Reference Guide

598 | Multicast Source Discovery Protocol
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RPs advertise each (S,G) in its domain in Type, Length, Value (TLV) format. The total number of TLVs
contained in the SA is indicated in the “Entry Count” field. SA messages are transmitted every 60 seconds,
and immediately when a new source is detected.
Figure 31-2. MSDP SA Message Format
Implementation Information
• The FTOS implementation of MSDP is in accordance with RFC 3618 and Anycast RP is in accordance
with RFC 3446.
Configuring Multicast Source Discovery Protocol
Configuring MSDP is a three-step process:
1. Enable an exterior gateway protocol (EGP) with at least two routing domains.
Figure 31-5 and MSDP Sample Configurations show the OSPF-BGP configuration used in this chapter
for MSDP. Otherwise, refer to the Open Shortest Path First (OSPFv2 and OSPFv3) chapter and
the Border Gateway Protocol IPv4 (BGPv4) chapter.
2. Configure PIM-SM within each EGP routing domain.
Figure 31-5 and MSDP Sample Configurations show the PIM-SM configuration in this chapter for
MSDP. Otherwise, refer to the PIM Sparse-Mode chapter.
3. Enable MSDP.
4. Peer the RPs in each routing domain with each other. Refer to Enable MSDP.
Source Port
Seq. Number
Dest. Port
(639)
Type
Length
Entry Count
RP Address
MSDP 00
1
Reserved
Sprefix Length
(/32)
Group Address
Source Address
Code: 1: IPv4 Source-active
2: IPv4 Source-active Request
3: IPv4 Souce-active Response
4: Keepalive
5: Reserved
6: MSDP traceroute in progress
7: MSDP traceroute reply
Ack. Number
Offset
Reserved
Flags
Window
Checksum
Options Data
Urgent