PIM Source-Specific Mode (PIM-SSM)
PIM source-specific mode (PIM-SSM) is a multicast protocol that forwards multicast traffic from a single source to a subnet. In the other
versions of protocol independent multicast (PIM), a receiver subscribes to a group only. The receiver receives traffic not just from the
source in which it is interested but from all sources sending to that group. PIM-SSM requires that receivers specify the sources in which
they are interested using IGMPv3 include messages to avoid receiving unwanted traffic.
PIM-SSM is more efficient than PIM-SM because it immediately creates shortest path trees (SPT) to the source rather than first using
shared trees. PIM-SM requires a shared tree rooted at the RP because IGMPv2 receivers do not know about the source sending multicast
data. Multicast traffic passes from the source to the receiver through the RP, until the receiver learns the source address, at which point it
switches to the SPT. PIM-SSM uses IGMPv3. Because receivers subscribe to a source and group, the RP and shared tree is unnecessary;
only SPTs are used. On Dell Networking systems, it is possible to use PIM-SM with IGMPv3 to achieve the same result, but PIM-SSM
eliminates the unnecessary protocol overhead.
PIM-SSM also solves the multicast address allocation problem. Applications must use unique multicast addresses because if multiple
applications use the same address, receivers receive unwanted traffic. However, global multicast address space is limited. Currently GLOP/
EGLOP is used to statically assign Internet-routable multicast addresses, but each autonomous system number yields only 255 multicast
addresses. For short-term applications, an address could be leased, but no global dynamic multicast address allocation scheme has been
accepted yet. PIM-SSM eliminates the need for unique multicast addresses because routing decisions for (S1, G1) are independent from
(S2, G1). As a result, subnets do not receive unwanted traffic when multiple applications use the same address.
Topics:
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Use PIM-SSM with IGMP Version 2 Hosts
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Electing an RP using the BSR Mechanism
Implementation Information
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The Dell Networking implementation of PIM-SSM is based on RFC 3569.
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The Dell Networking OS reduces the number of control messages sent between multicast routers by bundling Join and Prune requests
in the same message.
Important Points to Remember
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The default SSM range is 232/8 always. Applying an SSM range does not overwrite the default range. Both the default range and SSM
range are effective even when the default range is not added to the SSM ACL.
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Extended ACLs cannot be used for configuring SSM range. Be sure to create the ACL first and then apply it to the SSM range.
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The default range is always supported, so range can never be smaller than the default.
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PIM Source-Specific Mode (PIM-SSM)
Содержание S4048T-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 11 2 1 ...
Страница 148: ...Figure 10 BFD Three Way Handshake State Changes 148 Bidirectional Forwarding Detection BFD ...
Страница 251: ...Dell Control Plane Policing CoPP 251 ...
Страница 363: ... RPM Synchronization GARP VLAN Registration Protocol GVRP 363 ...
Страница 511: ...Figure 64 Inspecting the LAG Configuration Link Aggregation Control Protocol LACP 511 ...
Страница 512: ...Figure 65 Inspecting Configuration of LAG 10 on ALPHA 512 Link Aggregation Control Protocol LACP ...
Страница 515: ...Figure 67 Inspecting a LAG Port on BRAVO Using the show interface Command Link Aggregation Control Protocol LACP 515 ...
Страница 516: ...Figure 68 Inspecting LAG 10 Using the show interfaces port channel Command 516 Link Aggregation Control Protocol LACP ...
Страница 558: ...Figure 84 Configuring Interfaces for MSDP 558 Multicast Source Discovery Protocol MSDP ...
Страница 559: ...Figure 85 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 559 ...
Страница 560: ...Figure 86 Configuring PIM in Multiple Routing Domains 560 Multicast Source Discovery Protocol MSDP ...
Страница 564: ...Figure 88 MSDP Default Peer Scenario 2 564 Multicast Source Discovery Protocol MSDP ...
Страница 565: ...Figure 89 MSDP Default Peer Scenario 3 Multicast Source Discovery Protocol MSDP 565 ...
Страница 729: ...protocol spanning tree pvst no disable vlan 300 bridge priority 4096 Per VLAN Spanning Tree Plus PVST 729 ...
Страница 841: ...Figure 115 Single and Double Tag TPID Match Service Provider Bridging 841 ...
Страница 842: ...Figure 116 Single and Double Tag First byte TPID Match 842 Service Provider Bridging ...