Dell FCX624-I Laptop User Manual


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742 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
PIM Sparse
25
Configuration notes
If the TTL for an interface is greater than 1, PIM packets received on the interface are always
forwarded in software because each packet TTL must be examined. Therefore, Dell does not
recommend modifying the TTL under normal operating conditions.
Multicast packets with a TTL value of 1 are switched within the same VLAN. These packets
cannot be routed between different VLANs.
Configuration syntax
To configure a TTL of 24, enter the following.
PowerConnect(config-if-3/24)#ip pim ttl 24
Syntax: ip pim ttl <1-31>
Dropping PIM traffic in hardware
Unwanted PIM Dense or PIM Sparse multicast traffic can be dropped in hardware on Layer 3
Switches. This feature does not apply to DVMRP traffic. Refer to “Passive multicast route insertion”
on page 763.
PIM Sparse
Dell PowerConnect devices support Protocol Independent Multicast (PIM) Sparse version 2. PIM
Sparse provides multicasting that is especially suitable for widely distributed multicast
environments. The Dell implementation is based on RFC 2362.
In a PIM Sparse network, a PIM Sparse router that is connected to a host that wants to receive
information for a multicast group must explicitly send a join request on behalf of the receiver (host).
PIM Sparse routers are organized into domains. A PIM Sparse domain is a contiguous set of routers
that all implement PIM and are configured to operate within a common boundary. Figure 122
shows a simple example of a PIM Sparse domain. This example shows three Layer 3 Switches
configured as PIM Sparse routers. The configuration is described in detail following the figure.