In-Order Delivery; About Reordering Network Frames - Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual

Chapter 26 Configuring Fibre Channel Routing Services and Protocols
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

In-Order Delivery

In-Order Delivery (IOD) of data frames guarantees frame delivery to a destination in the same order that
they were sent by the originator.
Some Fibre Channel protocols or applications cannot handle out-of-order frame delivery. In these cases,
switches in the Cisco MDS 9000 Family preserve frame ordering in the frame flow. The source ID (SID),
destination ID (DID), and optionally the originator exchange ID (OX ID) identify the flow of the frame.
On any given switch with IOD enabled, all frames received by a specific ingress port and destined to a
certain egress port are always delivered in the same order in which they were received.
Use IOD only if your environment cannot support out-of-order frame delivery.
If you enable the in-order delivery feature, the graceful shutdown feature is not implemented.
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About Reordering Network Frames

When you experience a route change in the network, the new selected path may be faster or less
congested than the old route.
Figure 26-5
Switch 1
OL-18084-01, Cisco MDS NX-OS Release 4.x
About Reordering Network Frames, page 26-13
About Reordering PortChannel Frames, page 26-14
About Enabling In-Order Delivery, page 26-14
Enabling In-Order Delivery Globally, page 26-16
Enabling In-Order Delivery for a VSAN, page 26-16
Displaying the In-Order Delivery Status, page 26-16
Configuring the Drop Latency Time, page 26-17
Displaying Latency Information, page 26-17
Route Change Delivery
Switch 2
Frame 2
Switch 3
Frame 1
Frame 4 Frame 3
Switch 4
Cisco MDS 9000 Family CLI Configuration Guide
In-Order Delivery
Old path
New path
26-13