Multicast Source Filter API draftietfidmrmsfapi00 txt Dave Thaler

Multicast Source Filter API draft-ietf-idmr-msf-api-00. txt Dave Thaler (Microsoft) Bill Fenner (AT&T Research) Bob Quinn (Stardust. com)

Goals • Express multicast source filters for IPv 4 and IPv 6 • Provide version-independent API not present in RFC 2553 • Basic (delta-based) version for most uses • Advanced version for large atomic operations, switching modes, etc. • Minimize changes to existing API

Existing IPv 4 Multicast API struct ip_mreq { struct in_addr imr_multiaddr; /* IP multicast address of group */ struct in_addr imr_interface; /* local IP address of interface */ }; socket options: IP_{ADD, DROP}_MEMBERSHIP

Semantics of Existing API • “Delta”-based – To join/leave a set of (sub)set of groups, call API once for each group to join or leave • NOT “final-state” based (don’t specify new set of groups to be joined to) • Often join multiple groups (e. g. , different media), but this is not a problem

Structure for new IPv 4 basic operations struct ip_mreq_source { struct in_addr imr_multiaddr; /* group address */ struct in_addr imr_sourceaddr; /* source address */ struct in_addr imr_interface; /* iface address*/ };

Socket Operations (setsockopt) • IP_{ADD, DROP}_SOURCE_MEMBERSHIP for inclusion list changes • IP_{ADD, DROP}_MEMBERSHIP existing API for exclude mode • IP_{ALLOW, BLOCK}_SOURCE - for exclusion list changes

Semantics of Basic API • For source-inclusion, just do IP_ADD_SOURCE_MEMBERSHIP per source • For source-exclusion, do IP_ADD_MEMBERSHIP, and IP_DROP_SOURCE_MEMBERSHIP per source • Functionally equivalent to abstract API • Always delta-based so more consistent with existing API

Advanced API • Basic API doesn’t let app switch modes without leaving group • Basic API is very inefficient with large source lists • Advanced API is final-state based: just set the complete filter

Structure for advanced IPv 4 operations struct ip_msfilter { struct in_addr imsf_multiaddr; /* group address */ struct in_addr imsf_interface; /* iface address */ uint 32_t imsf_fmode; /* filter mode */ uint 32_t imsf_numsrc; /* # sources */ struct in_addr imsf_slist[1]; /* source list */ }; #define IP_MSFILTER_SIZE(numsrc). . . (size of buffer with numsrc sources in list) fmode=MCAST_{INCLUDE, EXCLUDE}

Socket Operations • setsockopt: – IP_MULTICAST_FILTER • ioctl: – SIO_GET_MULTICAST_FILTER • Open issue: change set to ioctl SIO_SET_MULTICAST_FILTER?

Protocol-Independent API • E. g. Resolve DNS name to sockaddr • Could be v 4 or v 6, want to use same API in spirit of RFC 2553 • Just need to use structures containing sockaddr_storage instead of addresses • Use indices to identify interfaces (not addresses!) as in current IPv 6 -specific API.

Basic Structures struct ip_mcast_req { uint 32_t imr_interface; struct sockaddr_storage imr_group; }; struct ip_mcast_source_req uint 32_t struct sockaddr_storage }; { imsr_interface; imsr_group; imsr_source;

Advanced Structure struct ip_mcast_filter { uint 32_t struct sockaddr_storage }; imf_interface; imf_group; imf_fmode; imf_numsrc; imf_slist[1]; #define IP_MCAST_FILTER_SIZE(numsrc). . . (size of buffer with numsrc sources)

Socket Operations • setsockopt: – IP_{JOIN, LEAVE}_GROUP_SOURCE – IP_{BLOCK, ALLOW}_SOURCE • ioctl – SIO_{GET, SET}_MULTICAST_FILTER