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PowerConnect B-Series FCX Configuration Guide
53-1002266-01
PIM Sparse
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To enhance overall network performance, Layer 3 Switches use the RP to forward only the first
packet from a group source to the group receivers. After the first packet, the Layer 3 Switch
calculates the shortest path between the receiver and source (the Shortest Path Tree, or SPT)
and uses the SPT for subsequent packets from the source to the receiver. The Layer 3 Switch
calculates a separate SPT for each source-receiver pair.
NOTE
Dell recommends that you configure the same ports as candidate BSRs and RPs.
RP paths and SPT paths
Figure 122
shows two paths for packets from the source for group 239.255.162.1 and a receiver
for the group. The source is attached to PIM Sparse Switch A and the recipient is attached to PIM
Sparse Switch C. PIM Sparse Switch B in is the RP for this multicast group. As a result, the default
path for packets from the source to the receiver is through the RP. However, the path through the
RP sometimes is not the shortest path. In this case, the shortest path between the source and the
receiver is over the direct link between Switch A and Switch C, which bypasses the RP (Switch B).
To optimize PIM traffic, the protocol contains a mechanism for calculating the Shortest Path Tree
(SPT) between a given source and receiver. PIM Sparse switches can use the SPT as an alternative
to using the RP for forwarding traffic from a source to a receiver. By default, Layer 3 Switches
forward the first packet they receive from a given source to a given receiver using the RP path, but
forward subsequent packets from that source to that receiver through the SPT. In
Figure 122
,
Switch A forwards the first packet from group 239.255.162.1 source to the destination by sending
the packet to Switch B, which is the RP. Switch B then sends the packet to Switch C. For the second
and all future packets that Switch A receives from the source for the receiver, Switch A forwards
them directly to Switch C using the SPT path.
Configuring PIM Sparse
To configure a Layer 3 Switch for PIM Sparse, perform the following tasks:
•
Configure the following global parameter:
•
Enable the PIM Sparse mode of multicast routing.
•
Configure the following interface parameters:
•
Configure an IP address on the interface
•
Enable PIM Sparse.
•
Identify the interface as a PIM Sparse border, if applicable.
NOTE
You cannot configure a routing interface as a PMBR interface for PIM Sparse.
•
Configure the following PIM Sparse global parameters:
•
Identify the Layer 3 Switch as a candidate PIM Sparse Bootstrap Router (BSR), if
applicable.
•
Identify the Layer 3 Switch as a candidate PIM Sparse Rendezvous Point (RP), if
applicable.
•
Specify the IP address of the RP (if you want to statically select the RP).
Summary of Contents for PowerConnect B-FCXs
Page 1: ...53 1002266 01 18 March 2011 PowerConnect B Series FCX Configuration Guide ...
Page 248: ...206 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IPv6 management commands 7 ...
Page 374: ...332 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Jumbo frame support 9 ...
Page 568: ...526 PowerConnect B Series FCX Configuration Guide 53 1002266 01 CLI examples 14 ...
Page 588: ...546 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Sample application 15 ...
Page 684: ...642 PowerConnect B Series FCX Configuration Guide 53 1002266 01 VLAN based mirroring 20 ...
Page 724: ...682 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Reading CDP packets 23 ...
Page 930: ...888 PowerConnect B Series FCX Configuration Guide 53 1002266 01 26 ...
Page 948: ...906 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Configuring MLD snooping 27 ...
Page 1348: ...1306 PowerConnect B Series FCX Configuration Guide 53 1002266 01 Example configurations 36 ...
Page 1406: ...1364 PowerConnect B Series FCX Configuration Guide 53 1002266 01 IP source guard 39 ...