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802.1D – Selective Multicast

802.1D – Selective Multicast. Network Protocols and Standards Autumn 2004-2005. Selective Multicast: Reasons. Part of IEEE 802.1D standard Problems Broadcasting of multicast traffic over slower links  Link Saturation

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802.1D – Selective Multicast

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  1. 802.1D – Selective Multicast Network Protocols and Standards Autumn 2004-2005 CS573: Network Protocols and Standards

  2. Selective Multicast: Reasons • Part of IEEE 802.1D standard • Problems • Broadcasting of multicast traffic over slower links  Link Saturation • Even for networks with all high speed links, transmitting something that no one will use is not a good idea  Should limit Multicast volume! • Solution • Allow users to explicitly indicate their interest in receiving traffic on given multicast addresses CS573: Network Protocols and Standards

  3. C’s MAC Address B’s MAC Address A’s MAC Address 0 1 1 0 1 0 The Filtering Database Bridge B1 Filtering Database A C B Port 1 Port 2 Outbound Port 1 Outbound Port 2 Frame: A  B 0: filtering 1: forwarding Frame: A  C A bridge maintains a forwarding database (FDB) which it uses to decide where to send the incoming packet CS573: Network Protocols and Standards

  4. The Filtering Database • The filtering database contains filtering entries that can be: • Static Entries – explicitly configured by the administrator and management • Dynamic Entries – automatically entered into the FDB by the normal operation of the bridge • Each entry (static or dynamic) consists of: • A MAC address specification • A port map which specifies the filtering state for that MAC address on each outbound port CS573: Network Protocols and Standards

  5. Basic Filtering Services • An 802.1D bridge must support these services • Allow the specification of the following FDB entries: • For individual MAC addresses • Static entries  Management • Dynamic entries  Learning Process • For a specific group MAC address • Static entries  Management • No static entry  Broadcast • These entries indicate, for each outgoing port, if the frames destined for the individual or group LAN addresses be forwarded or filtered on that port CS573: Network Protocols and Standards

  6. Extended Filtering Services • Add the following capabilities to the basic filtering services • For individual addresses • Static entries may contain a value which indicates that the dynamic filtering information should be used for a specific port rather than always forward or always filter • For a specific group MAC address • Static entries may contain a value which indicates that the dynamic filtering information should be used • Group registration entries that are created and maintained through the use of GMRP protocol • Entries corresponding to all group addresses which do not have a specific group MAC address entry • Entries corresponding to all unregistered group addresses which do not have a specific group MAC address entry CS573: Network Protocols and Standards

  7. Default Group Filtering Behavior • Each port may be assigned a default behavior for forwarding frames with group MAC addresses • Three default behaviors have been defined: • Forward all groups: Frame is forwarded unless an explicit static filtering entry exists • Forward all unregistered groups: The frame is forwarded unless: • An explicit static filtering entry exists • An applicable group registration entry exists • Filter unregistered groups: The frame is filtered unless: • An explicit static forwarding entry exists • An applicable group registration entry exists CS573: Network Protocols and Standards

  8. GMRP • GARP Multicast Registration Protocol • A mechanism that allows: • End stations to dynamically register (and subsequently de-register) group membership information with the MAC bridges attached to the same LAN segment • Bridges to disseminate that information across all bridges in the bridged LAN that support extended filtering services • Operation of GMRP depends upon the services provided by GARP (Generic Attribute Registration Protocol) CS573: Network Protocols and Standards

  9. Result of Group Membership Information Registration and Propagation • Frames sent to a particular group: • Can be received on all LAN segments to which registered GMRP participants are attached • Bridges filter frames on ports which have not had group registration entries created by GMRP • Multicast frames are not transmitted on those LAN segments which: • Neither have registered GARP participants • Nor are in the path, through active topology, from source to registered members CS573: Network Protocols and Standards

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