Two Problems L3 and L2 multicast L3 Copying L3 L3 Broadcast - - PowerPoint PPT Presentation

Two Problems

• L3 and L2 multicast

L3 L3 L3 L3

S

L2

D D

L2 L2 Copying Broadcast & select


• r bridging

D

Multicast Membership Discovery

• IGMP - Internet Group Management Protocol
• Version 1
• Version 2 - group leave message
• Version 3 - source specific multicast (SSM)
• Messages
• Host Membership Query (MAC broadcast to 224.0.0.1)
• Host Membership Report
• IGMP Snooping

Multicast Router Discovery

• IPv6: IP -> ICMPv6 header -> MRD message
• ICMPv6 messages 151 (Multicast Router Advertisement), 152

(Multicast Router Solicitation) and 153 (Multicast Router Termination).

• IPv4: IP -> IGMP header -> MRD message
• IGMP messages 0x30 (Multicast Router Advertisement), 0x31

(Multicast Router Solicitation) and 0x32 (Multicast Router Termination).

• All-snoopers multicast addresses 224.0.0.106 and

FF02:0:0:0:0:0:0:6A

• IPv4 TTL / IPv6 Hop Limit set to 1

DVMRP

• Distance Vector Multicast Routing Protocol
• use a distance vector routing protocol to establish unicast

routing between multicast routers connected via tunnels

• use reverse path forwarding to flood multicast traffic
• PRUNE - tell neighbor that you are not interested in multicast

traffic from a particular group & and a source - creates soft state

• GRAFT - notify router of a change of situation (renewed interest

in a group/source)

OSPF (review)

• Open Shortest Path First
• link state routing algorithm
• two-level hierarchy
• user-defined link weights
• Version history:
• OSPF (1989)
• OSPFv2 (1998)
• OSPFv3 (2008, IPv6)

Area 0 Area 1 Area 2 Area N R R R R R R R R R

MOSPF

• Multicast OSPF
• on demand multicast routing
• routers discover local multicast membership
• group membership is flooded within an area
• multicast traffic is forwarded along the spanning tree from the

source (equal cost multi-path problem)

• border routers are by default members of all multicast groups

CBT

• Core-Based Trees
• receiver-initiated join sent towards the core node
• state (multicast routes) created along the way
• Issue: core location

PIM

• Protocol Independent Multicast
• … “independent” of the underlying unicast protocols
• Two modes proposed (one size does not fit all)
• Dense Mode (DM)
• similar to DVMRP (flood and prune)
• Sparse Mode (SM)
• similar to Core Based Trees
• Applications
• PIM-SM: IPTV

PIM-SM

• Designated Router (DR)
• each source/destination has one
• Rendez Vous Point (RP)
• does most of the copying work

S RP DR D D DR D Register Data