HP 5500 Ei 5500 Si Switch Series Configuration Guide

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2.
 
Check that . Use the  display current-configuration  command to verify that multicast routing is 
enabled. If not, carry out the  multicast routing-enable command in system view to enable IP 
multicast routing. In addition, check that IGMP  is enabled on the corresponding interfaces.  
3. Use the  display igmp interface  command to verify that the IGMP  version on the interface is lower 
than that on the host.  
4.  Use the  display current-configuration interface  command to verify that no...

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Configuring PIM (available only on the HP 
5500 EI) 
PIM overview 
Protocol Independent Multicast (PIM) provides IP multicast forwarding by leveraging unicast static routes 
or unicast routing tables generated by any unicast ro uting protocol, such as routing information protocol 
(RIP), open shortest path first (OSPF), intermediate system to intermediate system (IS-IS), or border 
gateway protocol (BGP). Independent of the unicast routing protocols running on the device, multicast 
routing can be...

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The working mechanism of PIM-DM is summarized as follows:  
•  Neighbor discovery 
•   SPT building 
•   Graft 
•   Assert 
Neighbor discovery 
In a PIM domain, a PIM router discovers PIM neighbors, maintains PIM neighboring relationships with 
other routers, and builds and maintains SPTs by peri odically multicasting hello messages to all other PIM 
routers (224.0.0.13) on the local subnet. 
 
  NOTE: 
Every PIM-enabled interface on a router sends hello  messages periodically, and thus learns the...

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Figure 38 SPT building 
 
 
The flood-and-prune process takes place periodically. A pruned state timeout mechanism is provided. A 
pruned branch restarts multicast forwarding when th e pruned state times out and then is pruned again 
when it no longer has any multicast receiver. 
 
  NOTE: 
Pruning has a similar implementation in PIM-SM.  
 
Graft 
When a host attached to a pruned node joins a multicast group, to reduce the join latency, PIM-DM uses 
a graft mechanism to resume data forwarding to...

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Figure 39 Assert mechanism 
 
 
As shown in Figure 39, after Router A and Router B receive an (S, G) packet from the upstream node, they 
both forward the packet to the local subnet. As a result, the downstream node Router C receives two 
identical multicast packets, and both Router A and Ro uter B, on their own local interface, receive a 
duplicate packet forwarded by the other. After detect ing this condition, both routers send an assert 
message to all PIM routers (224.0.0.13) on the local...

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unicast until it receives a register-stop message from the RP. The arrival of a register message at the 
RP triggers the establishment of an SPT. Then, the multicast source sends subsequent multicast 
packets along the SPT to the RP. After reaching the RP, the multicast packet is duplicated and 
delivered to the receivers along the RPT. 
 
  NOTE: 
Multicast traffic is duplicated only where the distribution tree branches, and this process automatically 
repeats until the multicast tr affic reaches...

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Figure 40 DR election 
 
 
As shown in Figure 40, the  DR election process is as follows: 
1. Routers on the multi-access network send hello messages to one another. The hello messages 
contain the router priority for DR election. The router with the highest DR priority will become the 
DR. 
2. In the case of a tie in the router priority, or if any router in the network does not support carrying 
the DR-election priority in hello messages, the ro uter with the highest IP address will win the DR...

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multicast groups and RPs. The BSR then encapsulates the RP-set in the bootstrap messages (BSMs) that it 
periodically originates and floods the bootstrap messages to the entire PIM-SM domain. 
Figure 41  BSR and C-RPs 
 
 
Based on the information in the RP-sets, all routers in the network can calculate the location of the 
corresponding RPs based on the following rules:  
1. The C-RP with the highest priority wins.  
2. If all the C-RPs have the same priority, their  hash values are calculated...

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RPT building 
Figure 42 RPT building in a PIM-SM domain  
 
 
As shown in Figure 42, the pr ocess of building an RPT is as follows:  
1. When a receiver joins multicast group G, it us es an IGMP message to inform the directly 
connected DR. 
2.  After getting the receiver information, the DR se nds a join message, which is forwarded hop by 
hop to the RP that corresponds to the multicast group.  
3.  The routers along the path from the DR to the RP fo rm an RPT branch. Each router on this branch...

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Figure 43 Multicast source registration 
 
 
As shown in Figure 43, the  multicast source registers with the RP as follows: 
1. The multicast source S sends the  first multicast packet to multicast group G. After receiving the 
multicast packet, the DR that dire ctly connects to the multicast source encapsulates the packet in a 
PIM register message. Then it sends the message to the corresponding RP by unicast.  
2.  When the RP receives the register message, it  extracts the multicast packet from...