Dynamic Bandwidth Management; Out-Of-Service Interfaces; Buffer Credit Allocation - Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual

Buffer Credit Allocation

S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
Table 15-6
Part Number
DS-X9248-48K9

Dynamic Bandwidth Management

On port switching modules where bandwidth is shared, the bandwidth available to each port within a port
group can be configured based on the port rate mode and speed configurations. Within a port group, some
ports can be configured in dedicated rate mode while others operate in shared mode.
Ports configured in dedicated rate mode are allocated the required bandwidth to sustain a line rate of
traffic at the maximum configured operating speed, and ports configured in shared mode share the
available remaining bandwidth within the port group. Bandwidth allocation among the shared mode
ports is based on the operational speed of the ports. For example, if four ports operating at speeds 1 Gbps,
1 Gbps, 2 Gbps, and 4 Gbps share bandwidth of 8 Gbps, the ratio of allocation would be 1:1:2:4.

Out-of-Service Interfaces

On supported modules and fabric switches, you might need to allocate all the shared resources for one
or more interfaces to another interface in the port group or module. You can take interfaces out of service
to release shared resources that are needed for dedicated bandwidth. When an interface is taken out of
service, all shared resources are released and made available to the other interface in the port group or
module. These shared resources include bandwidth, rate mode, BB_credits, and extended BB_credits.
All shared resource configurations are returned to their default values when the interface is brought back
into service. Corresponding resources must be made available in order for the port to be successfully
returned to service.
Caution If you need to bring an interface back into service, you might disrupt traffic if you need to release shared
resources from other interfaces in the same port group.
Buffer Credit Allocation
This section describes how buffer credits are allocated to switches and modules, and includes the
following topics:
•
•
•
Cisco MDS 9000 Family CLI Configuration Guide
15-8
Dedicated Rate Mode Bandwidth Reservation for Generation 3 Fibre Channel
Modules (continued)
Product Name/
Description
4/44-port 8-Gbps
Host-Optimized
Fibre Channel
switching module
Buffer Pools, page 15-9
BB_Credit Buffers for Switching Modules, page 15-11
BB_Credit Buffers for Fabric Switches, page 15-21
Chapter 15 Configuring Generation 2 and Generation 3 Switching Modules
Dedicated Maximum
Bandwidth Allowed Ports
per Port that can come up Ports in Shared Mode
8 Gbps 4 Ports
4 Gbps 12 Ports
2 Gbps 24 Ports
1 Gbps 48 Ports
All the remaining ports
are 4 Gbps shared (8 Gbps
of bandwidth can be
provided only to one port
per port group in
Dedicated or Shared rate
mode).
OL-18084-01, Cisco MDS NX-OS Release 4.x