remote peers. If the TTL value is greater than the threshold, the MSDP peer reduces the TTL
value in the IP header of the multicast packet by 1, and then encapsulates the multicast packet
in an SA message and sends the message out.
Rules for Creating, Receiving, and Forwarding SA Messages
By default, MSDP switchs receive all SA messages that pass the RPF check and forward them
to all MSDP peers.
To control the transmission of SA messages between MSDP peers, you can configure filtering
rules by using the following methods:
l Setting rules for filtering SA messages based on multicast sources on the source RP
The source RP filters active multicast sources that register with the local switch, and then
determines whether to send (S, G) entries based on the rules.
l Setting rules for filtering SA messages received from remote MSDP peers
When an SA message sent by a remote MSDP peer reaches the local switch, the switch
determines whether to receive the message based on the rules.
l Setting rules for filtering SA messages forwarded to remote MSDP peers
Before forwarding an SA message to a remote MSDP peer, the local switch determines
whether to forward it based on the rules.
Multi-Instance MSDP
MSDP peer relationships can be set up between interfaces on multicast switchs that belong to
the same instance (including the public instance and VPN instance). MSDP peers exchange SA
message with each other. The inter-domain VPN multicast is thus implemented.
Multicast switchs on which multi-instance is applied maintain a set of MSDP mechanisms for
each instance. Multicast switchs also guarantee the information separation among different
instances; therefore, only MSDP and PIM-SM that belong to the same instance can interact.
By applying multi-instance, the S7700 implements inter-domain VPN multicast.
NOTE
For details of inter-domain VPN multicast, refer to the chapter Multicast VPN Configuration.
MSDP Authentication
Configuring MSDP MD5 or Key-Chain authentication can improve the security of TCP
connections set up between MSDP peers. Note that the MSDP peers must be configured with
the same authentication password; otherwise, the TCP connection cannot be set up between
MSDP peers and MSDP messages cannot be transmitted.
7.3 Configuring PIM-SM Inter-domain Multicast
This section describes how to set up an MSDP peer relationship between PIM-SM domains in
an AS and how to configure MSDP peers.
7.3.1 Establishing the Configuration Task
Before configuring PIM-SM inter-domain multicast, you need to configure intra-domain
multicast.
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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