Multicast%20Source%20Filter%20API%20%20%20draft-ietf-idmr-msf-api-00.txt

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Multicast Source Filter API
draft-ietf-idmr-msf-api-00.txt

• Dave Thaler (Microsoft)
• Bill Fenner (ATT Research)
• Bob Quinn (Stardust.com)

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Goals

• Express multicast source filters for IPv4 and
  IPv6
• 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

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Existing IPv4 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

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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 (dont specify new set of
  groups to be joined to)
• Often join multiple groups (e.g., different
  media), but this is not a problem

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Structure for new IPv4 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/

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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

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Semantics of Basic API

• For source-inclusion, just do IP_ADD_SOURCE_MEMBER
  SHIP 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

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Advanced API

• Basic API doesnt 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

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Structure for advanced IPv4 operations

• struct ip_msfilter
• struct in_addr imsf_multiaddr / group
  address /
• struct in_addr imsf_interface / iface
  address /
• uint32_t imsf_fmode / filter mode
  /
• uint32_t imsf_numsrc / sources
  /
• struct in_addr imsf_slist1 / source list
  /
• define IP_MSFILTER_SIZE(numsrc) ...
• (size of buffer with numsrc sources in list)
• fmodeMCAST_INCLUDE,EXCLUDE

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Socket Operations

• setsockopt
• IP_MULTICAST_FILTER
• ioctl
• SIO_GET_MULTICAST_FILTER
• Open issue change set to ioctl
  SIO_SET_MULTICAST_FILTER?

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Protocol-Independent API

• E.g. Resolve DNS name to sockaddr
• Could be v4 or v6, 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 IPv6-specific API.

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Basic Structures

• struct ip_mcast_req
• uint32_t imr_interface
• struct sockaddr_storage imr_group
• struct ip_mcast_source_req
• uint32_t imsr_interface
• struct sockaddr_storage imsr_group
• struct sockaddr_storage imsr_source

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Advanced Structure

• struct ip_mcast_filter
• uint32_t imf_interface
• struct sockaddr_storage imf_group
• uint32_t imf_fmode
• uint32_t imf_numsrc
• struct sockaddr_storage imf_slist1
• define IP_MCAST_FILTER_SIZE(numsrc) ...
• (size of buffer with numsrc sources)

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Socket Operations

• setsockopt
• IP_JOIN,LEAVE_GROUP
• IP_JOIN,LEAVE_GROUP_SOURCE
• IP_BLOCK,ALLOW_SOURCE
• ioctl
• SIO_GET,SET_MULTICAST_FILTER