Only network segments with active receivers that have explicitly requested the data will receive the traffic. Unlike dense mode interfaces, sparse mode interfaces are added to the multicast routing table only when periodic Join messages are received from downstream routers, or when a directly connected member is on the interface.
If so, the packets are encapsulated and sent toward the RP. When no RP is known, the packet is flooded in a dense mode fashion. If the multicast traffic from a specific source is sufficient, the first hop router of the receiver may send Join messages toward the source to build a source-based distribution tree.
PIM-SM distributes information about active sources by forwarding data packets on the shared tree. The RP must be administratively configured in the network. In sparse mode, a router assumes that other routers do not want to forward multicast packets for a group, unless there is an explicit request for the traffic.
The RP tracks multicast groups. Hosts that send multicast packets are registered with the RP by the first hop router of that host. The RP then sends Join messages toward the source.
At this point, packets are forwarded on a shared distribution tree. If the multicast traffic from a specific source is sufficient, the first hop router of the host may send Join messages toward the source to build a source-based distribution tree. First-hop designated routers with directly connected sources register with the RP and then data is forwarded down the shared tree to the receivers. The edge routers learn about a particular source when they receive data packets on the shared tree from that source through the RP.
Each router along the reverse path compares the unicast routing metric of the RP address to the metric of the source address. In this case, the shared tree and the source tree would be considered congruent. If the shared tree is not an optimal path between the source and the receiver, the routers dynamically create a source tree and stop traffic from flowing down the shared tree. This behavior is the default behavior in Cisco IOS software.
Network administrators can force traffic to stay on the shared tree by using the Cisco IOS ip pim spt-threshold infinity command. The explicit join mechanism prevents unwanted traffic from flooding the WAN links.
The Vif1 interface is similar to a loopback interface--it is a logical IP interface that is always up when the router is active. The Vif1 interface maintains information about the input interface, private-to-public mgroup mappings, mask length, which defines your pool range, and the source of the translated packet. Cisco multicast service reflection is an application running in Cisco IOS software interrupt level switching that processes packets forwarded by Cisco IOS software to the Vif1 interface.
Multicast service reflection is especially useful when users that have not yet moved to the new multicast group still need to receive the untranslated stream. Multicast service reflection is implemented using an interface CLI statement. Each configured multicast service reflection CLI statement establishes a packet match and rewrite operation acting on packets sent by Cisco IOS unicast or multicast packet routing onto the Vif1 interface. The matched and rewritten packet is sent back into Cisco IOS unicast or multicast packet routing, where it is handled like any other packet arriving from an interface.
The Vif1 interface is a receiver for the original stream and makes it appear that the new stream is coming from a source directly connected to the Vif1 subnet. More than one multicast service reflection operation can be configured to match the same packets, which allows you to replicate the same received traffic to multiple destination addresses. Perform this task to configure multicast service reflection. Enter your password if prompted. Use the distributed keyword to enable the Multicast Distributed Switching feature.
Enters interface configuration mode for the specified interface type and number. Enables PIM sparse mode on the interface. Exits interface configuration mode, and returns to global configuration mode. Repeat Steps 4 through 7 for each PIM interface.
Enters interface configuration mode for the Vif1 interface. Sets a primary or secondary IP address for an interface. Enables PIM sparse mode on an interface. Matches and rewrites multicast packets routed onto the Vif1 interface. The matched and rewritten packets are sent back into Cisco multicast packet routing or unicast routing if the destination is unicast , where they are handled like any other packets arriving from an interface.
Configures the router to be a statically connected member of the specified group on the interface, and forwards traffic destined for the multicast group onto the interface.
This step is only applicable for multicast-to-multicast and multicast-to-unicast scenarios. Exits interface configuration mode, and returns to privileged EXEC mode. The following example shows how to implement multicast service reflection multicast-to-multicast destination translation in a service provider network. In this example topology, a content provider is sending financial market information to a service provider, which in turn is sending that information to active receivers brokerage houses.
The service provider may be receiving market data from multiple content providers. Router R1 has a loopback interface and is acting as the RP for the Router R1 has a Vif1 interface and is running the multicast service reflection application. Router R2 has a loopback interface and is acting as the RP for the Enter these commands on the router running the multicast service reflection application R1 :.
Enter these commands on the router that is the RP in the service provider network R2 :. The following example shows how to implement multicast service reflection multicast-to-unicast destination translation in a service provider network.
Routers R2 and R3 are non PIM enabled routers running unicast routing only in the service provider network. The following example shows how to implement multicast service reflection multicast-to-multicast destination splitting where the multicast single stream is converted into two unique multicast streams in a service provider network.
Get the technology you need today to drive business transformation and optimize your IT spend with flexible consumption solutions. Services your way. Instead of one-size-fits-all, choose the right mix of end-to-end services for you. Get Pricing and Product Info.
Max logical capacity up to 8. For small to midrange enterprise data centers. Saves space and lowers cost with single-enclosure footprint. Max Throughput with DD Boost. Full Specs.
Data Sheet. Request a Quote. Explore the DD Data Domain Spec Sheet. Data Domain Data Sheet.
0コメント