Users Guide

34
Multicast Features
NOTE: Multicast routing is supported on secondary IP addresses; it is not supported on IPv6.
NOTE: Multicast routing is supported across default and non-default VRFs.
The Dell Networking operating system (OS) supports the following multicast protocols:
• PIM Sparse-Mode (PIM-SM)
• Internet Group Management Protocol (IGMP)
• Multicast Source Discovery Protocol (MSDP)
Enabling IP Multicast
Prior to enabling any multicast protocols, you must enable multicast routing. To enable multicast routing, use the following command.
• Enable multicast routing.
CONFIGURATION mode
ip multicast-routing
Implementation Information
Because protocol control trac in the Dell Networking OS is redirected using the MAC address, and multicast control trac and
multicast data trac might map to the same MAC address, the Dell Networking OS might forward data trac with certain MAC
addresses to the CPU in addition to control trac.
As the upper 5 bits of an IP Multicast address are dropped in the translation, 32 dierent multicast group IDs all map to the same
Ethernet address. For example, 224.0.0.5 is a known IP address for open shortest path rst (OSPF) that maps to the multicast MAC
address 01:00:5e:00:00:05. However, 225.0.0.5, 226.0.0.5, and so on, map to the same multicast MAC address. The Layer 2
forwarding information base (FIB) alone cannot dierentiate multicast control trac and multicast data trac with the same
address, so if you use IP address 225.0.0.5 for data trac, both the multicast data and OSPF control trac match the same entry
and are forwarded to the CPU. Therefore, do not use well-known protocol multicast addresses for data transmission, such as the
following:
Protocol
Ethernet Address
OSPF
01:00:5e:00:00:05
01:00:5e:00:00:06
RIP 01:00:5e:00:00:09
NTP 01:00:5e:00:01:01
VRRP 01:00:5e:00:00:12
PIM-SM 01:00:5e:00:00:0d
• The Dell Networking OS implementation of MTRACE is in accordance with IETF draft draft-fenner-traceroute-ipm.
Multicast Features
559