Description

This article provides information about the IGMPv3 record types and file modes on EX switches.

Symptoms

An IGMPv3 report can contain multiple group records.

Solution


Record Types and Filter Modes

The following filter modes are used in IGMPv3:

  • Include mode - Data from the specified sources are filtered and forwarded towards the hosts by the multicast router.
  • Exclude mode - Data from the specified sources are filtered and not forwarded towards the hosts.

Note : IGMPv3 allows IGMP snooping to filter multicast streams based on the source address of the multicast stream. Junos software for EX-series switches supports IGMPv3 packets that are in the 'Include' mode only. IGMPv3 packets that are in any other mode are dropped.

IGMPv3 categorizes the group record information into three types:

  • Current-State Record (CSR) - This indicates the current reception state with respect to one multicast group at a given interface. It contains the filter mode (include or exclude) and the set of related sources. A CSR record type is either MODE_IS_INCLUDE or MODE_IS_EXCLUDE .

  • Filter-Mode-Change Record (FMCR) - This indicates that the filter-mode of the reception state has changed. It contains the new filter-mode and the set of related sources. A FMCR record type is either CHANGE_TO_INCLUDE_MODE or CHANGE_TO_EXCLUDE_MODE .

  • Source-List-Change Record (SLCR) - This indicates that the group's associated sources have changed. A SLCR record type is ALLOW_NEW_SOURCES , when data from a new set of sources are to be received. It is BLOCK_OLD_SOURCES , when data from an existing set of sources are not required.

The following example shows the different IGMPv3 messages counters: 
IGMP packet statistics for all interfaces
IGMP Message type      Received       Sent  Rx errors
Membership Query           3395     122962          0
V1 Membership Report          0          0          0
DVMRP                         0          0          0
PIM V1                        0          0          0
Cisco Trace                   0          0          0
V2 Membership Report    1030558          0          0
Group Leave               57732          0          0
Mtrace Response               0          0          0
Mtrace Request                0          0          0
Domain Wide Report            0          0          0
V3 Membership Report        322          0          0
Other Unknown types                                 0
IGMP v3 unsupported type                            0 > No of messages received with unknown
and unsupported IGMP version 3 message types.
IGMP v3 source required for SSM                  3276 > Number of IGMP version 3 messages received that contained no source.  
IGMP v3 mode not applicable for SSM                 0  > Number of IGMP version 3 messages
 received that did not contain a mode applicable for source-specific multicast (SSM).  
IGMP Global Statistics
Bad Length                    0
Bad Checksum                  0
Bad Receive If                0
Rx non-local                 14
Timed out                 40892
Rejected Report               0