HP 4500G PWR 24-Port, Руководство по настройке

Страница: 886 / 1968

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Configuring SA Message Filtering Rules
By configuring an SA message creation rule, you can enable the router to filter the (S, G) entries to be
advertised when creating an SA message, so that the propagation of messages of multicast sources is
controlled.
By configuring a filtering rule for receiving or forwarding SA messages, you can enable the router to filter
the (S, G) forwarding entries to be advertised when receiving or forwarding an SA message, so that the
propagation of multicast source information is controlled at SA message reception or forwarding.
By configuring a TTL threshold for multicast data packet encapsulation in SA messages, you can control
the multicast data packet encapsulation in SA messages and limit the propagation range of SA
messages:
z
Before creating an SA message with an encapsulated multicast data packet, the router checks the
TTL value of the multicast data packet. If the TTL value is less than the threshold, the router does
not create an SA message; if the TTL value is greater than or equal to the threshold, the router
encapsulates the multicast data in an SA message and sends the SA message out.
z
Upon receiving an SA message with an encapsulated multicast data packet, the router decrements
the TTL value of the multicast packet by 1 and then checks the TTL value. If the TTL value is less
than the threshold, the router does not forward the SA message to the designated MSDP peer; if
the TTL value is greater than or equal to the threshold, the router re-encapsulates the multicast
data in an SA message and sends the SA message out.
Follow these steps to configure a filtering rule for receiving or forwarding SA messages:
To do... Use the command... Remarks
Enter system view
system-view
—
Enter MSDP view
msdp
—
Configure an SA message
creation rule
import-source
[
acl
acl-number
]
Required
No restrictions on (S, G) entries
by default
Configure a filtering rule for
receiving or forwarding SA
messages
peer peer-address sa-policy
{
import
|
export
} [
acl
acl-number
]
Required
No filtering rule by default
Configure the TTL threshold for
multicast data packet
encapsulation in SA messages
peer peer-address
minimum-ttl ttl-value
Optional
0 by default
Configuring the SA Cache Mechanism
To reduce the time spent in obtaining the multicast information, you can enable the SA cache
mechanism to cache (S, G) entries contained in SA messages locally on the router. However, the more
(S, G) entries are cached, the larger memory space of the router is used.
With the SA cache mechanism enabled, when receiving a new (*, G) join message, the router searches
its SA cache first:
z
If the corresponding (S, G) entry does not exist in the cache, the router waits for the SA message its
MSDP peer will send in the next cycle;
z
If the corresponding (S, G) entry exists in the cache, the router joins the corresponding SPT rooted
at S.