Fujitsu Siemens Computers PRIMERGY BX, Description

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Features of the Switch Introduction
Lan Switch and Router Blade
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it will take priority over a static designation.
Source Sending Data
As soon as an active source sends a packet to the DR that is attached to this source, the DR is
responsible for “Registering” this source with the RP and requesting the RP to build a tree back
to that DR. The DR encapsulates the multicast data from the source in a special PIM-SM
message called the 'Register message' with the multicast data encapsulated in the message.
After the sources register with the RP the data is forwarded down the shared tree to the
receivers.
Receiver Requesting Data
PIM Sparse mode uses the explicit join model whereby; the receivers send PIM Join messages
to a designated “Rendezvous Point” (RP). In order to join a multicast group G, a host (receiver)
conveys the membership information through the IGMP to DR. When a DR gets a membership
indication from IGMP for a new group, DR looks up the RP associated to the group and sends
a join message to the RP.
The router can switch to a source's shortest path tree (SP- tree) if the data rate of packets
received from a specific source over the shared tree exceeds the threshold value during a
specified time interval. The routers (RP and the last hop DR of the receiver) dynamically create
a source specific shortest path tree using Join/Prune messages and stop traffic from flowing
down the shared RP tree (using Register Stop Messages when the RP has no downstream
receivers for the group or that particular source) when the data rate reaches a threshold value.
Distance Vector Multicast Routing Protocol (DVMRP)
The Distance Vector Multicast Routing Protocol (
DVMRP
) is a hop-based method of
building multicast delivery trees from multicast sources to all nodes of a network. The delivery
trees are built by pruned and grafted messages, therefore the tree is shortest path to multicast
source and is relatively efficient. The multicast group information forward by a distance-vector
algorithm, therefore, the propagation is slow. DVMRP is used for optimized high delay (high
latency) relatively low bandwidth networks.
DVMRP resembles the Routing Information Protocol (RIP). The DVMRP module
exchanges probe packets and report packet with the multicast group member hosts sitting in
the directly connected network. Based on the information exchange, the DVMRP module
creates a database (multicast routing table) for each of the interfaces in the multicast router.
The database consists of information types as:
Multicast group entries
Timers
Counters
Flags
Dependencies
States
The multicast router uses the database of information to route multicast packets from the
source (that is not sitting in the same LAN as the hosts) to the member hosts.