User Manual UMN:CLI
V5808
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no debug pim timer joinprune [jt
| et | ppt | kat | ot]
no debug pim timer register [rst]
9.3.4 Source Specific Multicast (SSM)
Multicast supports both many-to-many and one-to-many models, which are also known
as Any Source Multicast (ASM). In this model, receivers may join and leave multicast
groups with (*, G) state that indicates any source and group G. Since there is no means to
specify the source’s information, source discovery such as the RP mechanism in PIM-SM
is needed, which is the key feature of ASM. Each group address is identified as 224.0.0.0
to 239.255.255.255 (224/4).
Source-Specific Multicast (SSM) is another multicast model especially for one-to-many. In
the SSM service model, receivers can receive multicast traffic by subscribing to channel
(S, G) that indicates specific source S and group G. Since SSM assumes that receivers
already know the source’s information, no further source discovery is provided. Thus,
receivers need to know the source’s information using an out of band mechanism. The
SSM group address range is defined as 232.0.0.0 to 232.255.255.255 (232/8) by default.
9.3.4.1 PIM-SSM
PIM Source-Specific Multicast (PIM-SSM) is a subset of PIM-SM. It is much simpler than
PIM-SM, because it only considers one-to-many multicast service model. PIM-SSM only
use a shortest path tree (SPT) to deliver multicast traffic, so the PIM-SM’s complex
mechanisms such as RP, BSR, SPT switchover and a shared tree are not necessary any
more. PIM-SSM uses the same PIM messages as PIM-SM’s for its operation.
If all routers are configured with PIM-SM and IGMPv3, only by using the ip pim ssm
command, PIM-SSM will be enabled. You can also define an additional SSM group other
than the default SSM group range 232/8.
To enable PIM-SSM, use the following command.
Enables PIM-SSM for the group range 232/8.
ip pim ssm range {<1-99> |
WORD}
Enables PIM-SSM for a specified group range.
1-99: standard access list
WORD: access list name
9.3.4.2 Static SSM Mapping
The purpose of static SSM mapping is to provide SSM service on IGMPv1 and IGMPv2
messages. It means that it enables a multicast host to signal to a router which groups it
wants to receive multicast traffic from, and from which sources this traffic is expected. You
can specify a source address of multicast server to receive the multicast traffic from
specified sources. If V5808 receives IGMPv1 or IGMPv2 report message from the host
when static SSM mapping is enabled, it handles as if it receives IGMPv3 report
messages.
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