No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search


To have a better experience, please upgrade your IE browser.


Configuration Guide - IP Multicast

S7700 and S9700 V200R013C00

This document describes the configurations of IP multicast, including IP multicast basics, IGMP, MLD, IPv4 PIM, IPv6 PIM, MSDP, multicast VPN, layer 3 multicast CAC, IPv4 multicast route management, IPv6 multicast route management, IGMP snooping, MLD snooping, static multicast MAC address, multicast VLAN replication, layer 2 multicast CAC, multicast network management.
Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
MSDP Packets

MSDP Packets

MSDP packets are encapsulated in TCP datagrams, in the format of Type Length Value (TLV), as shown in Figure 6-2.

Figure 6-2  MSDP packet format

  • Type: indicates the packet type. Table 6-1 lists types of MSDP packet.
  • Length: indicates the packet length.
  • Value: indicates the packet content, which varies depending on the packet type.
Table 6-1  Types of MSDP packet


MSDP Packet Type


Major Information Contained




Carries multiple (S, G) entries and is transmitted among several RPs.

  • IP address of the source RP
  • Number of (S, G) entries contained in an SA message
  • List of active (S, G) entries in the domain

Encapsulates PIM-SM multicast data.

  • IP address of the source RP

  • PIM-SM multicast data


Source-Active Request


Requests (S, G) list of a specified group G to reduce the delay in joining the group.

Address of the group G


Source-Active Response


Responds to SA request messages.

  • IP address of the source RP
  • Number of (S, G) entries contained in an SA-Resp message
  • List of active (S, G) entries in the domain



Maintains MSDP peer connections. Keepalive packets are sent only when no other protocol packets are exchanged between MSDP peers.




This packet type is reserved and used as Notification messages at present.



Traceroute in Progress

Traces and detects the RPF path along which SA messages are transmitted.

  • IP address of the source RP
  • List of active (S, G) entries in the domain
  • Search ID
  • Returned search information
  • Number of hops


Traceroute Reply

As described in Table 6-1, SA messages carry (S, G) information and encapsulate multicast packets. MSDP peers share (S, G) information by exchanging SA messages. If an SA message contains only (S, G) information, remote users may not receive multicast data because the (S, G) entry has already timed out when reaching the remote domain. If multicast data packets are encapsulated in an SA message, remote users can still receive multicast data when the (S, G) entry times out.

When a user joins a group, the user must wait for the SA message sent from the MSDP peer in the next period because SA messages are sent periodically. To reduce the delay for the user to join the source SPT, MSDP supports SA request and response messages of Type 2 and Type 3, which enables active source information to be updated more quickly.

Updated: 2019-04-08

Document ID: EDOC1100065742

Views: 48330

Downloads: 46

Average rating:
This Document Applies to these Products
Related Version
Related Documents
Previous Next