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Multicast - Coggle Diagram
Multicast
PIM
(Protocol Independant Multicast)
For IP multicast routing
Dense Mode
(PIM-DM)
Flood traffic to all network
and then a prune message corrects it
Sparse Mode
(PIM-SM)
Send traffic only to interesting directions
RFC 7761
Most used
also uses Rendezvous Point
Static RP
Auto-RP
takes precedence over static RP
Components
Candidate RP
Willing to be RP
Send to 224.0.1.39
(CISCO-RP-ANNOUNCE)
RP Mapping agents
advertise authoritative mapping to
224.0.1.40 (CISCO-RP-DISCOVERY)
Cisco Proprietary
BSR (BootStrap Router)
Broadcasts RP sets to all routers
more info RFC5059
Excludes auto-RP
Enhancements
BIDIR-PIM mode
SSM
232.0.0.0/8
IP Multicast Group Addresses
(RFC 5771)
Class D addresses
224.0.0.0 - 239.255.255.255
224.0.0.0 - 224.0.0.255
Local scope
For Network protocols use
224.0.0.1 - all hosts
224.0.0.2 All IPv4 routers
224.0.0.13 all PIMv2 routers
224.0.0.5, 224.0.0.6,
224.0.0.6, 224.0.0.9,
224.0.0.9, 224.0.0.10
used by routing protocols
224.0.1.0 - 238.255.255.255
Global Scope
Dynamically allocated through Internet
239.0.0.0 - 239.255.255.255
Administratively scoped
Used inside private domains
Concepts
traffic sent to registered receivers only
routers make copies of the single sent packet
Multicast Distribution Trees
Source Trees
aka SPT (Shortest Path Trees)
The root is at the source
each sender is the root of its tree
Notation (S,G)
Shared Trees
Predetermined Root called RP (Rendez-vous Point)
Notation (*,G)
because multiple sources possible
Suboptimal paths possible
IGMP
(Internet Group Management Protocol)
Enables hosts to subscribe to a group
RFCs
RFC112 - IGMP v1
Uses a query response model
RFC2236 - IGMP v2
Adjusts some timeouts and
accelerates the process of leaving a group
Group specific queries
Leave group message
Querier election mechanism
Lowest unicast IP
Query Interval Response Time
RFC3366 - IGMP v3
Source specific multicast capability
Source Filtering