Руководство По Проектированию для Cisco Cisco Nexus 5010 Switch
![Cisco](https://files.manualsbrain.com/attachments/7380d0050044647c30f5c24bbbf5d0c0b6d9bb84/common/fit/150/50/faa183d287233c52228cfea3dbc2a127fe780f60564fcb0955d9c3d1cd23/brand_logo.png)
© 2015 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information.
Page 68 of 119
If the NIF is congested, the fabric extender flow controls the source.
In certain design scenarios, it is useful to put N2H traffic in a no-drop class. The congestion then can then be
pushed from the HIF ports back to the originating fabric ports on the Cisco Nexus 5000 Series Switch, which in
turns pushes the congestion back to multiple VoQs on multiple ports, thus using the full buffering capacity of the
switch.
Figure 29. Congestion Handling on the Fabric Extender for Drop Classes
The behavior for no-drop traffic classes is as follows (Figure 30): If an HIF is congested, the fabric extender asserts
priority flow control (PFC) for the no-drop class to the Cisco Nexus 5000 Series Switch. As a result, the Cisco
Nexus 5000 Series Switch controls the flow for the individual VoQs on the respective ingress ports for that specific
class. This approach creates a situation in which the Cisco Nexus 5000 Series Switch can provide the aggregated
capacity of the ingress ports buffers.