Internet Engineering Task Force MAGMA WG INTERNET-DRAFT Bill Fenner/AT&T draft-ietf-magma-msnip-00.txt Hugh Holbrook/Cisco Isidor Kouvelas/Cisco 21 February 2002 Expires: August 2002 IPv4 Multicast Source Notification of Interest Protocol (MSNIP) Status of this Document This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This document is a product of the IETF MAGMA WG. Comments should be addressed to the authors, or the WG's mailing list at pim@catarina.usc.edu. Abstract This document discusses the Multicast Source Interest Notification Protocol (MSNIP). MSNIP is an extension to IGMPv3 that provides membership notification services for sources of multicast traffic. Fenner/Holbrook/Kouvelas [Page 1]
INTERNET-DRAFT Expires: August 2002 February 2002 Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . 3 2. Routing Protocol Support. . . . . . . . . . . . . . . . 3 3. API for Requesting Membership Notification. . . . . . . 4 3.1. API Usage. . . . . . . . . . . . . . . . . . . . . . 5 4. MSNIP Managed Address Range Negotiation . . . . . . . . 5 4.1. Router Coordination. . . . . . . . . . . . . . . . . 6 4.1.1. MSNIP Operation Option. . . . . . . . . . . . . . 6 4.1.2. SSM Range Option. . . . . . . . . . . . . . . . . 7 4.2. Communicating Range to Source Systems. . . . . . . . 7 5. Requesting and Receiving Notifications. . . . . . . . . 8 5.1. Host Interest Solicitation . . . . . . . . . . . . . 8 5.2. Router Receiver Membership Reports . . . . . . . . . 9 6. Application Notification. . . . . . . . . . . . . . . . 10 7. Router Processing . . . . . . . . . . . . . . . . . . . 12 8. Message Formats . . . . . . . . . . . . . . . . . . . . 14 8.1. Interest Solicitation Packet . . . . . . . . . . . . 14 8.2. Receiver Membership Report Packet. . . . . . . . . . 15 9. Constants Timers and Default Values . . . . . . . . . . 17 10. Todo list... . . . . . . . . . . . . . . . . . . . . . 17 11. Acknowledgements . . . . . . . . . . . . . . . . . . . 18 12. Authors' Addresses . . . . . . . . . . . . . . . . . . 18 13. References . . . . . . . . . . . . . . . . . . . . . . 19 Fenner/Holbrook/Kouvelas [Page 2]
INTERNET-DRAFT Expires: August 2002 February 2002 1. Introduction The Multicast Source Notification of Interest Protocol (MSNIP) is an extension to version 3 of the Internet Group Membership Protocol (IGMPv3 [1] ). MSNIP operates between multicast sources and their first- hop routers to provide information on the presence of receivers to the source systems. Using the services offered by MSNIP an application on an IP system wishing to source multicast data can register to be notified when receivers join and leave the session. This enables multicast sources to avoid the work of transmitting packets onto their first-hop link when there are no joined receivers. A common scenario where MSNIP may be useful is one where there is a multicast server offering a large pool of potential flows that map onto separate multicast destination addresses but receivers exist only for a small subset of the flows. If the source were to continuously transmit data for all the flows that could potentially have receivers, significant resources would be wasted in the system itself as well as the first-hop link. Using a higher level control protocol to determine the existence of receivers for particular flows may not be practical as there may be many potential receivers in each active session. Information on which multicast destination addresses have receivers for a particular sender is typically available to the multicast routing protocol on the first hop router for a source. MSNIP uses this information to notify the application in the sending system of when it should start or stop transmitting. This is achieved without any destination address specific state on the first-hop router for potential sources without receivers. 2. Routing Protocol Support For reasons described in this section, MSNIP only supports transmission control for applications that use multicast destination addresses that are routed using Source Specific Multicast (SSM). Many currently deployed multicast routing protocols, require data from an active source to be propagated past the first-hop router before information on the existence of receivers becomes available on the first-hop. In addition, such protocols require that this activity is repeated periodically to maintain source liveness state on remote routers. All dense-mode protocols fall under this category as well as sparse-mode protocols that use shared trees for source discovery (such as PIM-SM [3] ). In order to provide receiver interest notification for such protocols, the default mode of operation would require that the source IP system periodically transmits on all potential destination addresses and the first-hop routers prune the traffic back. Such a Fenner/Holbrook/Kouvelas Section 2. [Page 3]
INTERNET-DRAFT Expires: August 2002 February 2002 flood-and-prune behaviour on the first-hop link significantly diminishes the benefits of managing source transmission. In contrast, with source-specific sparse-mode protocols such as PIM-SSM [3] availability of receiver membership information on the first-hop routers is independent of data transmission. Such protocols use an external mechanism for source discovery (like source-specific IGMPv3 membership reports) to build source-specific multicast trees. Clearly these two classes of routing protocols require different handling for the problem MSNIP is trying to solve. In addition the second type covers the majority of applications that MSNIP is targeted at. MSNIP avoids the extra complication in supporting routing protocols that require a flood and prune behaviour. 3. API for Requesting Membership Notification Applications within an IP system that wish to source multicast packets and are interested in being notified on the existence of receivers must register with the IP layer of the system. MSNIP requires that within the IP system, there is (at least conceptually) an Application Programming Interface or API that can be used to register with the IP layer for such notifications. A system's IP API must support the following operation or any logical equivalent: IPMulticastsSourceRegister (socket, source-address, multicast-address) IPMulticastsSourceDeregister (socket, source-address, multicast-address) In addition the application must provide the following API for receiving notifications from the IP system: IPMulticastSourceStart (socket, source-address, multicast-address) IPMulticastSourceStop (socket, source-address, multicast-address) where: socket is an implementation-specific parameter used to distinguish amongst different requesting entities (e.g., programs or processes) within the system; the socket parameter of BSD Unix system calls is a specific example. source-address is the IP unicast source address that the application wishes to use in transmitting data to the specified multicast address. The specified address must be one of the IP addresses associated with the network interfaces of the IP system. Note that an interface in an IP system may be associated with more than one IP addresses. An Fenner/Holbrook/Kouvelas Section 3. [Page 4]
INTERNET-DRAFT Expires: August 2002 February 2002 implementation may allow a special "unspecified" value to be passed as the source-address parameter, in which case the request would apply to the "primary" IP address of the "primary" or "default" interface of the system (perhaps established by system configuration). If transmission to the same multicast address is desired using more than one source IP address, IPMulticastSourceRegister is invoked separately for each desired source address. multicast-address is the IP multicast destination address to which the request pertains. If the application wishes to transmit data to more than one multicast addresses for a given source address, IPMulticastSourceRegister is invoked separately for each desired multicast address. 3.1. API Usage Applications wishing to use MSNIP to control their multicast data transmission to destination G from source address S operate as follows. Initially the application contacts the IP system to obtain the socket handle for use on all subsequent interactions. The application invokes IPMulticastSourceRegister for the desired S and G and then waits without transmitting any packets for the IP system to notify that receivers for the session exist. If and when the IP system notifies the application that receivers exist using the IPMulticastSourceStart call, the application may start transmitting data. After the application has been notified to send, if all receivers for the session leave, the IP system will notify the application using the IPMulticastSourceStop call. At this point the application should stop transmitting data until it is notified again that receivers have joined through another IPMulticastSourceStart call. When the application no longer wishes to transmit data it should invoke the IPMulticastsSourceDeregister call to let the IP system know that it is no longer interested in notifications for this source and destination. The IPMulticastsSourceDeregister call should be implicit in the teardown of the associated socket state. 4. MSNIP Managed Address Range Negotiation With current multicast deployment in the Internet, different multicast routing protocols coexist and operate under separate parts of the multicast address space. Multicast routers are consistently Fenner/Holbrook/Kouvelas Section 4. [Page 5]
INTERNET-DRAFT Expires: August 2002 February 2002 configured with information that maps specific multicast address ranges to multicast routing protocols. Part of this configuration describes the subset of the address space that is used by source-specific multicast (SSM) [4]. As described in section 2 MSNIP only tries to control application transmission within the SSM address range. It is desirable for applications within an IP system that supports MSNIP to have a consistent API for multicast transmission that does require the application to be aware of the SSM address range. MSNIP supports this by allowing applications to use the API described in section 3 for multicast destination addresses that are outside its operating range. When an application registers for notifications for a destination address that is not managed by MSNIP it is immediately notified to start transmitting. This complies with the default behaviour of IP multicast without MSNIP support which forces multicast applications to assume that there are multicast receivers present in the network. 4.1. Router Coordination In order for MSNIP to operate on a shared link where more than one multicast routers may be present all multicast routers must be MSNIP capable and have a consistent configuration for the SSM address range. MSNIP enforces these requirements by using two new options in the IGMP Multicast Router Discovery protocol [5]. 4.1.1. MSNIP Operation Option A multicast router advertises that it is participating in MSNIP using the MSNIP Operation Multicast Router Discovery protocol option. This option MUST be included in all Multicast Router Advertisement messages of a router that is configured for MSNIP. The format of the option is as follows: 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=X | Length=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ A multicast router uses received Multicast Router Advertisement messages to determine if all live neighbour multicast routers on each interface are participating in MSNIP. When a Multicast Router Advertisement message not containing an MSNIP option is received by a router participating in MSNIP, a miss-configuration should be logged to the operation in a rate-limited manner. Fenner/Holbrook/Kouvelas Section 4.1.1. [Page 6]
INTERNET-DRAFT Expires: August 2002 February 2002 If even one multicast router on a link does not have MSNIP capability then ALL routers on that link MUST be configured to not provide MSNIP services and to not advertise the MSNIP Operation option. 4.1.2. SSM Range Option The SSM Range Multicast Router Discover option advertises the SSM Range with which the router is configured. The option is defined in [7]. 4.2. Communicating Range to Source Systems When an application in an IP system uses the MSNIP API to register for notification, the IP system must behave differently depending on whether or not the destination address for which the application registered is operating under SSM (and is being managed by MSNIP). For SSM channels, the IP system should only instruct the application to transmit when there are receivers for the multicast destination. For non-SSM destination addresses the IP system will not be able to determine if there are receivers and should immediately instruct the application to transmit. The MSNIP managed range discovery mechanism in a source IP system has to deal with three different link configurations: o A link connected to a multicast routed infrastructure where the first- hop multicast routers are configured for MSNIP operation. o A link connected to a multicast routed infrastructure where the first- hop multicast routers are not participating in MSNIP. o A link with no multicast routers. To be able to differentiate between the three cases and in each case discover the MSNIP managed range an MSNIP capable source IP system must process IGMP Queries as well as Multicast Router Discovery Advertisement messages. The presence of an IGMP querier differentiates between the first two cases, where the host is in a multicast routed network, and the third, where there is no multicast routing. Multicast Router Discovery Advertisements provide the differentiation between the first two cases. If the MRD Advertisements contain the MSNIP Operation option then the IP system knows that routers on that interface are configured for MSNIP operation. Fenner/Holbrook/Kouvelas Section 4.2. [Page 7]
INTERNET-DRAFT Expires: August 2002 February 2002 In each of the three cases the MSNIP managed range is defined as follows: MSNIP capable multicast routers: The IP system should use as the MSNIP range the SSM range provided by the last SSM Range option [7] received in a Multicast Router Discovery message. Multicast routers not participating in MSNIP: The IP system should use an empty MSNIP managed range. This provides a compatibility mode where all group ranges default to flooding. Link without multicast routing: The IP system should use as the MSNIP managed range the default SSM range of 232/8 defined in [6]. This allows directly connected receivers to perform the router side of the MSNIP protocol and control the source transmission within the default SSM range. 5. Requesting and Receiving Notifications Like IGMP, MSNIP is an asymmetric protocol specifying different behaviours for systems wishing to source traffic and for multicast routers. Host IP systems multicast Host Interest Solicitation messages to register for notification with their first-hop routers. Routers unicast Router Receiver Membership Reports to IP system to notify them of the arrival of the first or departure of the last receivers for a session. Note that a system may perform at the same time both of the above functions. An example is a router that wishes to source traffic. 5.1. Host Interest Solicitation Source systems that wish to be managed by MSNIP periodically transmit an Interest Solicitation message. This message is multicast with a multicast destination address of ALL_IGMPv3_ROUTERS (224.0.0.22) and is transmitted every [Interest Solicitation Interval] seconds. The Interest Solicitation message contains a holdtime which is set to [Interest Solicitation Holdtime] and instructs the multicast first-hop routers to maintain MSNIP state for this IP system for the specified period. A generation ID is also included in the Interest Solicitation message to provide support for routers to detect IP system crashes (see section 8.1). When an IP system first comes up it transmits [Robustness Variable] Interest Solicitation messages randomly spaced over [Initial Interest Solicitation Interval] seconds. Fenner/Holbrook/Kouvelas Section 5.1. [Page 8]
INTERNET-DRAFT Expires: August 2002 February 2002 All MSNIP capable routers that receive an Interest Solicitation message from an IP system, maintain a system interest record of the form: (IP system address, holdtime timer) Each time an Interest Solicitation message is received from the IP system, the holdtime timer is reset to the holdtime in the received message. In addition the router responds to the solicitation message with a Receiver Membership Report message described in section 5.2. The message contains a TRANSMIT record for each of the multicast destination addresses within the MSNIP managed range for which the routing protocol indicates there are receivers for this source system. When the holdtime timer of a specific system interest record expires, the record is deleted. 5.2. Router Receiver Membership Reports Receiver Membership Report messages are used by routers to communicate the receiver membership status of particular multicast destination addresses to a specific IP system. Each message contains a list of transmission control records of either TRANSMIT or HOLD type that instruct a system to respectively start or stop sending traffic on this link to the specified multicast destination address. Receiver Membership Report messages are unicast to the target system. In addition to the receipt of an Interest Solicitation message, routers send unsolicited Receiver Membership Reports to IP systems when the receiver membership status reported by the multicast routing protocol changes for a specific source and multicast destination. Such reports are only sent if the destination address is managed by MSNIP and the router has a system interest record created by a previously received Interest Solicitation message with a IP system address equal to the source address. If the source destination pair satisfy these conditions then [Robustness Variable] Receiver Membership Reports are sent out within [Unsolicited Membership Report Interval] seconds. If during the [Unsolicited Membership Report Interval] an additional membership change occurs for the same destination address and source system, transmission of any related pending Receiver Membership Report messages is cancelled and a new set of [Robustness Variable] messages is scheduled. When an IP system receives a Receiver Membership Report message, for each of the TRANSMIT records listed in the message it creates or updates a transmission record of the form: (router address, source address, multicast address, holdtime timer) Fenner/Holbrook/Kouvelas Section 5.2. [Page 9]
INTERNET-DRAFT Expires: August 2002 February 2002 The router address is obtained from the source address on the IP header of the received message. The source address is obtained from the destination address in the of the IP header. The holdtime timer is set to [Interest Solicitation Holdtime] seconds. For each HOLD record present in the message, the system deletes the matching previously created transmission record from its state. Note that creation and deletion of transmission records in an IP systems state may cause local applications to be notified to start and stop transmitting data (see section 6). 6. Application Notification This section describes the relation between protocol events and notifications to source applications within an IP system. The state machine below is specific to each source address of the IP system and each multicast destination address. The initial state is the No Info state. +-----------------------------------+ | Figures omitted from text version | +-----------------------------------+ Figure 1: Per source-address (S) and multicast destination address (G) state machine at an IP system Fenner/Holbrook/Kouvelas Section 6. [Page 10]
INTERNET-DRAFT Expires: August 2002 February 2002 In tabular form, the state-machine is: +-----------+-----------------------------------------------------------+ | | Event | | +----------+-----------+------------+-----------+-----------+ |Prev State |New |Start |Stop |Recv |Recv last | | |Register |Manage |Manage |TRANSMIT |HOLD or | | | | | | |timeout | +-----------+----------+-----------+------------+-----------+-----------+ | |Start new |-> Hold |- |- |- | |No Info | |Stop ALL | | | | | | |registered | | | | +-----------+----------+-----------+------------+-----------+-----------+ | |- |- |-> No Info |-> |- | |Hold | | | |Transmit | | | | | |Stop ALL |Start ALL | | | | | |registered |registered | | +-----------+----------+-----------+------------+-----------+-----------+ | |Start new |- |-> No Info |- |-> Hold | |Transmit | | | | |Stop ALL | | | | | | |registered | +-----------+----------+-----------+------------+-----------+-----------+ The events in state machine above have the following meaning: New register A new application has registered through a call to IPMulticastsSourceRegister for this S and G. Start manage We received a SSM Range option in an MRD packet on the interface that S belongs to that changed the status of G from a non-managed to a MSNIP managed destination address. Stop manage We received a SSM Range option in an MRD packet on the interface that S belongs to that changed the status of G from a MSNIP managed to a non-managed destination address or the mapping state that caused this destination address to be managed expired. Receive TRANSMIT We received a Receiver Membership Report with S as the IP destination address that contains a TRANSMIT record for G. Fenner/Holbrook/Kouvelas Section 6. [Page 11]
INTERNET-DRAFT Expires: August 2002 February 2002 Receive last HOLD or timeout We either received a Receiver Membership Report with S as the IP destination address that contains a HOLD record for G or a TRANSMIT record for S and G expired and there are no other TRANSMIT records for S and G. This means that the last router that was reporting receivers no longer does so and there are no routers left wishing to receive traffic from this S to destination address G. The state machine actions have the following meaning: Start new Send an IPMulticastSourceStart notification to the application that just registered for this S and G. Start ALL registered Send an IPMulticastSourceStart notification to all applications that are registered for this S and G. Stop ALL registered Send an IPMulticastSourceStop notification to all applications that are registered for this S and G. 7. Router Processing This section describes the per-source system tracking state machine operated by each first-hop router. The initial state is No Info. +-----------------------------------+ | Figures omitted from text version | +-----------------------------------+ Figure 2: Per IP source system (S) state machine at a router Fenner/Holbrook/Kouvelas Section 7. [Page 12]
INTERNET-DRAFT Expires: August 2002 February 2002 In tabular form, the state-machine is: +------------+----------------------------------------------------------+ | | Event | | +------------+-----------+--------------+------------------+ |Prev State | Receive | HIS | Receivers | Receivers | | | HIS | timeout | for new | of G leave | | | | | destination | | | | | | G | | +------------+------------+-----------+--------------+------------------+ | | -> | - | - | - | | | Tracking | | | | | | Set HT to | | | | |Not | message | | | | |tracking | holdtime | | | | | | Send ALL | | | | | | existing | | | | | | TRANSMITs | | | | +------------+------------+-----------+--------------+------------------+ |Tracking | Set HT to | -> Not | Send | Send HOLD | | | message | tracking | TRANSMIT | for G | | | holdtime | | for G | | +------------+------------+-----------+--------------+------------------+ The events in state machine above have the following meaning: Receive HIS The router has received a Host Interest Solicitation from S. HIS timeout The holdtime timer (HT) associated with S has expired. Receivers for new destination G The routing protocol has informed MSNIP that it now has receivers for the MSNIP managed destination address G and source IP system S. Receivers of G leave The routing protocol has informed MSNIP that all receivers for the MSNIP managed destination address G and source IP system S have left the channel. The state machine actions have the following meaning: Fenner/Holbrook/Kouvelas Section 7. [Page 13]
INTERNET-DRAFT Expires: August 2002 February 2002 Set HT to message holdtime The holdtime timer associated with S is restarted to the value of the holdtime in the received Host Interest Solicitation message. Send ALL existing TRANSMITs The router builds and transmits Receiver Membership Reports to S that contain a TRANSMIT record for each of the MSNIP managed destination addresses that have receivers for S. Send TRANSMIT for G The router builds and transmits a Receiver Membership Report to S that contains a TRANSMIT record for the destination address G. Send HOLD for G The router builds and transmits a Receiver Membership Report to S that contains a HOLD record for the destination address G. 8. Message Formats Like all other IGMP messages, MSNIP messages are encapsulated in IPv4 datagrams, with an IP protocol number of 2. Every MSNIP message described in this document is sent with an IP Time-to-Live of 1, and carries an IP Router Alert option [RFC-2113] in its IP header. There are two IGMP message types of concern to the MSNIP protocol described in this document: +-------------------+----------------------------+ | Type Number (hex) | Message Name | +-------------------+----------------------------+ | 0x23 | Interest Solicitation | +-------------------+----------------------------+ | 0x24 | Receiver Membership Report | +-------------------+----------------------------+ 8.1. Interest Solicitation Packet A Interest Solicitation packet is periodically multicast by MSNIP capable systems to declare interest in Receiver Membership Reports from multicast routers on the link. The Interest Solicitation message is multicast with a destination address of ALL_IGMPv3_ROUTERS (224.0.0.22). Fenner/Holbrook/Kouvelas Section 8.1. [Page 14]
INTERNET-DRAFT Expires: August 2002 February 2002 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 = 0x24 | Reserved | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Holdtime | GenID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved Transmitted as zero. Ignored upon receipt. Checksum Calculated as for Range Map packet. Holdtime The amount of time a receiving router must keep the system interest state alive, in seconds. GenID Generation ID of the IP system. A number that is selected randomly for each of the [Robustness Variable] initial Interest Solicitation messages when the system comes up and afterwards remains fixed to the value used in the last of the initial messages throughout the system lifetime. The GenID is used by routers to detect system crashes. 8.2. Receiver Membership Report Packet A Receiver Membership Report packet is unicast by first-hop multicast routers and targeted at potential sources to inform them of the existence or not of receivers for the listed multicast destination addresses. Fenner/Holbrook/Kouvelas Section 8.2. [Page 15]
INTERNET-DRAFT Expires: August 2002 February 2002 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 = 0x25 | Dest Count | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Record-Type-1 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination-Address-1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . | | . | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Dest Count The number of multicast destination address records present in this message. Checksum Calculated as for Range Map packet. Record-Type-1 The type of the first transmission control record in this message. Valid values are: +-------------+----------------------------------------------+-------+ | Record Type | Description | Value | +-------------+----------------------------------------------+-------+ | TRANSMIT | Request to start transmitting to destination | 1 | +-------------+----------------------------------------------+-------+ | HOLD | Request to stop transmitting to destination | 2 | +-------------+----------------------------------------------+-------+ Reserved Transmitted as zero. Ignored upon receipt. Destination-Address-1 The multicast destination address of the first record in the message. Fenner/Holbrook/Kouvelas Section 8.2. [Page 16]
INTERNET-DRAFT Expires: August 2002 February 2002 9. Constants Timers and Default Values Robustness Variable The Robustness Variable allows tuning for the expected packet loss on a network. If a network is expected to be lossy, the Robustness Variable may be increased. MSNIP is robust to (Robustness Variable - 1) packet losses. The Robustness Variable MUST NOT be zero, and SHOULD NOT be one. Default: 2 Interest Solicitation Interval The interval used by MSNIP capable systems between transmissions of Interest Solicitation messages. Default: 60 secs Interest Solicitation Holdtime The interval inserted in Interest Solicitation messages by systems to instruct routers how long they should maintain system interest state for. This MUST be ((the Robustness Variable) times (the Interest Solicitation Interval) plus (one second)). Initial Interest Solicitation Interval The interval used by systems to send out the initial Interest Solicitation messages when they first come up. Default: 1 second. Unsolicited Membership Report Interval The interval used by routers to send out a set of Membership Report messages when the receiver membership changes for a specific system. Default: 1 second. 10. Todo list... o Add security considerations section. o If application ignores or does not ask for notification in managed range host OS should filter packets. o Maybe provide masks for registration / notification API. Fenner/Holbrook/Kouvelas Section 10. [Page 17]
INTERNET-DRAFT Expires: August 2002 February 2002 o When we hear out-of-order IGMP query resend interest registration. o Only send interest registration when application is interested. This is not possible if we do host filtering... o Maybe add API to ask the kernel for the state of a particular destination. bool IpMulticastSourceHasInterest (socket, source- address, multicast-address). o Add GenID changes to router FSM. 11. Acknowledgements The authors would like to thank Dave Thaler and Jon Crowcroft for their contribution to this specification. 12. Authors' Addresses Bill Fenner AT&T Labs - Research 75 Willow Road Menlo Park, CA 94025 fenner@research.att.com Hugh Holbrook Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 holbrook@cisco.com Isidor Kouvelas Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 kouvelas@cisco.com Fenner/Holbrook/Kouvelas Section 12. [Page 18]
INTERNET-DRAFT Expires: August 2002 February 2002 13. References [1] B. Cain, S Deering, W. Fenner, I Kouvelas, A. Thyagarajan, "Internet Group Management Protocol, Version 3", Work In Progress, <draft- ietf-idmr-igmp-v3-05.txt>, 2000. [2] S. Kent, R. Atkinson, "Security Architecture for the Internet Protocol.", RFC 2401. [3] B. Fenner, M. Handley, H. Holbrook, I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", Work In Progress, <draft-ietf-pim-sm- v2-new-??.txt>, 2002. [4] Z. Albanna, K. Almeroth, D. Meyer, "IANA Guidelines for IPv4 Multicast Address Allocation", Best Current Practices, <draft-ietf- iana-IPv4-mcast-guidelines-00.txt>, 2001. [5] S. Biswas, B. Haberman, "IGMP Multicast Router Discovery", Work In Progress, <draft-ietf-idmr-igmp-mrdisc-08.txt>, 2001. [6] H. Holbrook, B. Cain, "Source-Specific Multicast for IP", work in progress, <draft-ietf-ssm-arch-00.txt>, 21 November 2001. [7] I. Kouvelas, "Multicast Router Discovery SSM Range Option", work in progress, <draft-ietf-magma-mrdssm-00.txt>, February 2002. Fenner/Holbrook/Kouvelas Section 13. [Page 19]
INTERNET-DRAFT Expires: August 2002 February 2002 Fenner/Holbrook/Kouvelas Section 13. [Page 20]
