A network administrator is managing a network that deploys a multicast service. The administrator has multiple streams successfully being routed by PIM-DM in the network. The administrator then adds a new stream with a destination address of 239.0.0.1. However, clients who have not joined the stream are receiving it.
What should the administrator do to fix this problem?
To resolve the issue where clients who have not joined a multicast stream are receiving it, the network administrator should change the destination multicast address. Specifically, the destination multicast address of 239.0.0.1 overlaps with link-local multicast addresses and can cause unwanted broadcasting to all clients. Using an address within the x.0.0.x or x.128.0.x range can create problems due to MAC/IP overlap, leading to unintended traffic distribution. Therefore, changing the destination multicast address to 239.1.1.1 will avoid these overlaps and ensure that only subscribed clients receive the multicast stream.
We should never use x.0.0.x as destination
B correct not use x.0.0.x as destination because overlaps with linklocal - Study book
Which study book are you referring to and what page?
A wrong as solution already works. C wrong as this is PIM-DM D wrong as this is PIM-DM B correct. Due to MAC/IP overlap, guidelines is to not use x.0.0.x or x.128.0.x addresses.
Page 536 Study Guide: As a recommendation do not use x.0.0.x or x.128.0.x, since these addresses will overlay with the Link- Local Multicast address scope. [Aruba Networks]
B is correct page 252
I think it's A. Cause without IGMP enabled on switches between the streams it will be broadcasted to all known devices/clients.
B correct. Due to MAC/IP overlap, guidelines is to not use x.0.0.x or x.128.0.x addresses.
I think the answer is B
Why B?
B is coorect. MAC/IP overlap. 239.0.0.1 would be the same MAC for 224.0.0.1. 224.0.0.0/24 is always flooded over every port.
B: MAC/IP overlap. 239.0.0.1 would be the same MAC for 224.0.0.1. 224.0.0.0/24 is always flooded over every port.
Ebook ACSP Chapter IGMP - Multicast adressing - Overlapping adress issues: "Because only 23 bits of the 28 bits address are carried from the L3 to the L2 multicast adress, you will over some layer-3 multicast adress share the same L2 multicast adress. You should AVOID this situation. Basically, multicast adresses that include x.0.0.x and x.128.0.x will overlap. Multicast adresses in the 224.0.0.0/24 range are link local multicast adresses. They are used for protocol discovery and are flooded to every port... For a switch that is doing IGMP snooping, these are NOT added to the snooping list and thus are not filtered. Therefor, if you would use an IP adresse like 239.0.0.1, IGMP snooping would not filter its corresponding L2 multicast adress, thinking that this was an IGMP-related message."