7.1 MSDP Overview
MSDP functions to set up an MSDP peer relationship between RPs in different PIM-SM
domains. MSDP peers exchange (S, G) information by sending SA messages. In this manner,
MSDP peers share multicast source information and hosts can receive multicast data from the
multicast sources in another PIM-SM domain.
In the general PIM-SM mode, a multicast source registers only with the local rendezvous point
(RP). The information on the inter-domain multicast sources is isolated. The RP knows only the
source in its domain, establishes a multicast distribution tree (MDT) in its domain, and distributes
the data sent by the source to the local users.
A mechanism is required to enable the local RP to share the information on the multicast sources
of other domains. With the mechanism, the local RP can send Join messages to the multicast
sources of other domains and establish MDTs. Therefore, multicast packets can be transmitted
across domains, and hosts in the local domain can receive data sent by multicast sources in other
domains.
The Multicast Source Discovery Protocol (MSDP) is an inter-area multicast solution based on
multiple interconnected PIM-SM domains, and can solve the preceding problem.
MSDP achieves this objective by setting up the MSDP peer relationship between RPs of different
domains. MSDP peers share the information on multicast sources by sending Source Active
(SA) messages. They transmit the (S, G) information from the RP that the source S registers
with to other RPs connected to members of G.
MSDP peers are connected through the TCP connection. MSDP peers perform the RPF check
on received SA messages.
NOTE
MSDP is applicable only to PIM-SM domains, and useful only for the Any-Source Multicast (ASM) mode.
7.2 MSDP Features Supported by the S7700
MSDP is used to implement PIM-SM inter-domain multicast and anycast RP in a PIM-SM
domain. You can control connections between MSDP peers, adjust SA message parameters, and
configure authentication for MSDP peers and filtering policies for SA messages to enhance
MSDP security. The system supports multi-instance MSDP.
PIM-SM Inter-Domain Multicast
When a multicast network is divided into multiple PIM-SM domains, MSDP is used to connect
RPs in each domain to share the multicast source information. In this manner, hosts in a domain
can receive multicast data sent by multicast sources in other domains.
You can configure a loopback interface as a C-RP or a static RP or specify the address of a
loopback interface as a logical RP address for SA messages.
PIM-SM Intra-Domain Anycast RP
After anycast RP is applied to a PIM-SM domain, the multicast source registers with the nearest
RP and receivers send Join messages to the nearest RP. This reduces the burden of a single RP,
implements RP backup, and optimizes the forwarding path.
Quidway S7700 Smart Routing Switch
Configuration Guide - Multicast 7 MSDP Configuration
Issue 01 (2011-07-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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