How is MSDP used to interconnect multiple PIM-SM domains?
How is MSDP used to interconnect multiple PIM-SM domains?
MSDP allows a rendezvous point to dynamically discover active sources outside of its domain. This enables multiple PIM-SM domains to exchange information about active multicast sources, facilitating the efficient forwarding of multicast traffic across domain boundaries.
From Cisco Document, matches A exactly https://www.cisco.com/c/en/us/td/docs/ios/12_4t/ip_mcast/configuration/guide/mctmsdp.html#wp1054452 Benefits of Using MSDP to Interconnect Multiple PIM-SM Domains •Allows a rendezvous points (RP) to dynamically discover active sources outside of its domain.
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/xe-3s/asr903/imc-pim-xe-3s-asr903-book/imc_msdp.pdf Page 2 : Benefits of Using MSDP to Interconnect Multiple PIM-SM Domains • Allows a rendezvous point (RP) to dynamically discover active sources outside of its domain
A is the answer. The purpose of MSDP is to discover multicast sources in other PIM domains. The main advantage of MSDP is that it reduces the complexity of interconnecting multiple PIM-SM domains by allowing PIM-SM domains to use an interdomain source tree (rather than an common shared tree). When MSDP is configured in a network, RPs exchange source information with RPs in other domains. An RP can join the interdomain source tree for sources that are sending to groups for which it has receivers. The RP can do that because it is the root of the shared tree within its domain, which has branches to all points in the domain where there are active receivers. When a last-hop router learns of a new source outside the PIM-SM domain (through the arrival of a multicast packet from the source down the shared tree), it then can send a join toward the source and join the interdomain source tree. https://www.cisco.com/c/en/us/td/docs/ios/12_4t/ip_mcast/configuration/guide/mctmsdp.html
SA Request Messages SA request messages are used to request a list of active sources for a specific group. These messages are sent to an MSDP SA cache that is maintains a list of active (S, G) pairs in its SA cache. Join latency can be reduced by using SA request messages to request the list of active sources for a group instead of having to wait up to 60 seconds for all active sources in the group to be readvertised by originating RPs. https://www.cisco.com/c/en/us/td/docs/ios/12_4t/ip_mcast/configuration/guide/mctmsdp.html
Selected Answer B. ( Not A :) )
Pay attention to the Question: "How is MSDP used"? it does not ask 'WHAT(protocol) is MSDP DEPENDS'
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/xe-16/imc-pim-xe-16-book/imc-msdp-im-pim-sim.html according to the link, I paste somet content here: 1. Allows a rendezvous point (RP) to dynamically discover active sources outside of its domain. ==> matches option A 2. SA request messages are used to request a list of active sources for a specific group. ==> matches option B 3. MSDP depends on BGP or multiprotocol BGP (MBGP) for interdomain operation. We recommended that you run MSDP on RPs sending to global multicast groups. ==> matches option C 4. SA messages are used to advertise active sources in a domain. ==> it's SA message, not all 4 types of MSDP messages, so it's wrong Is there any possibility that the question asked you to select an INCORRECT option?
MSDP provides inter-domain access to multicast sources in all domains by enabling all Rendezvous Points (RPs) to discover multicast sources outside of their domains
Based on this IP Multicast Guide from Cisco the answer is C Prerequisites for Using MSDP to Interconnect Multiple PIM-SM Domains. Before you configure MSDP, the addresses of all MSDP peers must be known in Border Gateway Protocol (BGP) https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/xe-16/imc-pim-xe-16-book/imc-msdp-im-pim-sim.html
Prerequisites for Using MSDP to Interconnect Multiple PIM-SM Domains. Before you configure MSDP, the addresses of all MSDP peers must be known in Border Gateway Protocol (BGP) https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/xe-16/imc-pim-xe-16-book/imc-msdp-im-pim-sim.html
it´s A MSDP (Multicast Source Discovery Protocol) facilitates the interconnection of multiple PIM-SM (Protocol Independent Multicast - Sparse Mode) domains. It enables rendezvous points (RPs) in different PIM-SM domains to exchange information about active multicast sources. This allows an RP in one domain to dynamically discover active sources in other domains, facilitating efficient multicast traffic forwarding across domain boundaries.
The correct answer is: A. MSDP allows a rendezvous point to dynamically discover active sources outside of its domain. MSDP enables multiple PIM-SM domains to exchange information about active multicast sources, allowing each domain's Rendezvous Point (RP) to dynamically discover sources located in other domains. This facilitates interdomain multicast communication by allowing multicast traffic from sources in one domain to be distributed to receivers in other domains.
answer is clearly A
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/xe-16/imc-pim-xe-16-book/imc-msdp-im-pim-sim.html#GUID-56896581-339B-407F-9CE2-00566608F35E
MSDP depends on BGP or multiprotocol BGP (MBGP) for interdomain operation. We recommended that you run MSDP on RPs sending to global multicast groups.
Multicast Source Discovery Protocol- MSDP, If listeners exist, it triggers a PIM join into the source domain towards the data source. In a peering relationship, one MSDP peer listens for new TCP connections on the well-known port 639.
MSDP operates independently of BGP (Border Gateway Protocol). While BGP can be used in some scenarios to carry MSDP messages between MSDP peers in different domains, it is not a strict dependency for MSDP to function. MSDP primarily relies on TCP connections between MSDP peers to exchange information about active multicast sources across different PIM-SM domains. Therefore, option C is not the most accurate description of how MSDP is used to interconnect multiple PIM-SM domains.
Nope, C: Prerequisites for Using MSDP to Interconnect Multiple PIM-SM Domains Before you configure MSDP, the addresses of all MSDP peers must be known in Border Gateway Protocol (BGP).
Is there MSDP in the Cert. Guide? Surely not in the blueprint