Msdp - Zte ZXR10 5900E Series User Manual

ZXR10 5900E Series User Manual (IPv4 Volume)
A router can determine the location of the RP by three methods.
The first method is the manual static configuration RP running
routers of the PIM-SM. The other two methods are dynamic. They
are determined according to the PIM-SM version adopted by the
network. The PIM-SM V 1 adopts the Auto-RP whereas PIM-SM V2
adopts Candidate-RP advertising mode. The Candidate-RP with
higher priority is the formal RP.
PIM-SM V2 manually configures some routers running PIM-SM as
Candidate-BSR (BootStrap Router) and selects the Candidate-BSR
as the formal BSR. The BSR is responsible for collecting Candi-
date-RP information of multicast routers. If finding some Candi-
date-RP, the BSR advertises them to all PIM routers in the PIM
area. These PIM routers according to the similar Hash rules select
one with higher priority as the formal RP from the same candi-
date-RP set. The candidate-RP is manually configured.
The routers running PIM-SM find them and maintain the adjacency
by exchanging the Hello messages. In the Multi-access network
the Hello message also contains the priority information of the
router. According to the parameter, select the Designate Router
(DR).
Multicast source or the first hop router (DR directly connected with
the source) encapsulates the packet in a registration message and
sends it to the RP through the unicast router. When receiving the
registration message the RP decapsulates and takes out the packet
and sends it to the receiver of the group along the RPT.
Each mainframe acting as the receiver joins the multicast group
through the member report message of the IGMP. The last hop
router (or the DR in the multi-access network) sends the received
joining message to the RP for registration level by level. Interme-
diary router checks whether to have the router of the group after
receiving the joining message. If so, the intermediary router adds
the request router of the downstream to the RPT as a branch. If
not, it continues to send the joining message to the RP.
When the RP or the multicast router is directly connected with the
receiver they can switch to the source-based shortest path tree
from the RPT. When the RP receives registration messages sent
from a new multicast source, the RP returns a joining message
to the DR directly connected with the multicast source. Thus, the
shortest path tree from the source to the RP is established.
A DR or router directly connected with the multicast members
receives the first multicast packet from the multicast or the re-
ceived packet reaches a threshold. They can switch to the source-
based shortest path tree from the RPT. Once switchover occurs,
the router will send a prune message to the neighbor of the up-
stream and require leaving the RPT.

MSDP

MSDP is a mechanism that allows RPs in each PIM-SM domain to
share information about active sources. Each RP knows the re-
ceivers within the local domain. When RPs has learned informa-
tion about active sources in remote domains, they can transfer the
information to receivers in local domain. Thus, multicast packets
can be forwarded among domains.
68 Confidential and Proprietary Information of ZTE CORPORATION