【正文】 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 Please Complete Your Evaluation Form Session 2214 90 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 PIMSM—Evaluation ? Effective for sparse or dense distribution of multicast receivers ? Advantages: – Traffic only sent down ―joined‖ branches – Can switch to optimal sourcetrees for high traffic sources dynamically – Unicast routing protocolindependent – Basis for interdomain multicast routing ?When used with MBGP and MSDP 86 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 PIMSM SPT Switchover Receiver RP Source Source Tree Shared Tree (S, G) Traffic flow is now pruned off of the Shared Tree and is flowing to the Receiver via the Source Tree. Traffic Flow 82 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 PIMSM Sender Registration Receiver RP Source Shared Tree Source Tree RP sends a RegisterStop back to the firsthop router to stop the Register process. (S, G) RegisterStop (unicast) Traffic Flow (S, G) Register (unicast) (S, G) traffic begins arriving at the RP via the Source tree. 78 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 PIMDM — Evaluation ? Most effective for small pilot works ? Advantages: – Easy to configure—two mands – Simple flood and prune mechanism ? Potential issues... – Inefficient flood and prune behavior – Complex Assert mechanism – Mixed control and data planes ?Results in (S, G) state in every router in the work ?Can result in nondeterministic topological behaviors – No support for shared trees 74 169。 Prune Results After Pruning Source Receiver Multicast Packets Flood amp。 Prune Source Initial Flooding Receiver Multicast Packets (S, G) State created in every router in the work! 70 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 External AS Area 1 Area 2 MABR1 Area 0 (S1 , B) (S2 , A) MABR2 MASBR MOSPF InterDomain Traffic Wildcard Receiver Flag (*, *) Wildcard Receiver Flag (*, *) Unnecessary traffic may flow all the way to the MASBR Router!! 67 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 Area 1 Area 2 MABR1 Area 0 (S1 , B) (S2 , A) MABR2 MOSPF InterArea Traffic MA MA MB MB MA 63 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 Area 1 Area 2 MABR1 Area 0 (S1 , B) (S2 , A) MABR2 MOSPF IntraArea Traffic MA MA MB MB MA Not receiving (S2 , A) traffic 59 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 Receiver 2 (Group ―G‖) Source ―S‖ Receiver 1 (Group ―G‖) E X Y A B C D mrouted mrouted mrouted mrouted mrouted Truncated Broadcast Tree based on DVMRP route metrics (S, G) Multicast Packet Flow DVMRP—Grafting Router D Responds with a ―GraftAck‖ GraftAck Begins Forwarding (S, G) Packets mrouted mrouted 55 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 DVMRP—Flood amp。 Prune Routers X, and Y are also Leaf Nodes so they send ―Prune (S, G)‖ Messages Prune Prune Source ―S‖ Receiver 1 (Group ―G‖) E X Y A B C D mrouted mrouted mrouted mrouted mrouted mrouted Router E prunes interface. mrouted Truncated Broadcast Tree based on DVMRP route metrics (S, G) Multicast Packet Flow 50 169。 Prune Source ―S‖ Receiver 1 (Group ―G‖) Truncated Broadcast Tree based on DVMRP route metrics (S, G) Multicast Packet Flow Initial Flooding of (S, G) Multicast Packets Down Truncated Broadcast Tree E X Y A B C D 1 mrouted mrouted mrouted mrouted mrouted mrouted mrouted 48 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 DVMRP—Source Trees Forwarding onto Multiaccess Networks Network X A B C 2 2 1 1 mrouted mrouted mrouted Route advertisement for work X of metric ―n‖ n ? Both B and C have routes to work X. ? To avoid duplicates, only one router can be ―Designated Forwarder‖ for work X. ? Router with best metric is elected as the ―Designated Forwarder‖. ? Lowest IP address used as tiebreaker. ? Router C wins in this example. (Note: IP Address of C B ) 45 169。 Prune behavior (typically every 3 minutes) ?Sparsemode ? Uses ―Pull‖ Model ? Traffic sent only to where it is requested ? Explicit Join behavior 41 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 Multicast Forwarding A closer look: RPF Check Succeeds RPF Check Succeeds! Unicast Route Table Network Interface E0 S1 S0 S2 Multicast Packet from Source Packet Arrived on Correct Interface! Forward out all outgoing interfaces. (i. e. down the distribution tree) 38 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 Multicast Forwarding ? What is RPF? A router forwards a multicast datagram only if received on the up stream interface to the source (. it follows the distribution tree). ? The RPF Check ? The routing table used for multicasting is checked against the ―source‖ IP address in the packet. ? If the datagram arrived on the interface specified in the routing table for the source address。 minimizes delay ? Shared trees Uses less memory O(G) but you may get suboptimal paths from source to all receivers。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 Receiver 1 B E A D F Source 1 Notation: (S, G) S = Source G = Group C Receiver 2 Source 2 Multicast Distribution Trees Shortest Path or Source Distribution Tree 29 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 ?draftietfidmrigmpv3??.txt ?Early implementations now in beta – Enables hosts to listen only to a specified subset of the hosts sending to the group IGMPv3 25 169。 2022, Cisco Systems, Inc. 2214 1197_05_2022_c2 H3 ? Host sends IGMP Report to join group Repor