HP 6125G HP 6125G & 6125G/XG Blade Switches IP Multicast Configuration - Page 90

Enhancements in query and report capabilities, IS_IN, IS_EX, TO_IN

Page 90 highlights

• If it needs to reject multicast data from specific sources like S1, S2, ..., it sends a report with the Filter-Mode denoted as "Exclude Sources (S1, S2, ...)." As shown in Figure 30, the network comprises two multicast sources, Source 1 (S1) and Source 2 (S2), both of which can send multicast data to multicast group G. Host B is only interested in the multicast data that Source 1 sends to G but not in the data from Source 2. Figure 30 Flow paths of source-and-group-specific multicast traffic In the case of IGMPv1 or IGMPv2, Host B cannot select multicast sources when it joins multicast group G. Therefore, multicast streams from both Source 1 and Source 2 will flow to Host B whether or not it needs them. When IGMPv3 is running between the hosts and routers, Host B can explicitly express that it needs to receive the multicast data that Source 1 sends to multicast group G-denoted as (S1, G), rather than the multicast data that Source 2 sends to multicast group G-denoted as (S2, G). Thus, only multicast data from Source 1 will be delivered to Host B. Enhancements in query and report capabilities 1. Query message carrying the source addresses IGMPv3 supports not only general queries (feature of IGMPv1) and group-specific queries (feature of IGMPv2), but also group-and-source-specific queries. { A general query does not carry a group address or a source address. { A group-specific query carries a group address, but no source address. { A group-and-source-specific query carries a group address and one or more source addresses. 2. Reports containing multiple group records Unlike an IGMPv1 or IGMPv2 report message, an IGMPv3 report message is destined to 224.0.0.22 and contains one or more group records. Each group record contains a multicast group address and a multicast source address list. Group records fall into the following categories: { IS_IN-The source filtering mode is Include. The report sender requests the multicast data from only the sources defined in the specified multicast source list. { IS_EX-The source filtering mode is Exclude. The report sender requests the multicast data from any sources but those defined in the specified multicast source list. { TO_IN-The filtering mode has changed from Exclude to Include. 79

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79
If it needs to reject multicast data from specific sources like S1, S2, …, it sends a report with the
Filter-Mode denoted as "Exclude Sources (S1, S2, …)."
As shown in
Figure 30
, the network comprises two multicast sources, Source 1 (S1) and Source 2 (S2),
both of which can send multicast data to multicast group G. Host B is only interested in the multicast data
that Source 1 sends to G but not in the data from Source 2.
Figure 30
Flow paths of source-and-group-specific multicast traffic
In the case of IGMPv1 or IGMPv2, Host B cannot select multicast sources when it joins multicast group G.
Therefore, multicast streams from both Source 1 and Source 2 will flow to Host B whether or not it needs
them.
When IGMPv3 is running between the hosts and routers, Host B can explicitly express that it needs to
receive the multicast data that Source 1 sends to multicast group G
denoted as (S1, G), rather than the
multicast data that Source 2 sends to multicast group G
denoted as (S2, G). Thus, only multicast data
from Source 1 will be delivered to Host B.
Enhancements in query and report capabilities
1.
Query message carrying the source addresses
IGMPv3 supports not only general queries (feature of IGMPv1) and group-specific queries (feature
of IGMPv2), but also group-and-source-specific queries.
{
A general query does not carry a group address or a source address.
{
A group-specific query carries a group address, but no source address.
{
A group-and-source-specific query carries a group address and one or more source addresses.
2.
Reports containing multiple group records
Unlike an IGMPv1 or IGMPv2 report message, an IGMPv3 report message is destined to
224.0.0.22 and contains one or more group records. Each group record contains a multicast
group address and a multicast source address list.
Group records fall into the following categories:
{
IS_IN
—The source filtering mode is Include. The report sender requests the multicast data from
only the sources defined in the specified multicast source list.
{
IS_EX
—The source filtering mode is Exclude. The report sender requests the multicast data from
any sources but those defined in the specified multicast source list.
{
TO_IN
—The filtering mode has changed from Exclude to Include.