Mld
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MLD is the IPv6 equivalent of IGMPv2 for IPv4. It uses ICMPv6 messages to enable routers to discover the set of multicast addresses for which there are listening nodes on each attached interface. MLD messages include Multicast Listener Query to query for listeners, Multicast Listener Report for listeners to report interest, and Multicast Listener Done for listeners to inform routers they are no longer listening.
Mld
- 1. Multicast Listener Discovery MLD is the IPv6 equivalent of IGMPv2 for IPv4 MLD is a set of messages exchanged by routers and nodes To enable routers to discover the set of multicast addresses for which there are listening nodes for each attached interface MLD only discovers the list of multicast addresses for which there is at least one listener ( same as IGMP ) Not the list of individual multicast listeners for each multicast address ( same as IGMP ) MLD uses ICMPv6 messages instead of defining its own message structure ( Unlike IGMP) MLD messages are ICMPv6 messages types 130, 131, and 132 Multicast Listener Query Multicast Listener Report Multicast Listener Done
- 2. MLD message packet format An MLD message packet consists of IPv6 header a Hop-by-Hop Options extension header MLD message The Hop-by-Hop Options extension header contains the IPv6 Router Alert Option documented in RFC 2711. It is used to ensure that routers process MLD messages sent to multicast addresses on which the router is not listening
- 3. MLD messages 1 . Multicast Listener Query Used by a router to query a link for multicast listeners. There are two types : The General Query The General Query is used to query for multicast listeners of all multicast addresses. The Multicast-Address-Specific Query. Used to query for multicast listeners of a specific multicast address. The two message types are distinguished by the multicast destination address in the IPv6 header and a multicast address within the Multicast Listener Query message
- 4. MLD messages 1 . Multicast Listener Query MLD Multicast Listener Query message is equivalent to the IGMPv2 Host Membership Query message It is used by a router to query an attached link for listening hosts In the IPv6 header, the source address is the link-local address of the interface on which the query is being sent The Hop Limit field is set to 1 For the General Query, the destination address is the link-local scope all-nodes multicast address (FF02::1) For the Multicast-Address-Specific Query, the destination address is the specific multicast address being queried
- 5. MLD messages 1 . Multicast Listener Query In the MLD message, The Type field is set to 130 The Code field is set to 0. The Maximum Response Delay is the maximum amount of time in milliseconds within which a multicast group member must report its membership using an MLD Report message. In the General Query, the Multicast Address field is set to the unspecified address (::). In the Multicast-Address-Specific Query, the Multicast Address field is set to the specific multicast address that is being queried .
- 6. MLD messages 2.Multicast Listener Report Used by a multicast listener To either report interest in receiving multicast traffic for a specific multicast address OR To respond to a Multicast Listener Query MLD Multicast Listener Report message is equivalent to the IGMPv2 Host Membership Report message.
- 7. MLD messages 2.Multicast Listener Report In the IPv6 header The source address is the link-local address of the interface on which the report is being sent. The Hop Limit field is set to 1 The destination address is the specific multicast address being reported.
- 8. MLD messages 2.Multicast Listener Report In the MLD Multicast Listener Report message The Type field is set to 131 The Code field is set to 0. The Maximum Response Delay field is not used in a Multicast Listener Report message and is set to 0. The Multicast Address field is set to the specific multicast address that is being reported.
- 9. MLD messages 3. Multicast Listener Done An MLD Multicast Listener Done message is equivalent to the IGMPv2 Leave Group message. It is used by a multicast group member to inform local routers that it might be the last group member on the subnet.
- 10. MLD messages 3. Multicast Listener Done In the IPv6 header the source address is the link-local address of the interface on which the report is being sent. The Hop Limit field is set to 1 The destination address is the link-local scope all-routers multicast address (FF02::2).
- 11. MLD messages 3. Multicast Listener Done In the MLD Multicast Listener Done message The Type field is set to 132 The Code field is set to 0 The Maximum Response Delay field is not used in a Multicast Listener Done message and is set to 0. The Multicast Address field is set to the specific multicast address for which the sending node is informing local routers that it is no longer as listener.