP attributes
Slide 15Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Name Description
Withdrawn routes List of telephone numbers that are no longer available.
Reachable routes List of reachable telephone numbers.
Next hop address The network and routing number pattern of the next hop.
Advertisement path The path that the route advertisement has traveled. Loop avoidance.
Routed path Path for signaling.
Atomic aggregate Indicates that the path can contain networks not included in Routed Path.
Local preference The intra-domain preference of the route.
Multi exit disc The inter-domain preference of the route if several links are used.
Communities For grouping destinations in groups with similar properties.
IP destination Indicates the origin of the route to a prefix on the IP network.
Number portability state Indicates the state of a moving number.
Domain topology For advertising the TAD topology to other servers in the same TAD.
Converted route Indicates that the Application Protocol has been converted.
CTRIP attributesCTRIP attributesCTRIP attributesCTRIP attributes
New
New
Modified
Modified
Slide 16Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Name Description
Withdrawn routes List of telephone numbers that are no longer available.
Reachable routes List of reachable telephone numbers.
Next hop address The network and routing number pattern of the next hop.
Advertisement path The path that the route advertisement has traveled. Loop avoidance.
Routed path Path for signaling.
Atomic aggregate Indicates that the path can contain networks not included in Routed Path.
Local preference The intra-domain preference of the route.
Multi exit disc The inter-domain preference of the route if several links are used.
Communities For grouping destinations in groups with similar properties.
IP destination Indicates the origin of the route to a prefix on the IP network.
Number portability state Indicates the state of a moving number.
Domain topology For advertising the TAD topology to other servers in the same TAD.
Converted route Indicates that the Application Protocol has been converted.
CTRIP attributesCTRIP attributesCTRIP attributesCTRIP attributes
New
New
Modified
Modified
1. Routing number• Generated with a regular expression from the directory number
2. Query to obtain routing number• Protocol (LDAP, INAP, MAP)• Address (IPv4, IPv6, DPC+SSN)• Directory number modified with regex• Other parameters
Slide 17Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Name Description
Withdrawn routes List of telephone numbers that are no longer available.
Reachable routes List of reachable telephone numbers.
Next hop address The network and routing number pattern of the next hop.
Advertisement path The path that the route advertisement has traveled. Loop avoidance.
Routed path Path for signaling.
Atomic aggregate Indicates that the path can contain networks not included in Routed Path.
Local preference The intra-domain preference of the route.
Multi exit disc The inter-domain preference of the route if several links are used.
Communities For grouping destinations in groups with similar properties.
IP destination Indicates the origin of the route to a prefix on the IP network.
Number portability state Indicates the state of a moving number.
Domain topology For advertising the TAD topology to other servers in the same TAD.
Converted route Indicates that the Application Protocol has been converted.
CTRIP attributesCTRIP attributesCTRIP attributesCTRIP attributes
New
New
Modified
Modified
List of path segments:• Type (unordersed/ordered)• List of hops:
• TAD identifier• Application protocol (e.g. SIP, H.323, SCN)
Slide 18Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Name Description
Withdrawn routes List of telephone numbers that are no longer available.
Reachable routes List of reachable telephone numbers.
Next hop address The network and routing number pattern of the next hop.
Advertisement path The path that the route advertisement has traveled. Loop avoidance.
Routed path Path for signaling.
Atomic aggregate Indicates that the path can contain networks not included in Routed Path.
Local preference The intra-domain preference of the route.
Multi exit disc The inter-domain preference of the route if several links are used.
Communities For grouping destinations in groups with similar properties.
IP destination Indicates the origin of the route to a prefix on the IP network.
Number portability state Indicates the state of a moving number.
Domain topology For advertising the TAD topology to other servers in the same TAD.
Converted route Indicates that the Application Protocol has been converted.
CTRIP attributesCTRIP attributesCTRIP attributesCTRIP attributes
New
New
Modified
Modified
Indicates the originating protocol (ENUM or TRIP) for a route to an IP terminal
Slide 19Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Name Description
Withdrawn routes List of telephone numbers that are no longer available.
Reachable routes List of reachable telephone numbers.
Next hop address The network and routing number pattern of the next hop.
Advertisement path The path that the route advertisement has traveled. Loop avoidance.
Routed path Path for signaling.
Atomic aggregate Indicates that the path can contain networks not included in Routed Path.
Local preference The intra-domain preference of the route.
Multi exit disc The inter-domain preference of the route if several links are used.
Communities For grouping destinations in groups with similar properties.
IP destination Indicates the origin of the route to a prefix on the IP network.
Number portability state Indicates the state of a moving number.
Domain topology For advertising the TAD topology to other servers in the same TAD.
Converted route Indicates that the Application Protocol has been converted.
CTRIP attributesCTRIP attributesCTRIP attributesCTRIP attributes
New
New
Modified
Modified
For synchronizing moving numbers
Slide 20Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Name Description
Withdrawn routes List of telephone numbers that are no longer available.
Reachable routes List of reachable telephone numbers.
Next hop server The IP address of the next hop signaling server.
Advertisement path The path that the route advertisement has traveled. Loop avoidance.
Routed path Path for signaling.
Atomic aggregate Indicates that the path can contain networks not included in Routed Path.
Local preference The intra-domain preference of the route.
Multi exit disc The inter-domain preference of the route if several links are used.
Communities For grouping destinations in groups with similar properties.
IP destination Indicates the origin of the route to a prefix on the IP network.
Number portability state Indicates the state of a moving number.
Domain topology For advertising the TAD topology to other servers in the same TAD.
Converted route Indicates that the Application Protocol has been converted.
TRIP attributesTRIP attributesTRIP attributesTRIP attributes
New
Extended routed path Path for signaling (compatible with CTRIP)New
New
Slide 21Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Purpose • Translates between TRIP and CTRIP• Inserts the gateway on the path
Design principles• Simple because of similarity between TRIP and CTRIP• Well defined• No policies• Can be integrated into a TRIP or CTRIP node• Transparent to its peer nodes
Numbering gatewayNumbering gatewayNumbering gatewayNumbering gateway
CTRIPTRIP
CTRIP
CTRIP
CTRIP
Numbering gateway CTRIP
TRIPCTRIP
CTRIP
CTRIP
independent of ownership}
Slide 22Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Routing with TRIP/CTRIPRouting with TRIP/CTRIPRouting with TRIP/CTRIPRouting with TRIP/CTRIP
Application layer routing protocol• Addressing: E.164 directory numbers• Forms a new layer above the network layer
Next Hop Address• TRIP: IP address of the next signaling server or gateway• CTRIP: Regular expression for generating routing number based on the directory number• CTRIP supports INAP, LDAP and MAP queries
Aggregation reduces information• Sequence of prefixes with same properties can be combined to a single shorter prefix• Hides topology details
Slide 23Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
1. Litterature research on routing in SCN and IP networks, number portability, TRIP and ENUM
2. Development of a solution The architecture was defined The CTRIP protocol was developed Some new attributes were added to TRIP The numbering gateway was defined Applications and usage scenarios were examined
3. A basic implementation was made to verify the central concepts
ResultsResultsResultsResults
Slide 24Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Advantages Simplifies management of routing information
• Increasing load due to more services, more service providers, number portability• Simplifies movement to IP based technology
Automatic• Generates routes between networks and network technologies• Generates the TRIP information at its source
Policy based• General policy functions can be defined centrally
ConclusionsConclusionsConclusionsConclusions
Slide 25Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Advantages (cont.)
Based on a routing protocol• Responds to changing network conditions• Searches for optimal paths and most suitable gateway
Reduces number of media/signaling protocol conversions• For example in a IP to SCN call where the B-number has ported to an IP network and the originating network is not aware of it
Allows for number portability between SCN and IP networks
Expandable protocol• New attributes can be added to describe the routes and gateways
ConclusionsConclusionsConclusionsConclusions
Slide 26Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
CTRIP and TRIP provide a common protocol for distributing routinginformation on the SCN, the IP network and between them
Further work• Implementation and testing of TRIP, CTRIP and numbering gateway• Testing with real scenarios, scalability testing• Development of location server and integration with SIP clients
ConclusionsConclusionsConclusionsConclusions
Slide 27Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks
Thank you for Thank you for your attention!your attention!
Questions?Questions?
Thank you for Thank you for your attention!your attention!
Questions?Questions?