2013 Latest Cisco 350-001 Exam Section 5: Rendezvous Points

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2013 Latest Cisco 350-001 Exam Section 5: Rendezvous Points (4 Questions)

QUESTION NO: 1
The TestKing network is shown in the following exhibit:
ip multicast-routing

interface loopback0
ip address 192.168.1.1 255.255.255.0

ip pim send-RP-announce loopback0 scope 16 group-list 1
ip pim send-RP-discovery loopback0 scope 16

access-list 1 permit 239.0.0.0 0.255.255.255

RouterTK2 is configured as follows:
ip multicast-routing

interface loopback 0
ip address 192.168.11.1 255.255.255.0

ip pim send-RP-announce loopback0 scope 16 group-list 1
ip pim send-RP-discovery loopback0 scope 16

access-list 1 permit 239.0.0.0 0.255.255.255

Which of the routers will take on the function of Mapping Agent and source Auto-RP Discovery messages to the 224.0.1.40 group?
A. Router TK1
B. Router TK2
C. Both Router TK1 and Router TK2
D. Neither, since the access lists configured do not match 224.0.1.40 multicast traffic.
Answer: C
Explanation:
If several RPs announce themselves for a multicast group range, the mapping agent chooses only one, which is the RP with the highest IP address. However, this is for selecting the RP. There is no election process for selecting the mapping agent that will source auto-RP discovery message. Both A and B will source this message.
Incorrect Answers:
A, B. If only one router were elected as a mapping agent, this would adversely affect the other source, since it would not have a mapping agent.
B. This would be the correct choice if the question were related to the RP election, and not the mapping agent election. When multiple routers contend to be the Rendezvous Point, the router with the highest IP address wins the tie-breaker and will be elected as the RP. However, there can be multiple mapping agents in the network, as would be the case in this situation.
D. All PIM-enabled routers automatically join the Cisco RP discovery group (224.0.1.40) that allows them to receive all group-to-RP mapping information. This information is distributed by an entity called RP mapping agent. Therefore, the access list is irrelevant in this case.

QUESTION NO: 2
The TestKing network is shown in the following exhibit:
While troubleshooting a problem with the IP multicast network, you see the following on router TK1:
(*, 224.1.1.1), 00:00:03/00:00:00, RP 171.68.28.140, flags: SP
Incoming interface: Serial0, RPF nbr 171.68.28.191,
Outgoing interfaces list: Null

(171.68.37.121/32, 224.1.1.1), 00:00:03/00:02:56, flags FPT
Incoming interface: Ethernet0, RPF nbr 0.0.0.0, Registering
Outgoing interface list: Null

Which of the following could be the cause of the “Registering” condition on TK1? (Choose all that apply)
A. Router TK1 has incorrectly calculated the RPF interface for the source (171.68.37.121) as Serial1.
B.Router TK3 (RP) failed to send a “Register-Stop” message to Router TK2.
C.Router TK2 is IGMP version 1 while Router TK1 is an IGMP version 2 speaker.
D.PIM is not enabled on Router TK2.
E.Registering is the normal operational status of an operational multicast session.
Answer: B, D
Explanation:
The Rendezvous Point will need to send a “Register Stop” in order to clear the registration process, and all routers in between the RP and the multicast source must be multicast enabled.
Incorrect Answers:
A. The output shows that this is not the problem, as router TK1 is correctly calculating the incoming interface as Ethernet 0.
C. IGMP is used by hosts, and IGMP version 2 is backwards compatible with version 1.
Reference:
Developing IP Multicast Networks, (from page 259, PIM register process).

QUESTION NO 3:
What interface command must be configured for auto-rp to function properly?

A. ip pim dense-mode
B. ip pim sparse-dense-mode
C. ip pim sparse-mode
D. ip multicast helper
Answer: B
Explanation:
RPs are used by senders to a multicast group to announce their existence and by receivers
of multicast packets to learn about new senders.
Auto-RP is a feature that automates the distribution of group-to-RP mappings in a PIM
network. Auto-RP has the following benefits:

Configuring the use of multiple RPs within a network to serve different group ranges is
easy.

Auto-RP allows load splitting among different RPs and arrangement of RPs according to the location of group participants.
Auto-RP avoids inconsistent, manual RP configurations that can cause connectivity
problems.
Example configuration using Auto-RP:

ip multicast-routing
interface ethernet 0/0
ip pim sparse-dense-mode
ip pim send-rp-announce ethernet 0 scope 16 group-list 1
ip pim rp-address 10.8.0.20 1

Incorrect Answers:
A. Rendezvous points are used in sparse mode multicasts, not dense mode.
C. If router interfaces are configured in sparse mode only a static RP address must also configured.
D. This is an invalid command.

QUESTION NO: 4 The TestKing network is utilizing IP multicast technology. Along with this, router TK1 is configured as an anycast Rendezvous Point (RP). What best describes the functionality of Anycast RP?
A. Anycast RP is a useful application of MSDP, MBGP and SSM that configures a multicast sparse mode network to provide for fault tolerance and load sharing within a single multicast domain.
B. Only a maximum of two RPs are configured with the same IP address (for example, 10.0.0.10) on loopback interfaces. The loopback address should not be configured as a host address (with a 32-bit mask). All the downstream routers are configured so that they know that 10.0.0.10 is the IP address of their local RP.
C. IP routing automatically selects the topologically closest RP for each source and receiver. Because some sources use only one RP and some receivers a different RP, MBGP enables RPs to exchange information about active sources. All the RPs are configured to be MSDP peers of each other.
D. Each RP will know about the active sources in its own area. If RP fails, IP routing converges and backup RP would become the active RP os this areas using HSRP.
E. Anycast RP is an implementation strategy that allows load sharing and redundancy in PIM sparse mode (PIM-SM) networks by configuring two or more RPs that have the same IP asddress anda re using Multicast Source Discovery Protocol to share active source information.
Answer: E
Explanation:
IP multicast is deployed as an integral component in mission-critical networked applications throughout the world. These applications must be robust, hardened, and scalable to deliver the reliability that users demand. Using Anycast RP is an implementation strategy that provides load sharing and redundancy in Protocol Independent Multicast sparse mode (PIM-SM) networks. Anycast RP allows two or more rendezvous points (RPs) to share the load for source registration and the ability to act as hot backup routers for each other. Multicast Source Discovery Protocol (MSDP) is the key protocol that makes Anycast RP possible. The main purpose of an Anycast RP implementation is that the downstream multicast routers will “see” just one address for an RP.
Reference:
http://www.cisco.com/en/US/tech/tk828/technologies_white_paper09186a00800d6b60.shtml#57583
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