© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Deployments Introducing Cisco Gatekeepers

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Cisco Gatekeeper Overview Typical gatekeeper functions: A gatekeeper is an H.323 entity on the network. A gatekeeper provides these services: –Address translation –Network access control for H.323 terminals, gateways, and MCUs Primary functions are admission control, zone management, and E.164 address translation. Gatekeepers are logically separated from H.323 endpoints such as terminals and gateways. Gatekeepers are optional devices in a network.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Cisco Gatekeeper Overview (Cont.) Mandatory: Address translation: Translates H.323 IDs (such as and E.164 numbers (standard telephone numbers) to endpoint IP addresses. Admission control: Controls endpoint admission into the H.323 network. Bandwidth control: Consists of managing endpoint bandwidth requirements. Zone management: Provides zone management for all registered endpoints in the zone. Optional: Call authorization: The gatekeeper can restrict access to certain terminals or gateways or have time-of-day policies restrict access. Call management: With this option, the gatekeeper maintains active call information and uses it to indicate busy endpoints or redirect calls. Bandwidth management: With this option, the gatekeeper can reject admission when the required bandwidth is not available. Call control signaling: With this option, the gatekeeper can route call signaling messages between H.323 endpoints using the GKRCS model. Alternatively, it allows endpoints to send H.225 call signaling messages directly to each other.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Cisco Gatekeeper Overview (Cont.) Phone Phone Phone Phone Phone GK2 Gatekeeper Gatekeeper can be responsible for admission control. Gatekeeper can forward calls to other gatekeepers in different zones. Terminal Endpoints can be registered at the gatekeeper. Cisco Unified CallManager cluster can be registered at the Gatekeeper Gateways can be registered at the gatekeeper. Endpoints are registered in zones. Each endpoint can be registered in one zone. Phone GK1 Gatekeeper can control bandwidth in the network. Gatekeeper GK1 = Gatekeeper 1 GK2 = Gatekeeper 2

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Terms and Definitions Zones: –H.323 endpoints are grouped into zones. –Each zone has one gatekeeper that manages all the endpoints in the zone. Zone prefixes: –A zone prefix is the part of the called number that identifies the zone to which a call goes. –Zone prefixes are usually used to associate an area or country code to a configured zone.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Terms and Definitions (Cont.) Technology prefixes: –Is an optional H.323 standard-based feature, supported by Cisco gateways and gatekeepers, that enables more flexibility in call routing within an H.323 VoIP network. –The Cisco gatekeeper uses technology prefixes to group endpoints of the same type together. Technology prefix with hop off: –Calls will be routed to a specified zone, regardless of what the zone prefix in the address is.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Hardware and Software Requirements Cisco IOS Gatekeeper functionality is available with IP Voice Image Advanced Enterprise Image IP/H323 Image Advanced IP Services Image SP Services Image

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Signaling Cisco Unified CallManager Cisco Unified CallManager Express H.225 RAS (UDP) H.225 Call Setup (TCP) H.245 Call Setup (TCP) Dual RTP (UDP) Stream Gatekeeper

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v H.225 RAS Messages Location: Location Request (LRQ) Location Confirmation (LCF) Location Reject (LRJ) Admission: Admission Request (ARQ) Admission Confirmation (ACF) Admission Reject (ARJ) Disengage: Disengage Request (DRQ) Request in progress: Request in Progress (RIP) Status: Info Request (IRQ) Info Request Response (IRR) Info_Request_Acknowledge (IACK) Info_Request_Neg_Acknowledge (INAK) Discovery: Gatekeeper Request (GRQ) Gatekeeper Confirmation (GCF) Gatekeeper Reject (GRJ) Registration: Registration Request (RRQ) Registration Confirmation (RCF) Registration Reject (RRJ) Unregistration: Unregistration Request (URQ) Unregistration Confirmation (UCF) Unregistration Reject (URJ) Resource availability: Resource Availability Indicator (RAI) Resource Availability Confirmation (RAC) Bandwidth: Bandwidth Request (BRQ) Bandwidth Confirmation (BCF) Bandwidth Reject (BRJ)

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Discovery Straightforward procedure Used by an endpoint to determine with which gatekeeper it should register Uses either ot these: –Unicast discovery –Multicast discovery Gateway A Gatekeeper Gateway B GRQ (Unicast) GRQ (Multicast) GCF

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Registration Request Registration is the process by which gateways, terminals, and/or MCUs join a zone and inform the gatekeeper of their IP and alias addresses. Registration occurs after the discovery process. The H.323 gateway registers with an H.323 ID or an E.164 address. Gateway A Gatekeeper Terminal RRQ RCF

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Lightweight Registration Prior to H.323 v2, the gateway sent a full registration every 30 seconds. The gateway initializes with full registration to the gatekeeper. The gateway negotiates timers for lightweight registration with the gatekeeper. Gateways send lightweight registration based on negotiated timeout, similar to keepalive. RCF TTL RRQ Gatekeeper sends a TTL timer in an RCF message. RRQ Keepalive The gateway sends na RRQ message with Keepalive = True before the TTL timer expires.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Admission Request Gateway AGateway B H.225 Call Setup (TCP) H.245 Call Setup (TCP) Dual RTP (UDP) Stream Gatekeeper ARQ ACF ARQ ACF Dial Plan: xxxx : Gateway A xxxx : Gateway B

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Information Request The gatekeeper can use the RAS channel to obtain status information from endpoints. Status information is always triggered by a gatekeeper request. Gateway A Gatekeeper IRR IRQ

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Location Request LRQ messages are commonly used between interzone gatekeepers to get the IP of different zone endpoints. Gateway A Gatekeeper A RIP ARQ Directory Gatekeeper ACF LRQ LCF

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Signaling: LRQ Sequential LRQs are forwarded using one of two methods: –Sequential Sequential LRQs sent to a remote zone gatekeeper. Gatekeeper A will wait for a timeout before sending the next LRQ. –Blast GKA Gateway A ARQ GKB GKC GKD 1 LRQ zone local GKA cisco.com zone remote GKB cisco.com zone remote GKC cisco.com zone remote GKD cisco.com zone prefix GKB seq zone prefix GKC seq zone prefix GKD seq 2 LRQ 3 LRQ GKA = Gatekeeper A GKB = Gatekeeper B GKC = Gatekeeper C GKD = Gatekeeper D

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Signaling: LRQ Blast LRQs are forwarded using one of two methods: –Sequential –Blast Simultaneous LRQs are sent to remote zone gatekeepers. zone local GKA cisco.com zone remote GKB cisco.com zone remote GKC cisco.com zone remote GKD cisco.com zone prefix GKB blast zone prefix GKC blast zone prefix GKD blast GKA Gateway A ARQ GKB GKC GKD LRQ GKA = Gatekeeper A GKB = Gatekeeper B GKC = Gatekeeper C GKD = Gatekeeper D

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Intrazone Call Setup Gateway AGateway B GK = Phone A dials Phone B. 2 = ARQ sent. 3 = ACF returned. 4 = H.225 call is set up. 5 = H.225 call proceeding. 6 = ARQ sent. 7 = ACF returned. 8 = H.245 negotiations occur, and logical channels open. 9 = Call extended to phone. 10 = Gateway B sends call connect to gateway A. 11 = Dual RTP streams flow. Phone APhone B GK = Gatekeeper

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Interzone Call Setup Gateway A Gateway B GK GK = Phone A dials Phone B. 2 = ARQ sent. 3 = Gatekeeper 1 sends LRQ to GK2. 4 = Gatekeeper 2 returns LCF to GK1. 5 = Gatekeeper 1 returns ACF. 6 = Gateway A sends a call setup to Gateway B. 7 = Gateway B returns a call proceeding to Gateway A. 8 = Gatekeeper B sends ARQ to Gatekeeper 2. 9 = Gatekeeper 2 returns ACF to Gateway B. 10 = H.245 capability exchange and open logical channels. 11 = Gateway B sets up POTS call to Phone B. 12 = Gateway B sends a call connect to Gateway A. 13 = Dual RTP streams between gateways. Phone APhone B 12 GK1 = Gatekeeper 1 GK2 = Gatekeeper 2

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Call Disconnect Gateway AGateway B GK GK2 3 1 = Phone B hangs up. 2 = Gateway B sends DRQ to Gatekeeper 2. 3 = Gateway B sends H.225 release complete to Gateway A. 4 = Gateway A sends DRQ to Gatekeeper 1. 5 = Gateway A signals call disconnect to voice network. Phone APhone B DCF GK1 = Gatekeeper 1 GK2 = Gatekeeper 2

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Directory Gatekeepers Phone Phone Zone SanJose Zone Chicago GK1GK2 Phone Phone Dials Forwards call setup to directory gatekeeper. Forwards call setup to Phone2-2. Zone Directory Gatekeeper Forwards LRQ (call setup) to Gatekeeper 2. Forwards call setup to gateway. Cisco Unified CallManager forwards call setup to Gatekeeper 1. GK1 = Gatekeeper 1 GK2 = Gatekeeper 2

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Directory Gatekeeper Characteristics Directory gatekeepers are used for: Scaling large VoIP networks LRQ forwarding between gatekeepers Eliminating the requirement for a full mesh by having gatekeepers point to the directory gatekeeper Providing a hierarchical centralized dial plan

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Hierarchical Gatekeepers 1. Small NetworkGateways Only2. Small NetworkSimplified with a Gatekeeper 3. Medium NetworkMultiple Gatekeepers 4. Medium to Large NetworkMultiple Gatekeepers and a Directory Gatekeeper GatewayGatekeeperDirectory Gatekeeper

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Directory Gatekeeper Signaling Gateway A GK = ARQ from Gateway A to Gatekeeper 1. 2 = LRQ from Gatekeeper 1 to Directory Gatekeeper. 3 = RIP from Gatekeeper 1 to Gateway. 4 = LRQ from Directory Gatekeeper to Gatekeeper 2. 5 = LCF/LRJ from Gatekeeper 2 to Directory Gatekeeper. 6 = LCF/LRJ from Directory Gatekeeper to Gatekeeper 1. 7 = ACF/ARJ from Gatekeeper 1 to Gateway. 8 = Setup from Gateway A to Gateway B. 9 = ARQ from Gateway B to Gatekeeper = ACF/ARJ from Gatekeeper 2 to Gateway B. 11 = Alert/Connect from Gateway B to Gateway A. 12 = Gateway A and Gateway B initiate H.245 capabilities. exchange and open logical channels. 13 = Gateway B sets up POTS call to Phone B. 14 = Dual RTP streams between IP phones. DGKGK Gateway B Phone A Phone B GK1 = Gatekeeper 1 GK2 = Gatekeeper 2

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Technology Prefix Gateways can register with a gatekeeper using a technology prefix. Technology prefixes can be used to influence call routing for different services: –For example, voice calls and video calls Usually identified with the # sign, but can be any E.164 string –For example, 1# for voice calls and 2# for video calls A gatekeeper will route a call only to a gateway with a matching technology prefix: –If no technology prefix is included in the dialed number, a default technology prefix can be used.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Call Routing Technology prefix match? Zone prefix match? Target zone = matched zone Is target address registered? Default technology prefix set? Send LRQ Send ACF Hopoff technology prefix? Send ACF Send ARJ Send LRQ Send ARJ Y Y Y Y N N N Y Y Target zone = source zone? N N Y Y N N N N Y Y Y Y N N Strip technical prefix Is ARQ reject-unknown-prefix set? Is target zone local? Was a local gateway with the technology prefix found? Was a technology prefix found in step 1? Select a local gateway with the default technology prefix?

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Call Routing: Zone Prefixes and Default Technology Prefixes Local Zone: CHI Zone Prefix: 1312* Local Zone: DEN Zone Prefix: 1303* GK Gateway A Technology Prefix: 1# Gateway B Technology Prefix: 1# Phone Phone Default Technology Prefix: 1# Call to Technolgy prefix match? No Zone prefix match? Yes Target zone = DEN Is DEN a local zone? Yes registered? No Was a technology prefix found? No Default technology prefix set? 1# Select a gateway in DEN with technology prefix 1#. ARQ to ACF, destination Router GK = Gatekeeper

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Call Routing: Zone Prefixes and Technology Prefixes Local Zone: CHI Zone Prefix: 1312* Local Zone: DEN Zone Prefix: 1303* GK Gateway A Technology Prefix: 1# Dial Peer Technology Prefix: 1# Gateway B Technology Prefix: 1# Phone Phone Call to Technolgy prefix match? Yes, 1# Hopoff prefix? No Zone prefix match? Yes Target zone = DEN ARQ to 1# Is DEN local? Yes registered? No Was a technology prefix found? Yes Select a gateway in DEN with tech prefix 1#. ACF, destination Router GK = Gatekeeper

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Call Routing: Zone Prefixes and Registered Numbers Local Zone: CHI Zone Prefix: 1312* Local Zone: DEN Zone Prefix: 1303* GK Gateway A Technology Prefix: 1# Gateway B Technology Prefix: 1# E Phone Phone Technology prefix match? No Zone prefix match? Yes Target zone = DEN Is DEN a local zone? Yes registered? Yes ACF, destination Router4 ARQ to Call to GK = Gatekeeper

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Local Zone: BOS Zone Prefix: 1857* Gatekeeper Call Routing: Remote Zone Local Zone: CHI Zone Prefix: 1312* Remote Zone: BOS Zone Prefix: 1857* GK1 Gateway A Technology Prefix: 1# Phone Call to GK2 Technology prefix match? No Zone prefix match? Yes Target zone = BOS Is BOS a local zone? No LRQ to GK2, RIP to Router3ARQ to GK1 = Gatekeeper 1 GK2 = Gatekeeper 2

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Local Zone: VIDEO Zone Prefix: * Gatekeeper Call Routing: Hopoff Technology Prefix Local Zone: CHI Zone Prefix: 1312* Hopoff Prefix: 2# to Gatekeeper 2 GK1 H.323 Video Client Technology prefix match? Yes Hopoff prefix? Yes, to Gatekeeper 2 LRQ to Gatekeeper 2, RIP to endpoint ARQ to 2# Call to 2# GK2 H.320 Video Gateway Technology Prefix 2# Video Calls GK1 = Gatekeeper 1 GK2 = Gatekeeper 2

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Transaction Message Protocol GKTMP provides a transaction-oriented application protocol that allows an external application to modify gatekeeper behavior by processing specified RAS messages GKTMP provides an external application with a way to learn endpoints and call information. Multiple GKTMP servers (sometimes referred to as route servers) may exist for divided functionality, redundancy, and scalability. GKTMP is an independent platform and can run on Solaris, Linux, or Microsoft Windows.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Gatekeeper Transaction Message Protocol (Cont.) GK GKTMP GKTMP notifies an external platform when RAS messages are received by the gatekeeper. RAS messages with external interfaces: –RRQ, URQ, and GRQ: Application servers that perform endpoint authorization. –ARQ and LRQ: Provide digit translation call authorization. H.323 RAS Messages GK = Gatekeeper

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Summary Gatekeepers are optional devices that are responsible for admission control, zone management, and E.164 address translation. The gatekeeper hardware and software requirements depend on the Cisco IOS version and feature set. The initial signaling between a gateway and a gatekeeper is done through H.225 RAS. There are several RAS messages for discovery, registration, location request, and admission. Directory gatekeepers forward LRQs to gatekeepers. They are used for eliminating full-meshed gatekeeper networks.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v Summary (Cont.) Technology prefixes are used by gatekeepers to be more flexible in call routing. Default technology prefixes are used as a gateway of last resort. A gatekeeper has a logical process for call routing that depends on technology and prefix matching. Gatekeeper deployment scenarios depend on the size of the network. One gatekeeper can be responsible for one or more local zones. GKTMP provides an interface for call control of a gatekeeper.

© 2006 Cisco Systems, Inc. All rights reserved. GWGK v