Cisco 15327 User Manual download pdf (Page 232)

14-24

Ethernet Card Software Feature and Configuration Guide, R7.2

Chapter 14 Configuring Quality of Service

Understanding Multicast QoS and Priority Multicast Queuing

ML-Series card QoS supports the creation of two priority classes for multicast traffic in addition to the

default multiclass traffic class. Creating a multicast priority queuing class of traffic configures the

ML-Series card to recognize an existing CoS value in ingressing multicast traffic for priority treatment.

The multicast priority queuing CoS match is based on the “internal" CoS value of each packet. This value

is normally the same as the egress CoS value (after policer marking if enabled) but differs in two cases.

The internal CoS value is not the same as the egress value when dot1q-tunneling is used. Under

dot1q-tunnel, the internal CoS value is always the value of the outer tag CoS, both when entering the

dot1q tunnel and leaving the dot1q tunnel. The internal CoS value is also not the same as the egress value

if a packet is transported over a VLAN, and the VLAN tag is removed on egress to send the packet

untagged. In this case, the internal CoS is the CoS of the removed tag (including ingress policing and

marking if enabled).

The cos priority-mcast command does not modify the CoS of the multicast packets, but only the

bandwidth allocation for the multicast priority queuing class. The command guarantees a minimum

amount of bandwidth and is queued separately from the default multicast/broadcast queue.

Creating a multicast priority queuing class allows for special handling of certain types of multiclass

traffic. This is especially valuable for multicast video distribution and service provider multicast traffic.

For example, a service provider might want to guarantee the protection of their own multicast

management traffic. To do this, they could create a multicast priority queuing class on the ML-Series

card for the CoS value of the multicast management traffic and guarantee its minimum bandwidth. For

multicast video distribution, a multicast priority queuing class on the ML-Series card for the CoS value

of the multicast video traffic enables networks to efficiently manage multicast video bandwidth demands

on a network shared with VoIP and other Ethernet services.

Note

Multicast priority queuing traffic uses port-based load-balancing over Cisco proprietary RPR and

EtherChannel. Default multicast traffic is load-balanced over Cisco proprietary RPR , but not over

EtherChannel. Multicast load balancing maps GigabitEthernet Port 0 to POS Port 0 and GigabitEthernet

Port 1 to POS Port 1. Multicast load balancing maps Fast Ethernet Port 0 and all even-numbered Fast

Ethernet ports to POS 0 and all odd-numbered Fast Ethernet ports to POS 1.

Note

Multicast priority queuing bandwidth should not be oversubscribed for sustained periods with traffic

from multiple sources. This can result in reduced multicast priority queuing throughput.

Priority multicast feature is not required and is not supported in ML card while it is in IEEE-RPR mode,

as in this mode each queue created for a port can handle all of multicast,broadcast and unicast traffic.

Default Multicast QoS

Default multicast traffic is any multicast traffic (including flooded traffic) that is not classified as

multicast priority queuing. The default multicast class also includes broadcast data traffic, control traffic,

Layer 2 protocol tunneling, and flooding traffic of the unknown MAC during MAC learning.

With no QoS configured (no multicast priority queuing and no output policy map) on the ML-Series

card, the default multicast bandwidth is a 10 percent minimum of total bandwidth.

1 2 ... 227 228 229 230 231 232 233 234 235 236 237 ... 583 584

Comments to this Manuals

No comments

Cisco 15327 User Manual Page 232

Comments to this Manuals

Related products and manuals for Hardware Cisco 15327