1. ACHIEVING MULTIMEDIA QOS OVER HYBRID IP/PSTN INFRASTRUCTURES QOS Signalling and Media Gateway Control ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004 Tom Taylor -- taylor@nortelnetworks.com

2. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 1 Contents RSVP as the bandwidth reservation signalling protocol –New RSVP policy objects to help MGC and MG at the IP-PSTN boundary –Media gateway control –Separate paths for signalling and media Fitting RSVP into the media gateway control picture Supplementary Material –Detailed operation of RSVP signalling

3. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 2 Why RSVP? The need: ensure network expedites real- time media flows The network can't do it alone –the output from many real-time apps is difficult to identify The network needs help from the application –signalled QoS is a requirement RSVP works with all applications and signaling protocols –e.g., SIP, H.323

4. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 3 Reservation Parameters User Authentication (AUTH_USER) Application Identification (AUTH_APP) –  Solves application flow classification issues  DCLASS (DSCP) TCLASS (802.1p) SENDER_TSPEC / FLOW_SPEC –Token Bucket Rate, Token Bucket Size, Peak Data Rate SENDER_TEMPLATE / FILTER_SPEC –Source IP Address and Port number SESSION –Destination IP Address and Port number

5. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 4 Where is RSVP implemented? IP Phones, SoftPhones, IPT Gateways (Hosts) –Host signals network for desired QoS –Implement simple Host RSVP with Policy extensions Policy Enforcement Point (PEP) Routers –Edge routers maintain BW reservations for microflows –Core routers use DiffServ or TE’d paths –Implement COPS-for-RSVP client Policy Decision Point (PDP) Policy Server –Provides Policy Decisions to Network Elements and Hosts –Implement COPS-for-RSVP server

6. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 5 Architectural View DiffServ Domain DS Interior Nodes Ingress PEP Policy Server (PDP) Egress PEP Host 2 Host 1 Access Network

7. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 6 The Decomposed Gateway Model PSTN IP Network Media Gateway Controller Host Media Gateway Gatekeeper, Proxy, etc. Call Signalling Media Flows Gateway Control

8. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 7 Media Gateway Control and RSVP Media Gateway Controller both have to be involved in RSVP signalling –MGC has to handle authorization, billing –MGC knows other information (e.g. application class, destination address) –but RSVP messaging has to follow path of media flow -- most easily done if sent by MG Implies requirement for Megaco/H.248 package to pass necessary information from MGC to MG Only need QOS awareness at ingress and egress points No need for any intermediate call signalling entity to get involved

9. Supplementary Material Detailed operation of RSVP signalling These slides were taken from a presentation by Ralph Santitoro, Director of QoS Architecture, Nortel

10. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 9 RSVP Signaling Architectural Overview Hosts initiate and respond to RSVP messages –Reservation initiation, failure, termination or network policy change Edge Routers Police BW and Policy Reservations –DS Edge Routers maintain RSVP soft-state –DS Core Routers do not maintain RSVP soft-state Use DiffServ or TE’d paths to provide QoS assurances in the core Admission Control decided by Policy Server (PDP) or Router LDP RSVP messages flow end-to-end RSVP Reservations must be made separately in each directions RSVP-enabled hosts benefit –Non-RSVP-aware hosts either: Achieve no QoS Use other access technology-specific QoS Use proprietary mechanisms

11. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 10 RSVP Reservation - DS Edge Node DiffServ Domain DS Interior Nodes Ingress PEP Policy Server (PDP) Egress PEP 2. COPS-RSVP 2. Path Message encapsulated in COPS-RSVP message. PDP instructs ingress PEP to forward Path Msg. and keep soft-state for reservation  3. P-HOP 3. Ingress PEP adds egress interface to P-HOP (Route pinning). Router Alert Option disabled. 4. DS Interior Nodes forward Path Message 4. Path 5. Egress PEP processes Path Msg. and enables Router Alert Option 5. Process Path Msg.  If no BW is available for reservation, PEP initiates Path failure 1. Path 1. Host 1 initiates Path Msg. Host 2 Host 1 Access Network

12. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 11 RSVP Reservation - DS Edge Node (cont.) DiffServ Domain DS Interior Nodes Ingress PEP Policy Server (PDP) Egress PEP 8. COPS-PR 8. If reservation succeeds, PDP sends new filters down to PEP 9. COPS-RSVP 9. Resv message sent by Ingress PEP to PDP to confirm reservation. PDP can return DCLASS object to be sent in Resv msg. sent to Host 1. 7. COPS-RSVP 7. If no BW available, PDP informs Egress PEP to generate ResvErr to Host 1. If reservation accepted, Egress PEP forwards Resv to Host 1. Path 6. Resv 6. Host 2 generates Resv Msg. Host 1 Host 2 Access Network

13. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 12 RSVP Reservation - DS Edge Node (cont.) DiffServ Domain DS Interior Nodes Ingress PEP Policy Server (PDP) Egress PEP 10. COPS-PR 10. PDP sends new filters down to PEP. 11. Resv 11. Ingress PEP accepts reservation by sending RESV message to Host 1. If PDP rejected reservation, PEP sends ResvErr back to interface specified inside RSVP N-HOP object. Path Host 1 Host 2 Access Network

14. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 13 DS Domain 1 DS Interior Node Ingress Edge PEP Egress Edge PEP DS Domain 2 Boundary PEP Policy Server (PDP) DS Interior Node Path 4a. COPS-RSVP 4a. Path Msg. encapsulated in COPS-RSVP message. PDP instructs boundary PEP to forward Path Msg. and keep soft-state for reservation  RSVP Reservation - DS Boundary Node The following steps are introduced into the reservation if there are RSVP-capable Boundary Nodes interconnecting DS Domains  If no BW is available for reservation, PEP initiates Path failure 4c. DS Interior Nodes forward Path Message 4c. Path 4b. Boundary PEP adds its egress interface to RSVP P-HOP object 4b. New P-HOP Host 1 Host 2 Access Network

15. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 14 DS Domain 1 DS Interior Node Ingress Edge PEP Egress Edge PEP DS Domain 2 Boundary PEP Policy Server (PDP) DS Interior Node Path Resv RSVP Reservation - DS Boundary Node (cont.) 8a. If no BW available, PDP informs boundary PEP to generate ResvErr to Host 1. If reservation accepted, Egress PEP forwards Resv to Host 1. 8a. COPS-RSVP Path 8b. COPS-PR 8b. If reservation succeeds, PDP sends new filters down to PEP 8c. Resv 8c. Boundary PEP admits reservation by sending RESV message to Host 1. If PDP rejected reservation, PEP sends ResvErr back to interface specified in RSVP N-HOP object. Host 1 Host 2 Access Network

16. PTT: 26 Apr 2001ITU-T SG13/SG16 Workshop on IP Networking and Mediacom 2004, - 15 References “Resource ReSerVation Protocol (RSVP), RFC 2205 “Identity Representation for RSVP”, RFC 2752 “RSVP Extensions for Policy Control”, RFC 2750 “COPS usage for RSVP”, RFC 2749 “Application and Sub Application Identity Policy Element for Use with RSVP”, RFC 2872 “Format for RSVP DCLASS Object”, RFC 2996 “Standardized Application Identifiers for RSVP Identity Policy Element”, draft-santitoro-rap-policy-appids-01.txt “New RSVP ErrorValues to Modify Sender Behavior”, draft- santitoro-rap-policy-errorcodes-01.txt “Session Authorization for RSVP”, draft-hkg-rap-rsvp- authsession-00.txt “Session setup with media authorization”, draft-hamer-sip- session-auth-00.txt