Multicast Flashcards
What is multicast traffic?
One to many communication.
What is the multicast IP address range?
- 0.0.0 /4
224. 0.0.0 - 239.255.255.255
What is the multicast IP address range?
- 0.0.0 /4
224. 0.0.0 - 239.255.255.255
What is the ‘Local Network Control Block’ for multicast addresses?
224.0.0.0 /24
addresses in this block do not leave the L2 broadcast domain.
What is the ‘Internetwork Control Block’ in multicast?
224.0.1.0 /24
This block can be routed over the internet
What is the ‘administratively scoped block’ in multicast?
239.0.0.0 /8
This is the private multicast range (not publicly routed)
How do you differentiate between unicast and multicast Mac addresses?
Unicast have an even or zeroed second digit
Multicast are always an odd digit
0200 - unicast
0100 - multicast
What is multicast MAC 0100.0CCC.CCCC reserved for?
CDP, VTP and UDLD
What is multicast MAC 0100.0CCC.CCCD reserved for?
RSTP
What is multicast MAC 0180.C200.0000 reserved for?
802.1D spanning tree
What MAC address range is reserved for IPv4 Multicast?
- 5E00.000 ->
0100. 5E7F.FFFF
What is the broadcast MAC address for a subnets broadcast IP?
FFFF.FFFF.FFFF
What does IGMP stand for?
Internet Group Management Protocol
What is IGMP used for?
IGMP is used between receiving devices and their next hop gateway to instruct multicast routers which multicast groups they would like to receive.
What is an IGMP multicast report?
It is the message sent from a receiving device to the multicast address group it would like to join.
How does a receiver leave a multicast group?
They send a ‘Leave Group’ message to their next hop router.
What is a IGMP Membership Query?
It is the message sent by a next hop router to determine which hosts would like to receive multicast traffic.
They are sent every 60 seconds to multicast address 224.0.0.1 (TTL 1)
What IP protocol number field does IGMP use?
IP protocol number 2
What is IGMP snooping?
The mechanism in which Cisco switch’s learn which switch ports must forward multicast traffic
How does IGMP snooping work?
The switch will sniff IGMP membership reports increasing a switch port. this mapping is stored in the CAM table for later forwarding.
It will remove the entry when a IGMP leave message is detected.
What does PIM stand for?
Protocol Independent Multicast
It is a multicast routing protocol.
How does PIM dense mode work?
The router will default flood all multicast traffic except the receiving port.
If the receiving router or downstream routers have no multicast group members, they send a prune message to end communication.
If the link has been pruned, downstream routers can send a upstream Graft message to reestablish forwarding.
How does PIM sparse mode work?
Routers by default will forward no multicast traffic.
Downstream routers will initiate a connection with a PIM join request after receiving IGMP meme verschul reports.
When a router no longer needs the multicast traffic, it will send a upstream prune message.
What multicast address and IP number does PIM use for hello messages?
224.0.0.13
IP 103
