Cisco Cisco Prime Virtual Network Analysis Module (vNAM) 6.1 White Paper
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Cisco Virtualized Multiservice Data Center (VMDC) Virtual Services Architecture (VSA) 1.0
Design Guide
Chapter 3 VMDC VSA 1.0 Design Details
System Level Design Considerations
Note
The Nexus 2000 Fabric Extender provides only two user queues for QoS support: one for all no-drop
classes and the other for all drop classes. The classes configured on its parent switch are mapped to one
of these queues; traffic for no-drop classes is mapped one queue and traffic for all drop classes is mapped
to the other. Egress policies are also restricted to these classes. Further, at this writing (NX-OS 6.1.3),
queueing is not supported on Nexus 2000 host interface ports when connected to an upstream Nexus
7000 switch. Traffic is sent to the default fabric queue on the Nexus 7000, and queuing must be applied
on FEX trunk (network interface) ports. Future NX-OS releases will feature enhanced Nexus 7000
support for FEX QoS, adding network QoS and default queuing policy support on downstream Nexus
2000 host interfaces.
classes and the other for all drop classes. The classes configured on its parent switch are mapped to one
of these queues; traffic for no-drop classes is mapped one queue and traffic for all drop classes is mapped
to the other. Egress policies are also restricted to these classes. Further, at this writing (NX-OS 6.1.3),
queueing is not supported on Nexus 2000 host interface ports when connected to an upstream Nexus
7000 switch. Traffic is sent to the default fabric queue on the Nexus 7000, and queuing must be applied
on FEX trunk (network interface) ports. Future NX-OS releases will feature enhanced Nexus 7000
support for FEX QoS, adding network QoS and default queuing policy support on downstream Nexus
2000 host interfaces.
Before NX-OS release 6.1.3, only two ingress queues are supported on the F2/F2E Nexus 7000 line
cards. Release 6.1.3 adds support for four ingress queues. These line cards support four egress queues.
cards. Release 6.1.3 adds support for four ingress queues. These line cards support four egress queues.
Shaping and Policing
Policing and shaping are used to enforce a maximum bandwidth rate (MBR) on a traffic stream; while
policing effectively does this by dropping out-of-contract traffic, shaping does this by delaying
out-of-contract traffic. VMDC uses policing in and at the edges of the cloud data center QoS domain to
rate-limit data and priority traffic classes. At the data center WAN edge/PE, hierarchical QoS (HQoS)
may be implemented on egress to the cloud data center; this uses a combination of shaping and policing
in which L2 traffic is shaped at the aggregate (port) level per class, while policing is used to enforce
per-tenant aggregates.
policing effectively does this by dropping out-of-contract traffic, shaping does this by delaying
out-of-contract traffic. VMDC uses policing in and at the edges of the cloud data center QoS domain to
rate-limit data and priority traffic classes. At the data center WAN edge/PE, hierarchical QoS (HQoS)
may be implemented on egress to the cloud data center; this uses a combination of shaping and policing
in which L2 traffic is shaped at the aggregate (port) level per class, while policing is used to enforce
per-tenant aggregates.
Sample bandwidth port reservation percentages are shown in
Figure 3-22
Sample Bandwidth Port Reservations
and