HP A5500 EI Switch Series, Руководство по настройке

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sends, HP recommends you to establish MSDP peering relationships between RP 1 and RP 3 and
between RP 3 and RP 2, respectively.
Figure 55 MSDP peering relationships
RP 1
DR 1
Source
PIM-SM 1
PIM-SM 3
PIM-SM 2
PIM-SM 4
RP 3
RP 2
DR 2
MSDP peers
SA message
Join message
Multicast packets
Register message
Receiver
The process of implementing inter-domain multicast delivery by leveraging MSDP peers is as follows:
1.
When the multicast source in PIM-SM 1 sends the first multicast packet to multicast group G, DR 1
encapsulates the multicast data within a register message and sends the register message to RP 1.
Then, RP 1 identifies the information related to the multicast source.
2.
As the source-side RP, RP 1 creates SA messages and periodically sends the SA messages to its
MSDP peer. An SA message contains the source address (S), the multicast group address (G), and
the address of the RP that has created this SA message—namely, RP 1.
3.
On MSDP peers, each SA message undergoes an RPF check and multicast policy–based filtering,
so that only SA messages that have arrived along the correct path and passed the filtering are
received and forwarded. This avoids delivery loops of SA messages. In addition, configure MSDP
peers into an MSDP mesh group to avoid flooding of SA messages between MSDP peers.
4.
SA messages are forwarded from one MSDP peer to another, and finally information about the
multicast source traverses all PIM-SM domains with MSDP peers—PIM-SM 2 and PIM-SM 3, in this
example.
5.
After receiving the SA message that RP 1 created, RP 2 in PIM-SM 2 determines whether any
receivers for the multicast group exist in the domain.
{
If there are receivers for the multicast group in the domain, the RPT for the multicast group G is
maintained between RP 2 and the receivers. RP 2 creates an (S, G) entry and sends an (S, G)
join message hop by hop toward DR 1 at the multicast source side, so that it can directly join
the SPT rooted at the source over other PIM-SM domains. Then, the multicast data can flow
along the SPT to RP 2, and RP 2 can forward the data to the receivers along the RPT. After
receiving the multicast traffic, the receiver-side DR—DR 2—determines whether to initiate an
RPT-to-SPT switchover process.