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• Allocate More Buffer Memory for Multicast WRED
• Allocate More Bandwidth to Multicast using Egress WFQ
Allocate More Buffer Memory for Multicast WRED
Allocate more buffer memory to multicast WRED (Weighted Random Early Detection) for bursty
multicast traffic that might temporarily become oversubscribed. For example, the example WRED profile
in Figure 41-14 on page 872 allocates multicast traffic a minimum of 40 megabytes (out of 80 megabytes)
of buffer memory and up to 60 megabytes.
Figure 30-9. Allocating More Bandwidth for Multicast WRED
Allocate More Bandwidth to Multicast using Egress WFQ
Egress Weighted Fair Queuing (WFQ) determines per port the ratio of egress bandwidth allocated to
multicast, replication, and unicast traffic. By default, FTOS provides 1/64 to multicast, 1/64 to replication,
and 62/64 for unicast, which is shared between 8 unicast queues. Allocate more bandwidth for multicast
using the command
queue egress multicast linecard (from CONFIGURATION mode) with the keyword
bandwidth-percent. For example, allocate 80% of egress bandwidth to multicast on all line cards using the
command
queue egress multicast linecard all bandwidth-percent 80.
Tune the Central Scheduler for Multicast
The Central Scheduler is responsible for scheduling unicast and multicast packets via the Terabit
backplane. The default configuration of the Central Scheduler is optimized for network environments that
forward primarily unicast traffic—80% of the scheduler weight is for unicast traffic and 20% is for
multicast traffic.
FTOS provides the ability to adjust the scheduling weight for multicast traffic. For example, if the majority
of your traffic is multicast, the default configuration might yield greater latency. In this case, allocate more
backplane bandwidth for multicast using the command
queue multicast bandwidth-percent from
CONFIGURATION mode. View your configuration using the command
show queue backplane multicast
bandwidth-percentage
.
Figure 30-10. Tuning the Central Scheduler for Multicast
FTOS(Conf)#queue egress multicast linecard all wred-profile Egress
FTOS(conf)#wred-profile Egress
FTOS(conf-wred)# threshold min 40960 max 61440
FTOS#show queue backplane multicast bandwidth-percent
Configured multicast bandwidth percentage is 80