Chapter 25: Multicast
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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Bonded Multicast is not supported since this requires MDF and Dynamic Bonding Change (DBC) messages in order to
convey to DOCSIS 3.0 CMs the DSID(s) associated with user-joined multicast.
With this feature enabled, multicast traffic is treated by the C4/c CMTS as a global default multicast flow with regard to
QoS handling in the same way that a statically provisioned multicast session is handled.
With this feature enabled, DSG tunnel traffic is forwarded to all downstream channels in the MAC domain.
Effects of Enabling MDF on the MAC Domain
Multicast flows will behave differently on a MAC domain depending on whether Multicast DSID-based Forwarding (MDF) is
enabled. If Forced Downstream Replication of Multicast and MDF are both enabled for a given MAC Domain, then on that
MAC domain the following will occur:
Dynamic multicast with an MDF-enabled D3.0 CM is not possible since the DBC exchange does not take place to convey
a DSID to the CM.
Dynamic multicast with a pre-DOCSIS 3.0 (i.e., MDF-incapable) modem is possible since this modem does not require
DSID-based signaling. In this case the modem uses pre-DOCSIS 3.0 mechanisms and snoops for IGMPv2 messages.
IGMPv3 is not supported since this requires DSID-based signaling.
IPv6 CPEs are supported behind DOCSIS 3.0 CMs (or behind DOCSIS 2.0+ IPv6 CMs with GMAC Explicit mode).
Bonded Multicast is not supported because it requires a DSID exchange with the CM. For more information on the use
of bonded multicast flows for IP video, see
If the Forced Downstream Replication of Multicast feature is enabled but MDF is disabled for a given MAC Domain, then on
that MAC domain the following will occur:
Multicast is supported on Pre-DOCSIS 3.0 cable modems with this feature enabled.
Multicast with a DOCSIS 3.0 CM is possible. In the MDF-disabled case, the modem reverts to pre-DOCSIS 3.0 behavior,
i.e., snooping for IGMPv2 messages.
IGMPv3 is not supported since this requires MDF and DSID-based signaling to the CM.
IPv6 CPEs behind DOCSIS 3.0 CMs are not supported since this requires MDF and DSID-based signaling to the CM.
IPv6 CPEs behind DOCSIS 2.0+IPv6 CMs cannot be supported with GMAC Explicit operation since this requires MDF and
DSID-based signaling to the CM.
Bonded Multicast is not supported because it requires MDF and a DSID exchange with the CM.