Concept Guide

Protocol Ethernet Address
NTP 01:00:5e:00:01:01
VRRP 01:00:5e:00:00:12
PIM-SM 01:00:5e:00:00:0d
• The Dell EMC Networking OS implementation of MTRACE is in accordance with IETF draft draft-fenner-traceroute-ipm.
• Multicast is not supported on secondary IP addresses.
• If you enable multicast routing, egress Layer 3 ACL is not applied to multicast data trac.
• Multicast trac can be forwarded to a maximum of 15 VLANs with the same outgoing interface.
First Packet Forwarding for Lossless Multicast
All initial multicast packets are forwarded to receivers to achieve lossless multicast.
When the Dell Networking system is the RP, and has receivers for a group G, it forwards all initial multicast packets for the group based on
the (*,G) entry rather than discarding them until the (S,G) entry is created, making Dell Networking systems suitable for applications
sensitive to multicast packet loss.
NOTE: When a source begins sending trac, the Source DR forwards the initial packets to the RP as encapsulated registered
packets. These packets are forwarded via the soft path at a maximum rate of 70 packets/second. Incoming packets beyond this
rate are dropped.
Multicast Policies
The Dell Networking OS supports multicast features for IPv4. IPv6 multicast is not supported.
• IPv4 Multicast Policies
IPv4 Multicast Policies
The following sections describe IPv4 multicast policies.
• Limiting the Number of Multicast Routes
• Preventing a Host from Joining a Group
• Rate Limiting IGMP Join Requests
• Preventing a PIM Router from Forming an Adjacency
• Preventing a Source from Registering with the RP
• Preventing a PIM Router from Processing a Join
Limiting the Number of Multicast Routes
When the total number of multicast routes on a system limit is reached, Dell Networking OS does not process any IGMP or multicast
listener discovery protocol (MLD) joins to PIM — though it still processes leave messages — until the number of entries decreases below
95% of the limit.
When the limit falls below 95% after hitting the maximum, the system begins relearning route entries through IGMP, MLD, and MSDP.
• If the limit is increased after it is reached, join subsequent join requests are accepted. In this case, increase the limit by at least 10% for
IGMP and MLD to resume.
• If the limit is decreased after it is reached, Dell Networking OS does not clear the existing sessions. Entries are cleared after a timeout
(you may also clear entries using clear ip mroute).
Multicast Features
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