Internet Engineering Task Force C.Y. Lee INTERNET DRAFT Nortel 24 March 1998 PIM-SM over ATM and Proxy PAR Status of This Memo This document is an Internet Draft, Internet Drafts are working documents of the Internet Engineering Task Force (IETF), its Areas, and its Working Groups. Note that other groups may also distribute working documents as Internet Drafts. Internet Drafts are draft documents valid for a maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material, or to cite them other than as a ``working draft'' or ``work in progress.'' Please check the I-D abstract listing contained in each Internet Draft directory to learn the current status of this or any other Internet Draft. Abstract This document describes how PIM-SM [PIM-SM, PIM] operates in ATM networks in the presence of Proxy PAR. [PPAR, OSPF_PPAR]. The mechanisms described allow for simpler, more efficient and cost-effective network designs. 2. Scope 2.1 Scoping PIM-SM over Proxy PAR PIM-SM over Proxy PAR [PPAR] is scoped to prevent information from being flooded unnecessarily throughout the ATM network. In this document, the PAR advertisement for PIM-SM would be limited to PIM-SM scope only (level 60 only as shown in Figure 1). These advertisements may be propagated to the BGMP scope (level 40 in Figure 1) but the purpose and mechanism is beyond the scope of this document. +-+ | | PNNI peer group # PPAR capable @ PNNI capable * Router +-+ switch switch leecy Expires 24 September 1998 [Page 1] Internet Draft PIM-SM over ATM and Proxy PAR 22 March 1998 Level 40 - BGMP +---------------------------+ | | | | | @ ---- @ ---- @ | | | | | +----- | ----------- | -----+ | | Level 60 - PIM-SM | | Level 60 - PIM-SM +------------- | ---+ +-- | --------------+ | | | | | | R1* ------#-P1------@ | | @---------P3-#------- * R3 | | | | | | R2* ------#-P2------+ | | +---------P4-#------- * R4 | | | | +-------------------+ +-------------------+ Figure 1: Scoping PIM-SM and BGMP over Proxy PAR (ATM Topology) (Modified for IP multicasting from [PPAR]) 2.2 Model This document describes 2 different models for PIM-SM over ATM. The first, Model A is the same model described in [INTRALIS]. The document [INTRALIS] requires that "each router within a LIS knows IP and ATM addresses of all other routers within the LIS" but the mechanism to obtain this information is not specified. Section A of this document describes how Proxy PAR can be used by PIM-SM routers to auto discover their peers in a LIS (Logical IP Subnet) [IPOA]. The second Model B (FFS now), described in Section B is based on [INTRALIS], with the following differences: - this section describes multicasting over ATM within a PIM-SM routing domain - the mechanisms proposed in this section do not require a priori fully meshed distribution (point-to-multipoint) VC to exist among the routers in a LIS. - LIJ (Leaf Initiated Join) [AF-UNI] is used to setup point to multipoint VCs. 3. Section A 3.1 Auto Configuring PIM-SM routers Each PIM-SM router in a LIS is configured with its own IP address, mask, and router priority. This configuration information is leecy Expires 24 September 1998 [Page 2] Internet Draft PIM-SM over ATM and Proxy PAR 22 March 1998 bound to a local ATM end point address and registered by the router (Proxy PAR client) to the Proxy Server. Proxy PAR server detection is described in [ILMIDET]. The Proxy PAR server then flood the registered router information. A router may query the server to get information about other routers in the ATM cloud. Once the configuration information about each PIM-SM router in the LIS is learned via Proxy PAR, the shared distribution VCs described in [INTRALIS] may be setup. In PIM-SM a DR router is elected on a multi-access network using the Hello mechanism, the router with the largest network address assumes the role of DR. (With Hello extensions [HELLO_EXT], the Router with the highest priority will be elected). When PIM-SM is run over Proxy PAR the exchange of these Hellos to elect a DR may be replaced by Proxy PAR advertisements. 3.2 Service Definition of PIM-SM routers Each router register configuration information for each NSAP (ATM address) in the UNI Service IG. Within each UNI Service IG, a router register its routing protocol service, PIM-SM in this case, in the UNI IPv4 Service Definition IG and the PIM-SM specific configuration parameters in the UNI PIM-SM IPv4 Service Definition IG as shown in the figures below. This IG is then registered with the Proxy PAR server at the appropriate scope. If any of the parameters in the IG is changed, the client must reregister the new parameters with the Proxy PAR server. A - UNI Service IG B - UNI IPv4 Service Definition IG C - UNI PIM-SM IPv4 Service Definition IG <---------------------------- A --------------------------------> <------- B ---------> .... <----- B -------> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | C | ..... | C | .... | C | .... | C | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: PNNI IG (Information Groups) used by PIM-SM over Proxy PAR 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=784 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP instance | Padding | leecy Expires 24 September 1998 [Page 3] Internet Draft PIM-SM over ATM and Proxy PAR 22 March 1998 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP Address Mask | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Service Mask | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: UNI IPv4 Service Definition IG (Note: The UNI IPv4 Service Definition IG is reproduced here from [AF-PPAR] to illustrate its use) Type IG Type IP Instance The IP instance PIM-SM is registered for IP Address The IP address or IP address prefix PIM-SM is registered for IP Address Mask Contiguous mask fo the IP address/prefix. Service Mask Bitmask of registered services, Bit 11 = PIM-SM 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type=804 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Priority | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: UNI PIM-SM Service Definition IG Type 804 Length Length of IG Priority Used for DR election 4. Section B Editor's Note: This section is FFS. If the RP for the group in the multicast routing domain can be determined by querying the DNS as proposed in [STATIC_MCAST], Proxy PAR may be used to discover the DNS server in the ATM network. The only requirement is that a least one DNS server must be located within or attached to the ATM network. Using DNS to locate the RP reduces the amount of routing control leecy Expires 24 September 1998 [Page 4] Internet Draft PIM-SM over ATM and Proxy PAR 22 March 1998 information (BSR and C-RP advertisements) that must be flooded in the WAN and reduces the number of VCs required among routers. If a VC to the upstream router does not yet exist : A PIM-SM Join to an upstream router is preceeded by a LIJ to the upstream router : 1) if using a group shared point to multipoint VC, (224.0.0.1) is specified as the connection idenfifier in the LEAF SETUP MESSAGE. 2) if requiring a dedicated group specific point to multipoint VC [INTRALIS], Group specific Joins can be communicated to the upstream router using ATM LIJ, Leaf Initiated Join (specifying the IP multicast address as the LIJ connection identifier to the upstream router which is the root of the pt-mpt VC. In both cases, the ATM address of the upstream router may be obtained from Proxy PAR and must be specified in the LEAF SETUP MESSAGE. Note that LIJ to (224.0.0.1) is only setup if the LIJ VC does not exist. The upstream router will then establish a LIJ to the (224.0.0.1) to the downstream router. This will allow the PIM-SM Join to be sent to the upstream router. The need to establish a VC to the downstream router is either implicit in the connection identifier and/or additonal signalling information may be defined (eg B-LLI). The above procedures do not require a priori fully meshed distribution (point-to-multipoint) VC to exist among the routers in a LIS. The rules concerning eg. "Switching to a Source-Rooted Tree, Adding New Members to a Source-Rooted Tree, Handling the Packet Relection Problem" specified in [INTRALIS] still apply here. VC management relating to VC establishment and tear-down, VC sharing. will be discussed in more detail in the next version of the draft. 5. Acknowledgments Comments and contributions from Tony Przygienda and Patrick Droz are included in this work. Tony Przygienda suggested the use of LIJ to setup point to multipoint VC. The use of Join to setup VC was first proposed in [INTRALIS]. Thanks to Ahmed Helmy and Dave Thaler for clarifying the details of PIM-SM. 6. Security Consideration Security issues are not discussed in this memo. leecy Expires 24 September 1998 [Page 5] Internet Draft PIM-SM over ATM and Proxy PAR 22 March 1998 References [AF-PPAR] T. Przygienda and P. Droz. Proxy PAR Specification. ATM Forum 97-0495, 97-0705, 97-0882, July 1997. [PPAR] T. Przygienda and P. Droz. Proxy PAR, Internet Draft, November 1997 [OSPF_PPAR] T. Przygienda and P. Droz. OSPF over ATM and Proxy PAR, Internet Draft, October 1997 [AF-ILMI] ATM-Forum. Interim Local Management Interface (ILMI) Specification 4.0. ATM Forum 95-0417R8, June 1996. [AF-PNNIV1] ATM-Forum. Private Network-Network Interface Specification Version 1.0. ATM Forum af-pnni-0055.000, March 1996. [AF-UNI] ATM-Forum. Private Network-Network Interface Specification Version 4.0. ATM Forum af-sig-0061.000, July 1996. [AF-PNNIV2] ATM-Forum. Private Network-Network Interface Specification Version 2.0. ATM Forum LTD-PNNI-02.00 December 1997. [PIMSM] Estrin, Farinacci, Helmy, Thaler, Deering, Handley, Jacobson, Liu, Sharma, and Wei. Protocol independent multicast-sparse mode (PIM- SM): Specification. Internet Draft, September 1996. [INTRALIS] D. Farinaccci, D. Meyer, Y. Rekhter Intra-LIS IP multicast among routers over ATM using Sparse Mode, Internet Draft, 1997 [STATIC_MCAST] M. Ohta, J. Crowcroft Static Multicast, Internet Draft, March 1998 [PAR] R. Callon and al. An Overview of PNNI Augmented Routing. ATM Forum 96-0354, April 1996. [OPAQUE] R. Coltun and J. Heinanen. Opaque LSA in OSPF. Internet Draft, 1997. [AF-MIPAR] R. Coltun, T. Przygienda, and S. Shew. MIPAR: Minimal PNNI Augmented Routing. ATM Forum 96-0838, June 1996. [ILMI] M. Davison. Simple ILMI-Based Server Discovery. Internet Draft, 1997. leecy Expires 24 September 1998 [Page 6] Internet Draft PIM-SM over ATM and Proxy PAR 22 March 1998 [IPOA] M. Laubach. Classical IP and ARP over ATM, RFC 1577. January 1994. [SIG_IPOA] ATM Signalling Support for IP over ATM, RFC 1755, February 1995. [OSPF94] J. Moy. OSPFv2, RFC 1583. March 1994. [DEMAND] J. Moy. Extending OSPF to Support Demand Circuits, RFC 1793. April 1995. [OSPF98] J. Moy. OSPFv2, RFC 2178. July 1997. [MARS] G. Armitage. Support for Multicast over UNI 3.0/3.1 based ATM Networks, RFC 2022. November 1996. Authors' Addresses Cheng-Yin Lee Nortel PO Box 3511, Station C Ottawa, ON K1Y 4H7 Canada leecy@nortel.ca leecy Expires 24 September 1998 [Page 7]