Slide 1 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Nicklas Beijar Networking Laboratory Helsinki University of Technology P.O. Box 3000, HUT, Finland Master’s Thesis: HUT, Networking Laboratory, Espoo, 2002 Supervisor: Prof. Raimo Kantola Presentation: S Research Seminar,

Slide 2 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks 1. Background (Number portability, TRIP, ENUM) 2. Motivation and goals 3. Architecture 4. The CTRIP protocol 5. Scenario based on TRIP/CTRIP 6. CTRIP and TRIP attributes 7. Numbering gateway 8. Results 9. Conclusions Agenda Agenda

Slide 3 Nicklas 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 Background

Slide 4 Nicklas 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, ,... 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 > e164.arpa Background

Slide 5 Nicklas 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 Background

Slide 6 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Motivation 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 7 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Goal 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 8 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Application-layer routing SS Gateway Application layer Network layer SS Routing numbersIP-addresses E.164 Directory numbers

Slide 9 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks IP-network ITAD IP-network ITAD SCN network CTAD SCN network CTAD CTRIP node (SDF, switch,...) TRIP node (location server) Reference architecture External peer Internal peer External peer TRIPCTRIP CTRIP node (SDF, switch,...) TRIP node (location server) Numbering gateway Numbering gateway

Slide 10 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks CTRIP 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 11 Nicklas 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 CTRIP N G Protocol connections

Slide 12 Nicklas 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: 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)} 987xxxxx RP4 GW2 Routes formed by TRIP/CTRIP CTRIP TRIP CTRIP RP6 N G GW1

Slide 13 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Route 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 14 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks NameDescription Withdrawn routesList of telephone numbers that are no longer available. Reachable routesList of reachable telephone numbers. Next hop serverThe IP address of the next hop signaling server. Advertisement pathThe path that the route advertisement has traveled. Loop avoidance. Routed pathPath for signaling. Atomic aggregateIndicates that the path can contain networks not included in Routed Path. Local preferenceThe intra-domain preference of the route. Multi exit discThe inter-domain preference of the route if several links are used. CommunitiesFor grouping destinations in groups with similar properties. Domain topologyFor advertising the ITAD topology to other servers in the same ITAD. Converted routeIndicates that the Application Protocol has been converted. TRIP attributes

Slide 15 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks NameDescription Withdrawn routesList of telephone numbers that are no longer available. Reachable routesList of reachable telephone numbers. Next hop addressThe network and routing number pattern of the next hop. Advertisement pathThe path that the route advertisement has traveled. Loop avoidance. Routed pathPath for signaling. Atomic aggregateIndicates that the path can contain networks not included in Routed Path. Local preferenceThe intra-domain preference of the route. Multi exit discThe inter-domain preference of the route if several links are used. CommunitiesFor grouping destinations in groups with similar properties. IP destinationIndicates the origin of the route to a prefix on the IP network. Number portability stateIndicates the state of a moving number. Domain topologyFor advertising the TAD topology to other servers in the same TAD. Converted routeIndicates that the Application Protocol has been converted. CTRIP attributes New Modified

Slide 16 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks NameDescription Withdrawn routesList of telephone numbers that are no longer available. Reachable routesList of reachable telephone numbers. Next hop addressThe network and routing number pattern of the next hop. Advertisement pathThe path that the route advertisement has traveled. Loop avoidance. Routed pathPath for signaling. Atomic aggregateIndicates that the path can contain networks not included in Routed Path. Local preferenceThe intra-domain preference of the route. Multi exit discThe inter-domain preference of the route if several links are used. CommunitiesFor grouping destinations in groups with similar properties. IP destinationIndicates the origin of the route to a prefix on the IP network. Number portability stateIndicates the state of a moving number. Domain topologyFor advertising the TAD topology to other servers in the same TAD. Converted routeIndicates that the Application Protocol has been converted. CTRIP attributes New 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 17 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks NameDescription Withdrawn routesList of telephone numbers that are no longer available. Reachable routesList of reachable telephone numbers. Next hop addressThe network and routing number pattern of the next hop. Advertisement pathThe path that the route advertisement has traveled. Loop avoidance. Routed pathPath for signaling. Atomic aggregateIndicates that the path can contain networks not included in Routed Path. Local preferenceThe intra-domain preference of the route. Multi exit discThe inter-domain preference of the route if several links are used. CommunitiesFor grouping destinations in groups with similar properties. IP destinationIndicates the origin of the route to a prefix on the IP network. Number portability stateIndicates the state of a moving number. Domain topologyFor advertising the TAD topology to other servers in the same TAD. Converted routeIndicates that the Application Protocol has been converted. CTRIP attributes New Modified List of path segments: Type (unordersed/ordered) List of hops: TAD identifier Application protocol (e.g. SIP, H.323, SCN)

Slide 18 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks NameDescription Withdrawn routesList of telephone numbers that are no longer available. Reachable routesList of reachable telephone numbers. Next hop addressThe network and routing number pattern of the next hop. Advertisement pathThe path that the route advertisement has traveled. Loop avoidance. Routed pathPath for signaling. Atomic aggregateIndicates that the path can contain networks not included in Routed Path. Local preferenceThe intra-domain preference of the route. Multi exit discThe inter-domain preference of the route if several links are used. CommunitiesFor grouping destinations in groups with similar properties. IP destinationIndicates the origin of the route to a prefix on the IP network. Number portability stateIndicates the state of a moving number. Domain topologyFor advertising the TAD topology to other servers in the same TAD. Converted routeIndicates that the Application Protocol has been converted. CTRIP attributes New Modified Indicates the originating protocol (ENUM or TRIP) for a route to an IP terminal

Slide 19 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks NameDescription Withdrawn routesList of telephone numbers that are no longer available. Reachable routesList of reachable telephone numbers. Next hop addressThe network and routing number pattern of the next hop. Advertisement pathThe path that the route advertisement has traveled. Loop avoidance. Routed pathPath for signaling. Atomic aggregateIndicates that the path can contain networks not included in Routed Path. Local preferenceThe intra-domain preference of the route. Multi exit discThe inter-domain preference of the route if several links are used. CommunitiesFor grouping destinations in groups with similar properties. IP destinationIndicates the origin of the route to a prefix on the IP network. Number portability stateIndicates the state of a moving number. Domain topologyFor advertising the TAD topology to other servers in the same TAD. Converted routeIndicates that the Application Protocol has been converted. CTRIP attributes New Modified For synchronizing moving numbers

Slide 20 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks NameDescription Withdrawn routesList of telephone numbers that are no longer available. Reachable routesList of reachable telephone numbers. Next hop serverThe IP address of the next hop signaling server. Advertisement pathThe path that the route advertisement has traveled. Loop avoidance. Routed pathPath for signaling. Atomic aggregateIndicates that the path can contain networks not included in Routed Path. Local preferenceThe intra-domain preference of the route. Multi exit discThe inter-domain preference of the route if several links are used. CommunitiesFor grouping destinations in groups with similar properties. IP destinationIndicates the origin of the route to a prefix on the IP network. Number portability stateIndicates the state of a moving number. Domain topologyFor advertising the TAD topology to other servers in the same TAD. Converted routeIndicates that the Application Protocol has been converted. TRIP attributes New Extended routed path Path for signaling (compatible with CTRIP) New

Slide 21 Nicklas 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 gateway CTRIP TRIP CTRIP Numbering gateway CTRIP TRIP CTRIP independent of ownership }

Slide 22 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Routing 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 23 Nicklas 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 Results

Slide 24 Nicklas 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 Conclusions

Slide 25 Nicklas 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 Conclusions

Slide 26 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks CTRIP and TRIP provide a common protocol for distributing routing information 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 Conclusions

Slide 27 Nicklas Beijar - Distribution of Numbering Information in Interconnected Circuit and Packet Switched Networks Thank you for your attention! Questions? Thank you for your attention! Questions?